Merge tag 'for-3.8-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs

Pull new F2FS filesystem from Jaegeuk Kim:
"Introduce a new file system, Flash-Friendly File System (F2FS), to
Linux 3.8.

Highlights:
- Add initial f2fs source codes
- Fix an endian conversion bug
- Fix build failures on random configs
- Fix the power-off-recovery routine
- Minor cleanup, coding style, and typos patches"

From the Kconfig help text:

F2FS is based on Log-structured File System (LFS), which supports
versatile "flash-friendly" features. The design has been focused on
addressing the fundamental issues in LFS, which are snowball effect
of wandering tree and high cleaning overhead.

Since flash-based storages show different characteristics according to
the internal geometry or flash memory management schemes aka FTL, F2FS
and tools support various parameters not only for configuring on-disk
layout, but also for selecting allocation and cleaning algorithms.

and there's an article by Neil Brown about it on lwn.net:

http://lwn.net/Articles/518988/

* tag 'for-3.8-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (36 commits)
f2fs: fix tracking parent inode number
f2fs: cleanup the f2fs_bio_alloc routine
f2fs: introduce accessor to retrieve number of dentry slots
f2fs: remove redundant call to f2fs_put_page in delete entry
f2fs: make use of GFP_F2FS_ZERO for setting gfp_mask
f2fs: rewrite f2fs_bio_alloc to make it simpler
f2fs: fix a typo in f2fs documentation
f2fs: remove unused variable
f2fs: move error condition for mkdir at proper place
f2fs: remove unneeded initialization
f2fs: check read only condition before beginning write out
f2fs: remove unneeded memset from init_once
f2fs: show error in case of invalid mount arguments
f2fs: fix the compiler warning for uninitialized use of variable
f2fs: resolve build failures
f2fs: adjust kernel coding style
f2fs: fix endian conversion bugs reported by sparse
f2fs: remove unneeded version.h header file from f2fs.h
f2fs: update the f2fs document
f2fs: update Kconfig and Makefile
...

Documentation/filesystems/00-INDEX

···
 	- info, mount options and specifications for the Ext4 filesystem.
 files.txt
 	- info on file management in the Linux kernel.
+f2fs.txt
+	- info and mount options for the F2FS filesystem.
 fuse.txt
 	- info on the Filesystem in User SpacE including mount options.
 gfs2.txt

Documentation/filesystems/f2fs.txt

···
+================================================================================
+WHAT IS Flash-Friendly File System (F2FS)?
+================================================================================
+
+NAND flash memory-based storage devices, such as SSD, eMMC, and SD cards, have
+been equipped on a variety systems ranging from mobile to server systems. Since
+they are known to have different characteristics from the conventional rotating
+disks, a file system, an upper layer to the storage device, should adapt to the
+changes from the sketch in the design level.
+
+F2FS is a file system exploiting NAND flash memory-based storage devices, which
+is based on Log-structured File System (LFS). The design has been focused on
+addressing the fundamental issues in LFS, which are snowball effect of wandering
+tree and high cleaning overhead.
+
+Since a NAND flash memory-based storage device shows different characteristic
+according to its internal geometry or flash memory management scheme, namely FTL,
+F2FS and its tools support various parameters not only for configuring on-disk
+layout, but also for selecting allocation and cleaning algorithms.
+
+The file system formatting tool, "mkfs.f2fs", is available from the following
+git tree:
+>> git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs-tools.git
+
+For reporting bugs and sending patches, please use the following mailing list:
+>> [e-mail]
+
+================================================================================
+BACKGROUND AND DESIGN ISSUES
+================================================================================
+
+Log-structured File System (LFS)
+--------------------------------
+"A log-structured file system writes all modifications to disk sequentially in
+a log-like structure, thereby speeding up  both file writing and crash recovery.
+The log is the only structure on disk; it contains indexing information so that
+files can be read back from the log efficiently. In order to maintain large free
+areas on disk for fast writing, we divide  the log into segments and use a
+segment cleaner to compress the live information from heavily fragmented
+segments." from Rosenblum, M. and Ousterhout, J. K., 1992, "The design and
+implementation of a log-structured file system", ACM Trans. Computer Systems
+10, 1, 26–52.
+
+Wandering Tree Problem
+----------------------
+In LFS, when a file data is updated and written to the end of log, its direct
+pointer block is updated due to the changed location. Then the indirect pointer
+block is also updated due to the direct pointer block update. In this manner,
+the upper index structures such as inode, inode map, and checkpoint block are
+also updated recursively. This problem is called as wandering tree problem [1],
+and in order to enhance the performance, it should eliminate or relax the update
+propagation as much as possible.
+
+[1] Bityutskiy, A. 2005. JFFS3 design issues. http://www.linux-mtd.infradead.org/
+
+Cleaning Overhead
+-----------------
+Since LFS is based on out-of-place writes, it produces so many obsolete blocks
+scattered across the whole storage. In order to serve new empty log space, it
+needs to reclaim these obsolete blocks seamlessly to users. This job is called
+as a cleaning process.
+
+The process consists of three operations as follows.
+1. A victim segment is selected through referencing segment usage table.
+2. It loads parent index structures of all the data in the victim identified by
+   segment summary blocks.
+3. It checks the cross-reference between the data and its parent index structure.
+4. It moves valid data selectively.
+
+This cleaning job may cause unexpected long delays, so the most important goal
+is to hide the latencies to users. And also definitely, it should reduce the
+amount of valid data to be moved, and move them quickly as well.
+
+================================================================================
+KEY FEATURES
+================================================================================
+
+Flash Awareness
+---------------
+- Enlarge the random write area for better performance, but provide the high
+  spatial locality
+- Align FS data structures to the operational units in FTL as best efforts
+
+Wandering Tree Problem
+----------------------
+- Use a term, “node”, that represents inodes as well as various pointer blocks
+- Introduce Node Address Table (NAT) containing the locations of all the “node”
+  blocks; this will cut off the update propagation.
+
+Cleaning Overhead
+-----------------
+- Support a background cleaning process
+- Support greedy and cost-benefit algorithms for victim selection policies
+- Support multi-head logs for static/dynamic hot and cold data separation
+- Introduce adaptive logging for efficient block allocation
+
+================================================================================
+MOUNT OPTIONS
+================================================================================
+
+background_gc_off      Turn off cleaning operations, namely garbage collection,
+		       triggered in background when I/O subsystem is idle.
+disable_roll_forward   Disable the roll-forward recovery routine
+discard                Issue discard/TRIM commands when a segment is cleaned.
+no_heap                Disable heap-style segment allocation which finds free
+                       segments for data from the beginning of main area, while
+		       for node from the end of main area.
+nouser_xattr           Disable Extended User Attributes. Note: xattr is enabled
+                       by default if CONFIG_F2FS_FS_XATTR is selected.
+noacl                  Disable POSIX Access Control List. Note: acl is enabled
+                       by default if CONFIG_F2FS_FS_POSIX_ACL is selected.
+active_logs=%u         Support configuring the number of active logs. In the
+                       current design, f2fs supports only 2, 4, and 6 logs.
+                       Default number is 6.
+disable_ext_identify   Disable the extension list configured by mkfs, so f2fs
+                       does not aware of cold files such as media files.
+
+================================================================================
+DEBUGFS ENTRIES
+================================================================================
+
+/sys/kernel/debug/f2fs/ contains information about all the partitions mounted as
+f2fs. Each file shows the whole f2fs information.
+
+/sys/kernel/debug/f2fs/status includes:
+ - major file system information managed by f2fs currently
+ - average SIT information about whole segments
+ - current memory footprint consumed by f2fs.
+
+================================================================================
+USAGE
+================================================================================
+
+1. Download userland tools and compile them.
+
+2. Skip, if f2fs was compiled statically inside kernel.
+   Otherwise, insert the f2fs.ko module.
+ # insmod f2fs.ko
+
+3. Create a directory trying to mount
+ # mkdir /mnt/f2fs
+
+4. Format the block device, and then mount as f2fs
+ # mkfs.f2fs -l label /dev/block_device
+ # mount -t f2fs /dev/block_device /mnt/f2fs
+
+Format options
+--------------
+-l [label]   : Give a volume label, up to 256 unicode name.
+-a [0 or 1]  : Split start location of each area for heap-based allocation.
+               1 is set by default, which performs this.
+-o [int]     : Set overprovision ratio in percent over volume size.
+               5 is set by default.
+-s [int]     : Set the number of segments per section.
+               1 is set by default.
+-z [int]     : Set the number of sections per zone.
+               1 is set by default.
+-e [str]     : Set basic extension list. e.g. "mp3,gif,mov"
+
+================================================================================
+DESIGN
+================================================================================
+
+On-disk Layout
+--------------
+
+F2FS divides the whole volume into a number of segments, each of which is fixed
+to 2MB in size. A section is composed of consecutive segments, and a zone
+consists of a set of sections. By default, section and zone sizes are set to one
+segment size identically, but users can easily modify the sizes by mkfs.
+
+F2FS splits the entire volume into six areas, and all the areas except superblock
+consists of multiple segments as described below.
+
+                                            align with the zone size <-|
+                 |-> align with the segment size
+     _________________________________________________________________________
+    |            |            |    Node     |   Segment   |   Segment  |      |
+    | Superblock | Checkpoint |   Address   |    Info.    |   Summary  | Main |
+    |    (SB)    |   (CP)     | Table (NAT) | Table (SIT) | Area (SSA) |      |
+    |____________|_____2______|______N______|______N______|______N_____|__N___|
+                                                                       .      .
+                                                             .                .
+                                                 .                            .
+                                    ._________________________________________.
+                                    |_Segment_|_..._|_Segment_|_..._|_Segment_|
+                                    .           .
+                                    ._________._________
+                                    |_section_|__...__|_
+                                    .            .
+		                    .________.
+	                            |__zone__|
+
+- Superblock (SB)
+ : It is located at the beginning of the partition, and there exist two copies
+   to avoid file system crash. It contains basic partition information and some
+   default parameters of f2fs.
+
+- Checkpoint (CP)
+ : It contains file system information, bitmaps for valid NAT/SIT sets, orphan
+   inode lists, and summary entries of current active segments.
+
+- Node Address Table (NAT)
+ : It is composed of a block address table for all the node blocks stored in
+   Main area.
+
+- Segment Information Table (SIT)
+ : It contains segment information such as valid block count and bitmap for the
+   validity of all the blocks.
+
+- Segment Summary Area (SSA)
+ : It contains summary entries which contains the owner information of all the
+   data and node blocks stored in Main area.
+
+- Main Area
+ : It contains file and directory data including their indices.
+
+In order to avoid misalignment between file system and flash-based storage, F2FS
+aligns the start block address of CP with the segment size. Also, it aligns the
+start block address of Main area with the zone size by reserving some segments
+in SSA area.
+
+Reference the following survey for additional technical details.
+https://wiki.linaro.org/WorkingGroups/Kernel/Projects/FlashCardSurvey
+
+File System Metadata Structure
+------------------------------
+
+F2FS adopts the checkpointing scheme to maintain file system consistency. At
+mount time, F2FS first tries to find the last valid checkpoint data by scanning
+CP area. In order to reduce the scanning time, F2FS uses only two copies of CP.
+One of them always indicates the last valid data, which is called as shadow copy
+mechanism. In addition to CP, NAT and SIT also adopt the shadow copy mechanism.
+
+For file system consistency, each CP points to which NAT and SIT copies are
+valid, as shown as below.
+
+  +--------+----------+---------+
+  |   CP   |    NAT   |   SIT   |
+  +--------+----------+---------+
+  .         .          .          .
+  .            .              .              .
+  .               .                 .                 .
+  +-------+-------+--------+--------+--------+--------+
+  | CP #0 | CP #1 | NAT #0 | NAT #1 | SIT #0 | SIT #1 |
+  +-------+-------+--------+--------+--------+--------+
+     |             ^                          ^
+     |             |                          |
+     `----------------------------------------'
+
+Index Structure
+---------------
+
+The key data structure to manage the data locations is a "node". Similar to
+traditional file structures, F2FS has three types of node: inode, direct node,
+indirect node. F2FS assigns 4KB to an inode block which contains 923 data block
+indices, two direct node pointers, two indirect node pointers, and one double
+indirect node pointer as described below. One direct node block contains 1018
+data blocks, and one indirect node block contains also 1018 node blocks. Thus,
+one inode block (i.e., a file) covers:
+
+  4KB * (923 + 2 * 1018 + 2 * 1018 * 1018 + 1018 * 1018 * 1018) := 3.94TB.
+
+   Inode block (4KB)
+     |- data (923)
+     |- direct node (2)
+     |          `- data (1018)
+     |- indirect node (2)
+     |            `- direct node (1018)
+     |                       `- data (1018)
+     `- double indirect node (1)
+                         `- indirect node (1018)
+			              `- direct node (1018)
+	                                         `- data (1018)
+
+Note that, all the node blocks are mapped by NAT which means the location of
+each node is translated by the NAT table. In the consideration of the wandering
+tree problem, F2FS is able to cut off the propagation of node updates caused by
+leaf data writes.
+
+Directory Structure
+-------------------
+
+A directory entry occupies 11 bytes, which consists of the following attributes.
+
+- hash		hash value of the file name
+- ino		inode number
+- len		the length of file name
+- type		file type such as directory, symlink, etc
+
+A dentry block consists of 214 dentry slots and file names. Therein a bitmap is
+used to represent whether each dentry is valid or not. A dentry block occupies
+4KB with the following composition.
+
+  Dentry Block(4 K) = bitmap (27 bytes) + reserved (3 bytes) +
+	              dentries(11 * 214 bytes) + file name (8 * 214 bytes)
+
+                         [Bucket]
+             +--------------------------------+
+             |dentry block 1 | dentry block 2 |
+             +--------------------------------+
+             .               .
+       .                             .
+  .       [Dentry Block Structure: 4KB]       .
+  +--------+----------+----------+------------+
+  | bitmap | reserved | dentries | file names |
+  +--------+----------+----------+------------+
+  [Dentry Block: 4KB] .   .
+		 .               .
+            .                          .
+            +------+------+-----+------+
+            | hash | ino  | len | type |
+            +------+------+-----+------+
+            [Dentry Structure: 11 bytes]
+
+F2FS implements multi-level hash tables for directory structure. Each level has
+a hash table with dedicated number of hash buckets as shown below. Note that
+"A(2B)" means a bucket includes 2 data blocks.
+
+----------------------
+A : bucket
+B : block
+N : MAX_DIR_HASH_DEPTH
+----------------------
+
+level #0   | A(2B)
+           |
+level #1   | A(2B) - A(2B)
+           |
+level #2   | A(2B) - A(2B) - A(2B) - A(2B)
+     .     |   .       .       .       .
+level #N/2 | A(2B) - A(2B) - A(2B) - A(2B) - A(2B) - ... - A(2B)
+     .     |   .       .       .       .
+level #N   | A(4B) - A(4B) - A(4B) - A(4B) - A(4B) - ... - A(4B)
+
+The number of blocks and buckets are determined by,
+
+                            ,- 2, if n < MAX_DIR_HASH_DEPTH / 2,
+  # of blocks in level #n = |
+                            `- 4, Otherwise
+
+                             ,- 2^n, if n < MAX_DIR_HASH_DEPTH / 2,
+  # of buckets in level #n = |
+                             `- 2^((MAX_DIR_HASH_DEPTH / 2) - 1), Otherwise
+
+When F2FS finds a file name in a directory, at first a hash value of the file
+name is calculated. Then, F2FS scans the hash table in level #0 to find the
+dentry consisting of the file name and its inode number. If not found, F2FS
+scans the next hash table in level #1. In this way, F2FS scans hash tables in
+each levels incrementally from 1 to N. In each levels F2FS needs to scan only
+one bucket determined by the following equation, which shows O(log(# of files))
+complexity.
+
+  bucket number to scan in level #n = (hash value) % (# of buckets in level #n)
+
+In the case of file creation, F2FS finds empty consecutive slots that cover the
+file name. F2FS searches the empty slots in the hash tables of whole levels from
+1 to N in the same way as the lookup operation.
+
+The following figure shows an example of two cases holding children.
+       --------------> Dir <--------------
+       |                                 |
+    child                             child
+
+    child - child                     [hole] - child
+
+    child - child - child             [hole] - [hole] - child
+
+   Case 1:                           Case 2:
+   Number of children = 6,           Number of children = 3,
+   File size = 7                     File size = 7
+
+Default Block Allocation
+------------------------
+
+At runtime, F2FS manages six active logs inside "Main" area: Hot/Warm/Cold node
+and Hot/Warm/Cold data.
+
+- Hot node	contains direct node blocks of directories.
+- Warm node	contains direct node blocks except hot node blocks.
+- Cold node	contains indirect node blocks
+- Hot data	contains dentry blocks
+- Warm data	contains data blocks except hot and cold data blocks
+- Cold data	contains multimedia data or migrated data blocks
+
+LFS has two schemes for free space management: threaded log and copy-and-compac-
+tion. The copy-and-compaction scheme which is known as cleaning, is well-suited
+for devices showing very good sequential write performance, since free segments
+are served all the time for writing new data. However, it suffers from cleaning
+overhead under high utilization. Contrarily, the threaded log scheme suffers
+from random writes, but no cleaning process is needed. F2FS adopts a hybrid
+scheme where the copy-and-compaction scheme is adopted by default, but the
+policy is dynamically changed to the threaded log scheme according to the file
+system status.
+
+In order to align F2FS with underlying flash-based storage, F2FS allocates a
+segment in a unit of section. F2FS expects that the section size would be the
+same as the unit size of garbage collection in FTL. Furthermore, with respect
+to the mapping granularity in FTL, F2FS allocates each section of the active
+logs from different zones as much as possible, since FTL can write the data in
+the active logs into one allocation unit according to its mapping granularity.
+
+Cleaning process
+----------------
+
+F2FS does cleaning both on demand and in the background. On-demand cleaning is
+triggered when there are not enough free segments to serve VFS calls. Background
+cleaner is operated by a kernel thread, and triggers the cleaning job when the
+system is idle.
+
+F2FS supports two victim selection policies: greedy and cost-benefit algorithms.
+In the greedy algorithm, F2FS selects a victim segment having the smallest number
+of valid blocks. In the cost-benefit algorithm, F2FS selects a victim segment
+according to the segment age and the number of valid blocks in order to address
+log block thrashing problem in the greedy algorithm. F2FS adopts the greedy
+algorithm for on-demand cleaner, while background cleaner adopts cost-benefit
+algorithm.
+
+In order to identify whether the data in the victim segment are valid or not,
+F2FS manages a bitmap. Each bit represents the validity of a block, and the
+bitmap is composed of a bit stream covering whole blocks in main area.

fs/Kconfig

···
 source "fs/sysv/Kconfig"
 source "fs/ufs/Kconfig"
 source "fs/exofs/Kconfig"
+source "fs/f2fs/Kconfig"
 
 endif # MISC_FILESYSTEMS
 

fs/Makefile

···
 obj-$(CONFIG_OCFS2_FS)		+= ocfs2/
 obj-$(CONFIG_BTRFS_FS)		+= btrfs/
 obj-$(CONFIG_GFS2_FS)           += gfs2/
+obj-$(CONFIG_F2FS_FS)		+= f2fs/
 obj-y				+= exofs/ # Multiple modules
 obj-$(CONFIG_CEPH_FS)		+= ceph/
 obj-$(CONFIG_PSTORE)		+= pstore/

fs/f2fs/Kconfig

···
+config F2FS_FS
+	tristate "F2FS filesystem support (EXPERIMENTAL)"
+	depends on BLOCK
+	help
+	  F2FS is based on Log-structured File System (LFS), which supports
+	  versatile "flash-friendly" features. The design has been focused on
+	  addressing the fundamental issues in LFS, which are snowball effect
+	  of wandering tree and high cleaning overhead.
+
+	  Since flash-based storages show different characteristics according to
+	  the internal geometry or flash memory management schemes aka FTL, F2FS
+	  and tools support various parameters not only for configuring on-disk
+	  layout, but also for selecting allocation and cleaning algorithms.
+
+	  If unsure, say N.
+
+config F2FS_STAT_FS
+	bool "F2FS Status Information"
+	depends on F2FS_FS && DEBUG_FS
+	default y
+	help
+	  /sys/kernel/debug/f2fs/ contains information about all the partitions
+	  mounted as f2fs. Each file shows the whole f2fs information.
+
+	  /sys/kernel/debug/f2fs/status includes:
+	    - major file system information managed by f2fs currently
+	    - average SIT information about whole segments
+	    - current memory footprint consumed by f2fs.
+
+config F2FS_FS_XATTR
+	bool "F2FS extended attributes"
+	depends on F2FS_FS
+	default y
+	help
+	  Extended attributes are name:value pairs associated with inodes by
+	  the kernel or by users (see the attr(5) manual page, or visit
+	  <http://acl.bestbits.at/> for details).
+
+	  If unsure, say N.
+
+config F2FS_FS_POSIX_ACL
+	bool "F2FS Access Control Lists"
+	depends on F2FS_FS_XATTR
+	select FS_POSIX_ACL
+	default y
+	help
+	  Posix Access Control Lists (ACLs) support permissions for users and
+	  gourps beyond the owner/group/world scheme.
+
+	  To learn more about Access Control Lists, visit the POSIX ACLs for
+	  Linux website <http://acl.bestbits.at/>.
+
+	  If you don't know what Access Control Lists are, say N

fs/f2fs/Makefile

···
+obj-$(CONFIG_F2FS_FS) += f2fs.o
+
+f2fs-y		:= dir.o file.o inode.o namei.o hash.o super.o
+f2fs-y		+= checkpoint.o gc.o data.o node.o segment.o recovery.o
+f2fs-$(CONFIG_F2FS_STAT_FS) += debug.o
+f2fs-$(CONFIG_F2FS_FS_XATTR) += xattr.o
+f2fs-$(CONFIG_F2FS_FS_POSIX_ACL) += acl.o

fs/f2fs/acl.c

···
+/*
+ * fs/f2fs/acl.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext2/acl.c
+ *
+ * Copyright (C) 2001-2003 Andreas Gruenbacher, <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/f2fs_fs.h>
+#include "f2fs.h"
+#include "xattr.h"
+#include "acl.h"
+
+#define get_inode_mode(i)	((is_inode_flag_set(F2FS_I(i), FI_ACL_MODE)) ? \
+					(F2FS_I(i)->i_acl_mode) : ((i)->i_mode))
+
+static inline size_t f2fs_acl_size(int count)
+{
+	if (count <= 4) {
+		return sizeof(struct f2fs_acl_header) +
+			count * sizeof(struct f2fs_acl_entry_short);
+	} else {
+		return sizeof(struct f2fs_acl_header) +
+			4 * sizeof(struct f2fs_acl_entry_short) +
+			(count - 4) * sizeof(struct f2fs_acl_entry);
+	}
+}
+
+static inline int f2fs_acl_count(size_t size)
+{
+	ssize_t s;
+	size -= sizeof(struct f2fs_acl_header);
+	s = size - 4 * sizeof(struct f2fs_acl_entry_short);
+	if (s < 0) {
+		if (size % sizeof(struct f2fs_acl_entry_short))
+			return -1;
+		return size / sizeof(struct f2fs_acl_entry_short);
+	} else {
+		if (s % sizeof(struct f2fs_acl_entry))
+			return -1;
+		return s / sizeof(struct f2fs_acl_entry) + 4;
+	}
+}
+
+static struct posix_acl *f2fs_acl_from_disk(const char *value, size_t size)
+{
+	int i, count;
+	struct posix_acl *acl;
+	struct f2fs_acl_header *hdr = (struct f2fs_acl_header *)value;
+	struct f2fs_acl_entry *entry = (struct f2fs_acl_entry *)(hdr + 1);
+	const char *end = value + size;
+
+	if (hdr->a_version != cpu_to_le32(F2FS_ACL_VERSION))
+		return ERR_PTR(-EINVAL);
+
+	count = f2fs_acl_count(size);
+	if (count < 0)
+		return ERR_PTR(-EINVAL);
+	if (count == 0)
+		return NULL;
+
+	acl = posix_acl_alloc(count, GFP_KERNEL);
+	if (!acl)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < count; i++) {
+
+		if ((char *)entry > end)
+			goto fail;
+
+		acl->a_entries[i].e_tag  = le16_to_cpu(entry->e_tag);
+		acl->a_entries[i].e_perm = le16_to_cpu(entry->e_perm);
+
+		switch (acl->a_entries[i].e_tag) {
+		case ACL_USER_OBJ:
+		case ACL_GROUP_OBJ:
+		case ACL_MASK:
+		case ACL_OTHER:
+			acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
+			entry = (struct f2fs_acl_entry *)((char *)entry +
+					sizeof(struct f2fs_acl_entry_short));
+			break;
+
+		case ACL_USER:
+			acl->a_entries[i].e_uid =
+				make_kuid(&init_user_ns,
+						le32_to_cpu(entry->e_id));
+			entry = (struct f2fs_acl_entry *)((char *)entry +
+					sizeof(struct f2fs_acl_entry));
+			break;
+		case ACL_GROUP:
+			acl->a_entries[i].e_gid =
+				make_kgid(&init_user_ns,
+						le32_to_cpu(entry->e_id));
+			entry = (struct f2fs_acl_entry *)((char *)entry +
+					sizeof(struct f2fs_acl_entry));
+			break;
+		default:
+			goto fail;
+		}
+	}
+	if ((char *)entry != end)
+		goto fail;
+	return acl;
+fail:
+	posix_acl_release(acl);
+	return ERR_PTR(-EINVAL);
+}
+
+static void *f2fs_acl_to_disk(const struct posix_acl *acl, size_t *size)
+{
+	struct f2fs_acl_header *f2fs_acl;
+	struct f2fs_acl_entry *entry;
+	int i;
+
+	f2fs_acl = kmalloc(sizeof(struct f2fs_acl_header) + acl->a_count *
+			sizeof(struct f2fs_acl_entry), GFP_KERNEL);
+	if (!f2fs_acl)
+		return ERR_PTR(-ENOMEM);
+
+	f2fs_acl->a_version = cpu_to_le32(F2FS_ACL_VERSION);
+	entry = (struct f2fs_acl_entry *)(f2fs_acl + 1);
+
+	for (i = 0; i < acl->a_count; i++) {
+
+		entry->e_tag  = cpu_to_le16(acl->a_entries[i].e_tag);
+		entry->e_perm = cpu_to_le16(acl->a_entries[i].e_perm);
+
+		switch (acl->a_entries[i].e_tag) {
+		case ACL_USER:
+			entry->e_id = cpu_to_le32(
+					from_kuid(&init_user_ns,
+						acl->a_entries[i].e_uid));
+			entry = (struct f2fs_acl_entry *)((char *)entry +
+					sizeof(struct f2fs_acl_entry));
+			break;
+		case ACL_GROUP:
+			entry->e_id = cpu_to_le32(
+					from_kgid(&init_user_ns,
+						acl->a_entries[i].e_gid));
+			entry = (struct f2fs_acl_entry *)((char *)entry +
+					sizeof(struct f2fs_acl_entry));
+			break;
+		case ACL_USER_OBJ:
+		case ACL_GROUP_OBJ:
+		case ACL_MASK:
+		case ACL_OTHER:
+			entry = (struct f2fs_acl_entry *)((char *)entry +
+					sizeof(struct f2fs_acl_entry_short));
+			break;
+		default:
+			goto fail;
+		}
+	}
+	*size = f2fs_acl_size(acl->a_count);
+	return (void *)f2fs_acl;
+
+fail:
+	kfree(f2fs_acl);
+	return ERR_PTR(-EINVAL);
+}
+
+struct posix_acl *f2fs_get_acl(struct inode *inode, int type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	int name_index = F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT;
+	void *value = NULL;
+	struct posix_acl *acl;
+	int retval;
+
+	if (!test_opt(sbi, POSIX_ACL))
+		return NULL;
+
+	acl = get_cached_acl(inode, type);
+	if (acl != ACL_NOT_CACHED)
+		return acl;
+
+	if (type == ACL_TYPE_ACCESS)
+		name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;
+
+	retval = f2fs_getxattr(inode, name_index, "", NULL, 0);
+	if (retval > 0) {
+		value = kmalloc(retval, GFP_KERNEL);
+		if (!value)
+			return ERR_PTR(-ENOMEM);
+		retval = f2fs_getxattr(inode, name_index, "", value, retval);
+	}
+
+	if (retval < 0) {
+		if (retval == -ENODATA)
+			acl = NULL;
+		else
+			acl = ERR_PTR(retval);
+	} else {
+		acl = f2fs_acl_from_disk(value, retval);
+	}
+	kfree(value);
+	if (!IS_ERR(acl))
+		set_cached_acl(inode, type, acl);
+
+	return acl;
+}
+
+static int f2fs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	int name_index;
+	void *value = NULL;
+	size_t size = 0;
+	int error;
+
+	if (!test_opt(sbi, POSIX_ACL))
+		return 0;
+	if (S_ISLNK(inode->i_mode))
+		return -EOPNOTSUPP;
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;
+		if (acl) {
+			error = posix_acl_equiv_mode(acl, &inode->i_mode);
+			if (error < 0)
+				return error;
+			set_acl_inode(fi, inode->i_mode);
+			if (error == 0)
+				acl = NULL;
+		}
+		break;
+
+	case ACL_TYPE_DEFAULT:
+		name_index = F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT;
+		if (!S_ISDIR(inode->i_mode))
+			return acl ? -EACCES : 0;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	if (acl) {
+		value = f2fs_acl_to_disk(acl, &size);
+		if (IS_ERR(value)) {
+			cond_clear_inode_flag(fi, FI_ACL_MODE);
+			return (int)PTR_ERR(value);
+		}
+	}
+
+	error = f2fs_setxattr(inode, name_index, "", value, size);
+
+	kfree(value);
+	if (!error)
+		set_cached_acl(inode, type, acl);
+
+	cond_clear_inode_flag(fi, FI_ACL_MODE);
+	return error;
+}
+
+int f2fs_init_acl(struct inode *inode, struct inode *dir)
+{
+	struct posix_acl *acl = NULL;
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
+	int error = 0;
+
+	if (!S_ISLNK(inode->i_mode)) {
+		if (test_opt(sbi, POSIX_ACL)) {
+			acl = f2fs_get_acl(dir, ACL_TYPE_DEFAULT);
+			if (IS_ERR(acl))
+				return PTR_ERR(acl);
+		}
+		if (!acl)
+			inode->i_mode &= ~current_umask();
+	}
+
+	if (test_opt(sbi, POSIX_ACL) && acl) {
+
+		if (S_ISDIR(inode->i_mode)) {
+			error = f2fs_set_acl(inode, ACL_TYPE_DEFAULT, acl);
+			if (error)
+				goto cleanup;
+		}
+		error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);
+		if (error < 0)
+			return error;
+		if (error > 0)
+			error = f2fs_set_acl(inode, ACL_TYPE_ACCESS, acl);
+	}
+cleanup:
+	posix_acl_release(acl);
+	return error;
+}
+
+int f2fs_acl_chmod(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct posix_acl *acl;
+	int error;
+	mode_t mode = get_inode_mode(inode);
+
+	if (!test_opt(sbi, POSIX_ACL))
+		return 0;
+	if (S_ISLNK(mode))
+		return -EOPNOTSUPP;
+
+	acl = f2fs_get_acl(inode, ACL_TYPE_ACCESS);
+	if (IS_ERR(acl) || !acl)
+		return PTR_ERR(acl);
+
+	error = posix_acl_chmod(&acl, GFP_KERNEL, mode);
+	if (error)
+		return error;
+	error = f2fs_set_acl(inode, ACL_TYPE_ACCESS, acl);
+	posix_acl_release(acl);
+	return error;
+}
+
+static size_t f2fs_xattr_list_acl(struct dentry *dentry, char *list,
+		size_t list_size, const char *name, size_t name_len, int type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
+	const char *xname = POSIX_ACL_XATTR_DEFAULT;
+	size_t size;
+
+	if (!test_opt(sbi, POSIX_ACL))
+		return 0;
+
+	if (type == ACL_TYPE_ACCESS)
+		xname = POSIX_ACL_XATTR_ACCESS;
+
+	size = strlen(xname) + 1;
+	if (list && size <= list_size)
+		memcpy(list, xname, size);
+	return size;
+}
+
+static int f2fs_xattr_get_acl(struct dentry *dentry, const char *name,
+		void *buffer, size_t size, int type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
+	struct posix_acl *acl;
+	int error;
+
+	if (strcmp(name, "") != 0)
+		return -EINVAL;
+	if (!test_opt(sbi, POSIX_ACL))
+		return -EOPNOTSUPP;
+
+	acl = f2fs_get_acl(dentry->d_inode, type);
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+	if (!acl)
+		return -ENODATA;
+	error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
+	posix_acl_release(acl);
+
+	return error;
+}
+
+static int f2fs_xattr_set_acl(struct dentry *dentry, const char *name,
+		const void *value, size_t size, int flags, int type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
+	struct inode *inode = dentry->d_inode;
+	struct posix_acl *acl = NULL;
+	int error;
+
+	if (strcmp(name, "") != 0)
+		return -EINVAL;
+	if (!test_opt(sbi, POSIX_ACL))
+		return -EOPNOTSUPP;
+	if (!inode_owner_or_capable(inode))
+		return -EPERM;
+
+	if (value) {
+		acl = posix_acl_from_xattr(&init_user_ns, value, size);
+		if (IS_ERR(acl))
+			return PTR_ERR(acl);
+		if (acl) {
+			error = posix_acl_valid(acl);
+			if (error)
+				goto release_and_out;
+		}
+	} else {
+		acl = NULL;
+	}
+
+	error = f2fs_set_acl(inode, type, acl);
+
+release_and_out:
+	posix_acl_release(acl);
+	return error;
+}
+
+const struct xattr_handler f2fs_xattr_acl_default_handler = {
+	.prefix = POSIX_ACL_XATTR_DEFAULT,
+	.flags = ACL_TYPE_DEFAULT,
+	.list = f2fs_xattr_list_acl,
+	.get = f2fs_xattr_get_acl,
+	.set = f2fs_xattr_set_acl,
+};
+
+const struct xattr_handler f2fs_xattr_acl_access_handler = {
+	.prefix = POSIX_ACL_XATTR_ACCESS,
+	.flags = ACL_TYPE_ACCESS,
+	.list = f2fs_xattr_list_acl,
+	.get = f2fs_xattr_get_acl,
+	.set = f2fs_xattr_set_acl,
+};

fs/f2fs/acl.h

···
+/*
+ * fs/f2fs/acl.h
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext2/acl.h
+ *
+ * Copyright (C) 2001-2003 Andreas Gruenbacher, <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef __F2FS_ACL_H__
+#define __F2FS_ACL_H__
+
+#include <linux/posix_acl_xattr.h>
+
+#define F2FS_ACL_VERSION	0x0001
+
+struct f2fs_acl_entry {
+	__le16 e_tag;
+	__le16 e_perm;
+	__le32 e_id;
+};
+
+struct f2fs_acl_entry_short {
+	__le16 e_tag;
+	__le16 e_perm;
+};
+
+struct f2fs_acl_header {
+	__le32 a_version;
+};
+
+#ifdef CONFIG_F2FS_FS_POSIX_ACL
+
+extern struct posix_acl *f2fs_get_acl(struct inode *inode, int type);
+extern int f2fs_acl_chmod(struct inode *inode);
+extern int f2fs_init_acl(struct inode *inode, struct inode *dir);
+#else
+#define f2fs_check_acl	NULL
+#define f2fs_get_acl	NULL
+#define f2fs_set_acl	NULL
+
+static inline int f2fs_acl_chmod(struct inode *inode)
+{
+	return 0;
+}
+
+static inline int f2fs_init_acl(struct inode *inode, struct inode *dir)
+{
+	return 0;
+}
+#endif
+#endif /* __F2FS_ACL_H__ */

fs/f2fs/checkpoint.c

···
+/*
+ * fs/f2fs/checkpoint.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/bio.h>
+#include <linux/mpage.h>
+#include <linux/writeback.h>
+#include <linux/blkdev.h>
+#include <linux/f2fs_fs.h>
+#include <linux/pagevec.h>
+#include <linux/swap.h>
+
+#include "f2fs.h"
+#include "node.h"
+#include "segment.h"
+
+static struct kmem_cache *orphan_entry_slab;
+static struct kmem_cache *inode_entry_slab;
+
+/*
+ * We guarantee no failure on the returned page.
+ */
+struct page *grab_meta_page(struct f2fs_sb_info *sbi, pgoff_t index)
+{
+	struct address_space *mapping = sbi->meta_inode->i_mapping;
+	struct page *page = NULL;
+repeat:
+	page = grab_cache_page(mapping, index);
+	if (!page) {
+		cond_resched();
+		goto repeat;
+	}
+
+	/* We wait writeback only inside grab_meta_page() */
+	wait_on_page_writeback(page);
+	SetPageUptodate(page);
+	return page;
+}
+
+/*
+ * We guarantee no failure on the returned page.
+ */
+struct page *get_meta_page(struct f2fs_sb_info *sbi, pgoff_t index)
+{
+	struct address_space *mapping = sbi->meta_inode->i_mapping;
+	struct page *page;
+repeat:
+	page = grab_cache_page(mapping, index);
+	if (!page) {
+		cond_resched();
+		goto repeat;
+	}
+	if (f2fs_readpage(sbi, page, index, READ_SYNC)) {
+		f2fs_put_page(page, 1);
+		goto repeat;
+	}
+	mark_page_accessed(page);
+
+	/* We do not allow returning an errorneous page */
+	return page;
+}
+
+static int f2fs_write_meta_page(struct page *page,
+				struct writeback_control *wbc)
+{
+	struct inode *inode = page->mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	int err;
+
+	wait_on_page_writeback(page);
+
+	err = write_meta_page(sbi, page, wbc);
+	if (err) {
+		wbc->pages_skipped++;
+		set_page_dirty(page);
+	}
+
+	dec_page_count(sbi, F2FS_DIRTY_META);
+
+	/* In this case, we should not unlock this page */
+	if (err != AOP_WRITEPAGE_ACTIVATE)
+		unlock_page(page);
+	return err;
+}
+
+static int f2fs_write_meta_pages(struct address_space *mapping,
+				struct writeback_control *wbc)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(mapping->host->i_sb);
+	struct block_device *bdev = sbi->sb->s_bdev;
+	long written;
+
+	if (wbc->for_kupdate)
+		return 0;
+
+	if (get_pages(sbi, F2FS_DIRTY_META) == 0)
+		return 0;
+
+	/* if mounting is failed, skip writing node pages */
+	mutex_lock(&sbi->cp_mutex);
+	written = sync_meta_pages(sbi, META, bio_get_nr_vecs(bdev));
+	mutex_unlock(&sbi->cp_mutex);
+	wbc->nr_to_write -= written;
+	return 0;
+}
+
+long sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
+						long nr_to_write)
+{
+	struct address_space *mapping = sbi->meta_inode->i_mapping;
+	pgoff_t index = 0, end = LONG_MAX;
+	struct pagevec pvec;
+	long nwritten = 0;
+	struct writeback_control wbc = {
+		.for_reclaim = 0,
+	};
+
+	pagevec_init(&pvec, 0);
+
+	while (index <= end) {
+		int i, nr_pages;
+		nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+				PAGECACHE_TAG_DIRTY,
+				min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
+		if (nr_pages == 0)
+			break;
+
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+			lock_page(page);
+			BUG_ON(page->mapping != mapping);
+			BUG_ON(!PageDirty(page));
+			clear_page_dirty_for_io(page);
+			f2fs_write_meta_page(page, &wbc);
+			if (nwritten++ >= nr_to_write)
+				break;
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+
+	if (nwritten)
+		f2fs_submit_bio(sbi, type, nr_to_write == LONG_MAX);
+
+	return nwritten;
+}
+
+static int f2fs_set_meta_page_dirty(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct f2fs_sb_info *sbi = F2FS_SB(mapping->host->i_sb);
+
+	SetPageUptodate(page);
+	if (!PageDirty(page)) {
+		__set_page_dirty_nobuffers(page);
+		inc_page_count(sbi, F2FS_DIRTY_META);
+		F2FS_SET_SB_DIRT(sbi);
+		return 1;
+	}
+	return 0;
+}
+
+const struct address_space_operations f2fs_meta_aops = {
+	.writepage	= f2fs_write_meta_page,
+	.writepages	= f2fs_write_meta_pages,
+	.set_page_dirty	= f2fs_set_meta_page_dirty,
+};
+
+int check_orphan_space(struct f2fs_sb_info *sbi)
+{
+	unsigned int max_orphans;
+	int err = 0;
+
+	/*
+	 * considering 512 blocks in a segment 5 blocks are needed for cp
+	 * and log segment summaries. Remaining blocks are used to keep
+	 * orphan entries with the limitation one reserved segment
+	 * for cp pack we can have max 1020*507 orphan entries
+	 */
+	max_orphans = (sbi->blocks_per_seg - 5) * F2FS_ORPHANS_PER_BLOCK;
+	mutex_lock(&sbi->orphan_inode_mutex);
+	if (sbi->n_orphans >= max_orphans)
+		err = -ENOSPC;
+	mutex_unlock(&sbi->orphan_inode_mutex);
+	return err;
+}
+
+void add_orphan_inode(struct f2fs_sb_info *sbi, nid_t ino)
+{
+	struct list_head *head, *this;
+	struct orphan_inode_entry *new = NULL, *orphan = NULL;
+
+	mutex_lock(&sbi->orphan_inode_mutex);
+	head = &sbi->orphan_inode_list;
+	list_for_each(this, head) {
+		orphan = list_entry(this, struct orphan_inode_entry, list);
+		if (orphan->ino == ino)
+			goto out;
+		if (orphan->ino > ino)
+			break;
+		orphan = NULL;
+	}
+retry:
+	new = kmem_cache_alloc(orphan_entry_slab, GFP_ATOMIC);
+	if (!new) {
+		cond_resched();
+		goto retry;
+	}
+	new->ino = ino;
+	INIT_LIST_HEAD(&new->list);
+
+	/* add new_oentry into list which is sorted by inode number */
+	if (orphan) {
+		struct orphan_inode_entry *prev;
+
+		/* get previous entry */
+		prev = list_entry(orphan->list.prev, typeof(*prev), list);
+		if (&prev->list != head)
+			/* insert new orphan inode entry */
+			list_add(&new->list, &prev->list);
+		else
+			list_add(&new->list, head);
+	} else {
+		list_add_tail(&new->list, head);
+	}
+	sbi->n_orphans++;
+out:
+	mutex_unlock(&sbi->orphan_inode_mutex);
+}
+
+void remove_orphan_inode(struct f2fs_sb_info *sbi, nid_t ino)
+{
+	struct list_head *this, *next, *head;
+	struct orphan_inode_entry *orphan;
+
+	mutex_lock(&sbi->orphan_inode_mutex);
+	head = &sbi->orphan_inode_list;
+	list_for_each_safe(this, next, head) {
+		orphan = list_entry(this, struct orphan_inode_entry, list);
+		if (orphan->ino == ino) {
+			list_del(&orphan->list);
+			kmem_cache_free(orphan_entry_slab, orphan);
+			sbi->n_orphans--;
+			break;
+		}
+	}
+	mutex_unlock(&sbi->orphan_inode_mutex);
+}
+
+static void recover_orphan_inode(struct f2fs_sb_info *sbi, nid_t ino)
+{
+	struct inode *inode = f2fs_iget(sbi->sb, ino);
+	BUG_ON(IS_ERR(inode));
+	clear_nlink(inode);
+
+	/* truncate all the data during iput */
+	iput(inode);
+}
+
+int recover_orphan_inodes(struct f2fs_sb_info *sbi)
+{
+	block_t start_blk, orphan_blkaddr, i, j;
+
+	if (!is_set_ckpt_flags(F2FS_CKPT(sbi), CP_ORPHAN_PRESENT_FLAG))
+		return 0;
+
+	sbi->por_doing = 1;
+	start_blk = __start_cp_addr(sbi) + 1;
+	orphan_blkaddr = __start_sum_addr(sbi) - 1;
+
+	for (i = 0; i < orphan_blkaddr; i++) {
+		struct page *page = get_meta_page(sbi, start_blk + i);
+		struct f2fs_orphan_block *orphan_blk;
+
+		orphan_blk = (struct f2fs_orphan_block *)page_address(page);
+		for (j = 0; j < le32_to_cpu(orphan_blk->entry_count); j++) {
+			nid_t ino = le32_to_cpu(orphan_blk->ino[j]);
+			recover_orphan_inode(sbi, ino);
+		}
+		f2fs_put_page(page, 1);
+	}
+	/* clear Orphan Flag */
+	clear_ckpt_flags(F2FS_CKPT(sbi), CP_ORPHAN_PRESENT_FLAG);
+	sbi->por_doing = 0;
+	return 0;
+}
+
+static void write_orphan_inodes(struct f2fs_sb_info *sbi, block_t start_blk)
+{
+	struct list_head *head, *this, *next;
+	struct f2fs_orphan_block *orphan_blk = NULL;
+	struct page *page = NULL;
+	unsigned int nentries = 0;
+	unsigned short index = 1;
+	unsigned short orphan_blocks;
+
+	orphan_blocks = (unsigned short)((sbi->n_orphans +
+		(F2FS_ORPHANS_PER_BLOCK - 1)) / F2FS_ORPHANS_PER_BLOCK);
+
+	mutex_lock(&sbi->orphan_inode_mutex);
+	head = &sbi->orphan_inode_list;
+
+	/* loop for each orphan inode entry and write them in Jornal block */
+	list_for_each_safe(this, next, head) {
+		struct orphan_inode_entry *orphan;
+
+		orphan = list_entry(this, struct orphan_inode_entry, list);
+
+		if (nentries == F2FS_ORPHANS_PER_BLOCK) {
+			/*
+			 * an orphan block is full of 1020 entries,
+			 * then we need to flush current orphan blocks
+			 * and bring another one in memory
+			 */
+			orphan_blk->blk_addr = cpu_to_le16(index);
+			orphan_blk->blk_count = cpu_to_le16(orphan_blocks);
+			orphan_blk->entry_count = cpu_to_le32(nentries);
+			set_page_dirty(page);
+			f2fs_put_page(page, 1);
+			index++;
+			start_blk++;
+			nentries = 0;
+			page = NULL;
+		}
+		if (page)
+			goto page_exist;
+
+		page = grab_meta_page(sbi, start_blk);
+		orphan_blk = (struct f2fs_orphan_block *)page_address(page);
+		memset(orphan_blk, 0, sizeof(*orphan_blk));
+page_exist:
+		orphan_blk->ino[nentries++] = cpu_to_le32(orphan->ino);
+	}
+	if (!page)
+		goto end;
+
+	orphan_blk->blk_addr = cpu_to_le16(index);
+	orphan_blk->blk_count = cpu_to_le16(orphan_blocks);
+	orphan_blk->entry_count = cpu_to_le32(nentries);
+	set_page_dirty(page);
+	f2fs_put_page(page, 1);
+end:
+	mutex_unlock(&sbi->orphan_inode_mutex);
+}
+
+static struct page *validate_checkpoint(struct f2fs_sb_info *sbi,
+				block_t cp_addr, unsigned long long *version)
+{
+	struct page *cp_page_1, *cp_page_2 = NULL;
+	unsigned long blk_size = sbi->blocksize;
+	struct f2fs_checkpoint *cp_block;
+	unsigned long long cur_version = 0, pre_version = 0;
+	unsigned int crc = 0;
+	size_t crc_offset;
+
+	/* Read the 1st cp block in this CP pack */
+	cp_page_1 = get_meta_page(sbi, cp_addr);
+
+	/* get the version number */
+	cp_block = (struct f2fs_checkpoint *)page_address(cp_page_1);
+	crc_offset = le32_to_cpu(cp_block->checksum_offset);
+	if (crc_offset >= blk_size)
+		goto invalid_cp1;
+
+	crc = *(unsigned int *)((unsigned char *)cp_block + crc_offset);
+	if (!f2fs_crc_valid(crc, cp_block, crc_offset))
+		goto invalid_cp1;
+
+	pre_version = le64_to_cpu(cp_block->checkpoint_ver);
+
+	/* Read the 2nd cp block in this CP pack */
+	cp_addr += le32_to_cpu(cp_block->cp_pack_total_block_count) - 1;
+	cp_page_2 = get_meta_page(sbi, cp_addr);
+
+	cp_block = (struct f2fs_checkpoint *)page_address(cp_page_2);
+	crc_offset = le32_to_cpu(cp_block->checksum_offset);
+	if (crc_offset >= blk_size)
+		goto invalid_cp2;
+
+	crc = *(unsigned int *)((unsigned char *)cp_block + crc_offset);
+	if (!f2fs_crc_valid(crc, cp_block, crc_offset))
+		goto invalid_cp2;
+
+	cur_version = le64_to_cpu(cp_block->checkpoint_ver);
+
+	if (cur_version == pre_version) {
+		*version = cur_version;
+		f2fs_put_page(cp_page_2, 1);
+		return cp_page_1;
+	}
+invalid_cp2:
+	f2fs_put_page(cp_page_2, 1);
+invalid_cp1:
+	f2fs_put_page(cp_page_1, 1);
+	return NULL;
+}
+
+int get_valid_checkpoint(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_checkpoint *cp_block;
+	struct f2fs_super_block *fsb = sbi->raw_super;
+	struct page *cp1, *cp2, *cur_page;
+	unsigned long blk_size = sbi->blocksize;
+	unsigned long long cp1_version = 0, cp2_version = 0;
+	unsigned long long cp_start_blk_no;
+
+	sbi->ckpt = kzalloc(blk_size, GFP_KERNEL);
+	if (!sbi->ckpt)
+		return -ENOMEM;
+	/*
+	 * Finding out valid cp block involves read both
+	 * sets( cp pack1 and cp pack 2)
+	 */
+	cp_start_blk_no = le32_to_cpu(fsb->cp_blkaddr);
+	cp1 = validate_checkpoint(sbi, cp_start_blk_no, &cp1_version);
+
+	/* The second checkpoint pack should start at the next segment */
+	cp_start_blk_no += 1 << le32_to_cpu(fsb->log_blocks_per_seg);
+	cp2 = validate_checkpoint(sbi, cp_start_blk_no, &cp2_version);
+
+	if (cp1 && cp2) {
+		if (ver_after(cp2_version, cp1_version))
+			cur_page = cp2;
+		else
+			cur_page = cp1;
+	} else if (cp1) {
+		cur_page = cp1;
+	} else if (cp2) {
+		cur_page = cp2;
+	} else {
+		goto fail_no_cp;
+	}
+
+	cp_block = (struct f2fs_checkpoint *)page_address(cur_page);
+	memcpy(sbi->ckpt, cp_block, blk_size);
+
+	f2fs_put_page(cp1, 1);
+	f2fs_put_page(cp2, 1);
+	return 0;
+
+fail_no_cp:
+	kfree(sbi->ckpt);
+	return -EINVAL;
+}
+
+void set_dirty_dir_page(struct inode *inode, struct page *page)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct list_head *head = &sbi->dir_inode_list;
+	struct dir_inode_entry *new;
+	struct list_head *this;
+
+	if (!S_ISDIR(inode->i_mode))
+		return;
+retry:
+	new = kmem_cache_alloc(inode_entry_slab, GFP_NOFS);
+	if (!new) {
+		cond_resched();
+		goto retry;
+	}
+	new->inode = inode;
+	INIT_LIST_HEAD(&new->list);
+
+	spin_lock(&sbi->dir_inode_lock);
+	list_for_each(this, head) {
+		struct dir_inode_entry *entry;
+		entry = list_entry(this, struct dir_inode_entry, list);
+		if (entry->inode == inode) {
+			kmem_cache_free(inode_entry_slab, new);
+			goto out;
+		}
+	}
+	list_add_tail(&new->list, head);
+	sbi->n_dirty_dirs++;
+
+	BUG_ON(!S_ISDIR(inode->i_mode));
+out:
+	inc_page_count(sbi, F2FS_DIRTY_DENTS);
+	inode_inc_dirty_dents(inode);
+	SetPagePrivate(page);
+
+	spin_unlock(&sbi->dir_inode_lock);
+}
+
+void remove_dirty_dir_inode(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct list_head *head = &sbi->dir_inode_list;
+	struct list_head *this;
+
+	if (!S_ISDIR(inode->i_mode))
+		return;
+
+	spin_lock(&sbi->dir_inode_lock);
+	if (atomic_read(&F2FS_I(inode)->dirty_dents))
+		goto out;
+
+	list_for_each(this, head) {
+		struct dir_inode_entry *entry;
+		entry = list_entry(this, struct dir_inode_entry, list);
+		if (entry->inode == inode) {
+			list_del(&entry->list);
+			kmem_cache_free(inode_entry_slab, entry);
+			sbi->n_dirty_dirs--;
+			break;
+		}
+	}
+out:
+	spin_unlock(&sbi->dir_inode_lock);
+}
+
+void sync_dirty_dir_inodes(struct f2fs_sb_info *sbi)
+{
+	struct list_head *head = &sbi->dir_inode_list;
+	struct dir_inode_entry *entry;
+	struct inode *inode;
+retry:
+	spin_lock(&sbi->dir_inode_lock);
+	if (list_empty(head)) {
+		spin_unlock(&sbi->dir_inode_lock);
+		return;
+	}
+	entry = list_entry(head->next, struct dir_inode_entry, list);
+	inode = igrab(entry->inode);
+	spin_unlock(&sbi->dir_inode_lock);
+	if (inode) {
+		filemap_flush(inode->i_mapping);
+		iput(inode);
+	} else {
+		/*
+		 * We should submit bio, since it exists several
+		 * wribacking dentry pages in the freeing inode.
+		 */
+		f2fs_submit_bio(sbi, DATA, true);
+	}
+	goto retry;
+}
+
+/*
+ * Freeze all the FS-operations for checkpoint.
+ */
+void block_operations(struct f2fs_sb_info *sbi)
+{
+	int t;
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_ALL,
+		.nr_to_write = LONG_MAX,
+		.for_reclaim = 0,
+	};
+
+	/* Stop renaming operation */
+	mutex_lock_op(sbi, RENAME);
+	mutex_lock_op(sbi, DENTRY_OPS);
+
+retry_dents:
+	/* write all the dirty dentry pages */
+	sync_dirty_dir_inodes(sbi);
+
+	mutex_lock_op(sbi, DATA_WRITE);
+	if (get_pages(sbi, F2FS_DIRTY_DENTS)) {
+		mutex_unlock_op(sbi, DATA_WRITE);
+		goto retry_dents;
+	}
+
+	/* block all the operations */
+	for (t = DATA_NEW; t <= NODE_TRUNC; t++)
+		mutex_lock_op(sbi, t);
+
+	mutex_lock(&sbi->write_inode);
+
+	/*
+	 * POR: we should ensure that there is no dirty node pages
+	 * until finishing nat/sit flush.
+	 */
+retry:
+	sync_node_pages(sbi, 0, &wbc);
+
+	mutex_lock_op(sbi, NODE_WRITE);
+
+	if (get_pages(sbi, F2FS_DIRTY_NODES)) {
+		mutex_unlock_op(sbi, NODE_WRITE);
+		goto retry;
+	}
+	mutex_unlock(&sbi->write_inode);
+}
+
+static void unblock_operations(struct f2fs_sb_info *sbi)
+{
+	int t;
+	for (t = NODE_WRITE; t >= RENAME; t--)
+		mutex_unlock_op(sbi, t);
+}
+
+static void do_checkpoint(struct f2fs_sb_info *sbi, bool is_umount)
+{
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	nid_t last_nid = 0;
+	block_t start_blk;
+	struct page *cp_page;
+	unsigned int data_sum_blocks, orphan_blocks;
+	unsigned int crc32 = 0;
+	void *kaddr;
+	int i;
+
+	/* Flush all the NAT/SIT pages */
+	while (get_pages(sbi, F2FS_DIRTY_META))
+		sync_meta_pages(sbi, META, LONG_MAX);
+
+	next_free_nid(sbi, &last_nid);
+
+	/*
+	 * modify checkpoint
+	 * version number is already updated
+	 */
+	ckpt->elapsed_time = cpu_to_le64(get_mtime(sbi));
+	ckpt->valid_block_count = cpu_to_le64(valid_user_blocks(sbi));
+	ckpt->free_segment_count = cpu_to_le32(free_segments(sbi));
+	for (i = 0; i < 3; i++) {
+		ckpt->cur_node_segno[i] =
+			cpu_to_le32(curseg_segno(sbi, i + CURSEG_HOT_NODE));
+		ckpt->cur_node_blkoff[i] =
+			cpu_to_le16(curseg_blkoff(sbi, i + CURSEG_HOT_NODE));
+		ckpt->alloc_type[i + CURSEG_HOT_NODE] =
+				curseg_alloc_type(sbi, i + CURSEG_HOT_NODE);
+	}
+	for (i = 0; i < 3; i++) {
+		ckpt->cur_data_segno[i] =
+			cpu_to_le32(curseg_segno(sbi, i + CURSEG_HOT_DATA));
+		ckpt->cur_data_blkoff[i] =
+			cpu_to_le16(curseg_blkoff(sbi, i + CURSEG_HOT_DATA));
+		ckpt->alloc_type[i + CURSEG_HOT_DATA] =
+				curseg_alloc_type(sbi, i + CURSEG_HOT_DATA);
+	}
+
+	ckpt->valid_node_count = cpu_to_le32(valid_node_count(sbi));
+	ckpt->valid_inode_count = cpu_to_le32(valid_inode_count(sbi));
+	ckpt->next_free_nid = cpu_to_le32(last_nid);
+
+	/* 2 cp  + n data seg summary + orphan inode blocks */
+	data_sum_blocks = npages_for_summary_flush(sbi);
+	if (data_sum_blocks < 3)
+		set_ckpt_flags(ckpt, CP_COMPACT_SUM_FLAG);
+	else
+		clear_ckpt_flags(ckpt, CP_COMPACT_SUM_FLAG);
+
+	orphan_blocks = (sbi->n_orphans + F2FS_ORPHANS_PER_BLOCK - 1)
+					/ F2FS_ORPHANS_PER_BLOCK;
+	ckpt->cp_pack_start_sum = cpu_to_le32(1 + orphan_blocks);
+
+	if (is_umount) {
+		set_ckpt_flags(ckpt, CP_UMOUNT_FLAG);
+		ckpt->cp_pack_total_block_count = cpu_to_le32(2 +
+			data_sum_blocks + orphan_blocks + NR_CURSEG_NODE_TYPE);
+	} else {
+		clear_ckpt_flags(ckpt, CP_UMOUNT_FLAG);
+		ckpt->cp_pack_total_block_count = cpu_to_le32(2 +
+			data_sum_blocks + orphan_blocks);
+	}
+
+	if (sbi->n_orphans)
+		set_ckpt_flags(ckpt, CP_ORPHAN_PRESENT_FLAG);
+	else
+		clear_ckpt_flags(ckpt, CP_ORPHAN_PRESENT_FLAG);
+
+	/* update SIT/NAT bitmap */
+	get_sit_bitmap(sbi, __bitmap_ptr(sbi, SIT_BITMAP));
+	get_nat_bitmap(sbi, __bitmap_ptr(sbi, NAT_BITMAP));
+
+	crc32 = f2fs_crc32(ckpt, le32_to_cpu(ckpt->checksum_offset));
+	*(__le32 *)((unsigned char *)ckpt +
+				le32_to_cpu(ckpt->checksum_offset))
+				= cpu_to_le32(crc32);
+
+	start_blk = __start_cp_addr(sbi);
+
+	/* write out checkpoint buffer at block 0 */
+	cp_page = grab_meta_page(sbi, start_blk++);
+	kaddr = page_address(cp_page);
+	memcpy(kaddr, ckpt, (1 << sbi->log_blocksize));
+	set_page_dirty(cp_page);
+	f2fs_put_page(cp_page, 1);
+
+	if (sbi->n_orphans) {
+		write_orphan_inodes(sbi, start_blk);
+		start_blk += orphan_blocks;
+	}
+
+	write_data_summaries(sbi, start_blk);
+	start_blk += data_sum_blocks;
+	if (is_umount) {
+		write_node_summaries(sbi, start_blk);
+		start_blk += NR_CURSEG_NODE_TYPE;
+	}
+
+	/* writeout checkpoint block */
+	cp_page = grab_meta_page(sbi, start_blk);
+	kaddr = page_address(cp_page);
+	memcpy(kaddr, ckpt, (1 << sbi->log_blocksize));
+	set_page_dirty(cp_page);
+	f2fs_put_page(cp_page, 1);
+
+	/* wait for previous submitted node/meta pages writeback */
+	while (get_pages(sbi, F2FS_WRITEBACK))
+		congestion_wait(BLK_RW_ASYNC, HZ / 50);
+
+	filemap_fdatawait_range(sbi->node_inode->i_mapping, 0, LONG_MAX);
+	filemap_fdatawait_range(sbi->meta_inode->i_mapping, 0, LONG_MAX);
+
+	/* update user_block_counts */
+	sbi->last_valid_block_count = sbi->total_valid_block_count;
+	sbi->alloc_valid_block_count = 0;
+
+	/* Here, we only have one bio having CP pack */
+	if (is_set_ckpt_flags(ckpt, CP_ERROR_FLAG))
+		sbi->sb->s_flags |= MS_RDONLY;
+	else
+		sync_meta_pages(sbi, META_FLUSH, LONG_MAX);
+
+	clear_prefree_segments(sbi);
+	F2FS_RESET_SB_DIRT(sbi);
+}
+
+/*
+ * We guarantee that this checkpoint procedure should not fail.
+ */
+void write_checkpoint(struct f2fs_sb_info *sbi, bool blocked, bool is_umount)
+{
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	unsigned long long ckpt_ver;
+
+	if (!blocked) {
+		mutex_lock(&sbi->cp_mutex);
+		block_operations(sbi);
+	}
+
+	f2fs_submit_bio(sbi, DATA, true);
+	f2fs_submit_bio(sbi, NODE, true);
+	f2fs_submit_bio(sbi, META, true);
+
+	/*
+	 * update checkpoint pack index
+	 * Increase the version number so that
+	 * SIT entries and seg summaries are written at correct place
+	 */
+	ckpt_ver = le64_to_cpu(ckpt->checkpoint_ver);
+	ckpt->checkpoint_ver = cpu_to_le64(++ckpt_ver);
+
+	/* write cached NAT/SIT entries to NAT/SIT area */
+	flush_nat_entries(sbi);
+	flush_sit_entries(sbi);
+
+	reset_victim_segmap(sbi);
+
+	/* unlock all the fs_lock[] in do_checkpoint() */
+	do_checkpoint(sbi, is_umount);
+
+	unblock_operations(sbi);
+	mutex_unlock(&sbi->cp_mutex);
+}
+
+void init_orphan_info(struct f2fs_sb_info *sbi)
+{
+	mutex_init(&sbi->orphan_inode_mutex);
+	INIT_LIST_HEAD(&sbi->orphan_inode_list);
+	sbi->n_orphans = 0;
+}
+
+int create_checkpoint_caches(void)
+{
+	orphan_entry_slab = f2fs_kmem_cache_create("f2fs_orphan_entry",
+			sizeof(struct orphan_inode_entry), NULL);
+	if (unlikely(!orphan_entry_slab))
+		return -ENOMEM;
+	inode_entry_slab = f2fs_kmem_cache_create("f2fs_dirty_dir_entry",
+			sizeof(struct dir_inode_entry), NULL);
+	if (unlikely(!inode_entry_slab)) {
+		kmem_cache_destroy(orphan_entry_slab);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void destroy_checkpoint_caches(void)
+{
+	kmem_cache_destroy(orphan_entry_slab);
+	kmem_cache_destroy(inode_entry_slab);
+}

fs/f2fs/data.c

···
+/*
+ * fs/f2fs/data.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include <linux/writeback.h>
+#include <linux/backing-dev.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+
+#include "f2fs.h"
+#include "node.h"
+#include "segment.h"
+
+/*
+ * Lock ordering for the change of data block address:
+ * ->data_page
+ *  ->node_page
+ *    update block addresses in the node page
+ */
+static void __set_data_blkaddr(struct dnode_of_data *dn, block_t new_addr)
+{
+	struct f2fs_node *rn;
+	__le32 *addr_array;
+	struct page *node_page = dn->node_page;
+	unsigned int ofs_in_node = dn->ofs_in_node;
+
+	wait_on_page_writeback(node_page);
+
+	rn = (struct f2fs_node *)page_address(node_page);
+
+	/* Get physical address of data block */
+	addr_array = blkaddr_in_node(rn);
+	addr_array[ofs_in_node] = cpu_to_le32(new_addr);
+	set_page_dirty(node_page);
+}
+
+int reserve_new_block(struct dnode_of_data *dn)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
+
+	if (is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC))
+		return -EPERM;
+	if (!inc_valid_block_count(sbi, dn->inode, 1))
+		return -ENOSPC;
+
+	__set_data_blkaddr(dn, NEW_ADDR);
+	dn->data_blkaddr = NEW_ADDR;
+	sync_inode_page(dn);
+	return 0;
+}
+
+static int check_extent_cache(struct inode *inode, pgoff_t pgofs,
+					struct buffer_head *bh_result)
+{
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	pgoff_t start_fofs, end_fofs;
+	block_t start_blkaddr;
+
+	read_lock(&fi->ext.ext_lock);
+	if (fi->ext.len == 0) {
+		read_unlock(&fi->ext.ext_lock);
+		return 0;
+	}
+
+	sbi->total_hit_ext++;
+	start_fofs = fi->ext.fofs;
+	end_fofs = fi->ext.fofs + fi->ext.len - 1;
+	start_blkaddr = fi->ext.blk_addr;
+
+	if (pgofs >= start_fofs && pgofs <= end_fofs) {
+		unsigned int blkbits = inode->i_sb->s_blocksize_bits;
+		size_t count;
+
+		clear_buffer_new(bh_result);
+		map_bh(bh_result, inode->i_sb,
+				start_blkaddr + pgofs - start_fofs);
+		count = end_fofs - pgofs + 1;
+		if (count < (UINT_MAX >> blkbits))
+			bh_result->b_size = (count << blkbits);
+		else
+			bh_result->b_size = UINT_MAX;
+
+		sbi->read_hit_ext++;
+		read_unlock(&fi->ext.ext_lock);
+		return 1;
+	}
+	read_unlock(&fi->ext.ext_lock);
+	return 0;
+}
+
+void update_extent_cache(block_t blk_addr, struct dnode_of_data *dn)
+{
+	struct f2fs_inode_info *fi = F2FS_I(dn->inode);
+	pgoff_t fofs, start_fofs, end_fofs;
+	block_t start_blkaddr, end_blkaddr;
+
+	BUG_ON(blk_addr == NEW_ADDR);
+	fofs = start_bidx_of_node(ofs_of_node(dn->node_page)) + dn->ofs_in_node;
+
+	/* Update the page address in the parent node */
+	__set_data_blkaddr(dn, blk_addr);
+
+	write_lock(&fi->ext.ext_lock);
+
+	start_fofs = fi->ext.fofs;
+	end_fofs = fi->ext.fofs + fi->ext.len - 1;
+	start_blkaddr = fi->ext.blk_addr;
+	end_blkaddr = fi->ext.blk_addr + fi->ext.len - 1;
+
+	/* Drop and initialize the matched extent */
+	if (fi->ext.len == 1 && fofs == start_fofs)
+		fi->ext.len = 0;
+
+	/* Initial extent */
+	if (fi->ext.len == 0) {
+		if (blk_addr != NULL_ADDR) {
+			fi->ext.fofs = fofs;
+			fi->ext.blk_addr = blk_addr;
+			fi->ext.len = 1;
+		}
+		goto end_update;
+	}
+
+	/* Frone merge */
+	if (fofs == start_fofs - 1 && blk_addr == start_blkaddr - 1) {
+		fi->ext.fofs--;
+		fi->ext.blk_addr--;
+		fi->ext.len++;
+		goto end_update;
+	}
+
+	/* Back merge */
+	if (fofs == end_fofs + 1 && blk_addr == end_blkaddr + 1) {
+		fi->ext.len++;
+		goto end_update;
+	}
+
+	/* Split the existing extent */
+	if (fi->ext.len > 1 &&
+		fofs >= start_fofs && fofs <= end_fofs) {
+		if ((end_fofs - fofs) < (fi->ext.len >> 1)) {
+			fi->ext.len = fofs - start_fofs;
+		} else {
+			fi->ext.fofs = fofs + 1;
+			fi->ext.blk_addr = start_blkaddr +
+					fofs - start_fofs + 1;
+			fi->ext.len -= fofs - start_fofs + 1;
+		}
+		goto end_update;
+	}
+	write_unlock(&fi->ext.ext_lock);
+	return;
+
+end_update:
+	write_unlock(&fi->ext.ext_lock);
+	sync_inode_page(dn);
+	return;
+}
+
+struct page *find_data_page(struct inode *inode, pgoff_t index)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct address_space *mapping = inode->i_mapping;
+	struct dnode_of_data dn;
+	struct page *page;
+	int err;
+
+	page = find_get_page(mapping, index);
+	if (page && PageUptodate(page))
+		return page;
+	f2fs_put_page(page, 0);
+
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	err = get_dnode_of_data(&dn, index, RDONLY_NODE);
+	if (err)
+		return ERR_PTR(err);
+	f2fs_put_dnode(&dn);
+
+	if (dn.data_blkaddr == NULL_ADDR)
+		return ERR_PTR(-ENOENT);
+
+	/* By fallocate(), there is no cached page, but with NEW_ADDR */
+	if (dn.data_blkaddr == NEW_ADDR)
+		return ERR_PTR(-EINVAL);
+
+	page = grab_cache_page(mapping, index);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
+	if (err) {
+		f2fs_put_page(page, 1);
+		return ERR_PTR(err);
+	}
+	unlock_page(page);
+	return page;
+}
+
+/*
+ * If it tries to access a hole, return an error.
+ * Because, the callers, functions in dir.c and GC, should be able to know
+ * whether this page exists or not.
+ */
+struct page *get_lock_data_page(struct inode *inode, pgoff_t index)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct address_space *mapping = inode->i_mapping;
+	struct dnode_of_data dn;
+	struct page *page;
+	int err;
+
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	err = get_dnode_of_data(&dn, index, RDONLY_NODE);
+	if (err)
+		return ERR_PTR(err);
+	f2fs_put_dnode(&dn);
+
+	if (dn.data_blkaddr == NULL_ADDR)
+		return ERR_PTR(-ENOENT);
+
+	page = grab_cache_page(mapping, index);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	if (PageUptodate(page))
+		return page;
+
+	BUG_ON(dn.data_blkaddr == NEW_ADDR);
+	BUG_ON(dn.data_blkaddr == NULL_ADDR);
+
+	err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
+	if (err) {
+		f2fs_put_page(page, 1);
+		return ERR_PTR(err);
+	}
+	return page;
+}
+
+/*
+ * Caller ensures that this data page is never allocated.
+ * A new zero-filled data page is allocated in the page cache.
+ */
+struct page *get_new_data_page(struct inode *inode, pgoff_t index,
+						bool new_i_size)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct address_space *mapping = inode->i_mapping;
+	struct page *page;
+	struct dnode_of_data dn;
+	int err;
+
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	err = get_dnode_of_data(&dn, index, 0);
+	if (err)
+		return ERR_PTR(err);
+
+	if (dn.data_blkaddr == NULL_ADDR) {
+		if (reserve_new_block(&dn)) {
+			f2fs_put_dnode(&dn);
+			return ERR_PTR(-ENOSPC);
+		}
+	}
+	f2fs_put_dnode(&dn);
+
+	page = grab_cache_page(mapping, index);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	if (PageUptodate(page))
+		return page;
+
+	if (dn.data_blkaddr == NEW_ADDR) {
+		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
+	} else {
+		err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
+		if (err) {
+			f2fs_put_page(page, 1);
+			return ERR_PTR(err);
+		}
+	}
+	SetPageUptodate(page);
+
+	if (new_i_size &&
+		i_size_read(inode) < ((index + 1) << PAGE_CACHE_SHIFT)) {
+		i_size_write(inode, ((index + 1) << PAGE_CACHE_SHIFT));
+		mark_inode_dirty_sync(inode);
+	}
+	return page;
+}
+
+static void read_end_io(struct bio *bio, int err)
+{
+	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+
+	do {
+		struct page *page = bvec->bv_page;
+
+		if (--bvec >= bio->bi_io_vec)
+			prefetchw(&bvec->bv_page->flags);
+
+		if (uptodate) {
+			SetPageUptodate(page);
+		} else {
+			ClearPageUptodate(page);
+			SetPageError(page);
+		}
+		unlock_page(page);
+	} while (bvec >= bio->bi_io_vec);
+	kfree(bio->bi_private);
+	bio_put(bio);
+}
+
+/*
+ * Fill the locked page with data located in the block address.
+ * Read operation is synchronous, and caller must unlock the page.
+ */
+int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,
+					block_t blk_addr, int type)
+{
+	struct block_device *bdev = sbi->sb->s_bdev;
+	bool sync = (type == READ_SYNC);
+	struct bio *bio;
+
+	/* This page can be already read by other threads */
+	if (PageUptodate(page)) {
+		if (!sync)
+			unlock_page(page);
+		return 0;
+	}
+
+	down_read(&sbi->bio_sem);
+
+	/* Allocate a new bio */
+	bio = f2fs_bio_alloc(bdev, 1);
+
+	/* Initialize the bio */
+	bio->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
+	bio->bi_end_io = read_end_io;
+
+	if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
+		kfree(bio->bi_private);
+		bio_put(bio);
+		up_read(&sbi->bio_sem);
+		return -EFAULT;
+	}
+
+	submit_bio(type, bio);
+	up_read(&sbi->bio_sem);
+
+	/* wait for read completion if sync */
+	if (sync) {
+		lock_page(page);
+		if (PageError(page))
+			return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * This function should be used by the data read flow only where it
+ * does not check the "create" flag that indicates block allocation.
+ * The reason for this special functionality is to exploit VFS readahead
+ * mechanism.
+ */
+static int get_data_block_ro(struct inode *inode, sector_t iblock,
+			struct buffer_head *bh_result, int create)
+{
+	unsigned int blkbits = inode->i_sb->s_blocksize_bits;
+	unsigned maxblocks = bh_result->b_size >> blkbits;
+	struct dnode_of_data dn;
+	pgoff_t pgofs;
+	int err;
+
+	/* Get the page offset from the block offset(iblock) */
+	pgofs =	(pgoff_t)(iblock >> (PAGE_CACHE_SHIFT - blkbits));
+
+	if (check_extent_cache(inode, pgofs, bh_result))
+		return 0;
+
+	/* When reading holes, we need its node page */
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	err = get_dnode_of_data(&dn, pgofs, RDONLY_NODE);
+	if (err)
+		return (err == -ENOENT) ? 0 : err;
+
+	/* It does not support data allocation */
+	BUG_ON(create);
+
+	if (dn.data_blkaddr != NEW_ADDR && dn.data_blkaddr != NULL_ADDR) {
+		int i;
+		unsigned int end_offset;
+
+		end_offset = IS_INODE(dn.node_page) ?
+				ADDRS_PER_INODE :
+				ADDRS_PER_BLOCK;
+
+		clear_buffer_new(bh_result);
+
+		/* Give more consecutive addresses for the read ahead */
+		for (i = 0; i < end_offset - dn.ofs_in_node; i++)
+			if (((datablock_addr(dn.node_page,
+							dn.ofs_in_node + i))
+				!= (dn.data_blkaddr + i)) || maxblocks == i)
+				break;
+		map_bh(bh_result, inode->i_sb, dn.data_blkaddr);
+		bh_result->b_size = (i << blkbits);
+	}
+	f2fs_put_dnode(&dn);
+	return 0;
+}
+
+static int f2fs_read_data_page(struct file *file, struct page *page)
+{
+	return mpage_readpage(page, get_data_block_ro);
+}
+
+static int f2fs_read_data_pages(struct file *file,
+			struct address_space *mapping,
+			struct list_head *pages, unsigned nr_pages)
+{
+	return mpage_readpages(mapping, pages, nr_pages, get_data_block_ro);
+}
+
+int do_write_data_page(struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	block_t old_blk_addr, new_blk_addr;
+	struct dnode_of_data dn;
+	int err = 0;
+
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	err = get_dnode_of_data(&dn, page->index, RDONLY_NODE);
+	if (err)
+		return err;
+
+	old_blk_addr = dn.data_blkaddr;
+
+	/* This page is already truncated */
+	if (old_blk_addr == NULL_ADDR)
+		goto out_writepage;
+
+	set_page_writeback(page);
+
+	/*
+	 * If current allocation needs SSR,
+	 * it had better in-place writes for updated data.
+	 */
+	if (old_blk_addr != NEW_ADDR && !is_cold_data(page) &&
+				need_inplace_update(inode)) {
+		rewrite_data_page(F2FS_SB(inode->i_sb), page,
+						old_blk_addr);
+	} else {
+		write_data_page(inode, page, &dn,
+				old_blk_addr, &new_blk_addr);
+		update_extent_cache(new_blk_addr, &dn);
+		F2FS_I(inode)->data_version =
+			le64_to_cpu(F2FS_CKPT(sbi)->checkpoint_ver);
+	}
+out_writepage:
+	f2fs_put_dnode(&dn);
+	return err;
+}
+
+static int f2fs_write_data_page(struct page *page,
+					struct writeback_control *wbc)
+{
+	struct inode *inode = page->mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	loff_t i_size = i_size_read(inode);
+	const pgoff_t end_index = ((unsigned long long) i_size)
+							>> PAGE_CACHE_SHIFT;
+	unsigned offset;
+	int err = 0;
+
+	if (page->index < end_index)
+		goto out;
+
+	/*
+	 * If the offset is out-of-range of file size,
+	 * this page does not have to be written to disk.
+	 */
+	offset = i_size & (PAGE_CACHE_SIZE - 1);
+	if ((page->index >= end_index + 1) || !offset) {
+		if (S_ISDIR(inode->i_mode)) {
+			dec_page_count(sbi, F2FS_DIRTY_DENTS);
+			inode_dec_dirty_dents(inode);
+		}
+		goto unlock_out;
+	}
+
+	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
+out:
+	if (sbi->por_doing)
+		goto redirty_out;
+
+	if (wbc->for_reclaim && !S_ISDIR(inode->i_mode) && !is_cold_data(page))
+		goto redirty_out;
+
+	mutex_lock_op(sbi, DATA_WRITE);
+	if (S_ISDIR(inode->i_mode)) {
+		dec_page_count(sbi, F2FS_DIRTY_DENTS);
+		inode_dec_dirty_dents(inode);
+	}
+	err = do_write_data_page(page);
+	if (err && err != -ENOENT) {
+		wbc->pages_skipped++;
+		set_page_dirty(page);
+	}
+	mutex_unlock_op(sbi, DATA_WRITE);
+
+	if (wbc->for_reclaim)
+		f2fs_submit_bio(sbi, DATA, true);
+
+	if (err == -ENOENT)
+		goto unlock_out;
+
+	clear_cold_data(page);
+	unlock_page(page);
+
+	if (!wbc->for_reclaim && !S_ISDIR(inode->i_mode))
+		f2fs_balance_fs(sbi);
+	return 0;
+
+unlock_out:
+	unlock_page(page);
+	return (err == -ENOENT) ? 0 : err;
+
+redirty_out:
+	wbc->pages_skipped++;
+	set_page_dirty(page);
+	return AOP_WRITEPAGE_ACTIVATE;
+}
+
+#define MAX_DESIRED_PAGES_WP	4096
+
+static int f2fs_write_data_pages(struct address_space *mapping,
+			    struct writeback_control *wbc)
+{
+	struct inode *inode = mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	int ret;
+	long excess_nrtw = 0, desired_nrtw;
+
+	if (wbc->nr_to_write < MAX_DESIRED_PAGES_WP) {
+		desired_nrtw = MAX_DESIRED_PAGES_WP;
+		excess_nrtw = desired_nrtw - wbc->nr_to_write;
+		wbc->nr_to_write = desired_nrtw;
+	}
+
+	if (!S_ISDIR(inode->i_mode))
+		mutex_lock(&sbi->writepages);
+	ret = generic_writepages(mapping, wbc);
+	if (!S_ISDIR(inode->i_mode))
+		mutex_unlock(&sbi->writepages);
+	f2fs_submit_bio(sbi, DATA, (wbc->sync_mode == WB_SYNC_ALL));
+
+	remove_dirty_dir_inode(inode);
+
+	wbc->nr_to_write -= excess_nrtw;
+	return ret;
+}
+
+static int f2fs_write_begin(struct file *file, struct address_space *mapping,
+		loff_t pos, unsigned len, unsigned flags,
+		struct page **pagep, void **fsdata)
+{
+	struct inode *inode = mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct page *page;
+	pgoff_t index = ((unsigned long long) pos) >> PAGE_CACHE_SHIFT;
+	struct dnode_of_data dn;
+	int err = 0;
+
+	/* for nobh_write_end */
+	*fsdata = NULL;
+
+	f2fs_balance_fs(sbi);
+
+	page = grab_cache_page_write_begin(mapping, index, flags);
+	if (!page)
+		return -ENOMEM;
+	*pagep = page;
+
+	mutex_lock_op(sbi, DATA_NEW);
+
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	err = get_dnode_of_data(&dn, index, 0);
+	if (err) {
+		mutex_unlock_op(sbi, DATA_NEW);
+		f2fs_put_page(page, 1);
+		return err;
+	}
+
+	if (dn.data_blkaddr == NULL_ADDR) {
+		err = reserve_new_block(&dn);
+		if (err) {
+			f2fs_put_dnode(&dn);
+			mutex_unlock_op(sbi, DATA_NEW);
+			f2fs_put_page(page, 1);
+			return err;
+		}
+	}
+	f2fs_put_dnode(&dn);
+
+	mutex_unlock_op(sbi, DATA_NEW);
+
+	if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
+		return 0;
+
+	if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
+		unsigned start = pos & (PAGE_CACHE_SIZE - 1);
+		unsigned end = start + len;
+
+		/* Reading beyond i_size is simple: memset to zero */
+		zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
+		return 0;
+	}
+
+	if (dn.data_blkaddr == NEW_ADDR) {
+		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
+	} else {
+		err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
+		if (err) {
+			f2fs_put_page(page, 1);
+			return err;
+		}
+	}
+	SetPageUptodate(page);
+	clear_cold_data(page);
+	return 0;
+}
+
+static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
+		const struct iovec *iov, loff_t offset, unsigned long nr_segs)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+
+	if (rw == WRITE)
+		return 0;
+
+	/* Needs synchronization with the cleaner */
+	return blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
+						  get_data_block_ro);
+}
+
+static void f2fs_invalidate_data_page(struct page *page, unsigned long offset)
+{
+	struct inode *inode = page->mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	if (S_ISDIR(inode->i_mode) && PageDirty(page)) {
+		dec_page_count(sbi, F2FS_DIRTY_DENTS);
+		inode_dec_dirty_dents(inode);
+	}
+	ClearPagePrivate(page);
+}
+
+static int f2fs_release_data_page(struct page *page, gfp_t wait)
+{
+	ClearPagePrivate(page);
+	return 0;
+}
+
+static int f2fs_set_data_page_dirty(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = mapping->host;
+
+	SetPageUptodate(page);
+	if (!PageDirty(page)) {
+		__set_page_dirty_nobuffers(page);
+		set_dirty_dir_page(inode, page);
+		return 1;
+	}
+	return 0;
+}
+
+const struct address_space_operations f2fs_dblock_aops = {
+	.readpage	= f2fs_read_data_page,
+	.readpages	= f2fs_read_data_pages,
+	.writepage	= f2fs_write_data_page,
+	.writepages	= f2fs_write_data_pages,
+	.write_begin	= f2fs_write_begin,
+	.write_end	= nobh_write_end,
+	.set_page_dirty	= f2fs_set_data_page_dirty,
+	.invalidatepage	= f2fs_invalidate_data_page,
+	.releasepage	= f2fs_release_data_page,
+	.direct_IO	= f2fs_direct_IO,
+};

fs/f2fs/debug.c

···
+/*
+ * f2fs debugging statistics
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ * Copyright (c) 2012 Linux Foundation
+ * Copyright (c) 2012 Greg Kroah-Hartman <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/backing-dev.h>
+#include <linux/proc_fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/blkdev.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+#include "f2fs.h"
+#include "node.h"
+#include "segment.h"
+#include "gc.h"
+
+static LIST_HEAD(f2fs_stat_list);
+static struct dentry *debugfs_root;
+
+static void update_general_status(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_stat_info *si = sbi->stat_info;
+	int i;
+
+	/* valid check of the segment numbers */
+	si->hit_ext = sbi->read_hit_ext;
+	si->total_ext = sbi->total_hit_ext;
+	si->ndirty_node = get_pages(sbi, F2FS_DIRTY_NODES);
+	si->ndirty_dent = get_pages(sbi, F2FS_DIRTY_DENTS);
+	si->ndirty_dirs = sbi->n_dirty_dirs;
+	si->ndirty_meta = get_pages(sbi, F2FS_DIRTY_META);
+	si->total_count = (int)sbi->user_block_count / sbi->blocks_per_seg;
+	si->rsvd_segs = reserved_segments(sbi);
+	si->overp_segs = overprovision_segments(sbi);
+	si->valid_count = valid_user_blocks(sbi);
+	si->valid_node_count = valid_node_count(sbi);
+	si->valid_inode_count = valid_inode_count(sbi);
+	si->utilization = utilization(sbi);
+
+	si->free_segs = free_segments(sbi);
+	si->free_secs = free_sections(sbi);
+	si->prefree_count = prefree_segments(sbi);
+	si->dirty_count = dirty_segments(sbi);
+	si->node_pages = sbi->node_inode->i_mapping->nrpages;
+	si->meta_pages = sbi->meta_inode->i_mapping->nrpages;
+	si->nats = NM_I(sbi)->nat_cnt;
+	si->sits = SIT_I(sbi)->dirty_sentries;
+	si->fnids = NM_I(sbi)->fcnt;
+	si->bg_gc = sbi->bg_gc;
+	si->util_free = (int)(free_user_blocks(sbi) >> sbi->log_blocks_per_seg)
+		* 100 / (int)(sbi->user_block_count >> sbi->log_blocks_per_seg)
+		/ 2;
+	si->util_valid = (int)(written_block_count(sbi) >>
+						sbi->log_blocks_per_seg)
+		* 100 / (int)(sbi->user_block_count >> sbi->log_blocks_per_seg)
+		/ 2;
+	si->util_invalid = 50 - si->util_free - si->util_valid;
+	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_NODE; i++) {
+		struct curseg_info *curseg = CURSEG_I(sbi, i);
+		si->curseg[i] = curseg->segno;
+		si->cursec[i] = curseg->segno / sbi->segs_per_sec;
+		si->curzone[i] = si->cursec[i] / sbi->secs_per_zone;
+	}
+
+	for (i = 0; i < 2; i++) {
+		si->segment_count[i] = sbi->segment_count[i];
+		si->block_count[i] = sbi->block_count[i];
+	}
+}
+
+/*
+ * This function calculates BDF of every segments
+ */
+static void update_sit_info(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_stat_info *si = sbi->stat_info;
+	unsigned int blks_per_sec, hblks_per_sec, total_vblocks, bimodal, dist;
+	struct sit_info *sit_i = SIT_I(sbi);
+	unsigned int segno, vblocks;
+	int ndirty = 0;
+
+	bimodal = 0;
+	total_vblocks = 0;
+	blks_per_sec = sbi->segs_per_sec * (1 << sbi->log_blocks_per_seg);
+	hblks_per_sec = blks_per_sec / 2;
+	mutex_lock(&sit_i->sentry_lock);
+	for (segno = 0; segno < TOTAL_SEGS(sbi); segno += sbi->segs_per_sec) {
+		vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec);
+		dist = abs(vblocks - hblks_per_sec);
+		bimodal += dist * dist;
+
+		if (vblocks > 0 && vblocks < blks_per_sec) {
+			total_vblocks += vblocks;
+			ndirty++;
+		}
+	}
+	mutex_unlock(&sit_i->sentry_lock);
+	dist = sbi->total_sections * hblks_per_sec * hblks_per_sec / 100;
+	si->bimodal = bimodal / dist;
+	if (si->dirty_count)
+		si->avg_vblocks = total_vblocks / ndirty;
+	else
+		si->avg_vblocks = 0;
+}
+
+/*
+ * This function calculates memory footprint.
+ */
+static void update_mem_info(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_stat_info *si = sbi->stat_info;
+	unsigned npages;
+
+	if (si->base_mem)
+		goto get_cache;
+
+	si->base_mem = sizeof(struct f2fs_sb_info) + sbi->sb->s_blocksize;
+	si->base_mem += 2 * sizeof(struct f2fs_inode_info);
+	si->base_mem += sizeof(*sbi->ckpt);
+
+	/* build sm */
+	si->base_mem += sizeof(struct f2fs_sm_info);
+
+	/* build sit */
+	si->base_mem += sizeof(struct sit_info);
+	si->base_mem += TOTAL_SEGS(sbi) * sizeof(struct seg_entry);
+	si->base_mem += f2fs_bitmap_size(TOTAL_SEGS(sbi));
+	si->base_mem += 2 * SIT_VBLOCK_MAP_SIZE * TOTAL_SEGS(sbi);
+	if (sbi->segs_per_sec > 1)
+		si->base_mem += sbi->total_sections *
+			sizeof(struct sec_entry);
+	si->base_mem += __bitmap_size(sbi, SIT_BITMAP);
+
+	/* build free segmap */
+	si->base_mem += sizeof(struct free_segmap_info);
+	si->base_mem += f2fs_bitmap_size(TOTAL_SEGS(sbi));
+	si->base_mem += f2fs_bitmap_size(sbi->total_sections);
+
+	/* build curseg */
+	si->base_mem += sizeof(struct curseg_info) * NR_CURSEG_TYPE;
+	si->base_mem += PAGE_CACHE_SIZE * NR_CURSEG_TYPE;
+
+	/* build dirty segmap */
+	si->base_mem += sizeof(struct dirty_seglist_info);
+	si->base_mem += NR_DIRTY_TYPE * f2fs_bitmap_size(TOTAL_SEGS(sbi));
+	si->base_mem += 2 * f2fs_bitmap_size(TOTAL_SEGS(sbi));
+
+	/* buld nm */
+	si->base_mem += sizeof(struct f2fs_nm_info);
+	si->base_mem += __bitmap_size(sbi, NAT_BITMAP);
+
+	/* build gc */
+	si->base_mem += sizeof(struct f2fs_gc_kthread);
+
+get_cache:
+	/* free nids */
+	si->cache_mem = NM_I(sbi)->fcnt;
+	si->cache_mem += NM_I(sbi)->nat_cnt;
+	npages = sbi->node_inode->i_mapping->nrpages;
+	si->cache_mem += npages << PAGE_CACHE_SHIFT;
+	npages = sbi->meta_inode->i_mapping->nrpages;
+	si->cache_mem += npages << PAGE_CACHE_SHIFT;
+	si->cache_mem += sbi->n_orphans * sizeof(struct orphan_inode_entry);
+	si->cache_mem += sbi->n_dirty_dirs * sizeof(struct dir_inode_entry);
+}
+
+static int stat_show(struct seq_file *s, void *v)
+{
+	struct f2fs_stat_info *si, *next;
+	int i = 0;
+	int j;
+
+	list_for_each_entry_safe(si, next, &f2fs_stat_list, stat_list) {
+
+		mutex_lock(&si->stat_lock);
+		if (!si->sbi) {
+			mutex_unlock(&si->stat_lock);
+			continue;
+		}
+		update_general_status(si->sbi);
+
+		seq_printf(s, "\n=====[ partition info. #%d ]=====\n", i++);
+		seq_printf(s, "[SB: 1] [CP: 2] [NAT: %d] [SIT: %d] ",
+			   si->nat_area_segs, si->sit_area_segs);
+		seq_printf(s, "[SSA: %d] [MAIN: %d",
+			   si->ssa_area_segs, si->main_area_segs);
+		seq_printf(s, "(OverProv:%d Resv:%d)]\n\n",
+			   si->overp_segs, si->rsvd_segs);
+		seq_printf(s, "Utilization: %d%% (%d valid blocks)\n",
+			   si->utilization, si->valid_count);
+		seq_printf(s, "  - Node: %u (Inode: %u, ",
+			   si->valid_node_count, si->valid_inode_count);
+		seq_printf(s, "Other: %u)\n  - Data: %u\n",
+			   si->valid_node_count - si->valid_inode_count,
+			   si->valid_count - si->valid_node_count);
+		seq_printf(s, "\nMain area: %d segs, %d secs %d zones\n",
+			   si->main_area_segs, si->main_area_sections,
+			   si->main_area_zones);
+		seq_printf(s, "  - COLD  data: %d, %d, %d\n",
+			   si->curseg[CURSEG_COLD_DATA],
+			   si->cursec[CURSEG_COLD_DATA],
+			   si->curzone[CURSEG_COLD_DATA]);
+		seq_printf(s, "  - WARM  data: %d, %d, %d\n",
+			   si->curseg[CURSEG_WARM_DATA],
+			   si->cursec[CURSEG_WARM_DATA],
+			   si->curzone[CURSEG_WARM_DATA]);
+		seq_printf(s, "  - HOT   data: %d, %d, %d\n",
+			   si->curseg[CURSEG_HOT_DATA],
+			   si->cursec[CURSEG_HOT_DATA],
+			   si->curzone[CURSEG_HOT_DATA]);
+		seq_printf(s, "  - Dir   dnode: %d, %d, %d\n",
+			   si->curseg[CURSEG_HOT_NODE],
+			   si->cursec[CURSEG_HOT_NODE],
+			   si->curzone[CURSEG_HOT_NODE]);
+		seq_printf(s, "  - File   dnode: %d, %d, %d\n",
+			   si->curseg[CURSEG_WARM_NODE],
+			   si->cursec[CURSEG_WARM_NODE],
+			   si->curzone[CURSEG_WARM_NODE]);
+		seq_printf(s, "  - Indir nodes: %d, %d, %d\n",
+			   si->curseg[CURSEG_COLD_NODE],
+			   si->cursec[CURSEG_COLD_NODE],
+			   si->curzone[CURSEG_COLD_NODE]);
+		seq_printf(s, "\n  - Valid: %d\n  - Dirty: %d\n",
+			   si->main_area_segs - si->dirty_count -
+			   si->prefree_count - si->free_segs,
+			   si->dirty_count);
+		seq_printf(s, "  - Prefree: %d\n  - Free: %d (%d)\n\n",
+			   si->prefree_count, si->free_segs, si->free_secs);
+		seq_printf(s, "GC calls: %d (BG: %d)\n",
+			   si->call_count, si->bg_gc);
+		seq_printf(s, "  - data segments : %d\n", si->data_segs);
+		seq_printf(s, "  - node segments : %d\n", si->node_segs);
+		seq_printf(s, "Try to move %d blocks\n", si->tot_blks);
+		seq_printf(s, "  - data blocks : %d\n", si->data_blks);
+		seq_printf(s, "  - node blocks : %d\n", si->node_blks);
+		seq_printf(s, "\nExtent Hit Ratio: %d / %d\n",
+			   si->hit_ext, si->total_ext);
+		seq_printf(s, "\nBalancing F2FS Async:\n");
+		seq_printf(s, "  - nodes %4d in %4d\n",
+			   si->ndirty_node, si->node_pages);
+		seq_printf(s, "  - dents %4d in dirs:%4d\n",
+			   si->ndirty_dent, si->ndirty_dirs);
+		seq_printf(s, "  - meta %4d in %4d\n",
+			   si->ndirty_meta, si->meta_pages);
+		seq_printf(s, "  - NATs %5d > %lu\n",
+			   si->nats, NM_WOUT_THRESHOLD);
+		seq_printf(s, "  - SITs: %5d\n  - free_nids: %5d\n",
+			   si->sits, si->fnids);
+		seq_printf(s, "\nDistribution of User Blocks:");
+		seq_printf(s, " [ valid | invalid | free ]\n");
+		seq_printf(s, "  [");
+
+		for (j = 0; j < si->util_valid; j++)
+			seq_printf(s, "-");
+		seq_printf(s, "|");
+
+		for (j = 0; j < si->util_invalid; j++)
+			seq_printf(s, "-");
+		seq_printf(s, "|");
+
+		for (j = 0; j < si->util_free; j++)
+			seq_printf(s, "-");
+		seq_printf(s, "]\n\n");
+		seq_printf(s, "SSR: %u blocks in %u segments\n",
+			   si->block_count[SSR], si->segment_count[SSR]);
+		seq_printf(s, "LFS: %u blocks in %u segments\n",
+			   si->block_count[LFS], si->segment_count[LFS]);
+
+		/* segment usage info */
+		update_sit_info(si->sbi);
+		seq_printf(s, "\nBDF: %u, avg. vblocks: %u\n",
+			   si->bimodal, si->avg_vblocks);
+
+		/* memory footprint */
+		update_mem_info(si->sbi);
+		seq_printf(s, "\nMemory: %u KB = static: %u + cached: %u\n",
+				(si->base_mem + si->cache_mem) >> 10,
+				si->base_mem >> 10, si->cache_mem >> 10);
+		mutex_unlock(&si->stat_lock);
+	}
+	return 0;
+}
+
+static int stat_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, stat_show, inode->i_private);
+}
+
+static const struct file_operations stat_fops = {
+	.open = stat_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int init_stats(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
+	struct f2fs_stat_info *si;
+
+	sbi->stat_info = kzalloc(sizeof(struct f2fs_stat_info), GFP_KERNEL);
+	if (!sbi->stat_info)
+		return -ENOMEM;
+
+	si = sbi->stat_info;
+	mutex_init(&si->stat_lock);
+	list_add_tail(&si->stat_list, &f2fs_stat_list);
+
+	si->all_area_segs = le32_to_cpu(raw_super->segment_count);
+	si->sit_area_segs = le32_to_cpu(raw_super->segment_count_sit);
+	si->nat_area_segs = le32_to_cpu(raw_super->segment_count_nat);
+	si->ssa_area_segs = le32_to_cpu(raw_super->segment_count_ssa);
+	si->main_area_segs = le32_to_cpu(raw_super->segment_count_main);
+	si->main_area_sections = le32_to_cpu(raw_super->section_count);
+	si->main_area_zones = si->main_area_sections /
+				le32_to_cpu(raw_super->secs_per_zone);
+	si->sbi = sbi;
+	return 0;
+}
+
+int f2fs_build_stats(struct f2fs_sb_info *sbi)
+{
+	int retval;
+
+	retval = init_stats(sbi);
+	if (retval)
+		return retval;
+
+	if (!debugfs_root)
+		debugfs_root = debugfs_create_dir("f2fs", NULL);
+
+	debugfs_create_file("status", S_IRUGO, debugfs_root, NULL, &stat_fops);
+	return 0;
+}
+
+void f2fs_destroy_stats(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_stat_info *si = sbi->stat_info;
+
+	list_del(&si->stat_list);
+	mutex_lock(&si->stat_lock);
+	si->sbi = NULL;
+	mutex_unlock(&si->stat_lock);
+	kfree(sbi->stat_info);
+}
+
+void destroy_root_stats(void)
+{
+	debugfs_remove_recursive(debugfs_root);
+	debugfs_root = NULL;
+}

fs/f2fs/dir.c

···
+/*
+ * fs/f2fs/dir.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include "f2fs.h"
+#include "acl.h"
+
+static unsigned long dir_blocks(struct inode *inode)
+{
+	return ((unsigned long long) (i_size_read(inode) + PAGE_CACHE_SIZE - 1))
+							>> PAGE_CACHE_SHIFT;
+}
+
+static unsigned int dir_buckets(unsigned int level)
+{
+	if (level < MAX_DIR_HASH_DEPTH / 2)
+		return 1 << level;
+	else
+		return 1 << ((MAX_DIR_HASH_DEPTH / 2) - 1);
+}
+
+static unsigned int bucket_blocks(unsigned int level)
+{
+	if (level < MAX_DIR_HASH_DEPTH / 2)
+		return 2;
+	else
+		return 4;
+}
+
+static unsigned char f2fs_filetype_table[F2FS_FT_MAX] = {
+	[F2FS_FT_UNKNOWN]	= DT_UNKNOWN,
+	[F2FS_FT_REG_FILE]	= DT_REG,
+	[F2FS_FT_DIR]		= DT_DIR,
+	[F2FS_FT_CHRDEV]	= DT_CHR,
+	[F2FS_FT_BLKDEV]	= DT_BLK,
+	[F2FS_FT_FIFO]		= DT_FIFO,
+	[F2FS_FT_SOCK]		= DT_SOCK,
+	[F2FS_FT_SYMLINK]	= DT_LNK,
+};
+
+#define S_SHIFT 12
+static unsigned char f2fs_type_by_mode[S_IFMT >> S_SHIFT] = {
+	[S_IFREG >> S_SHIFT]	= F2FS_FT_REG_FILE,
+	[S_IFDIR >> S_SHIFT]	= F2FS_FT_DIR,
+	[S_IFCHR >> S_SHIFT]	= F2FS_FT_CHRDEV,
+	[S_IFBLK >> S_SHIFT]	= F2FS_FT_BLKDEV,
+	[S_IFIFO >> S_SHIFT]	= F2FS_FT_FIFO,
+	[S_IFSOCK >> S_SHIFT]	= F2FS_FT_SOCK,
+	[S_IFLNK >> S_SHIFT]	= F2FS_FT_SYMLINK,
+};
+
+static void set_de_type(struct f2fs_dir_entry *de, struct inode *inode)
+{
+	mode_t mode = inode->i_mode;
+	de->file_type = f2fs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
+}
+
+static unsigned long dir_block_index(unsigned int level, unsigned int idx)
+{
+	unsigned long i;
+	unsigned long bidx = 0;
+
+	for (i = 0; i < level; i++)
+		bidx += dir_buckets(i) * bucket_blocks(i);
+	bidx += idx * bucket_blocks(level);
+	return bidx;
+}
+
+static bool early_match_name(const char *name, int namelen,
+			f2fs_hash_t namehash, struct f2fs_dir_entry *de)
+{
+	if (le16_to_cpu(de->name_len) != namelen)
+		return false;
+
+	if (de->hash_code != namehash)
+		return false;
+
+	return true;
+}
+
+static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
+			const char *name, int namelen, int *max_slots,
+			f2fs_hash_t namehash, struct page **res_page)
+{
+	struct f2fs_dir_entry *de;
+	unsigned long bit_pos, end_pos, next_pos;
+	struct f2fs_dentry_block *dentry_blk = kmap(dentry_page);
+	int slots;
+
+	bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
+					NR_DENTRY_IN_BLOCK, 0);
+	while (bit_pos < NR_DENTRY_IN_BLOCK) {
+		de = &dentry_blk->dentry[bit_pos];
+		slots = GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
+
+		if (early_match_name(name, namelen, namehash, de)) {
+			if (!memcmp(dentry_blk->filename[bit_pos],
+							name, namelen)) {
+				*res_page = dentry_page;
+				goto found;
+			}
+		}
+		next_pos = bit_pos + slots;
+		bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
+				NR_DENTRY_IN_BLOCK, next_pos);
+		if (bit_pos >= NR_DENTRY_IN_BLOCK)
+			end_pos = NR_DENTRY_IN_BLOCK;
+		else
+			end_pos = bit_pos;
+		if (*max_slots < end_pos - next_pos)
+			*max_slots = end_pos - next_pos;
+	}
+
+	de = NULL;
+	kunmap(dentry_page);
+found:
+	return de;
+}
+
+static struct f2fs_dir_entry *find_in_level(struct inode *dir,
+		unsigned int level, const char *name, int namelen,
+			f2fs_hash_t namehash, struct page **res_page)
+{
+	int s = GET_DENTRY_SLOTS(namelen);
+	unsigned int nbucket, nblock;
+	unsigned int bidx, end_block;
+	struct page *dentry_page;
+	struct f2fs_dir_entry *de = NULL;
+	bool room = false;
+	int max_slots = 0;
+
+	BUG_ON(level > MAX_DIR_HASH_DEPTH);
+
+	nbucket = dir_buckets(level);
+	nblock = bucket_blocks(level);
+
+	bidx = dir_block_index(level, le32_to_cpu(namehash) % nbucket);
+	end_block = bidx + nblock;
+
+	for (; bidx < end_block; bidx++) {
+		/* no need to allocate new dentry pages to all the indices */
+		dentry_page = find_data_page(dir, bidx);
+		if (IS_ERR(dentry_page)) {
+			room = true;
+			continue;
+		}
+
+		de = find_in_block(dentry_page, name, namelen,
+					&max_slots, namehash, res_page);
+		if (de)
+			break;
+
+		if (max_slots >= s)
+			room = true;
+		f2fs_put_page(dentry_page, 0);
+	}
+
+	if (!de && room && F2FS_I(dir)->chash != namehash) {
+		F2FS_I(dir)->chash = namehash;
+		F2FS_I(dir)->clevel = level;
+	}
+
+	return de;
+}
+
+/*
+ * Find an entry in the specified directory with the wanted name.
+ * It returns the page where the entry was found (as a parameter - res_page),
+ * and the entry itself. Page is returned mapped and unlocked.
+ * Entry is guaranteed to be valid.
+ */
+struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
+			struct qstr *child, struct page **res_page)
+{
+	const char *name = child->name;
+	int namelen = child->len;
+	unsigned long npages = dir_blocks(dir);
+	struct f2fs_dir_entry *de = NULL;
+	f2fs_hash_t name_hash;
+	unsigned int max_depth;
+	unsigned int level;
+
+	if (npages == 0)
+		return NULL;
+
+	*res_page = NULL;
+
+	name_hash = f2fs_dentry_hash(name, namelen);
+	max_depth = F2FS_I(dir)->i_current_depth;
+
+	for (level = 0; level < max_depth; level++) {
+		de = find_in_level(dir, level, name,
+				namelen, name_hash, res_page);
+		if (de)
+			break;
+	}
+	if (!de && F2FS_I(dir)->chash != name_hash) {
+		F2FS_I(dir)->chash = name_hash;
+		F2FS_I(dir)->clevel = level - 1;
+	}
+	return de;
+}
+
+struct f2fs_dir_entry *f2fs_parent_dir(struct inode *dir, struct page **p)
+{
+	struct page *page = NULL;
+	struct f2fs_dir_entry *de = NULL;
+	struct f2fs_dentry_block *dentry_blk = NULL;
+
+	page = get_lock_data_page(dir, 0);
+	if (IS_ERR(page))
+		return NULL;
+
+	dentry_blk = kmap(page);
+	de = &dentry_blk->dentry[1];
+	*p = page;
+	unlock_page(page);
+	return de;
+}
+
+ino_t f2fs_inode_by_name(struct inode *dir, struct qstr *qstr)
+{
+	ino_t res = 0;
+	struct f2fs_dir_entry *de;
+	struct page *page;
+
+	de = f2fs_find_entry(dir, qstr, &page);
+	if (de) {
+		res = le32_to_cpu(de->ino);
+		kunmap(page);
+		f2fs_put_page(page, 0);
+	}
+
+	return res;
+}
+
+void f2fs_set_link(struct inode *dir, struct f2fs_dir_entry *de,
+		struct page *page, struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
+
+	mutex_lock_op(sbi, DENTRY_OPS);
+	lock_page(page);
+	wait_on_page_writeback(page);
+	de->ino = cpu_to_le32(inode->i_ino);
+	set_de_type(de, inode);
+	kunmap(page);
+	set_page_dirty(page);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+	mark_inode_dirty(dir);
+
+	/* update parent inode number before releasing dentry page */
+	F2FS_I(inode)->i_pino = dir->i_ino;
+
+	f2fs_put_page(page, 1);
+	mutex_unlock_op(sbi, DENTRY_OPS);
+}
+
+void init_dent_inode(struct dentry *dentry, struct page *ipage)
+{
+	struct f2fs_node *rn;
+
+	if (IS_ERR(ipage))
+		return;
+
+	wait_on_page_writeback(ipage);
+
+	/* copy dentry info. to this inode page */
+	rn = (struct f2fs_node *)page_address(ipage);
+	rn->i.i_namelen = cpu_to_le32(dentry->d_name.len);
+	memcpy(rn->i.i_name, dentry->d_name.name, dentry->d_name.len);
+	set_page_dirty(ipage);
+}
+
+static int init_inode_metadata(struct inode *inode, struct dentry *dentry)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+
+	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
+		int err;
+		err = new_inode_page(inode, dentry);
+		if (err)
+			return err;
+
+		if (S_ISDIR(inode->i_mode)) {
+			err = f2fs_make_empty(inode, dir);
+			if (err) {
+				remove_inode_page(inode);
+				return err;
+			}
+		}
+
+		err = f2fs_init_acl(inode, dir);
+		if (err) {
+			remove_inode_page(inode);
+			return err;
+		}
+	} else {
+		struct page *ipage;
+		ipage = get_node_page(F2FS_SB(dir->i_sb), inode->i_ino);
+		if (IS_ERR(ipage))
+			return PTR_ERR(ipage);
+		init_dent_inode(dentry, ipage);
+		f2fs_put_page(ipage, 1);
+	}
+	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK)) {
+		inc_nlink(inode);
+		f2fs_write_inode(inode, NULL);
+	}
+	return 0;
+}
+
+static void update_parent_metadata(struct inode *dir, struct inode *inode,
+						unsigned int current_depth)
+{
+	bool need_dir_update = false;
+
+	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
+		if (S_ISDIR(inode->i_mode)) {
+			inc_nlink(dir);
+			need_dir_update = true;
+		}
+		clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
+	}
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+	if (F2FS_I(dir)->i_current_depth != current_depth) {
+		F2FS_I(dir)->i_current_depth = current_depth;
+		need_dir_update = true;
+	}
+
+	if (need_dir_update)
+		f2fs_write_inode(dir, NULL);
+	else
+		mark_inode_dirty(dir);
+
+	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK))
+		clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
+}
+
+static int room_for_filename(struct f2fs_dentry_block *dentry_blk, int slots)
+{
+	int bit_start = 0;
+	int zero_start, zero_end;
+next:
+	zero_start = find_next_zero_bit_le(&dentry_blk->dentry_bitmap,
+						NR_DENTRY_IN_BLOCK,
+						bit_start);
+	if (zero_start >= NR_DENTRY_IN_BLOCK)
+		return NR_DENTRY_IN_BLOCK;
+
+	zero_end = find_next_bit_le(&dentry_blk->dentry_bitmap,
+						NR_DENTRY_IN_BLOCK,
+						zero_start);
+	if (zero_end - zero_start >= slots)
+		return zero_start;
+
+	bit_start = zero_end + 1;
+
+	if (zero_end + 1 >= NR_DENTRY_IN_BLOCK)
+		return NR_DENTRY_IN_BLOCK;
+	goto next;
+}
+
+int f2fs_add_link(struct dentry *dentry, struct inode *inode)
+{
+	unsigned int bit_pos;
+	unsigned int level;
+	unsigned int current_depth;
+	unsigned long bidx, block;
+	f2fs_hash_t dentry_hash;
+	struct f2fs_dir_entry *de;
+	unsigned int nbucket, nblock;
+	struct inode *dir = dentry->d_parent->d_inode;
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	struct page *dentry_page = NULL;
+	struct f2fs_dentry_block *dentry_blk = NULL;
+	int slots = GET_DENTRY_SLOTS(namelen);
+	int err = 0;
+	int i;
+
+	dentry_hash = f2fs_dentry_hash(name, dentry->d_name.len);
+	level = 0;
+	current_depth = F2FS_I(dir)->i_current_depth;
+	if (F2FS_I(dir)->chash == dentry_hash) {
+		level = F2FS_I(dir)->clevel;
+		F2FS_I(dir)->chash = 0;
+	}
+
+start:
+	if (current_depth == MAX_DIR_HASH_DEPTH)
+		return -ENOSPC;
+
+	/* Increase the depth, if required */
+	if (level == current_depth)
+		++current_depth;
+
+	nbucket = dir_buckets(level);
+	nblock = bucket_blocks(level);
+
+	bidx = dir_block_index(level, (le32_to_cpu(dentry_hash) % nbucket));
+
+	for (block = bidx; block <= (bidx + nblock - 1); block++) {
+		mutex_lock_op(sbi, DENTRY_OPS);
+		dentry_page = get_new_data_page(dir, block, true);
+		if (IS_ERR(dentry_page)) {
+			mutex_unlock_op(sbi, DENTRY_OPS);
+			return PTR_ERR(dentry_page);
+		}
+
+		dentry_blk = kmap(dentry_page);
+		bit_pos = room_for_filename(dentry_blk, slots);
+		if (bit_pos < NR_DENTRY_IN_BLOCK)
+			goto add_dentry;
+
+		kunmap(dentry_page);
+		f2fs_put_page(dentry_page, 1);
+		mutex_unlock_op(sbi, DENTRY_OPS);
+	}
+
+	/* Move to next level to find the empty slot for new dentry */
+	++level;
+	goto start;
+add_dentry:
+	err = init_inode_metadata(inode, dentry);
+	if (err)
+		goto fail;
+
+	wait_on_page_writeback(dentry_page);
+
+	de = &dentry_blk->dentry[bit_pos];
+	de->hash_code = dentry_hash;
+	de->name_len = cpu_to_le16(namelen);
+	memcpy(dentry_blk->filename[bit_pos], name, namelen);
+	de->ino = cpu_to_le32(inode->i_ino);
+	set_de_type(de, inode);
+	for (i = 0; i < slots; i++)
+		test_and_set_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
+	set_page_dirty(dentry_page);
+
+	update_parent_metadata(dir, inode, current_depth);
+
+	/* update parent inode number before releasing dentry page */
+	F2FS_I(inode)->i_pino = dir->i_ino;
+fail:
+	kunmap(dentry_page);
+	f2fs_put_page(dentry_page, 1);
+	mutex_unlock_op(sbi, DENTRY_OPS);
+	return err;
+}
+
+/*
+ * It only removes the dentry from the dentry page,corresponding name
+ * entry in name page does not need to be touched during deletion.
+ */
+void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
+						struct inode *inode)
+{
+	struct	f2fs_dentry_block *dentry_blk;
+	unsigned int bit_pos;
+	struct address_space *mapping = page->mapping;
+	struct inode *dir = mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
+	int slots = GET_DENTRY_SLOTS(le16_to_cpu(dentry->name_len));
+	void *kaddr = page_address(page);
+	int i;
+
+	mutex_lock_op(sbi, DENTRY_OPS);
+
+	lock_page(page);
+	wait_on_page_writeback(page);
+
+	dentry_blk = (struct f2fs_dentry_block *)kaddr;
+	bit_pos = dentry - (struct f2fs_dir_entry *)dentry_blk->dentry;
+	for (i = 0; i < slots; i++)
+		test_and_clear_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
+
+	/* Let's check and deallocate this dentry page */
+	bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
+			NR_DENTRY_IN_BLOCK,
+			0);
+	kunmap(page); /* kunmap - pair of f2fs_find_entry */
+	set_page_dirty(page);
+
+	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+
+	if (inode && S_ISDIR(inode->i_mode)) {
+		drop_nlink(dir);
+		f2fs_write_inode(dir, NULL);
+	} else {
+		mark_inode_dirty(dir);
+	}
+
+	if (inode) {
+		inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+		drop_nlink(inode);
+		if (S_ISDIR(inode->i_mode)) {
+			drop_nlink(inode);
+			i_size_write(inode, 0);
+		}
+		f2fs_write_inode(inode, NULL);
+		if (inode->i_nlink == 0)
+			add_orphan_inode(sbi, inode->i_ino);
+	}
+
+	if (bit_pos == NR_DENTRY_IN_BLOCK) {
+		truncate_hole(dir, page->index, page->index + 1);
+		clear_page_dirty_for_io(page);
+		ClearPageUptodate(page);
+		dec_page_count(sbi, F2FS_DIRTY_DENTS);
+		inode_dec_dirty_dents(dir);
+	}
+	f2fs_put_page(page, 1);
+
+	mutex_unlock_op(sbi, DENTRY_OPS);
+}
+
+int f2fs_make_empty(struct inode *inode, struct inode *parent)
+{
+	struct page *dentry_page;
+	struct f2fs_dentry_block *dentry_blk;
+	struct f2fs_dir_entry *de;
+	void *kaddr;
+
+	dentry_page = get_new_data_page(inode, 0, true);
+	if (IS_ERR(dentry_page))
+		return PTR_ERR(dentry_page);
+
+	kaddr = kmap_atomic(dentry_page);
+	dentry_blk = (struct f2fs_dentry_block *)kaddr;
+
+	de = &dentry_blk->dentry[0];
+	de->name_len = cpu_to_le16(1);
+	de->hash_code = 0;
+	de->ino = cpu_to_le32(inode->i_ino);
+	memcpy(dentry_blk->filename[0], ".", 1);
+	set_de_type(de, inode);
+
+	de = &dentry_blk->dentry[1];
+	de->hash_code = 0;
+	de->name_len = cpu_to_le16(2);
+	de->ino = cpu_to_le32(parent->i_ino);
+	memcpy(dentry_blk->filename[1], "..", 2);
+	set_de_type(de, inode);
+
+	test_and_set_bit_le(0, &dentry_blk->dentry_bitmap);
+	test_and_set_bit_le(1, &dentry_blk->dentry_bitmap);
+	kunmap_atomic(kaddr);
+
+	set_page_dirty(dentry_page);
+	f2fs_put_page(dentry_page, 1);
+	return 0;
+}
+
+bool f2fs_empty_dir(struct inode *dir)
+{
+	unsigned long bidx;
+	struct page *dentry_page;
+	unsigned int bit_pos;
+	struct	f2fs_dentry_block *dentry_blk;
+	unsigned long nblock = dir_blocks(dir);
+
+	for (bidx = 0; bidx < nblock; bidx++) {
+		void *kaddr;
+		dentry_page = get_lock_data_page(dir, bidx);
+		if (IS_ERR(dentry_page)) {
+			if (PTR_ERR(dentry_page) == -ENOENT)
+				continue;
+			else
+				return false;
+		}
+
+		kaddr = kmap_atomic(dentry_page);
+		dentry_blk = (struct f2fs_dentry_block *)kaddr;
+		if (bidx == 0)
+			bit_pos = 2;
+		else
+			bit_pos = 0;
+		bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
+						NR_DENTRY_IN_BLOCK,
+						bit_pos);
+		kunmap_atomic(kaddr);
+
+		f2fs_put_page(dentry_page, 1);
+
+		if (bit_pos < NR_DENTRY_IN_BLOCK)
+			return false;
+	}
+	return true;
+}
+
+static int f2fs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+	unsigned long pos = file->f_pos;
+	struct inode *inode = file->f_dentry->d_inode;
+	unsigned long npages = dir_blocks(inode);
+	unsigned char *types = NULL;
+	unsigned int bit_pos = 0, start_bit_pos = 0;
+	int over = 0;
+	struct f2fs_dentry_block *dentry_blk = NULL;
+	struct f2fs_dir_entry *de = NULL;
+	struct page *dentry_page = NULL;
+	unsigned int n = 0;
+	unsigned char d_type = DT_UNKNOWN;
+	int slots;
+
+	types = f2fs_filetype_table;
+	bit_pos = (pos % NR_DENTRY_IN_BLOCK);
+	n = (pos / NR_DENTRY_IN_BLOCK);
+
+	for ( ; n < npages; n++) {
+		dentry_page = get_lock_data_page(inode, n);
+		if (IS_ERR(dentry_page))
+			continue;
+
+		start_bit_pos = bit_pos;
+		dentry_blk = kmap(dentry_page);
+		while (bit_pos < NR_DENTRY_IN_BLOCK) {
+			d_type = DT_UNKNOWN;
+			bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
+							NR_DENTRY_IN_BLOCK,
+							bit_pos);
+			if (bit_pos >= NR_DENTRY_IN_BLOCK)
+				break;
+
+			de = &dentry_blk->dentry[bit_pos];
+			if (types && de->file_type < F2FS_FT_MAX)
+				d_type = types[de->file_type];
+
+			over = filldir(dirent,
+					dentry_blk->filename[bit_pos],
+					le16_to_cpu(de->name_len),
+					(n * NR_DENTRY_IN_BLOCK) + bit_pos,
+					le32_to_cpu(de->ino), d_type);
+			if (over) {
+				file->f_pos += bit_pos - start_bit_pos;
+				goto success;
+			}
+			slots = GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
+			bit_pos += slots;
+		}
+		bit_pos = 0;
+		file->f_pos = (n + 1) * NR_DENTRY_IN_BLOCK;
+		kunmap(dentry_page);
+		f2fs_put_page(dentry_page, 1);
+		dentry_page = NULL;
+	}
+success:
+	if (dentry_page && !IS_ERR(dentry_page)) {
+		kunmap(dentry_page);
+		f2fs_put_page(dentry_page, 1);
+	}
+
+	return 0;
+}
+
+const struct file_operations f2fs_dir_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.readdir	= f2fs_readdir,
+	.fsync		= f2fs_sync_file,
+	.unlocked_ioctl	= f2fs_ioctl,
+};

fs/f2fs/f2fs.h

···
+/*
+ * fs/f2fs/f2fs.h
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef _LINUX_F2FS_H
+#define _LINUX_F2FS_H
+
+#include <linux/types.h>
+#include <linux/page-flags.h>
+#include <linux/buffer_head.h>
+#include <linux/slab.h>
+#include <linux/crc32.h>
+#include <linux/magic.h>
+
+/*
+ * For mount options
+ */
+#define F2FS_MOUNT_BG_GC		0x00000001
+#define F2FS_MOUNT_DISABLE_ROLL_FORWARD	0x00000002
+#define F2FS_MOUNT_DISCARD		0x00000004
+#define F2FS_MOUNT_NOHEAP		0x00000008
+#define F2FS_MOUNT_XATTR_USER		0x00000010
+#define F2FS_MOUNT_POSIX_ACL		0x00000020
+#define F2FS_MOUNT_DISABLE_EXT_IDENTIFY	0x00000040
+
+#define clear_opt(sbi, option)	(sbi->mount_opt.opt &= ~F2FS_MOUNT_##option)
+#define set_opt(sbi, option)	(sbi->mount_opt.opt |= F2FS_MOUNT_##option)
+#define test_opt(sbi, option)	(sbi->mount_opt.opt & F2FS_MOUNT_##option)
+
+#define ver_after(a, b)	(typecheck(unsigned long long, a) &&		\
+		typecheck(unsigned long long, b) &&			\
+		((long long)((a) - (b)) > 0))
+
+typedef u64 block_t;
+typedef u32 nid_t;
+
+struct f2fs_mount_info {
+	unsigned int	opt;
+};
+
+static inline __u32 f2fs_crc32(void *buff, size_t len)
+{
+	return crc32_le(F2FS_SUPER_MAGIC, buff, len);
+}
+
+static inline bool f2fs_crc_valid(__u32 blk_crc, void *buff, size_t buff_size)
+{
+	return f2fs_crc32(buff, buff_size) == blk_crc;
+}
+
+/*
+ * For checkpoint manager
+ */
+enum {
+	NAT_BITMAP,
+	SIT_BITMAP
+};
+
+/* for the list of orphan inodes */
+struct orphan_inode_entry {
+	struct list_head list;	/* list head */
+	nid_t ino;		/* inode number */
+};
+
+/* for the list of directory inodes */
+struct dir_inode_entry {
+	struct list_head list;	/* list head */
+	struct inode *inode;	/* vfs inode pointer */
+};
+
+/* for the list of fsync inodes, used only during recovery */
+struct fsync_inode_entry {
+	struct list_head list;	/* list head */
+	struct inode *inode;	/* vfs inode pointer */
+	block_t blkaddr;	/* block address locating the last inode */
+};
+
+#define nats_in_cursum(sum)		(le16_to_cpu(sum->n_nats))
+#define sits_in_cursum(sum)		(le16_to_cpu(sum->n_sits))
+
+#define nat_in_journal(sum, i)		(sum->nat_j.entries[i].ne)
+#define nid_in_journal(sum, i)		(sum->nat_j.entries[i].nid)
+#define sit_in_journal(sum, i)		(sum->sit_j.entries[i].se)
+#define segno_in_journal(sum, i)	(sum->sit_j.entries[i].segno)
+
+static inline int update_nats_in_cursum(struct f2fs_summary_block *rs, int i)
+{
+	int before = nats_in_cursum(rs);
+	rs->n_nats = cpu_to_le16(before + i);
+	return before;
+}
+
+static inline int update_sits_in_cursum(struct f2fs_summary_block *rs, int i)
+{
+	int before = sits_in_cursum(rs);
+	rs->n_sits = cpu_to_le16(before + i);
+	return before;
+}
+
+/*
+ * For INODE and NODE manager
+ */
+#define XATTR_NODE_OFFSET	(-1)	/*
+					 * store xattrs to one node block per
+					 * file keeping -1 as its node offset to
+					 * distinguish from index node blocks.
+					 */
+#define RDONLY_NODE		1	/*
+					 * specify a read-only mode when getting
+					 * a node block. 0 is read-write mode.
+					 * used by get_dnode_of_data().
+					 */
+#define F2FS_LINK_MAX		32000	/* maximum link count per file */
+
+/* for in-memory extent cache entry */
+struct extent_info {
+	rwlock_t ext_lock;	/* rwlock for consistency */
+	unsigned int fofs;	/* start offset in a file */
+	u32 blk_addr;		/* start block address of the extent */
+	unsigned int len;	/* lenth of the extent */
+};
+
+/*
+ * i_advise uses FADVISE_XXX_BIT. We can add additional hints later.
+ */
+#define FADVISE_COLD_BIT	0x01
+
+struct f2fs_inode_info {
+	struct inode vfs_inode;		/* serve a vfs inode */
+	unsigned long i_flags;		/* keep an inode flags for ioctl */
+	unsigned char i_advise;		/* use to give file attribute hints */
+	unsigned int i_current_depth;	/* use only in directory structure */
+	unsigned int i_pino;		/* parent inode number */
+	umode_t i_acl_mode;		/* keep file acl mode temporarily */
+
+	/* Use below internally in f2fs*/
+	unsigned long flags;		/* use to pass per-file flags */
+	unsigned long long data_version;/* lastes version of data for fsync */
+	atomic_t dirty_dents;		/* # of dirty dentry pages */
+	f2fs_hash_t chash;		/* hash value of given file name */
+	unsigned int clevel;		/* maximum level of given file name */
+	nid_t i_xattr_nid;		/* node id that contains xattrs */
+	struct extent_info ext;		/* in-memory extent cache entry */
+};
+
+static inline void get_extent_info(struct extent_info *ext,
+					struct f2fs_extent i_ext)
+{
+	write_lock(&ext->ext_lock);
+	ext->fofs = le32_to_cpu(i_ext.fofs);
+	ext->blk_addr = le32_to_cpu(i_ext.blk_addr);
+	ext->len = le32_to_cpu(i_ext.len);
+	write_unlock(&ext->ext_lock);
+}
+
+static inline void set_raw_extent(struct extent_info *ext,
+					struct f2fs_extent *i_ext)
+{
+	read_lock(&ext->ext_lock);
+	i_ext->fofs = cpu_to_le32(ext->fofs);
+	i_ext->blk_addr = cpu_to_le32(ext->blk_addr);
+	i_ext->len = cpu_to_le32(ext->len);
+	read_unlock(&ext->ext_lock);
+}
+
+struct f2fs_nm_info {
+	block_t nat_blkaddr;		/* base disk address of NAT */
+	nid_t max_nid;			/* maximum possible node ids */
+	nid_t init_scan_nid;		/* the first nid to be scanned */
+	nid_t next_scan_nid;		/* the next nid to be scanned */
+
+	/* NAT cache management */
+	struct radix_tree_root nat_root;/* root of the nat entry cache */
+	rwlock_t nat_tree_lock;		/* protect nat_tree_lock */
+	unsigned int nat_cnt;		/* the # of cached nat entries */
+	struct list_head nat_entries;	/* cached nat entry list (clean) */
+	struct list_head dirty_nat_entries; /* cached nat entry list (dirty) */
+
+	/* free node ids management */
+	struct list_head free_nid_list;	/* a list for free nids */
+	spinlock_t free_nid_list_lock;	/* protect free nid list */
+	unsigned int fcnt;		/* the number of free node id */
+	struct mutex build_lock;	/* lock for build free nids */
+
+	/* for checkpoint */
+	char *nat_bitmap;		/* NAT bitmap pointer */
+	int bitmap_size;		/* bitmap size */
+};
+
+/*
+ * this structure is used as one of function parameters.
+ * all the information are dedicated to a given direct node block determined
+ * by the data offset in a file.
+ */
+struct dnode_of_data {
+	struct inode *inode;		/* vfs inode pointer */
+	struct page *inode_page;	/* its inode page, NULL is possible */
+	struct page *node_page;		/* cached direct node page */
+	nid_t nid;			/* node id of the direct node block */
+	unsigned int ofs_in_node;	/* data offset in the node page */
+	bool inode_page_locked;		/* inode page is locked or not */
+	block_t	data_blkaddr;		/* block address of the node block */
+};
+
+static inline void set_new_dnode(struct dnode_of_data *dn, struct inode *inode,
+		struct page *ipage, struct page *npage, nid_t nid)
+{
+	dn->inode = inode;
+	dn->inode_page = ipage;
+	dn->node_page = npage;
+	dn->nid = nid;
+	dn->inode_page_locked = 0;
+}
+
+/*
+ * For SIT manager
+ *
+ * By default, there are 6 active log areas across the whole main area.
+ * When considering hot and cold data separation to reduce cleaning overhead,
+ * we split 3 for data logs and 3 for node logs as hot, warm, and cold types,
+ * respectively.
+ * In the current design, you should not change the numbers intentionally.
+ * Instead, as a mount option such as active_logs=x, you can use 2, 4, and 6
+ * logs individually according to the underlying devices. (default: 6)
+ * Just in case, on-disk layout covers maximum 16 logs that consist of 8 for
+ * data and 8 for node logs.
+ */
+#define	NR_CURSEG_DATA_TYPE	(3)
+#define NR_CURSEG_NODE_TYPE	(3)
+#define NR_CURSEG_TYPE	(NR_CURSEG_DATA_TYPE + NR_CURSEG_NODE_TYPE)
+
+enum {
+	CURSEG_HOT_DATA	= 0,	/* directory entry blocks */
+	CURSEG_WARM_DATA,	/* data blocks */
+	CURSEG_COLD_DATA,	/* multimedia or GCed data blocks */
+	CURSEG_HOT_NODE,	/* direct node blocks of directory files */
+	CURSEG_WARM_NODE,	/* direct node blocks of normal files */
+	CURSEG_COLD_NODE,	/* indirect node blocks */
+	NO_CHECK_TYPE
+};
+
+struct f2fs_sm_info {
+	struct sit_info *sit_info;		/* whole segment information */
+	struct free_segmap_info *free_info;	/* free segment information */
+	struct dirty_seglist_info *dirty_info;	/* dirty segment information */
+	struct curseg_info *curseg_array;	/* active segment information */
+
+	struct list_head wblist_head;	/* list of under-writeback pages */
+	spinlock_t wblist_lock;		/* lock for checkpoint */
+
+	block_t seg0_blkaddr;		/* block address of 0'th segment */
+	block_t main_blkaddr;		/* start block address of main area */
+	block_t ssa_blkaddr;		/* start block address of SSA area */
+
+	unsigned int segment_count;	/* total # of segments */
+	unsigned int main_segments;	/* # of segments in main area */
+	unsigned int reserved_segments;	/* # of reserved segments */
+	unsigned int ovp_segments;	/* # of overprovision segments */
+};
+
+/*
+ * For directory operation
+ */
+#define	NODE_DIR1_BLOCK		(ADDRS_PER_INODE + 1)
+#define	NODE_DIR2_BLOCK		(ADDRS_PER_INODE + 2)
+#define	NODE_IND1_BLOCK		(ADDRS_PER_INODE + 3)
+#define	NODE_IND2_BLOCK		(ADDRS_PER_INODE + 4)
+#define	NODE_DIND_BLOCK		(ADDRS_PER_INODE + 5)
+
+/*
+ * For superblock
+ */
+/*
+ * COUNT_TYPE for monitoring
+ *
+ * f2fs monitors the number of several block types such as on-writeback,
+ * dirty dentry blocks, dirty node blocks, and dirty meta blocks.
+ */
+enum count_type {
+	F2FS_WRITEBACK,
+	F2FS_DIRTY_DENTS,
+	F2FS_DIRTY_NODES,
+	F2FS_DIRTY_META,
+	NR_COUNT_TYPE,
+};
+
+/*
+ * FS_LOCK nesting subclasses for the lock validator:
+ *
+ * The locking order between these classes is
+ * RENAME -> DENTRY_OPS -> DATA_WRITE -> DATA_NEW
+ *    -> DATA_TRUNC -> NODE_WRITE -> NODE_NEW -> NODE_TRUNC
+ */
+enum lock_type {
+	RENAME,		/* for renaming operations */
+	DENTRY_OPS,	/* for directory operations */
+	DATA_WRITE,	/* for data write */
+	DATA_NEW,	/* for data allocation */
+	DATA_TRUNC,	/* for data truncate */
+	NODE_NEW,	/* for node allocation */
+	NODE_TRUNC,	/* for node truncate */
+	NODE_WRITE,	/* for node write */
+	NR_LOCK_TYPE,
+};
+
+/*
+ * The below are the page types of bios used in submti_bio().
+ * The available types are:
+ * DATA			User data pages. It operates as async mode.
+ * NODE			Node pages. It operates as async mode.
+ * META			FS metadata pages such as SIT, NAT, CP.
+ * NR_PAGE_TYPE		The number of page types.
+ * META_FLUSH		Make sure the previous pages are written
+ *			with waiting the bio's completion
+ * ...			Only can be used with META.
+ */
+enum page_type {
+	DATA,
+	NODE,
+	META,
+	NR_PAGE_TYPE,
+	META_FLUSH,
+};
+
+struct f2fs_sb_info {
+	struct super_block *sb;			/* pointer to VFS super block */
+	struct buffer_head *raw_super_buf;	/* buffer head of raw sb */
+	struct f2fs_super_block *raw_super;	/* raw super block pointer */
+	int s_dirty;				/* dirty flag for checkpoint */
+
+	/* for node-related operations */
+	struct f2fs_nm_info *nm_info;		/* node manager */
+	struct inode *node_inode;		/* cache node blocks */
+
+	/* for segment-related operations */
+	struct f2fs_sm_info *sm_info;		/* segment manager */
+	struct bio *bio[NR_PAGE_TYPE];		/* bios to merge */
+	sector_t last_block_in_bio[NR_PAGE_TYPE];	/* last block number */
+	struct rw_semaphore bio_sem;		/* IO semaphore */
+
+	/* for checkpoint */
+	struct f2fs_checkpoint *ckpt;		/* raw checkpoint pointer */
+	struct inode *meta_inode;		/* cache meta blocks */
+	struct mutex cp_mutex;			/* for checkpoint procedure */
+	struct mutex fs_lock[NR_LOCK_TYPE];	/* for blocking FS operations */
+	struct mutex write_inode;		/* mutex for write inode */
+	struct mutex writepages;		/* mutex for writepages() */
+	int por_doing;				/* recovery is doing or not */
+
+	/* for orphan inode management */
+	struct list_head orphan_inode_list;	/* orphan inode list */
+	struct mutex orphan_inode_mutex;	/* for orphan inode list */
+	unsigned int n_orphans;			/* # of orphan inodes */
+
+	/* for directory inode management */
+	struct list_head dir_inode_list;	/* dir inode list */
+	spinlock_t dir_inode_lock;		/* for dir inode list lock */
+	unsigned int n_dirty_dirs;		/* # of dir inodes */
+
+	/* basic file system units */
+	unsigned int log_sectors_per_block;	/* log2 sectors per block */
+	unsigned int log_blocksize;		/* log2 block size */
+	unsigned int blocksize;			/* block size */
+	unsigned int root_ino_num;		/* root inode number*/
+	unsigned int node_ino_num;		/* node inode number*/
+	unsigned int meta_ino_num;		/* meta inode number*/
+	unsigned int log_blocks_per_seg;	/* log2 blocks per segment */
+	unsigned int blocks_per_seg;		/* blocks per segment */
+	unsigned int segs_per_sec;		/* segments per section */
+	unsigned int secs_per_zone;		/* sections per zone */
+	unsigned int total_sections;		/* total section count */
+	unsigned int total_node_count;		/* total node block count */
+	unsigned int total_valid_node_count;	/* valid node block count */
+	unsigned int total_valid_inode_count;	/* valid inode count */
+	int active_logs;			/* # of active logs */
+
+	block_t user_block_count;		/* # of user blocks */
+	block_t total_valid_block_count;	/* # of valid blocks */
+	block_t alloc_valid_block_count;	/* # of allocated blocks */
+	block_t last_valid_block_count;		/* for recovery */
+	u32 s_next_generation;			/* for NFS support */
+	atomic_t nr_pages[NR_COUNT_TYPE];	/* # of pages, see count_type */
+
+	struct f2fs_mount_info mount_opt;	/* mount options */
+
+	/* for cleaning operations */
+	struct mutex gc_mutex;			/* mutex for GC */
+	struct f2fs_gc_kthread	*gc_thread;	/* GC thread */
+
+	/*
+	 * for stat information.
+	 * one is for the LFS mode, and the other is for the SSR mode.
+	 */
+	struct f2fs_stat_info *stat_info;	/* FS status information */
+	unsigned int segment_count[2];		/* # of allocated segments */
+	unsigned int block_count[2];		/* # of allocated blocks */
+	unsigned int last_victim[2];		/* last victim segment # */
+	int total_hit_ext, read_hit_ext;	/* extent cache hit ratio */
+	int bg_gc;				/* background gc calls */
+	spinlock_t stat_lock;			/* lock for stat operations */
+};
+
+/*
+ * Inline functions
+ */
+static inline struct f2fs_inode_info *F2FS_I(struct inode *inode)
+{
+	return container_of(inode, struct f2fs_inode_info, vfs_inode);
+}
+
+static inline struct f2fs_sb_info *F2FS_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+static inline struct f2fs_super_block *F2FS_RAW_SUPER(struct f2fs_sb_info *sbi)
+{
+	return (struct f2fs_super_block *)(sbi->raw_super);
+}
+
+static inline struct f2fs_checkpoint *F2FS_CKPT(struct f2fs_sb_info *sbi)
+{
+	return (struct f2fs_checkpoint *)(sbi->ckpt);
+}
+
+static inline struct f2fs_nm_info *NM_I(struct f2fs_sb_info *sbi)
+{
+	return (struct f2fs_nm_info *)(sbi->nm_info);
+}
+
+static inline struct f2fs_sm_info *SM_I(struct f2fs_sb_info *sbi)
+{
+	return (struct f2fs_sm_info *)(sbi->sm_info);
+}
+
+static inline struct sit_info *SIT_I(struct f2fs_sb_info *sbi)
+{
+	return (struct sit_info *)(SM_I(sbi)->sit_info);
+}
+
+static inline struct free_segmap_info *FREE_I(struct f2fs_sb_info *sbi)
+{
+	return (struct free_segmap_info *)(SM_I(sbi)->free_info);
+}
+
+static inline struct dirty_seglist_info *DIRTY_I(struct f2fs_sb_info *sbi)
+{
+	return (struct dirty_seglist_info *)(SM_I(sbi)->dirty_info);
+}
+
+static inline void F2FS_SET_SB_DIRT(struct f2fs_sb_info *sbi)
+{
+	sbi->s_dirty = 1;
+}
+
+static inline void F2FS_RESET_SB_DIRT(struct f2fs_sb_info *sbi)
+{
+	sbi->s_dirty = 0;
+}
+
+static inline bool is_set_ckpt_flags(struct f2fs_checkpoint *cp, unsigned int f)
+{
+	unsigned int ckpt_flags = le32_to_cpu(cp->ckpt_flags);
+	return ckpt_flags & f;
+}
+
+static inline void set_ckpt_flags(struct f2fs_checkpoint *cp, unsigned int f)
+{
+	unsigned int ckpt_flags = le32_to_cpu(cp->ckpt_flags);
+	ckpt_flags |= f;
+	cp->ckpt_flags = cpu_to_le32(ckpt_flags);
+}
+
+static inline void clear_ckpt_flags(struct f2fs_checkpoint *cp, unsigned int f)
+{
+	unsigned int ckpt_flags = le32_to_cpu(cp->ckpt_flags);
+	ckpt_flags &= (~f);
+	cp->ckpt_flags = cpu_to_le32(ckpt_flags);
+}
+
+static inline void mutex_lock_op(struct f2fs_sb_info *sbi, enum lock_type t)
+{
+	mutex_lock_nested(&sbi->fs_lock[t], t);
+}
+
+static inline void mutex_unlock_op(struct f2fs_sb_info *sbi, enum lock_type t)
+{
+	mutex_unlock(&sbi->fs_lock[t]);
+}
+
+/*
+ * Check whether the given nid is within node id range.
+ */
+static inline void check_nid_range(struct f2fs_sb_info *sbi, nid_t nid)
+{
+	BUG_ON((nid >= NM_I(sbi)->max_nid));
+}
+
+#define F2FS_DEFAULT_ALLOCATED_BLOCKS	1
+
+/*
+ * Check whether the inode has blocks or not
+ */
+static inline int F2FS_HAS_BLOCKS(struct inode *inode)
+{
+	if (F2FS_I(inode)->i_xattr_nid)
+		return (inode->i_blocks > F2FS_DEFAULT_ALLOCATED_BLOCKS + 1);
+	else
+		return (inode->i_blocks > F2FS_DEFAULT_ALLOCATED_BLOCKS);
+}
+
+static inline bool inc_valid_block_count(struct f2fs_sb_info *sbi,
+				 struct inode *inode, blkcnt_t count)
+{
+	block_t	valid_block_count;
+
+	spin_lock(&sbi->stat_lock);
+	valid_block_count =
+		sbi->total_valid_block_count + (block_t)count;
+	if (valid_block_count > sbi->user_block_count) {
+		spin_unlock(&sbi->stat_lock);
+		return false;
+	}
+	inode->i_blocks += count;
+	sbi->total_valid_block_count = valid_block_count;
+	sbi->alloc_valid_block_count += (block_t)count;
+	spin_unlock(&sbi->stat_lock);
+	return true;
+}
+
+static inline int dec_valid_block_count(struct f2fs_sb_info *sbi,
+						struct inode *inode,
+						blkcnt_t count)
+{
+	spin_lock(&sbi->stat_lock);
+	BUG_ON(sbi->total_valid_block_count < (block_t) count);
+	BUG_ON(inode->i_blocks < count);
+	inode->i_blocks -= count;
+	sbi->total_valid_block_count -= (block_t)count;
+	spin_unlock(&sbi->stat_lock);
+	return 0;
+}
+
+static inline void inc_page_count(struct f2fs_sb_info *sbi, int count_type)
+{
+	atomic_inc(&sbi->nr_pages[count_type]);
+	F2FS_SET_SB_DIRT(sbi);
+}
+
+static inline void inode_inc_dirty_dents(struct inode *inode)
+{
+	atomic_inc(&F2FS_I(inode)->dirty_dents);
+}
+
+static inline void dec_page_count(struct f2fs_sb_info *sbi, int count_type)
+{
+	atomic_dec(&sbi->nr_pages[count_type]);
+}
+
+static inline void inode_dec_dirty_dents(struct inode *inode)
+{
+	atomic_dec(&F2FS_I(inode)->dirty_dents);
+}
+
+static inline int get_pages(struct f2fs_sb_info *sbi, int count_type)
+{
+	return atomic_read(&sbi->nr_pages[count_type]);
+}
+
+static inline block_t valid_user_blocks(struct f2fs_sb_info *sbi)
+{
+	block_t ret;
+	spin_lock(&sbi->stat_lock);
+	ret = sbi->total_valid_block_count;
+	spin_unlock(&sbi->stat_lock);
+	return ret;
+}
+
+static inline unsigned long __bitmap_size(struct f2fs_sb_info *sbi, int flag)
+{
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+
+	/* return NAT or SIT bitmap */
+	if (flag == NAT_BITMAP)
+		return le32_to_cpu(ckpt->nat_ver_bitmap_bytesize);
+	else if (flag == SIT_BITMAP)
+		return le32_to_cpu(ckpt->sit_ver_bitmap_bytesize);
+
+	return 0;
+}
+
+static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
+{
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	int offset = (flag == NAT_BITMAP) ?
+			le32_to_cpu(ckpt->sit_ver_bitmap_bytesize) : 0;
+	return &ckpt->sit_nat_version_bitmap + offset;
+}
+
+static inline block_t __start_cp_addr(struct f2fs_sb_info *sbi)
+{
+	block_t start_addr;
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	unsigned long long ckpt_version = le64_to_cpu(ckpt->checkpoint_ver);
+
+	start_addr = le32_to_cpu(F2FS_RAW_SUPER(sbi)->cp_blkaddr);
+
+	/*
+	 * odd numbered checkpoint should at cp segment 0
+	 * and even segent must be at cp segment 1
+	 */
+	if (!(ckpt_version & 1))
+		start_addr += sbi->blocks_per_seg;
+
+	return start_addr;
+}
+
+static inline block_t __start_sum_addr(struct f2fs_sb_info *sbi)
+{
+	return le32_to_cpu(F2FS_CKPT(sbi)->cp_pack_start_sum);
+}
+
+static inline bool inc_valid_node_count(struct f2fs_sb_info *sbi,
+						struct inode *inode,
+						unsigned int count)
+{
+	block_t	valid_block_count;
+	unsigned int valid_node_count;
+
+	spin_lock(&sbi->stat_lock);
+
+	valid_block_count = sbi->total_valid_block_count + (block_t)count;
+	sbi->alloc_valid_block_count += (block_t)count;
+	valid_node_count = sbi->total_valid_node_count + count;
+
+	if (valid_block_count > sbi->user_block_count) {
+		spin_unlock(&sbi->stat_lock);
+		return false;
+	}
+
+	if (valid_node_count > sbi->total_node_count) {
+		spin_unlock(&sbi->stat_lock);
+		return false;
+	}
+
+	if (inode)
+		inode->i_blocks += count;
+	sbi->total_valid_node_count = valid_node_count;
+	sbi->total_valid_block_count = valid_block_count;
+	spin_unlock(&sbi->stat_lock);
+
+	return true;
+}
+
+static inline void dec_valid_node_count(struct f2fs_sb_info *sbi,
+						struct inode *inode,
+						unsigned int count)
+{
+	spin_lock(&sbi->stat_lock);
+
+	BUG_ON(sbi->total_valid_block_count < count);
+	BUG_ON(sbi->total_valid_node_count < count);
+	BUG_ON(inode->i_blocks < count);
+
+	inode->i_blocks -= count;
+	sbi->total_valid_node_count -= count;
+	sbi->total_valid_block_count -= (block_t)count;
+
+	spin_unlock(&sbi->stat_lock);
+}
+
+static inline unsigned int valid_node_count(struct f2fs_sb_info *sbi)
+{
+	unsigned int ret;
+	spin_lock(&sbi->stat_lock);
+	ret = sbi->total_valid_node_count;
+	spin_unlock(&sbi->stat_lock);
+	return ret;
+}
+
+static inline void inc_valid_inode_count(struct f2fs_sb_info *sbi)
+{
+	spin_lock(&sbi->stat_lock);
+	BUG_ON(sbi->total_valid_inode_count == sbi->total_node_count);
+	sbi->total_valid_inode_count++;
+	spin_unlock(&sbi->stat_lock);
+}
+
+static inline int dec_valid_inode_count(struct f2fs_sb_info *sbi)
+{
+	spin_lock(&sbi->stat_lock);
+	BUG_ON(!sbi->total_valid_inode_count);
+	sbi->total_valid_inode_count--;
+	spin_unlock(&sbi->stat_lock);
+	return 0;
+}
+
+static inline unsigned int valid_inode_count(struct f2fs_sb_info *sbi)
+{
+	unsigned int ret;
+	spin_lock(&sbi->stat_lock);
+	ret = sbi->total_valid_inode_count;
+	spin_unlock(&sbi->stat_lock);
+	return ret;
+}
+
+static inline void f2fs_put_page(struct page *page, int unlock)
+{
+	if (!page || IS_ERR(page))
+		return;
+
+	if (unlock) {
+		BUG_ON(!PageLocked(page));
+		unlock_page(page);
+	}
+	page_cache_release(page);
+}
+
+static inline void f2fs_put_dnode(struct dnode_of_data *dn)
+{
+	if (dn->node_page)
+		f2fs_put_page(dn->node_page, 1);
+	if (dn->inode_page && dn->node_page != dn->inode_page)
+		f2fs_put_page(dn->inode_page, 0);
+	dn->node_page = NULL;
+	dn->inode_page = NULL;
+}
+
+static inline struct kmem_cache *f2fs_kmem_cache_create(const char *name,
+					size_t size, void (*ctor)(void *))
+{
+	return kmem_cache_create(name, size, 0, SLAB_RECLAIM_ACCOUNT, ctor);
+}
+
+#define RAW_IS_INODE(p)	((p)->footer.nid == (p)->footer.ino)
+
+static inline bool IS_INODE(struct page *page)
+{
+	struct f2fs_node *p = (struct f2fs_node *)page_address(page);
+	return RAW_IS_INODE(p);
+}
+
+static inline __le32 *blkaddr_in_node(struct f2fs_node *node)
+{
+	return RAW_IS_INODE(node) ? node->i.i_addr : node->dn.addr;
+}
+
+static inline block_t datablock_addr(struct page *node_page,
+		unsigned int offset)
+{
+	struct f2fs_node *raw_node;
+	__le32 *addr_array;
+	raw_node = (struct f2fs_node *)page_address(node_page);
+	addr_array = blkaddr_in_node(raw_node);
+	return le32_to_cpu(addr_array[offset]);
+}
+
+static inline int f2fs_test_bit(unsigned int nr, char *addr)
+{
+	int mask;
+
+	addr += (nr >> 3);
+	mask = 1 << (7 - (nr & 0x07));
+	return mask & *addr;
+}
+
+static inline int f2fs_set_bit(unsigned int nr, char *addr)
+{
+	int mask;
+	int ret;
+
+	addr += (nr >> 3);
+	mask = 1 << (7 - (nr & 0x07));
+	ret = mask & *addr;
+	*addr |= mask;
+	return ret;
+}
+
+static inline int f2fs_clear_bit(unsigned int nr, char *addr)
+{
+	int mask;
+	int ret;
+
+	addr += (nr >> 3);
+	mask = 1 << (7 - (nr & 0x07));
+	ret = mask & *addr;
+	*addr &= ~mask;
+	return ret;
+}
+
+/* used for f2fs_inode_info->flags */
+enum {
+	FI_NEW_INODE,		/* indicate newly allocated inode */
+	FI_NEED_CP,		/* need to do checkpoint during fsync */
+	FI_INC_LINK,		/* need to increment i_nlink */
+	FI_ACL_MODE,		/* indicate acl mode */
+	FI_NO_ALLOC,		/* should not allocate any blocks */
+};
+
+static inline void set_inode_flag(struct f2fs_inode_info *fi, int flag)
+{
+	set_bit(flag, &fi->flags);
+}
+
+static inline int is_inode_flag_set(struct f2fs_inode_info *fi, int flag)
+{
+	return test_bit(flag, &fi->flags);
+}
+
+static inline void clear_inode_flag(struct f2fs_inode_info *fi, int flag)
+{
+	clear_bit(flag, &fi->flags);
+}
+
+static inline void set_acl_inode(struct f2fs_inode_info *fi, umode_t mode)
+{
+	fi->i_acl_mode = mode;
+	set_inode_flag(fi, FI_ACL_MODE);
+}
+
+static inline int cond_clear_inode_flag(struct f2fs_inode_info *fi, int flag)
+{
+	if (is_inode_flag_set(fi, FI_ACL_MODE)) {
+		clear_inode_flag(fi, FI_ACL_MODE);
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * file.c
+ */
+int f2fs_sync_file(struct file *, loff_t, loff_t, int);
+void truncate_data_blocks(struct dnode_of_data *);
+void f2fs_truncate(struct inode *);
+int f2fs_setattr(struct dentry *, struct iattr *);
+int truncate_hole(struct inode *, pgoff_t, pgoff_t);
+long f2fs_ioctl(struct file *, unsigned int, unsigned long);
+
+/*
+ * inode.c
+ */
+void f2fs_set_inode_flags(struct inode *);
+struct inode *f2fs_iget_nowait(struct super_block *, unsigned long);
+struct inode *f2fs_iget(struct super_block *, unsigned long);
+void update_inode(struct inode *, struct page *);
+int f2fs_write_inode(struct inode *, struct writeback_control *);
+void f2fs_evict_inode(struct inode *);
+
+/*
+ * namei.c
+ */
+struct dentry *f2fs_get_parent(struct dentry *child);
+
+/*
+ * dir.c
+ */
+struct f2fs_dir_entry *f2fs_find_entry(struct inode *, struct qstr *,
+							struct page **);
+struct f2fs_dir_entry *f2fs_parent_dir(struct inode *, struct page **);
+ino_t f2fs_inode_by_name(struct inode *, struct qstr *);
+void f2fs_set_link(struct inode *, struct f2fs_dir_entry *,
+				struct page *, struct inode *);
+void init_dent_inode(struct dentry *, struct page *);
+int f2fs_add_link(struct dentry *, struct inode *);
+void f2fs_delete_entry(struct f2fs_dir_entry *, struct page *, struct inode *);
+int f2fs_make_empty(struct inode *, struct inode *);
+bool f2fs_empty_dir(struct inode *);
+
+/*
+ * super.c
+ */
+int f2fs_sync_fs(struct super_block *, int);
+
+/*
+ * hash.c
+ */
+f2fs_hash_t f2fs_dentry_hash(const char *, int);
+
+/*
+ * node.c
+ */
+struct dnode_of_data;
+struct node_info;
+
+int is_checkpointed_node(struct f2fs_sb_info *, nid_t);
+void get_node_info(struct f2fs_sb_info *, nid_t, struct node_info *);
+int get_dnode_of_data(struct dnode_of_data *, pgoff_t, int);
+int truncate_inode_blocks(struct inode *, pgoff_t);
+int remove_inode_page(struct inode *);
+int new_inode_page(struct inode *, struct dentry *);
+struct page *new_node_page(struct dnode_of_data *, unsigned int);
+void ra_node_page(struct f2fs_sb_info *, nid_t);
+struct page *get_node_page(struct f2fs_sb_info *, pgoff_t);
+struct page *get_node_page_ra(struct page *, int);
+void sync_inode_page(struct dnode_of_data *);
+int sync_node_pages(struct f2fs_sb_info *, nid_t, struct writeback_control *);
+bool alloc_nid(struct f2fs_sb_info *, nid_t *);
+void alloc_nid_done(struct f2fs_sb_info *, nid_t);
+void alloc_nid_failed(struct f2fs_sb_info *, nid_t);
+void recover_node_page(struct f2fs_sb_info *, struct page *,
+		struct f2fs_summary *, struct node_info *, block_t);
+int recover_inode_page(struct f2fs_sb_info *, struct page *);
+int restore_node_summary(struct f2fs_sb_info *, unsigned int,
+				struct f2fs_summary_block *);
+void flush_nat_entries(struct f2fs_sb_info *);
+int build_node_manager(struct f2fs_sb_info *);
+void destroy_node_manager(struct f2fs_sb_info *);
+int create_node_manager_caches(void);
+void destroy_node_manager_caches(void);
+
+/*
+ * segment.c
+ */
+void f2fs_balance_fs(struct f2fs_sb_info *);
+void invalidate_blocks(struct f2fs_sb_info *, block_t);
+void locate_dirty_segment(struct f2fs_sb_info *, unsigned int);
+void clear_prefree_segments(struct f2fs_sb_info *);
+int npages_for_summary_flush(struct f2fs_sb_info *);
+void allocate_new_segments(struct f2fs_sb_info *);
+struct page *get_sum_page(struct f2fs_sb_info *, unsigned int);
+struct bio *f2fs_bio_alloc(struct block_device *, int);
+void f2fs_submit_bio(struct f2fs_sb_info *, enum page_type, bool sync);
+int write_meta_page(struct f2fs_sb_info *, struct page *,
+					struct writeback_control *);
+void write_node_page(struct f2fs_sb_info *, struct page *, unsigned int,
+					block_t, block_t *);
+void write_data_page(struct inode *, struct page *, struct dnode_of_data*,
+					block_t, block_t *);
+void rewrite_data_page(struct f2fs_sb_info *, struct page *, block_t);
+void recover_data_page(struct f2fs_sb_info *, struct page *,
+				struct f2fs_summary *, block_t, block_t);
+void rewrite_node_page(struct f2fs_sb_info *, struct page *,
+				struct f2fs_summary *, block_t, block_t);
+void write_data_summaries(struct f2fs_sb_info *, block_t);
+void write_node_summaries(struct f2fs_sb_info *, block_t);
+int lookup_journal_in_cursum(struct f2fs_summary_block *,
+					int, unsigned int, int);
+void flush_sit_entries(struct f2fs_sb_info *);
+int build_segment_manager(struct f2fs_sb_info *);
+void reset_victim_segmap(struct f2fs_sb_info *);
+void destroy_segment_manager(struct f2fs_sb_info *);
+
+/*
+ * checkpoint.c
+ */
+struct page *grab_meta_page(struct f2fs_sb_info *, pgoff_t);
+struct page *get_meta_page(struct f2fs_sb_info *, pgoff_t);
+long sync_meta_pages(struct f2fs_sb_info *, enum page_type, long);
+int check_orphan_space(struct f2fs_sb_info *);
+void add_orphan_inode(struct f2fs_sb_info *, nid_t);
+void remove_orphan_inode(struct f2fs_sb_info *, nid_t);
+int recover_orphan_inodes(struct f2fs_sb_info *);
+int get_valid_checkpoint(struct f2fs_sb_info *);
+void set_dirty_dir_page(struct inode *, struct page *);
+void remove_dirty_dir_inode(struct inode *);
+void sync_dirty_dir_inodes(struct f2fs_sb_info *);
+void block_operations(struct f2fs_sb_info *);
+void write_checkpoint(struct f2fs_sb_info *, bool, bool);
+void init_orphan_info(struct f2fs_sb_info *);
+int create_checkpoint_caches(void);
+void destroy_checkpoint_caches(void);
+
+/*
+ * data.c
+ */
+int reserve_new_block(struct dnode_of_data *);
+void update_extent_cache(block_t, struct dnode_of_data *);
+struct page *find_data_page(struct inode *, pgoff_t);
+struct page *get_lock_data_page(struct inode *, pgoff_t);
+struct page *get_new_data_page(struct inode *, pgoff_t, bool);
+int f2fs_readpage(struct f2fs_sb_info *, struct page *, block_t, int);
+int do_write_data_page(struct page *);
+
+/*
+ * gc.c
+ */
+int start_gc_thread(struct f2fs_sb_info *);
+void stop_gc_thread(struct f2fs_sb_info *);
+block_t start_bidx_of_node(unsigned int);
+int f2fs_gc(struct f2fs_sb_info *, int);
+void build_gc_manager(struct f2fs_sb_info *);
+int create_gc_caches(void);
+void destroy_gc_caches(void);
+
+/*
+ * recovery.c
+ */
+void recover_fsync_data(struct f2fs_sb_info *);
+bool space_for_roll_forward(struct f2fs_sb_info *);
+
+/*
+ * debug.c
+ */
+#ifdef CONFIG_F2FS_STAT_FS
+struct f2fs_stat_info {
+	struct list_head stat_list;
+	struct f2fs_sb_info *sbi;
+	struct mutex stat_lock;
+	int all_area_segs, sit_area_segs, nat_area_segs, ssa_area_segs;
+	int main_area_segs, main_area_sections, main_area_zones;
+	int hit_ext, total_ext;
+	int ndirty_node, ndirty_dent, ndirty_dirs, ndirty_meta;
+	int nats, sits, fnids;
+	int total_count, utilization;
+	int bg_gc;
+	unsigned int valid_count, valid_node_count, valid_inode_count;
+	unsigned int bimodal, avg_vblocks;
+	int util_free, util_valid, util_invalid;
+	int rsvd_segs, overp_segs;
+	int dirty_count, node_pages, meta_pages;
+	int prefree_count, call_count;
+	int tot_segs, node_segs, data_segs, free_segs, free_secs;
+	int tot_blks, data_blks, node_blks;
+	int curseg[NR_CURSEG_TYPE];
+	int cursec[NR_CURSEG_TYPE];
+	int curzone[NR_CURSEG_TYPE];
+
+	unsigned int segment_count[2];
+	unsigned int block_count[2];
+	unsigned base_mem, cache_mem;
+};
+
+#define stat_inc_call_count(si)	((si)->call_count++)
+
+#define stat_inc_seg_count(sbi, type)					\
+	do {								\
+		struct f2fs_stat_info *si = sbi->stat_info;		\
+		(si)->tot_segs++;					\
+		if (type == SUM_TYPE_DATA)				\
+			si->data_segs++;				\
+		else							\
+			si->node_segs++;				\
+	} while (0)
+
+#define stat_inc_tot_blk_count(si, blks)				\
+	(si->tot_blks += (blks))
+
+#define stat_inc_data_blk_count(sbi, blks)				\
+	do {								\
+		struct f2fs_stat_info *si = sbi->stat_info;		\
+		stat_inc_tot_blk_count(si, blks);			\
+		si->data_blks += (blks);				\
+	} while (0)
+
+#define stat_inc_node_blk_count(sbi, blks)				\
+	do {								\
+		struct f2fs_stat_info *si = sbi->stat_info;		\
+		stat_inc_tot_blk_count(si, blks);			\
+		si->node_blks += (blks);				\
+	} while (0)
+
+int f2fs_build_stats(struct f2fs_sb_info *);
+void f2fs_destroy_stats(struct f2fs_sb_info *);
+void destroy_root_stats(void);
+#else
+#define stat_inc_call_count(si)
+#define stat_inc_seg_count(si, type)
+#define stat_inc_tot_blk_count(si, blks)
+#define stat_inc_data_blk_count(si, blks)
+#define stat_inc_node_blk_count(sbi, blks)
+
+static inline int f2fs_build_stats(struct f2fs_sb_info *sbi) { return 0; }
+static inline void f2fs_destroy_stats(struct f2fs_sb_info *sbi) { }
+static inline void destroy_root_stats(void) { }
+#endif
+
+extern const struct file_operations f2fs_dir_operations;
+extern const struct file_operations f2fs_file_operations;
+extern const struct inode_operations f2fs_file_inode_operations;
+extern const struct address_space_operations f2fs_dblock_aops;
+extern const struct address_space_operations f2fs_node_aops;
+extern const struct address_space_operations f2fs_meta_aops;
+extern const struct inode_operations f2fs_dir_inode_operations;
+extern const struct inode_operations f2fs_symlink_inode_operations;
+extern const struct inode_operations f2fs_special_inode_operations;
+#endif

fs/f2fs/file.c

···
+/*
+ * fs/f2fs/file.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/stat.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/falloc.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/mount.h>
+
+#include "f2fs.h"
+#include "node.h"
+#include "segment.h"
+#include "xattr.h"
+#include "acl.h"
+
+static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
+						struct vm_fault *vmf)
+{
+	struct page *page = vmf->page;
+	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	block_t old_blk_addr;
+	struct dnode_of_data dn;
+	int err;
+
+	f2fs_balance_fs(sbi);
+
+	sb_start_pagefault(inode->i_sb);
+
+	mutex_lock_op(sbi, DATA_NEW);
+
+	/* block allocation */
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	err = get_dnode_of_data(&dn, page->index, 0);
+	if (err) {
+		mutex_unlock_op(sbi, DATA_NEW);
+		goto out;
+	}
+
+	old_blk_addr = dn.data_blkaddr;
+
+	if (old_blk_addr == NULL_ADDR) {
+		err = reserve_new_block(&dn);
+		if (err) {
+			f2fs_put_dnode(&dn);
+			mutex_unlock_op(sbi, DATA_NEW);
+			goto out;
+		}
+	}
+	f2fs_put_dnode(&dn);
+
+	mutex_unlock_op(sbi, DATA_NEW);
+
+	lock_page(page);
+	if (page->mapping != inode->i_mapping ||
+			page_offset(page) >= i_size_read(inode) ||
+			!PageUptodate(page)) {
+		unlock_page(page);
+		err = -EFAULT;
+		goto out;
+	}
+
+	/*
+	 * check to see if the page is mapped already (no holes)
+	 */
+	if (PageMappedToDisk(page))
+		goto out;
+
+	/* fill the page */
+	wait_on_page_writeback(page);
+
+	/* page is wholly or partially inside EOF */
+	if (((page->index + 1) << PAGE_CACHE_SHIFT) > i_size_read(inode)) {
+		unsigned offset;
+		offset = i_size_read(inode) & ~PAGE_CACHE_MASK;
+		zero_user_segment(page, offset, PAGE_CACHE_SIZE);
+	}
+	set_page_dirty(page);
+	SetPageUptodate(page);
+
+	file_update_time(vma->vm_file);
+out:
+	sb_end_pagefault(inode->i_sb);
+	return block_page_mkwrite_return(err);
+}
+
+static const struct vm_operations_struct f2fs_file_vm_ops = {
+	.fault        = filemap_fault,
+	.page_mkwrite = f2fs_vm_page_mkwrite,
+};
+
+static int need_to_sync_dir(struct f2fs_sb_info *sbi, struct inode *inode)
+{
+	struct dentry *dentry;
+	nid_t pino;
+
+	inode = igrab(inode);
+	dentry = d_find_any_alias(inode);
+	if (!dentry) {
+		iput(inode);
+		return 0;
+	}
+	pino = dentry->d_parent->d_inode->i_ino;
+	dput(dentry);
+	iput(inode);
+	return !is_checkpointed_node(sbi, pino);
+}
+
+int f2fs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct inode *inode = file->f_mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	unsigned long long cur_version;
+	int ret = 0;
+	bool need_cp = false;
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_ALL,
+		.nr_to_write = LONG_MAX,
+		.for_reclaim = 0,
+	};
+
+	if (inode->i_sb->s_flags & MS_RDONLY)
+		return 0;
+
+	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (ret)
+		return ret;
+
+	mutex_lock(&inode->i_mutex);
+
+	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
+		goto out;
+
+	mutex_lock(&sbi->cp_mutex);
+	cur_version = le64_to_cpu(F2FS_CKPT(sbi)->checkpoint_ver);
+	mutex_unlock(&sbi->cp_mutex);
+
+	if (F2FS_I(inode)->data_version != cur_version &&
+					!(inode->i_state & I_DIRTY))
+		goto out;
+	F2FS_I(inode)->data_version--;
+
+	if (!S_ISREG(inode->i_mode) || inode->i_nlink != 1)
+		need_cp = true;
+	if (is_inode_flag_set(F2FS_I(inode), FI_NEED_CP))
+		need_cp = true;
+	if (!space_for_roll_forward(sbi))
+		need_cp = true;
+	if (need_to_sync_dir(sbi, inode))
+		need_cp = true;
+
+	f2fs_write_inode(inode, NULL);
+
+	if (need_cp) {
+		/* all the dirty node pages should be flushed for POR */
+		ret = f2fs_sync_fs(inode->i_sb, 1);
+		clear_inode_flag(F2FS_I(inode), FI_NEED_CP);
+	} else {
+		while (sync_node_pages(sbi, inode->i_ino, &wbc) == 0)
+			f2fs_write_inode(inode, NULL);
+		filemap_fdatawait_range(sbi->node_inode->i_mapping,
+							0, LONG_MAX);
+	}
+out:
+	mutex_unlock(&inode->i_mutex);
+	return ret;
+}
+
+static int f2fs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	file_accessed(file);
+	vma->vm_ops = &f2fs_file_vm_ops;
+	return 0;
+}
+
+static int truncate_data_blocks_range(struct dnode_of_data *dn, int count)
+{
+	int nr_free = 0, ofs = dn->ofs_in_node;
+	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
+	struct f2fs_node *raw_node;
+	__le32 *addr;
+
+	raw_node = page_address(dn->node_page);
+	addr = blkaddr_in_node(raw_node) + ofs;
+
+	for ( ; count > 0; count--, addr++, dn->ofs_in_node++) {
+		block_t blkaddr = le32_to_cpu(*addr);
+		if (blkaddr == NULL_ADDR)
+			continue;
+
+		update_extent_cache(NULL_ADDR, dn);
+		invalidate_blocks(sbi, blkaddr);
+		dec_valid_block_count(sbi, dn->inode, 1);
+		nr_free++;
+	}
+	if (nr_free) {
+		set_page_dirty(dn->node_page);
+		sync_inode_page(dn);
+	}
+	dn->ofs_in_node = ofs;
+	return nr_free;
+}
+
+void truncate_data_blocks(struct dnode_of_data *dn)
+{
+	truncate_data_blocks_range(dn, ADDRS_PER_BLOCK);
+}
+
+static void truncate_partial_data_page(struct inode *inode, u64 from)
+{
+	unsigned offset = from & (PAGE_CACHE_SIZE - 1);
+	struct page *page;
+
+	if (!offset)
+		return;
+
+	page = find_data_page(inode, from >> PAGE_CACHE_SHIFT);
+	if (IS_ERR(page))
+		return;
+
+	lock_page(page);
+	wait_on_page_writeback(page);
+	zero_user(page, offset, PAGE_CACHE_SIZE - offset);
+	set_page_dirty(page);
+	f2fs_put_page(page, 1);
+}
+
+static int truncate_blocks(struct inode *inode, u64 from)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	unsigned int blocksize = inode->i_sb->s_blocksize;
+	struct dnode_of_data dn;
+	pgoff_t free_from;
+	int count = 0;
+	int err;
+
+	free_from = (pgoff_t)
+			((from + blocksize - 1) >> (sbi->log_blocksize));
+
+	mutex_lock_op(sbi, DATA_TRUNC);
+
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	err = get_dnode_of_data(&dn, free_from, RDONLY_NODE);
+	if (err) {
+		if (err == -ENOENT)
+			goto free_next;
+		mutex_unlock_op(sbi, DATA_TRUNC);
+		return err;
+	}
+
+	if (IS_INODE(dn.node_page))
+		count = ADDRS_PER_INODE;
+	else
+		count = ADDRS_PER_BLOCK;
+
+	count -= dn.ofs_in_node;
+	BUG_ON(count < 0);
+	if (dn.ofs_in_node || IS_INODE(dn.node_page)) {
+		truncate_data_blocks_range(&dn, count);
+		free_from += count;
+	}
+
+	f2fs_put_dnode(&dn);
+free_next:
+	err = truncate_inode_blocks(inode, free_from);
+	mutex_unlock_op(sbi, DATA_TRUNC);
+
+	/* lastly zero out the first data page */
+	truncate_partial_data_page(inode, from);
+
+	return err;
+}
+
+void f2fs_truncate(struct inode *inode)
+{
+	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+				S_ISLNK(inode->i_mode)))
+		return;
+
+	if (!truncate_blocks(inode, i_size_read(inode))) {
+		inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+		mark_inode_dirty(inode);
+	}
+
+	f2fs_balance_fs(F2FS_SB(inode->i_sb));
+}
+
+static int f2fs_getattr(struct vfsmount *mnt,
+			 struct dentry *dentry, struct kstat *stat)
+{
+	struct inode *inode = dentry->d_inode;
+	generic_fillattr(inode, stat);
+	stat->blocks <<= 3;
+	return 0;
+}
+
+#ifdef CONFIG_F2FS_FS_POSIX_ACL
+static void __setattr_copy(struct inode *inode, const struct iattr *attr)
+{
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	unsigned int ia_valid = attr->ia_valid;
+
+	if (ia_valid & ATTR_UID)
+		inode->i_uid = attr->ia_uid;
+	if (ia_valid & ATTR_GID)
+		inode->i_gid = attr->ia_gid;
+	if (ia_valid & ATTR_ATIME)
+		inode->i_atime = timespec_trunc(attr->ia_atime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_MTIME)
+		inode->i_mtime = timespec_trunc(attr->ia_mtime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_CTIME)
+		inode->i_ctime = timespec_trunc(attr->ia_ctime,
+						inode->i_sb->s_time_gran);
+	if (ia_valid & ATTR_MODE) {
+		umode_t mode = attr->ia_mode;
+
+		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+			mode &= ~S_ISGID;
+		set_acl_inode(fi, mode);
+	}
+}
+#else
+#define __setattr_copy setattr_copy
+#endif
+
+int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = dentry->d_inode;
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	int err;
+
+	err = inode_change_ok(inode, attr);
+	if (err)
+		return err;
+
+	if ((attr->ia_valid & ATTR_SIZE) &&
+			attr->ia_size != i_size_read(inode)) {
+		truncate_setsize(inode, attr->ia_size);
+		f2fs_truncate(inode);
+	}
+
+	__setattr_copy(inode, attr);
+
+	if (attr->ia_valid & ATTR_MODE) {
+		err = f2fs_acl_chmod(inode);
+		if (err || is_inode_flag_set(fi, FI_ACL_MODE)) {
+			inode->i_mode = fi->i_acl_mode;
+			clear_inode_flag(fi, FI_ACL_MODE);
+		}
+	}
+
+	mark_inode_dirty(inode);
+	return err;
+}
+
+const struct inode_operations f2fs_file_inode_operations = {
+	.getattr	= f2fs_getattr,
+	.setattr	= f2fs_setattr,
+	.get_acl	= f2fs_get_acl,
+#ifdef CONFIG_F2FS_FS_XATTR
+	.setxattr	= generic_setxattr,
+	.getxattr	= generic_getxattr,
+	.listxattr	= f2fs_listxattr,
+	.removexattr	= generic_removexattr,
+#endif
+};
+
+static void fill_zero(struct inode *inode, pgoff_t index,
+					loff_t start, loff_t len)
+{
+	struct page *page;
+
+	if (!len)
+		return;
+
+	page = get_new_data_page(inode, index, false);
+
+	if (!IS_ERR(page)) {
+		wait_on_page_writeback(page);
+		zero_user(page, start, len);
+		set_page_dirty(page);
+		f2fs_put_page(page, 1);
+	}
+}
+
+int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end)
+{
+	pgoff_t index;
+	int err;
+
+	for (index = pg_start; index < pg_end; index++) {
+		struct dnode_of_data dn;
+		struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+
+		mutex_lock_op(sbi, DATA_TRUNC);
+		set_new_dnode(&dn, inode, NULL, NULL, 0);
+		err = get_dnode_of_data(&dn, index, RDONLY_NODE);
+		if (err) {
+			mutex_unlock_op(sbi, DATA_TRUNC);
+			if (err == -ENOENT)
+				continue;
+			return err;
+		}
+
+		if (dn.data_blkaddr != NULL_ADDR)
+			truncate_data_blocks_range(&dn, 1);
+		f2fs_put_dnode(&dn);
+		mutex_unlock_op(sbi, DATA_TRUNC);
+	}
+	return 0;
+}
+
+static int punch_hole(struct inode *inode, loff_t offset, loff_t len, int mode)
+{
+	pgoff_t pg_start, pg_end;
+	loff_t off_start, off_end;
+	int ret = 0;
+
+	pg_start = ((unsigned long long) offset) >> PAGE_CACHE_SHIFT;
+	pg_end = ((unsigned long long) offset + len) >> PAGE_CACHE_SHIFT;
+
+	off_start = offset & (PAGE_CACHE_SIZE - 1);
+	off_end = (offset + len) & (PAGE_CACHE_SIZE - 1);
+
+	if (pg_start == pg_end) {
+		fill_zero(inode, pg_start, off_start,
+						off_end - off_start);
+	} else {
+		if (off_start)
+			fill_zero(inode, pg_start++, off_start,
+					PAGE_CACHE_SIZE - off_start);
+		if (off_end)
+			fill_zero(inode, pg_end, 0, off_end);
+
+		if (pg_start < pg_end) {
+			struct address_space *mapping = inode->i_mapping;
+			loff_t blk_start, blk_end;
+
+			blk_start = pg_start << PAGE_CACHE_SHIFT;
+			blk_end = pg_end << PAGE_CACHE_SHIFT;
+			truncate_inode_pages_range(mapping, blk_start,
+					blk_end - 1);
+			ret = truncate_hole(inode, pg_start, pg_end);
+		}
+	}
+
+	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
+		i_size_read(inode) <= (offset + len)) {
+		i_size_write(inode, offset);
+		mark_inode_dirty(inode);
+	}
+
+	return ret;
+}
+
+static int expand_inode_data(struct inode *inode, loff_t offset,
+					loff_t len, int mode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	pgoff_t index, pg_start, pg_end;
+	loff_t new_size = i_size_read(inode);
+	loff_t off_start, off_end;
+	int ret = 0;
+
+	ret = inode_newsize_ok(inode, (len + offset));
+	if (ret)
+		return ret;
+
+	pg_start = ((unsigned long long) offset) >> PAGE_CACHE_SHIFT;
+	pg_end = ((unsigned long long) offset + len) >> PAGE_CACHE_SHIFT;
+
+	off_start = offset & (PAGE_CACHE_SIZE - 1);
+	off_end = (offset + len) & (PAGE_CACHE_SIZE - 1);
+
+	for (index = pg_start; index <= pg_end; index++) {
+		struct dnode_of_data dn;
+
+		mutex_lock_op(sbi, DATA_NEW);
+
+		set_new_dnode(&dn, inode, NULL, NULL, 0);
+		ret = get_dnode_of_data(&dn, index, 0);
+		if (ret) {
+			mutex_unlock_op(sbi, DATA_NEW);
+			break;
+		}
+
+		if (dn.data_blkaddr == NULL_ADDR) {
+			ret = reserve_new_block(&dn);
+			if (ret) {
+				f2fs_put_dnode(&dn);
+				mutex_unlock_op(sbi, DATA_NEW);
+				break;
+			}
+		}
+		f2fs_put_dnode(&dn);
+
+		mutex_unlock_op(sbi, DATA_NEW);
+
+		if (pg_start == pg_end)
+			new_size = offset + len;
+		else if (index == pg_start && off_start)
+			new_size = (index + 1) << PAGE_CACHE_SHIFT;
+		else if (index == pg_end)
+			new_size = (index << PAGE_CACHE_SHIFT) + off_end;
+		else
+			new_size += PAGE_CACHE_SIZE;
+	}
+
+	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
+		i_size_read(inode) < new_size) {
+		i_size_write(inode, new_size);
+		mark_inode_dirty(inode);
+	}
+
+	return ret;
+}
+
+static long f2fs_fallocate(struct file *file, int mode,
+				loff_t offset, loff_t len)
+{
+	struct inode *inode = file->f_path.dentry->d_inode;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	long ret;
+
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+		return -EOPNOTSUPP;
+
+	if (mode & FALLOC_FL_PUNCH_HOLE)
+		ret = punch_hole(inode, offset, len, mode);
+	else
+		ret = expand_inode_data(inode, offset, len, mode);
+
+	f2fs_balance_fs(sbi);
+	return ret;
+}
+
+#define F2FS_REG_FLMASK		(~(FS_DIRSYNC_FL | FS_TOPDIR_FL))
+#define F2FS_OTHER_FLMASK	(FS_NODUMP_FL | FS_NOATIME_FL)
+
+static inline __u32 f2fs_mask_flags(umode_t mode, __u32 flags)
+{
+	if (S_ISDIR(mode))
+		return flags;
+	else if (S_ISREG(mode))
+		return flags & F2FS_REG_FLMASK;
+	else
+		return flags & F2FS_OTHER_FLMASK;
+}
+
+long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct inode *inode = filp->f_dentry->d_inode;
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	unsigned int flags;
+	int ret;
+
+	switch (cmd) {
+	case FS_IOC_GETFLAGS:
+		flags = fi->i_flags & FS_FL_USER_VISIBLE;
+		return put_user(flags, (int __user *) arg);
+	case FS_IOC_SETFLAGS:
+	{
+		unsigned int oldflags;
+
+		ret = mnt_want_write(filp->f_path.mnt);
+		if (ret)
+			return ret;
+
+		if (!inode_owner_or_capable(inode)) {
+			ret = -EACCES;
+			goto out;
+		}
+
+		if (get_user(flags, (int __user *) arg)) {
+			ret = -EFAULT;
+			goto out;
+		}
+
+		flags = f2fs_mask_flags(inode->i_mode, flags);
+
+		mutex_lock(&inode->i_mutex);
+
+		oldflags = fi->i_flags;
+
+		if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) {
+			if (!capable(CAP_LINUX_IMMUTABLE)) {
+				mutex_unlock(&inode->i_mutex);
+				ret = -EPERM;
+				goto out;
+			}
+		}
+
+		flags = flags & FS_FL_USER_MODIFIABLE;
+		flags |= oldflags & ~FS_FL_USER_MODIFIABLE;
+		fi->i_flags = flags;
+		mutex_unlock(&inode->i_mutex);
+
+		f2fs_set_inode_flags(inode);
+		inode->i_ctime = CURRENT_TIME;
+		mark_inode_dirty(inode);
+out:
+		mnt_drop_write(filp->f_path.mnt);
+		return ret;
+	}
+	default:
+		return -ENOTTY;
+	}
+}
+
+const struct file_operations f2fs_file_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= do_sync_read,
+	.write		= do_sync_write,
+	.aio_read	= generic_file_aio_read,
+	.aio_write	= generic_file_aio_write,
+	.open		= generic_file_open,
+	.mmap		= f2fs_file_mmap,
+	.fsync		= f2fs_sync_file,
+	.fallocate	= f2fs_fallocate,
+	.unlocked_ioctl	= f2fs_ioctl,
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= generic_file_splice_write,
+};

fs/f2fs/gc.c

···
+/*
+ * fs/f2fs/gc.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/backing-dev.h>
+#include <linux/proc_fs.h>
+#include <linux/init.h>
+#include <linux/f2fs_fs.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+#include <linux/freezer.h>
+#include <linux/blkdev.h>
+
+#include "f2fs.h"
+#include "node.h"
+#include "segment.h"
+#include "gc.h"
+
+static struct kmem_cache *winode_slab;
+
+static int gc_thread_func(void *data)
+{
+	struct f2fs_sb_info *sbi = data;
+	wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
+	long wait_ms;
+
+	wait_ms = GC_THREAD_MIN_SLEEP_TIME;
+
+	do {
+		if (try_to_freeze())
+			continue;
+		else
+			wait_event_interruptible_timeout(*wq,
+						kthread_should_stop(),
+						msecs_to_jiffies(wait_ms));
+		if (kthread_should_stop())
+			break;
+
+		f2fs_balance_fs(sbi);
+
+		if (!test_opt(sbi, BG_GC))
+			continue;
+
+		/*
+		 * [GC triggering condition]
+		 * 0. GC is not conducted currently.
+		 * 1. There are enough dirty segments.
+		 * 2. IO subsystem is idle by checking the # of writeback pages.
+		 * 3. IO subsystem is idle by checking the # of requests in
+		 *    bdev's request list.
+		 *
+		 * Note) We have to avoid triggering GCs too much frequently.
+		 * Because it is possible that some segments can be
+		 * invalidated soon after by user update or deletion.
+		 * So, I'd like to wait some time to collect dirty segments.
+		 */
+		if (!mutex_trylock(&sbi->gc_mutex))
+			continue;
+
+		if (!is_idle(sbi)) {
+			wait_ms = increase_sleep_time(wait_ms);
+			mutex_unlock(&sbi->gc_mutex);
+			continue;
+		}
+
+		if (has_enough_invalid_blocks(sbi))
+			wait_ms = decrease_sleep_time(wait_ms);
+		else
+			wait_ms = increase_sleep_time(wait_ms);
+
+		sbi->bg_gc++;
+
+		if (f2fs_gc(sbi, 1) == GC_NONE)
+			wait_ms = GC_THREAD_NOGC_SLEEP_TIME;
+		else if (wait_ms == GC_THREAD_NOGC_SLEEP_TIME)
+			wait_ms = GC_THREAD_MAX_SLEEP_TIME;
+
+	} while (!kthread_should_stop());
+	return 0;
+}
+
+int start_gc_thread(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_gc_kthread *gc_th;
+
+	gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
+	if (!gc_th)
+		return -ENOMEM;
+
+	sbi->gc_thread = gc_th;
+	init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
+	sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
+				GC_THREAD_NAME);
+	if (IS_ERR(gc_th->f2fs_gc_task)) {
+		kfree(gc_th);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void stop_gc_thread(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
+	if (!gc_th)
+		return;
+	kthread_stop(gc_th->f2fs_gc_task);
+	kfree(gc_th);
+	sbi->gc_thread = NULL;
+}
+
+static int select_gc_type(int gc_type)
+{
+	return (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
+}
+
+static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
+			int type, struct victim_sel_policy *p)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+
+	if (p->alloc_mode) {
+		p->gc_mode = GC_GREEDY;
+		p->dirty_segmap = dirty_i->dirty_segmap[type];
+		p->ofs_unit = 1;
+	} else {
+		p->gc_mode = select_gc_type(gc_type);
+		p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
+		p->ofs_unit = sbi->segs_per_sec;
+	}
+	p->offset = sbi->last_victim[p->gc_mode];
+}
+
+static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
+				struct victim_sel_policy *p)
+{
+	if (p->gc_mode == GC_GREEDY)
+		return (1 << sbi->log_blocks_per_seg) * p->ofs_unit;
+	else if (p->gc_mode == GC_CB)
+		return UINT_MAX;
+	else /* No other gc_mode */
+		return 0;
+}
+
+static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	unsigned int segno;
+
+	/*
+	 * If the gc_type is FG_GC, we can select victim segments
+	 * selected by background GC before.
+	 * Those segments guarantee they have small valid blocks.
+	 */
+	segno = find_next_bit(dirty_i->victim_segmap[BG_GC],
+						TOTAL_SEGS(sbi), 0);
+	if (segno < TOTAL_SEGS(sbi)) {
+		clear_bit(segno, dirty_i->victim_segmap[BG_GC]);
+		return segno;
+	}
+	return NULL_SEGNO;
+}
+
+static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	unsigned int secno = GET_SECNO(sbi, segno);
+	unsigned int start = secno * sbi->segs_per_sec;
+	unsigned long long mtime = 0;
+	unsigned int vblocks;
+	unsigned char age = 0;
+	unsigned char u;
+	unsigned int i;
+
+	for (i = 0; i < sbi->segs_per_sec; i++)
+		mtime += get_seg_entry(sbi, start + i)->mtime;
+	vblocks = get_valid_blocks(sbi, segno, sbi->segs_per_sec);
+
+	mtime = div_u64(mtime, sbi->segs_per_sec);
+	vblocks = div_u64(vblocks, sbi->segs_per_sec);
+
+	u = (vblocks * 100) >> sbi->log_blocks_per_seg;
+
+	/* Handle if the system time is changed by user */
+	if (mtime < sit_i->min_mtime)
+		sit_i->min_mtime = mtime;
+	if (mtime > sit_i->max_mtime)
+		sit_i->max_mtime = mtime;
+	if (sit_i->max_mtime != sit_i->min_mtime)
+		age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime),
+				sit_i->max_mtime - sit_i->min_mtime);
+
+	return UINT_MAX - ((100 * (100 - u) * age) / (100 + u));
+}
+
+static unsigned int get_gc_cost(struct f2fs_sb_info *sbi, unsigned int segno,
+					struct victim_sel_policy *p)
+{
+	if (p->alloc_mode == SSR)
+		return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
+
+	/* alloc_mode == LFS */
+	if (p->gc_mode == GC_GREEDY)
+		return get_valid_blocks(sbi, segno, sbi->segs_per_sec);
+	else
+		return get_cb_cost(sbi, segno);
+}
+
+/*
+ * This function is called from two pathes.
+ * One is garbage collection and the other is SSR segment selection.
+ * When it is called during GC, it just gets a victim segment
+ * and it does not remove it from dirty seglist.
+ * When it is called from SSR segment selection, it finds a segment
+ * which has minimum valid blocks and removes it from dirty seglist.
+ */
+static int get_victim_by_default(struct f2fs_sb_info *sbi,
+		unsigned int *result, int gc_type, int type, char alloc_mode)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	struct victim_sel_policy p;
+	unsigned int segno;
+	int nsearched = 0;
+
+	p.alloc_mode = alloc_mode;
+	select_policy(sbi, gc_type, type, &p);
+
+	p.min_segno = NULL_SEGNO;
+	p.min_cost = get_max_cost(sbi, &p);
+
+	mutex_lock(&dirty_i->seglist_lock);
+
+	if (p.alloc_mode == LFS && gc_type == FG_GC) {
+		p.min_segno = check_bg_victims(sbi);
+		if (p.min_segno != NULL_SEGNO)
+			goto got_it;
+	}
+
+	while (1) {
+		unsigned long cost;
+
+		segno = find_next_bit(p.dirty_segmap,
+						TOTAL_SEGS(sbi), p.offset);
+		if (segno >= TOTAL_SEGS(sbi)) {
+			if (sbi->last_victim[p.gc_mode]) {
+				sbi->last_victim[p.gc_mode] = 0;
+				p.offset = 0;
+				continue;
+			}
+			break;
+		}
+		p.offset = ((segno / p.ofs_unit) * p.ofs_unit) + p.ofs_unit;
+
+		if (test_bit(segno, dirty_i->victim_segmap[FG_GC]))
+			continue;
+		if (gc_type == BG_GC &&
+				test_bit(segno, dirty_i->victim_segmap[BG_GC]))
+			continue;
+		if (IS_CURSEC(sbi, GET_SECNO(sbi, segno)))
+			continue;
+
+		cost = get_gc_cost(sbi, segno, &p);
+
+		if (p.min_cost > cost) {
+			p.min_segno = segno;
+			p.min_cost = cost;
+		}
+
+		if (cost == get_max_cost(sbi, &p))
+			continue;
+
+		if (nsearched++ >= MAX_VICTIM_SEARCH) {
+			sbi->last_victim[p.gc_mode] = segno;
+			break;
+		}
+	}
+got_it:
+	if (p.min_segno != NULL_SEGNO) {
+		*result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
+		if (p.alloc_mode == LFS) {
+			int i;
+			for (i = 0; i < p.ofs_unit; i++)
+				set_bit(*result + i,
+					dirty_i->victim_segmap[gc_type]);
+		}
+	}
+	mutex_unlock(&dirty_i->seglist_lock);
+
+	return (p.min_segno == NULL_SEGNO) ? 0 : 1;
+}
+
+static const struct victim_selection default_v_ops = {
+	.get_victim = get_victim_by_default,
+};
+
+static struct inode *find_gc_inode(nid_t ino, struct list_head *ilist)
+{
+	struct list_head *this;
+	struct inode_entry *ie;
+
+	list_for_each(this, ilist) {
+		ie = list_entry(this, struct inode_entry, list);
+		if (ie->inode->i_ino == ino)
+			return ie->inode;
+	}
+	return NULL;
+}
+
+static void add_gc_inode(struct inode *inode, struct list_head *ilist)
+{
+	struct list_head *this;
+	struct inode_entry *new_ie, *ie;
+
+	list_for_each(this, ilist) {
+		ie = list_entry(this, struct inode_entry, list);
+		if (ie->inode == inode) {
+			iput(inode);
+			return;
+		}
+	}
+repeat:
+	new_ie = kmem_cache_alloc(winode_slab, GFP_NOFS);
+	if (!new_ie) {
+		cond_resched();
+		goto repeat;
+	}
+	new_ie->inode = inode;
+	list_add_tail(&new_ie->list, ilist);
+}
+
+static void put_gc_inode(struct list_head *ilist)
+{
+	struct inode_entry *ie, *next_ie;
+	list_for_each_entry_safe(ie, next_ie, ilist, list) {
+		iput(ie->inode);
+		list_del(&ie->list);
+		kmem_cache_free(winode_slab, ie);
+	}
+}
+
+static int check_valid_map(struct f2fs_sb_info *sbi,
+				unsigned int segno, int offset)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	struct seg_entry *sentry;
+	int ret;
+
+	mutex_lock(&sit_i->sentry_lock);
+	sentry = get_seg_entry(sbi, segno);
+	ret = f2fs_test_bit(offset, sentry->cur_valid_map);
+	mutex_unlock(&sit_i->sentry_lock);
+	return ret ? GC_OK : GC_NEXT;
+}
+
+/*
+ * This function compares node address got in summary with that in NAT.
+ * On validity, copy that node with cold status, otherwise (invalid node)
+ * ignore that.
+ */
+static int gc_node_segment(struct f2fs_sb_info *sbi,
+		struct f2fs_summary *sum, unsigned int segno, int gc_type)
+{
+	bool initial = true;
+	struct f2fs_summary *entry;
+	int off;
+
+next_step:
+	entry = sum;
+	for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
+		nid_t nid = le32_to_cpu(entry->nid);
+		struct page *node_page;
+		int err;
+
+		/*
+		 * It makes sure that free segments are able to write
+		 * all the dirty node pages before CP after this CP.
+		 * So let's check the space of dirty node pages.
+		 */
+		if (should_do_checkpoint(sbi)) {
+			mutex_lock(&sbi->cp_mutex);
+			block_operations(sbi);
+			return GC_BLOCKED;
+		}
+
+		err = check_valid_map(sbi, segno, off);
+		if (err == GC_ERROR)
+			return err;
+		else if (err == GC_NEXT)
+			continue;
+
+		if (initial) {
+			ra_node_page(sbi, nid);
+			continue;
+		}
+		node_page = get_node_page(sbi, nid);
+		if (IS_ERR(node_page))
+			continue;
+
+		/* set page dirty and write it */
+		if (!PageWriteback(node_page))
+			set_page_dirty(node_page);
+		f2fs_put_page(node_page, 1);
+		stat_inc_node_blk_count(sbi, 1);
+	}
+	if (initial) {
+		initial = false;
+		goto next_step;
+	}
+
+	if (gc_type == FG_GC) {
+		struct writeback_control wbc = {
+			.sync_mode = WB_SYNC_ALL,
+			.nr_to_write = LONG_MAX,
+			.for_reclaim = 0,
+		};
+		sync_node_pages(sbi, 0, &wbc);
+	}
+	return GC_DONE;
+}
+
+/*
+ * Calculate start block index that this node page contains
+ */
+block_t start_bidx_of_node(unsigned int node_ofs)
+{
+	block_t start_bidx;
+	unsigned int bidx, indirect_blks;
+	int dec;
+
+	indirect_blks = 2 * NIDS_PER_BLOCK + 4;
+
+	start_bidx = 1;
+	if (node_ofs == 0) {
+		start_bidx = 0;
+	} else if (node_ofs <= 2) {
+		bidx = node_ofs - 1;
+	} else if (node_ofs <= indirect_blks) {
+		dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);
+		bidx = node_ofs - 2 - dec;
+	} else {
+		dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);
+		bidx = node_ofs - 5 - dec;
+	}
+
+	if (start_bidx)
+		start_bidx = bidx * ADDRS_PER_BLOCK + ADDRS_PER_INODE;
+	return start_bidx;
+}
+
+static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
+		struct node_info *dni, block_t blkaddr, unsigned int *nofs)
+{
+	struct page *node_page;
+	nid_t nid;
+	unsigned int ofs_in_node;
+	block_t source_blkaddr;
+
+	nid = le32_to_cpu(sum->nid);
+	ofs_in_node = le16_to_cpu(sum->ofs_in_node);
+
+	node_page = get_node_page(sbi, nid);
+	if (IS_ERR(node_page))
+		return GC_NEXT;
+
+	get_node_info(sbi, nid, dni);
+
+	if (sum->version != dni->version) {
+		f2fs_put_page(node_page, 1);
+		return GC_NEXT;
+	}
+
+	*nofs = ofs_of_node(node_page);
+	source_blkaddr = datablock_addr(node_page, ofs_in_node);
+	f2fs_put_page(node_page, 1);
+
+	if (source_blkaddr != blkaddr)
+		return GC_NEXT;
+	return GC_OK;
+}
+
+static void move_data_page(struct inode *inode, struct page *page, int gc_type)
+{
+	if (page->mapping != inode->i_mapping)
+		goto out;
+
+	if (inode != page->mapping->host)
+		goto out;
+
+	if (PageWriteback(page))
+		goto out;
+
+	if (gc_type == BG_GC) {
+		set_page_dirty(page);
+		set_cold_data(page);
+	} else {
+		struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+		mutex_lock_op(sbi, DATA_WRITE);
+		if (clear_page_dirty_for_io(page) &&
+			S_ISDIR(inode->i_mode)) {
+			dec_page_count(sbi, F2FS_DIRTY_DENTS);
+			inode_dec_dirty_dents(inode);
+		}
+		set_cold_data(page);
+		do_write_data_page(page);
+		mutex_unlock_op(sbi, DATA_WRITE);
+		clear_cold_data(page);
+	}
+out:
+	f2fs_put_page(page, 1);
+}
+
+/*
+ * This function tries to get parent node of victim data block, and identifies
+ * data block validity. If the block is valid, copy that with cold status and
+ * modify parent node.
+ * If the parent node is not valid or the data block address is different,
+ * the victim data block is ignored.
+ */
+static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
+		struct list_head *ilist, unsigned int segno, int gc_type)
+{
+	struct super_block *sb = sbi->sb;
+	struct f2fs_summary *entry;
+	block_t start_addr;
+	int err, off;
+	int phase = 0;
+
+	start_addr = START_BLOCK(sbi, segno);
+
+next_step:
+	entry = sum;
+	for (off = 0; off < sbi->blocks_per_seg; off++, entry++) {
+		struct page *data_page;
+		struct inode *inode;
+		struct node_info dni; /* dnode info for the data */
+		unsigned int ofs_in_node, nofs;
+		block_t start_bidx;
+
+		/*
+		 * It makes sure that free segments are able to write
+		 * all the dirty node pages before CP after this CP.
+		 * So let's check the space of dirty node pages.
+		 */
+		if (should_do_checkpoint(sbi)) {
+			mutex_lock(&sbi->cp_mutex);
+			block_operations(sbi);
+			err = GC_BLOCKED;
+			goto stop;
+		}
+
+		err = check_valid_map(sbi, segno, off);
+		if (err == GC_ERROR)
+			goto stop;
+		else if (err == GC_NEXT)
+			continue;
+
+		if (phase == 0) {
+			ra_node_page(sbi, le32_to_cpu(entry->nid));
+			continue;
+		}
+
+		/* Get an inode by ino with checking validity */
+		err = check_dnode(sbi, entry, &dni, start_addr + off, &nofs);
+		if (err == GC_ERROR)
+			goto stop;
+		else if (err == GC_NEXT)
+			continue;
+
+		if (phase == 1) {
+			ra_node_page(sbi, dni.ino);
+			continue;
+		}
+
+		start_bidx = start_bidx_of_node(nofs);
+		ofs_in_node = le16_to_cpu(entry->ofs_in_node);
+
+		if (phase == 2) {
+			inode = f2fs_iget_nowait(sb, dni.ino);
+			if (IS_ERR(inode))
+				continue;
+
+			data_page = find_data_page(inode,
+					start_bidx + ofs_in_node);
+			if (IS_ERR(data_page))
+				goto next_iput;
+
+			f2fs_put_page(data_page, 0);
+			add_gc_inode(inode, ilist);
+		} else {
+			inode = find_gc_inode(dni.ino, ilist);
+			if (inode) {
+				data_page = get_lock_data_page(inode,
+						start_bidx + ofs_in_node);
+				if (IS_ERR(data_page))
+					continue;
+				move_data_page(inode, data_page, gc_type);
+				stat_inc_data_blk_count(sbi, 1);
+			}
+		}
+		continue;
+next_iput:
+		iput(inode);
+	}
+	if (++phase < 4)
+		goto next_step;
+	err = GC_DONE;
+stop:
+	if (gc_type == FG_GC)
+		f2fs_submit_bio(sbi, DATA, true);
+	return err;
+}
+
+static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
+						int gc_type, int type)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	int ret;
+	mutex_lock(&sit_i->sentry_lock);
+	ret = DIRTY_I(sbi)->v_ops->get_victim(sbi, victim, gc_type, type, LFS);
+	mutex_unlock(&sit_i->sentry_lock);
+	return ret;
+}
+
+static int do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
+				struct list_head *ilist, int gc_type)
+{
+	struct page *sum_page;
+	struct f2fs_summary_block *sum;
+	int ret = GC_DONE;
+
+	/* read segment summary of victim */
+	sum_page = get_sum_page(sbi, segno);
+	if (IS_ERR(sum_page))
+		return GC_ERROR;
+
+	/*
+	 * CP needs to lock sum_page. In this time, we don't need
+	 * to lock this page, because this summary page is not gone anywhere.
+	 * Also, this page is not gonna be updated before GC is done.
+	 */
+	unlock_page(sum_page);
+	sum = page_address(sum_page);
+
+	switch (GET_SUM_TYPE((&sum->footer))) {
+	case SUM_TYPE_NODE:
+		ret = gc_node_segment(sbi, sum->entries, segno, gc_type);
+		break;
+	case SUM_TYPE_DATA:
+		ret = gc_data_segment(sbi, sum->entries, ilist, segno, gc_type);
+		break;
+	}
+	stat_inc_seg_count(sbi, GET_SUM_TYPE((&sum->footer)));
+	stat_inc_call_count(sbi->stat_info);
+
+	f2fs_put_page(sum_page, 0);
+	return ret;
+}
+
+int f2fs_gc(struct f2fs_sb_info *sbi, int nGC)
+{
+	unsigned int segno;
+	int old_free_secs, cur_free_secs;
+	int gc_status, nfree;
+	struct list_head ilist;
+	int gc_type = BG_GC;
+
+	INIT_LIST_HEAD(&ilist);
+gc_more:
+	nfree = 0;
+	gc_status = GC_NONE;
+
+	if (has_not_enough_free_secs(sbi))
+		old_free_secs = reserved_sections(sbi);
+	else
+		old_free_secs = free_sections(sbi);
+
+	while (sbi->sb->s_flags & MS_ACTIVE) {
+		int i;
+		if (has_not_enough_free_secs(sbi))
+			gc_type = FG_GC;
+
+		cur_free_secs = free_sections(sbi) + nfree;
+
+		/* We got free space successfully. */
+		if (nGC < cur_free_secs - old_free_secs)
+			break;
+
+		if (!__get_victim(sbi, &segno, gc_type, NO_CHECK_TYPE))
+			break;
+
+		for (i = 0; i < sbi->segs_per_sec; i++) {
+			/*
+			 * do_garbage_collect will give us three gc_status:
+			 * GC_ERROR, GC_DONE, and GC_BLOCKED.
+			 * If GC is finished uncleanly, we have to return
+			 * the victim to dirty segment list.
+			 */
+			gc_status = do_garbage_collect(sbi, segno + i,
+					&ilist, gc_type);
+			if (gc_status != GC_DONE)
+				goto stop;
+			nfree++;
+		}
+	}
+stop:
+	if (has_not_enough_free_secs(sbi) || gc_status == GC_BLOCKED) {
+		write_checkpoint(sbi, (gc_status == GC_BLOCKED), false);
+		if (nfree)
+			goto gc_more;
+	}
+	mutex_unlock(&sbi->gc_mutex);
+
+	put_gc_inode(&ilist);
+	BUG_ON(!list_empty(&ilist));
+	return gc_status;
+}
+
+void build_gc_manager(struct f2fs_sb_info *sbi)
+{
+	DIRTY_I(sbi)->v_ops = &default_v_ops;
+}
+
+int create_gc_caches(void)
+{
+	winode_slab = f2fs_kmem_cache_create("f2fs_gc_inodes",
+			sizeof(struct inode_entry), NULL);
+	if (!winode_slab)
+		return -ENOMEM;
+	return 0;
+}
+
+void destroy_gc_caches(void)
+{
+	kmem_cache_destroy(winode_slab);
+}

fs/f2fs/gc.h

···
+/*
+ * fs/f2fs/gc.h
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#define GC_THREAD_NAME	"f2fs_gc_task"
+#define GC_THREAD_MIN_WB_PAGES		1	/*
+						 * a threshold to determine
+						 * whether IO subsystem is idle
+						 * or not
+						 */
+#define GC_THREAD_MIN_SLEEP_TIME	10000 /* milliseconds */
+#define GC_THREAD_MAX_SLEEP_TIME	30000
+#define GC_THREAD_NOGC_SLEEP_TIME	10000
+#define LIMIT_INVALID_BLOCK	40 /* percentage over total user space */
+#define LIMIT_FREE_BLOCK	40 /* percentage over invalid + free space */
+
+/* Search max. number of dirty segments to select a victim segment */
+#define MAX_VICTIM_SEARCH	20
+
+enum {
+	GC_NONE = 0,
+	GC_ERROR,
+	GC_OK,
+	GC_NEXT,
+	GC_BLOCKED,
+	GC_DONE,
+};
+
+struct f2fs_gc_kthread {
+	struct task_struct *f2fs_gc_task;
+	wait_queue_head_t gc_wait_queue_head;
+};
+
+struct inode_entry {
+	struct list_head list;
+	struct inode *inode;
+};
+
+/*
+ * inline functions
+ */
+static inline block_t free_user_blocks(struct f2fs_sb_info *sbi)
+{
+	if (free_segments(sbi) < overprovision_segments(sbi))
+		return 0;
+	else
+		return (free_segments(sbi) - overprovision_segments(sbi))
+			<< sbi->log_blocks_per_seg;
+}
+
+static inline block_t limit_invalid_user_blocks(struct f2fs_sb_info *sbi)
+{
+	return (long)(sbi->user_block_count * LIMIT_INVALID_BLOCK) / 100;
+}
+
+static inline block_t limit_free_user_blocks(struct f2fs_sb_info *sbi)
+{
+	block_t reclaimable_user_blocks = sbi->user_block_count -
+		written_block_count(sbi);
+	return (long)(reclaimable_user_blocks * LIMIT_FREE_BLOCK) / 100;
+}
+
+static inline long increase_sleep_time(long wait)
+{
+	wait += GC_THREAD_MIN_SLEEP_TIME;
+	if (wait > GC_THREAD_MAX_SLEEP_TIME)
+		wait = GC_THREAD_MAX_SLEEP_TIME;
+	return wait;
+}
+
+static inline long decrease_sleep_time(long wait)
+{
+	wait -= GC_THREAD_MIN_SLEEP_TIME;
+	if (wait <= GC_THREAD_MIN_SLEEP_TIME)
+		wait = GC_THREAD_MIN_SLEEP_TIME;
+	return wait;
+}
+
+static inline bool has_enough_invalid_blocks(struct f2fs_sb_info *sbi)
+{
+	block_t invalid_user_blocks = sbi->user_block_count -
+					written_block_count(sbi);
+	/*
+	 * Background GC is triggered with the following condition.
+	 * 1. There are a number of invalid blocks.
+	 * 2. There is not enough free space.
+	 */
+	if (invalid_user_blocks > limit_invalid_user_blocks(sbi) &&
+			free_user_blocks(sbi) < limit_free_user_blocks(sbi))
+		return true;
+	return false;
+}
+
+static inline int is_idle(struct f2fs_sb_info *sbi)
+{
+	struct block_device *bdev = sbi->sb->s_bdev;
+	struct request_queue *q = bdev_get_queue(bdev);
+	struct request_list *rl = &q->root_rl;
+	return !(rl->count[BLK_RW_SYNC]) && !(rl->count[BLK_RW_ASYNC]);
+}
+
+static inline bool should_do_checkpoint(struct f2fs_sb_info *sbi)
+{
+	unsigned int pages_per_sec = sbi->segs_per_sec *
+					(1 << sbi->log_blocks_per_seg);
+	int node_secs = ((get_pages(sbi, F2FS_DIRTY_NODES) + pages_per_sec - 1)
+			>> sbi->log_blocks_per_seg) / sbi->segs_per_sec;
+	int dent_secs = ((get_pages(sbi, F2FS_DIRTY_DENTS) + pages_per_sec - 1)
+			>> sbi->log_blocks_per_seg) / sbi->segs_per_sec;
+	return free_sections(sbi) <= (node_secs + 2 * dent_secs + 2);
+}

fs/f2fs/hash.c

···
+/*
+ * fs/f2fs/hash.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext3/hash.c
+ *
+ * Copyright (C) 2002 by Theodore Ts'o
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/cryptohash.h>
+#include <linux/pagemap.h>
+
+#include "f2fs.h"
+
+/*
+ * Hashing code copied from ext3
+ */
+#define DELTA 0x9E3779B9
+
+static void TEA_transform(unsigned int buf[4], unsigned int const in[])
+{
+	__u32 sum = 0;
+	__u32 b0 = buf[0], b1 = buf[1];
+	__u32 a = in[0], b = in[1], c = in[2], d = in[3];
+	int n = 16;
+
+	do {
+		sum += DELTA;
+		b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
+		b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
+	} while (--n);
+
+	buf[0] += b0;
+	buf[1] += b1;
+}
+
+static void str2hashbuf(const char *msg, int len, unsigned int *buf, int num)
+{
+	unsigned pad, val;
+	int i;
+
+	pad = (__u32)len | ((__u32)len << 8);
+	pad |= pad << 16;
+
+	val = pad;
+	if (len > num * 4)
+		len = num * 4;
+	for (i = 0; i < len; i++) {
+		if ((i % 4) == 0)
+			val = pad;
+		val = msg[i] + (val << 8);
+		if ((i % 4) == 3) {
+			*buf++ = val;
+			val = pad;
+			num--;
+		}
+	}
+	if (--num >= 0)
+		*buf++ = val;
+	while (--num >= 0)
+		*buf++ = pad;
+}
+
+f2fs_hash_t f2fs_dentry_hash(const char *name, int len)
+{
+	__u32 hash, minor_hash;
+	f2fs_hash_t f2fs_hash;
+	const char *p;
+	__u32 in[8], buf[4];
+
+	/* Initialize the default seed for the hash checksum functions */
+	buf[0] = 0x67452301;
+	buf[1] = 0xefcdab89;
+	buf[2] = 0x98badcfe;
+	buf[3] = 0x10325476;
+
+	p = name;
+	while (len > 0) {
+		str2hashbuf(p, len, in, 4);
+		TEA_transform(buf, in);
+		len -= 16;
+		p += 16;
+	}
+	hash = buf[0];
+	minor_hash = buf[1];
+
+	f2fs_hash = cpu_to_le32(hash & ~F2FS_HASH_COL_BIT);
+	return f2fs_hash;
+}

fs/f2fs/inode.c

···
+/*
+ * fs/f2fs/inode.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+
+#include "f2fs.h"
+#include "node.h"
+
+struct f2fs_iget_args {
+	u64 ino;
+	int on_free;
+};
+
+void f2fs_set_inode_flags(struct inode *inode)
+{
+	unsigned int flags = F2FS_I(inode)->i_flags;
+
+	inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE |
+			S_NOATIME | S_DIRSYNC);
+
+	if (flags & FS_SYNC_FL)
+		inode->i_flags |= S_SYNC;
+	if (flags & FS_APPEND_FL)
+		inode->i_flags |= S_APPEND;
+	if (flags & FS_IMMUTABLE_FL)
+		inode->i_flags |= S_IMMUTABLE;
+	if (flags & FS_NOATIME_FL)
+		inode->i_flags |= S_NOATIME;
+	if (flags & FS_DIRSYNC_FL)
+		inode->i_flags |= S_DIRSYNC;
+}
+
+static int f2fs_iget_test(struct inode *inode, void *data)
+{
+	struct f2fs_iget_args *args = data;
+
+	if (inode->i_ino != args->ino)
+		return 0;
+	if (inode->i_state & (I_FREEING | I_WILL_FREE)) {
+		args->on_free = 1;
+		return 0;
+	}
+	return 1;
+}
+
+struct inode *f2fs_iget_nowait(struct super_block *sb, unsigned long ino)
+{
+	struct f2fs_iget_args args = {
+		.ino = ino,
+		.on_free = 0
+	};
+	struct inode *inode = ilookup5(sb, ino, f2fs_iget_test, &args);
+
+	if (inode)
+		return inode;
+	if (!args.on_free)
+		return f2fs_iget(sb, ino);
+	return ERR_PTR(-ENOENT);
+}
+
+static int do_read_inode(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	struct page *node_page;
+	struct f2fs_node *rn;
+	struct f2fs_inode *ri;
+
+	/* Check if ino is within scope */
+	check_nid_range(sbi, inode->i_ino);
+
+	node_page = get_node_page(sbi, inode->i_ino);
+	if (IS_ERR(node_page))
+		return PTR_ERR(node_page);
+
+	rn = page_address(node_page);
+	ri = &(rn->i);
+
+	inode->i_mode = le16_to_cpu(ri->i_mode);
+	i_uid_write(inode, le32_to_cpu(ri->i_uid));
+	i_gid_write(inode, le32_to_cpu(ri->i_gid));
+	set_nlink(inode, le32_to_cpu(ri->i_links));
+	inode->i_size = le64_to_cpu(ri->i_size);
+	inode->i_blocks = le64_to_cpu(ri->i_blocks);
+
+	inode->i_atime.tv_sec = le64_to_cpu(ri->i_atime);
+	inode->i_ctime.tv_sec = le64_to_cpu(ri->i_ctime);
+	inode->i_mtime.tv_sec = le64_to_cpu(ri->i_mtime);
+	inode->i_atime.tv_nsec = le32_to_cpu(ri->i_atime_nsec);
+	inode->i_ctime.tv_nsec = le32_to_cpu(ri->i_ctime_nsec);
+	inode->i_mtime.tv_nsec = le32_to_cpu(ri->i_mtime_nsec);
+	inode->i_generation = le32_to_cpu(ri->i_generation);
+
+	fi->i_current_depth = le32_to_cpu(ri->i_current_depth);
+	fi->i_xattr_nid = le32_to_cpu(ri->i_xattr_nid);
+	fi->i_flags = le32_to_cpu(ri->i_flags);
+	fi->flags = 0;
+	fi->data_version = le64_to_cpu(F2FS_CKPT(sbi)->checkpoint_ver) - 1;
+	fi->i_advise = ri->i_advise;
+	fi->i_pino = le32_to_cpu(ri->i_pino);
+	get_extent_info(&fi->ext, ri->i_ext);
+	f2fs_put_page(node_page, 1);
+	return 0;
+}
+
+struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct inode *inode;
+	int ret;
+
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW))
+		return inode;
+	if (ino == F2FS_NODE_INO(sbi) || ino == F2FS_META_INO(sbi))
+		goto make_now;
+
+	ret = do_read_inode(inode);
+	if (ret)
+		goto bad_inode;
+
+	if (!sbi->por_doing && inode->i_nlink == 0) {
+		ret = -ENOENT;
+		goto bad_inode;
+	}
+
+make_now:
+	if (ino == F2FS_NODE_INO(sbi)) {
+		inode->i_mapping->a_ops = &f2fs_node_aops;
+		mapping_set_gfp_mask(inode->i_mapping, GFP_F2FS_ZERO);
+	} else if (ino == F2FS_META_INO(sbi)) {
+		inode->i_mapping->a_ops = &f2fs_meta_aops;
+		mapping_set_gfp_mask(inode->i_mapping, GFP_F2FS_ZERO);
+	} else if (S_ISREG(inode->i_mode)) {
+		inode->i_op = &f2fs_file_inode_operations;
+		inode->i_fop = &f2fs_file_operations;
+		inode->i_mapping->a_ops = &f2fs_dblock_aops;
+	} else if (S_ISDIR(inode->i_mode)) {
+		inode->i_op = &f2fs_dir_inode_operations;
+		inode->i_fop = &f2fs_dir_operations;
+		inode->i_mapping->a_ops = &f2fs_dblock_aops;
+		mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER_MOVABLE |
+				__GFP_ZERO);
+	} else if (S_ISLNK(inode->i_mode)) {
+		inode->i_op = &f2fs_symlink_inode_operations;
+		inode->i_mapping->a_ops = &f2fs_dblock_aops;
+	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
+			S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
+		inode->i_op = &f2fs_special_inode_operations;
+		init_special_inode(inode, inode->i_mode, inode->i_rdev);
+	} else {
+		ret = -EIO;
+		goto bad_inode;
+	}
+	unlock_new_inode(inode);
+
+	return inode;
+
+bad_inode:
+	iget_failed(inode);
+	return ERR_PTR(ret);
+}
+
+void update_inode(struct inode *inode, struct page *node_page)
+{
+	struct f2fs_node *rn;
+	struct f2fs_inode *ri;
+
+	wait_on_page_writeback(node_page);
+
+	rn = page_address(node_page);
+	ri = &(rn->i);
+
+	ri->i_mode = cpu_to_le16(inode->i_mode);
+	ri->i_advise = F2FS_I(inode)->i_advise;
+	ri->i_uid = cpu_to_le32(i_uid_read(inode));
+	ri->i_gid = cpu_to_le32(i_gid_read(inode));
+	ri->i_links = cpu_to_le32(inode->i_nlink);
+	ri->i_size = cpu_to_le64(i_size_read(inode));
+	ri->i_blocks = cpu_to_le64(inode->i_blocks);
+	set_raw_extent(&F2FS_I(inode)->ext, &ri->i_ext);
+
+	ri->i_atime = cpu_to_le64(inode->i_atime.tv_sec);
+	ri->i_ctime = cpu_to_le64(inode->i_ctime.tv_sec);
+	ri->i_mtime = cpu_to_le64(inode->i_mtime.tv_sec);
+	ri->i_atime_nsec = cpu_to_le32(inode->i_atime.tv_nsec);
+	ri->i_ctime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);
+	ri->i_mtime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
+	ri->i_current_depth = cpu_to_le32(F2FS_I(inode)->i_current_depth);
+	ri->i_xattr_nid = cpu_to_le32(F2FS_I(inode)->i_xattr_nid);
+	ri->i_flags = cpu_to_le32(F2FS_I(inode)->i_flags);
+	ri->i_pino = cpu_to_le32(F2FS_I(inode)->i_pino);
+	ri->i_generation = cpu_to_le32(inode->i_generation);
+	set_page_dirty(node_page);
+}
+
+int f2fs_write_inode(struct inode *inode, struct writeback_control *wbc)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct page *node_page;
+	bool need_lock = false;
+
+	if (inode->i_ino == F2FS_NODE_INO(sbi) ||
+			inode->i_ino == F2FS_META_INO(sbi))
+		return 0;
+
+	node_page = get_node_page(sbi, inode->i_ino);
+	if (IS_ERR(node_page))
+		return PTR_ERR(node_page);
+
+	if (!PageDirty(node_page)) {
+		need_lock = true;
+		f2fs_put_page(node_page, 1);
+		mutex_lock(&sbi->write_inode);
+		node_page = get_node_page(sbi, inode->i_ino);
+		if (IS_ERR(node_page)) {
+			mutex_unlock(&sbi->write_inode);
+			return PTR_ERR(node_page);
+		}
+	}
+	update_inode(inode, node_page);
+	f2fs_put_page(node_page, 1);
+	if (need_lock)
+		mutex_unlock(&sbi->write_inode);
+	return 0;
+}
+
+/*
+ * Called at the last iput() if i_nlink is zero
+ */
+void f2fs_evict_inode(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+
+	truncate_inode_pages(&inode->i_data, 0);
+
+	if (inode->i_ino == F2FS_NODE_INO(sbi) ||
+			inode->i_ino == F2FS_META_INO(sbi))
+		goto no_delete;
+
+	BUG_ON(atomic_read(&F2FS_I(inode)->dirty_dents));
+	remove_dirty_dir_inode(inode);
+
+	if (inode->i_nlink || is_bad_inode(inode))
+		goto no_delete;
+
+	set_inode_flag(F2FS_I(inode), FI_NO_ALLOC);
+	i_size_write(inode, 0);
+
+	if (F2FS_HAS_BLOCKS(inode))
+		f2fs_truncate(inode);
+
+	remove_inode_page(inode);
+no_delete:
+	clear_inode(inode);
+}

fs/f2fs/namei.c

···
+/*
+ * fs/f2fs/namei.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/pagemap.h>
+#include <linux/sched.h>
+#include <linux/ctype.h>
+
+#include "f2fs.h"
+#include "xattr.h"
+#include "acl.h"
+
+static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
+{
+	struct super_block *sb = dir->i_sb;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	nid_t ino;
+	struct inode *inode;
+	bool nid_free = false;
+	int err;
+
+	inode = new_inode(sb);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_lock_op(sbi, NODE_NEW);
+	if (!alloc_nid(sbi, &ino)) {
+		mutex_unlock_op(sbi, NODE_NEW);
+		err = -ENOSPC;
+		goto fail;
+	}
+	mutex_unlock_op(sbi, NODE_NEW);
+
+	inode->i_uid = current_fsuid();
+
+	if (dir->i_mode & S_ISGID) {
+		inode->i_gid = dir->i_gid;
+		if (S_ISDIR(mode))
+			mode |= S_ISGID;
+	} else {
+		inode->i_gid = current_fsgid();
+	}
+
+	inode->i_ino = ino;
+	inode->i_mode = mode;
+	inode->i_blocks = 0;
+	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+	inode->i_generation = sbi->s_next_generation++;
+
+	err = insert_inode_locked(inode);
+	if (err) {
+		err = -EINVAL;
+		nid_free = true;
+		goto out;
+	}
+
+	mark_inode_dirty(inode);
+	return inode;
+
+out:
+	clear_nlink(inode);
+	unlock_new_inode(inode);
+fail:
+	iput(inode);
+	if (nid_free)
+		alloc_nid_failed(sbi, ino);
+	return ERR_PTR(err);
+}
+
+static int is_multimedia_file(const unsigned char *s, const char *sub)
+{
+	int slen = strlen(s);
+	int sublen = strlen(sub);
+	int ret;
+
+	if (sublen > slen)
+		return 1;
+
+	ret = memcmp(s + slen - sublen, sub, sublen);
+	if (ret) {	/* compare upper case */
+		int i;
+		char upper_sub[8];
+		for (i = 0; i < sublen && i < sizeof(upper_sub); i++)
+			upper_sub[i] = toupper(sub[i]);
+		return memcmp(s + slen - sublen, upper_sub, sublen);
+	}
+
+	return ret;
+}
+
+/*
+ * Set multimedia files as cold files for hot/cold data separation
+ */
+static inline void set_cold_file(struct f2fs_sb_info *sbi, struct inode *inode,
+		const unsigned char *name)
+{
+	int i;
+	__u8 (*extlist)[8] = sbi->raw_super->extension_list;
+
+	int count = le32_to_cpu(sbi->raw_super->extension_count);
+	for (i = 0; i < count; i++) {
+		if (!is_multimedia_file(name, extlist[i])) {
+			F2FS_I(inode)->i_advise |= FADVISE_COLD_BIT;
+			break;
+		}
+	}
+}
+
+static int f2fs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+						bool excl)
+{
+	struct super_block *sb = dir->i_sb;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct inode *inode;
+	nid_t ino = 0;
+	int err;
+
+	inode = f2fs_new_inode(dir, mode);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	if (!test_opt(sbi, DISABLE_EXT_IDENTIFY))
+		set_cold_file(sbi, inode, dentry->d_name.name);
+
+	inode->i_op = &f2fs_file_inode_operations;
+	inode->i_fop = &f2fs_file_operations;
+	inode->i_mapping->a_ops = &f2fs_dblock_aops;
+	ino = inode->i_ino;
+
+	err = f2fs_add_link(dentry, inode);
+	if (err)
+		goto out;
+
+	alloc_nid_done(sbi, ino);
+
+	if (!sbi->por_doing)
+		d_instantiate(dentry, inode);
+	unlock_new_inode(inode);
+
+	f2fs_balance_fs(sbi);
+	return 0;
+out:
+	clear_nlink(inode);
+	unlock_new_inode(inode);
+	iput(inode);
+	alloc_nid_failed(sbi, ino);
+	return err;
+}
+
+static int f2fs_link(struct dentry *old_dentry, struct inode *dir,
+		struct dentry *dentry)
+{
+	struct inode *inode = old_dentry->d_inode;
+	struct super_block *sb = dir->i_sb;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	int err;
+
+	inode->i_ctime = CURRENT_TIME;
+	atomic_inc(&inode->i_count);
+
+	set_inode_flag(F2FS_I(inode), FI_INC_LINK);
+	err = f2fs_add_link(dentry, inode);
+	if (err)
+		goto out;
+
+	d_instantiate(dentry, inode);
+
+	f2fs_balance_fs(sbi);
+	return 0;
+out:
+	clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
+	iput(inode);
+	return err;
+}
+
+struct dentry *f2fs_get_parent(struct dentry *child)
+{
+	struct qstr dotdot = QSTR_INIT("..", 2);
+	unsigned long ino = f2fs_inode_by_name(child->d_inode, &dotdot);
+	if (!ino)
+		return ERR_PTR(-ENOENT);
+	return d_obtain_alias(f2fs_iget(child->d_inode->i_sb, ino));
+}
+
+static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
+		unsigned int flags)
+{
+	struct inode *inode = NULL;
+	struct f2fs_dir_entry *de;
+	struct page *page;
+
+	if (dentry->d_name.len > F2FS_MAX_NAME_LEN)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	de = f2fs_find_entry(dir, &dentry->d_name, &page);
+	if (de) {
+		nid_t ino = le32_to_cpu(de->ino);
+		kunmap(page);
+		f2fs_put_page(page, 0);
+
+		inode = f2fs_iget(dir->i_sb, ino);
+		if (IS_ERR(inode))
+			return ERR_CAST(inode);
+	}
+
+	return d_splice_alias(inode, dentry);
+}
+
+static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct super_block *sb = dir->i_sb;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct inode *inode = dentry->d_inode;
+	struct f2fs_dir_entry *de;
+	struct page *page;
+	int err = -ENOENT;
+
+	de = f2fs_find_entry(dir, &dentry->d_name, &page);
+	if (!de)
+		goto fail;
+
+	err = check_orphan_space(sbi);
+	if (err) {
+		kunmap(page);
+		f2fs_put_page(page, 0);
+		goto fail;
+	}
+
+	f2fs_delete_entry(de, page, inode);
+
+	/* In order to evict this inode,  we set it dirty */
+	mark_inode_dirty(inode);
+	f2fs_balance_fs(sbi);
+fail:
+	return err;
+}
+
+static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
+					const char *symname)
+{
+	struct super_block *sb = dir->i_sb;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct inode *inode;
+	unsigned symlen = strlen(symname) + 1;
+	int err;
+
+	inode = f2fs_new_inode(dir, S_IFLNK | S_IRWXUGO);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	inode->i_op = &f2fs_symlink_inode_operations;
+	inode->i_mapping->a_ops = &f2fs_dblock_aops;
+
+	err = f2fs_add_link(dentry, inode);
+	if (err)
+		goto out;
+
+	err = page_symlink(inode, symname, symlen);
+	alloc_nid_done(sbi, inode->i_ino);
+
+	d_instantiate(dentry, inode);
+	unlock_new_inode(inode);
+
+	f2fs_balance_fs(sbi);
+
+	return err;
+out:
+	clear_nlink(inode);
+	unlock_new_inode(inode);
+	iput(inode);
+	alloc_nid_failed(sbi, inode->i_ino);
+	return err;
+}
+
+static int f2fs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
+	struct inode *inode;
+	int err;
+
+	inode = f2fs_new_inode(dir, S_IFDIR | mode);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	inode->i_op = &f2fs_dir_inode_operations;
+	inode->i_fop = &f2fs_dir_operations;
+	inode->i_mapping->a_ops = &f2fs_dblock_aops;
+	mapping_set_gfp_mask(inode->i_mapping, GFP_F2FS_ZERO);
+
+	set_inode_flag(F2FS_I(inode), FI_INC_LINK);
+	err = f2fs_add_link(dentry, inode);
+	if (err)
+		goto out_fail;
+
+	alloc_nid_done(sbi, inode->i_ino);
+
+	d_instantiate(dentry, inode);
+	unlock_new_inode(inode);
+
+	f2fs_balance_fs(sbi);
+	return 0;
+
+out_fail:
+	clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
+	clear_nlink(inode);
+	unlock_new_inode(inode);
+	iput(inode);
+	alloc_nid_failed(sbi, inode->i_ino);
+	return err;
+}
+
+static int f2fs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = dentry->d_inode;
+	if (f2fs_empty_dir(inode))
+		return f2fs_unlink(dir, dentry);
+	return -ENOTEMPTY;
+}
+
+static int f2fs_mknod(struct inode *dir, struct dentry *dentry,
+				umode_t mode, dev_t rdev)
+{
+	struct super_block *sb = dir->i_sb;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct inode *inode;
+	int err = 0;
+
+	if (!new_valid_dev(rdev))
+		return -EINVAL;
+
+	inode = f2fs_new_inode(dir, mode);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	init_special_inode(inode, inode->i_mode, rdev);
+	inode->i_op = &f2fs_special_inode_operations;
+
+	err = f2fs_add_link(dentry, inode);
+	if (err)
+		goto out;
+
+	alloc_nid_done(sbi, inode->i_ino);
+	d_instantiate(dentry, inode);
+	unlock_new_inode(inode);
+
+	f2fs_balance_fs(sbi);
+
+	return 0;
+out:
+	clear_nlink(inode);
+	unlock_new_inode(inode);
+	iput(inode);
+	alloc_nid_failed(sbi, inode->i_ino);
+	return err;
+}
+
+static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
+			struct inode *new_dir, struct dentry *new_dentry)
+{
+	struct super_block *sb = old_dir->i_sb;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct inode *old_inode = old_dentry->d_inode;
+	struct inode *new_inode = new_dentry->d_inode;
+	struct page *old_dir_page;
+	struct page *old_page;
+	struct f2fs_dir_entry *old_dir_entry = NULL;
+	struct f2fs_dir_entry *old_entry;
+	struct f2fs_dir_entry *new_entry;
+	int err = -ENOENT;
+
+	old_entry = f2fs_find_entry(old_dir, &old_dentry->d_name, &old_page);
+	if (!old_entry)
+		goto out;
+
+	if (S_ISDIR(old_inode->i_mode)) {
+		err = -EIO;
+		old_dir_entry = f2fs_parent_dir(old_inode, &old_dir_page);
+		if (!old_dir_entry)
+			goto out_old;
+	}
+
+	mutex_lock_op(sbi, RENAME);
+
+	if (new_inode) {
+		struct page *new_page;
+
+		err = -ENOTEMPTY;
+		if (old_dir_entry && !f2fs_empty_dir(new_inode))
+			goto out_dir;
+
+		err = -ENOENT;
+		new_entry = f2fs_find_entry(new_dir, &new_dentry->d_name,
+						&new_page);
+		if (!new_entry)
+			goto out_dir;
+
+		f2fs_set_link(new_dir, new_entry, new_page, old_inode);
+
+		new_inode->i_ctime = CURRENT_TIME;
+		if (old_dir_entry)
+			drop_nlink(new_inode);
+		drop_nlink(new_inode);
+		if (!new_inode->i_nlink)
+			add_orphan_inode(sbi, new_inode->i_ino);
+		f2fs_write_inode(new_inode, NULL);
+	} else {
+		err = f2fs_add_link(new_dentry, old_inode);
+		if (err)
+			goto out_dir;
+
+		if (old_dir_entry) {
+			inc_nlink(new_dir);
+			f2fs_write_inode(new_dir, NULL);
+		}
+	}
+
+	old_inode->i_ctime = CURRENT_TIME;
+	set_inode_flag(F2FS_I(old_inode), FI_NEED_CP);
+	mark_inode_dirty(old_inode);
+
+	f2fs_delete_entry(old_entry, old_page, NULL);
+
+	if (old_dir_entry) {
+		if (old_dir != new_dir) {
+			f2fs_set_link(old_inode, old_dir_entry,
+						old_dir_page, new_dir);
+		} else {
+			kunmap(old_dir_page);
+			f2fs_put_page(old_dir_page, 0);
+		}
+		drop_nlink(old_dir);
+		f2fs_write_inode(old_dir, NULL);
+	}
+
+	mutex_unlock_op(sbi, RENAME);
+
+	f2fs_balance_fs(sbi);
+	return 0;
+
+out_dir:
+	if (old_dir_entry) {
+		kunmap(old_dir_page);
+		f2fs_put_page(old_dir_page, 0);
+	}
+	mutex_unlock_op(sbi, RENAME);
+out_old:
+	kunmap(old_page);
+	f2fs_put_page(old_page, 0);
+out:
+	return err;
+}
+
+const struct inode_operations f2fs_dir_inode_operations = {
+	.create		= f2fs_create,
+	.lookup		= f2fs_lookup,
+	.link		= f2fs_link,
+	.unlink		= f2fs_unlink,
+	.symlink	= f2fs_symlink,
+	.mkdir		= f2fs_mkdir,
+	.rmdir		= f2fs_rmdir,
+	.mknod		= f2fs_mknod,
+	.rename		= f2fs_rename,
+	.setattr	= f2fs_setattr,
+	.get_acl	= f2fs_get_acl,
+#ifdef CONFIG_F2FS_FS_XATTR
+	.setxattr	= generic_setxattr,
+	.getxattr	= generic_getxattr,
+	.listxattr	= f2fs_listxattr,
+	.removexattr	= generic_removexattr,
+#endif
+};
+
+const struct inode_operations f2fs_symlink_inode_operations = {
+	.readlink       = generic_readlink,
+	.follow_link    = page_follow_link_light,
+	.put_link       = page_put_link,
+	.setattr	= f2fs_setattr,
+#ifdef CONFIG_F2FS_FS_XATTR
+	.setxattr	= generic_setxattr,
+	.getxattr	= generic_getxattr,
+	.listxattr	= f2fs_listxattr,
+	.removexattr	= generic_removexattr,
+#endif
+};
+
+const struct inode_operations f2fs_special_inode_operations = {
+	.setattr        = f2fs_setattr,
+	.get_acl	= f2fs_get_acl,
+#ifdef CONFIG_F2FS_FS_XATTR
+	.setxattr       = generic_setxattr,
+	.getxattr       = generic_getxattr,
+	.listxattr	= f2fs_listxattr,
+	.removexattr    = generic_removexattr,
+#endif
+};

fs/f2fs/node.c

···
+/*
+ * fs/f2fs/node.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/mpage.h>
+#include <linux/backing-dev.h>
+#include <linux/blkdev.h>
+#include <linux/pagevec.h>
+#include <linux/swap.h>
+
+#include "f2fs.h"
+#include "node.h"
+#include "segment.h"
+
+static struct kmem_cache *nat_entry_slab;
+static struct kmem_cache *free_nid_slab;
+
+static void clear_node_page_dirty(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct f2fs_sb_info *sbi = F2FS_SB(mapping->host->i_sb);
+	unsigned int long flags;
+
+	if (PageDirty(page)) {
+		spin_lock_irqsave(&mapping->tree_lock, flags);
+		radix_tree_tag_clear(&mapping->page_tree,
+				page_index(page),
+				PAGECACHE_TAG_DIRTY);
+		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+
+		clear_page_dirty_for_io(page);
+		dec_page_count(sbi, F2FS_DIRTY_NODES);
+	}
+	ClearPageUptodate(page);
+}
+
+static struct page *get_current_nat_page(struct f2fs_sb_info *sbi, nid_t nid)
+{
+	pgoff_t index = current_nat_addr(sbi, nid);
+	return get_meta_page(sbi, index);
+}
+
+static struct page *get_next_nat_page(struct f2fs_sb_info *sbi, nid_t nid)
+{
+	struct page *src_page;
+	struct page *dst_page;
+	pgoff_t src_off;
+	pgoff_t dst_off;
+	void *src_addr;
+	void *dst_addr;
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+
+	src_off = current_nat_addr(sbi, nid);
+	dst_off = next_nat_addr(sbi, src_off);
+
+	/* get current nat block page with lock */
+	src_page = get_meta_page(sbi, src_off);
+
+	/* Dirty src_page means that it is already the new target NAT page. */
+	if (PageDirty(src_page))
+		return src_page;
+
+	dst_page = grab_meta_page(sbi, dst_off);
+
+	src_addr = page_address(src_page);
+	dst_addr = page_address(dst_page);
+	memcpy(dst_addr, src_addr, PAGE_CACHE_SIZE);
+	set_page_dirty(dst_page);
+	f2fs_put_page(src_page, 1);
+
+	set_to_next_nat(nm_i, nid);
+
+	return dst_page;
+}
+
+/*
+ * Readahead NAT pages
+ */
+static void ra_nat_pages(struct f2fs_sb_info *sbi, int nid)
+{
+	struct address_space *mapping = sbi->meta_inode->i_mapping;
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct page *page;
+	pgoff_t index;
+	int i;
+
+	for (i = 0; i < FREE_NID_PAGES; i++, nid += NAT_ENTRY_PER_BLOCK) {
+		if (nid >= nm_i->max_nid)
+			nid = 0;
+		index = current_nat_addr(sbi, nid);
+
+		page = grab_cache_page(mapping, index);
+		if (!page)
+			continue;
+		if (f2fs_readpage(sbi, page, index, READ)) {
+			f2fs_put_page(page, 1);
+			continue;
+		}
+		page_cache_release(page);
+	}
+}
+
+static struct nat_entry *__lookup_nat_cache(struct f2fs_nm_info *nm_i, nid_t n)
+{
+	return radix_tree_lookup(&nm_i->nat_root, n);
+}
+
+static unsigned int __gang_lookup_nat_cache(struct f2fs_nm_info *nm_i,
+		nid_t start, unsigned int nr, struct nat_entry **ep)
+{
+	return radix_tree_gang_lookup(&nm_i->nat_root, (void **)ep, start, nr);
+}
+
+static void __del_from_nat_cache(struct f2fs_nm_info *nm_i, struct nat_entry *e)
+{
+	list_del(&e->list);
+	radix_tree_delete(&nm_i->nat_root, nat_get_nid(e));
+	nm_i->nat_cnt--;
+	kmem_cache_free(nat_entry_slab, e);
+}
+
+int is_checkpointed_node(struct f2fs_sb_info *sbi, nid_t nid)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct nat_entry *e;
+	int is_cp = 1;
+
+	read_lock(&nm_i->nat_tree_lock);
+	e = __lookup_nat_cache(nm_i, nid);
+	if (e && !e->checkpointed)
+		is_cp = 0;
+	read_unlock(&nm_i->nat_tree_lock);
+	return is_cp;
+}
+
+static struct nat_entry *grab_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid)
+{
+	struct nat_entry *new;
+
+	new = kmem_cache_alloc(nat_entry_slab, GFP_ATOMIC);
+	if (!new)
+		return NULL;
+	if (radix_tree_insert(&nm_i->nat_root, nid, new)) {
+		kmem_cache_free(nat_entry_slab, new);
+		return NULL;
+	}
+	memset(new, 0, sizeof(struct nat_entry));
+	nat_set_nid(new, nid);
+	list_add_tail(&new->list, &nm_i->nat_entries);
+	nm_i->nat_cnt++;
+	return new;
+}
+
+static void cache_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid,
+						struct f2fs_nat_entry *ne)
+{
+	struct nat_entry *e;
+retry:
+	write_lock(&nm_i->nat_tree_lock);
+	e = __lookup_nat_cache(nm_i, nid);
+	if (!e) {
+		e = grab_nat_entry(nm_i, nid);
+		if (!e) {
+			write_unlock(&nm_i->nat_tree_lock);
+			goto retry;
+		}
+		nat_set_blkaddr(e, le32_to_cpu(ne->block_addr));
+		nat_set_ino(e, le32_to_cpu(ne->ino));
+		nat_set_version(e, ne->version);
+		e->checkpointed = true;
+	}
+	write_unlock(&nm_i->nat_tree_lock);
+}
+
+static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni,
+			block_t new_blkaddr)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct nat_entry *e;
+retry:
+	write_lock(&nm_i->nat_tree_lock);
+	e = __lookup_nat_cache(nm_i, ni->nid);
+	if (!e) {
+		e = grab_nat_entry(nm_i, ni->nid);
+		if (!e) {
+			write_unlock(&nm_i->nat_tree_lock);
+			goto retry;
+		}
+		e->ni = *ni;
+		e->checkpointed = true;
+		BUG_ON(ni->blk_addr == NEW_ADDR);
+	} else if (new_blkaddr == NEW_ADDR) {
+		/*
+		 * when nid is reallocated,
+		 * previous nat entry can be remained in nat cache.
+		 * So, reinitialize it with new information.
+		 */
+		e->ni = *ni;
+		BUG_ON(ni->blk_addr != NULL_ADDR);
+	}
+
+	if (new_blkaddr == NEW_ADDR)
+		e->checkpointed = false;
+
+	/* sanity check */
+	BUG_ON(nat_get_blkaddr(e) != ni->blk_addr);
+	BUG_ON(nat_get_blkaddr(e) == NULL_ADDR &&
+			new_blkaddr == NULL_ADDR);
+	BUG_ON(nat_get_blkaddr(e) == NEW_ADDR &&
+			new_blkaddr == NEW_ADDR);
+	BUG_ON(nat_get_blkaddr(e) != NEW_ADDR &&
+			nat_get_blkaddr(e) != NULL_ADDR &&
+			new_blkaddr == NEW_ADDR);
+
+	/* increament version no as node is removed */
+	if (nat_get_blkaddr(e) != NEW_ADDR && new_blkaddr == NULL_ADDR) {
+		unsigned char version = nat_get_version(e);
+		nat_set_version(e, inc_node_version(version));
+	}
+
+	/* change address */
+	nat_set_blkaddr(e, new_blkaddr);
+	__set_nat_cache_dirty(nm_i, e);
+	write_unlock(&nm_i->nat_tree_lock);
+}
+
+static int try_to_free_nats(struct f2fs_sb_info *sbi, int nr_shrink)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+
+	if (nm_i->nat_cnt < 2 * NM_WOUT_THRESHOLD)
+		return 0;
+
+	write_lock(&nm_i->nat_tree_lock);
+	while (nr_shrink && !list_empty(&nm_i->nat_entries)) {
+		struct nat_entry *ne;
+		ne = list_first_entry(&nm_i->nat_entries,
+					struct nat_entry, list);
+		__del_from_nat_cache(nm_i, ne);
+		nr_shrink--;
+	}
+	write_unlock(&nm_i->nat_tree_lock);
+	return nr_shrink;
+}
+
+/*
+ * This function returns always success
+ */
+void get_node_info(struct f2fs_sb_info *sbi, nid_t nid, struct node_info *ni)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
+	struct f2fs_summary_block *sum = curseg->sum_blk;
+	nid_t start_nid = START_NID(nid);
+	struct f2fs_nat_block *nat_blk;
+	struct page *page = NULL;
+	struct f2fs_nat_entry ne;
+	struct nat_entry *e;
+	int i;
+
+	memset(&ne, 0, sizeof(struct f2fs_nat_entry));
+	ni->nid = nid;
+
+	/* Check nat cache */
+	read_lock(&nm_i->nat_tree_lock);
+	e = __lookup_nat_cache(nm_i, nid);
+	if (e) {
+		ni->ino = nat_get_ino(e);
+		ni->blk_addr = nat_get_blkaddr(e);
+		ni->version = nat_get_version(e);
+	}
+	read_unlock(&nm_i->nat_tree_lock);
+	if (e)
+		return;
+
+	/* Check current segment summary */
+	mutex_lock(&curseg->curseg_mutex);
+	i = lookup_journal_in_cursum(sum, NAT_JOURNAL, nid, 0);
+	if (i >= 0) {
+		ne = nat_in_journal(sum, i);
+		node_info_from_raw_nat(ni, &ne);
+	}
+	mutex_unlock(&curseg->curseg_mutex);
+	if (i >= 0)
+		goto cache;
+
+	/* Fill node_info from nat page */
+	page = get_current_nat_page(sbi, start_nid);
+	nat_blk = (struct f2fs_nat_block *)page_address(page);
+	ne = nat_blk->entries[nid - start_nid];
+	node_info_from_raw_nat(ni, &ne);
+	f2fs_put_page(page, 1);
+cache:
+	/* cache nat entry */
+	cache_nat_entry(NM_I(sbi), nid, &ne);
+}
+
+/*
+ * The maximum depth is four.
+ * Offset[0] will have raw inode offset.
+ */
+static int get_node_path(long block, int offset[4], unsigned int noffset[4])
+{
+	const long direct_index = ADDRS_PER_INODE;
+	const long direct_blks = ADDRS_PER_BLOCK;
+	const long dptrs_per_blk = NIDS_PER_BLOCK;
+	const long indirect_blks = ADDRS_PER_BLOCK * NIDS_PER_BLOCK;
+	const long dindirect_blks = indirect_blks * NIDS_PER_BLOCK;
+	int n = 0;
+	int level = 0;
+
+	noffset[0] = 0;
+
+	if (block < direct_index) {
+		offset[n++] = block;
+		level = 0;
+		goto got;
+	}
+	block -= direct_index;
+	if (block < direct_blks) {
+		offset[n++] = NODE_DIR1_BLOCK;
+		noffset[n] = 1;
+		offset[n++] = block;
+		level = 1;
+		goto got;
+	}
+	block -= direct_blks;
+	if (block < direct_blks) {
+		offset[n++] = NODE_DIR2_BLOCK;
+		noffset[n] = 2;
+		offset[n++] = block;
+		level = 1;
+		goto got;
+	}
+	block -= direct_blks;
+	if (block < indirect_blks) {
+		offset[n++] = NODE_IND1_BLOCK;
+		noffset[n] = 3;
+		offset[n++] = block / direct_blks;
+		noffset[n] = 4 + offset[n - 1];
+		offset[n++] = block % direct_blks;
+		level = 2;
+		goto got;
+	}
+	block -= indirect_blks;
+	if (block < indirect_blks) {
+		offset[n++] = NODE_IND2_BLOCK;
+		noffset[n] = 4 + dptrs_per_blk;
+		offset[n++] = block / direct_blks;
+		noffset[n] = 5 + dptrs_per_blk + offset[n - 1];
+		offset[n++] = block % direct_blks;
+		level = 2;
+		goto got;
+	}
+	block -= indirect_blks;
+	if (block < dindirect_blks) {
+		offset[n++] = NODE_DIND_BLOCK;
+		noffset[n] = 5 + (dptrs_per_blk * 2);
+		offset[n++] = block / indirect_blks;
+		noffset[n] = 6 + (dptrs_per_blk * 2) +
+			      offset[n - 1] * (dptrs_per_blk + 1);
+		offset[n++] = (block / direct_blks) % dptrs_per_blk;
+		noffset[n] = 7 + (dptrs_per_blk * 2) +
+			      offset[n - 2] * (dptrs_per_blk + 1) +
+			      offset[n - 1];
+		offset[n++] = block % direct_blks;
+		level = 3;
+		goto got;
+	} else {
+		BUG();
+	}
+got:
+	return level;
+}
+
+/*
+ * Caller should call f2fs_put_dnode(dn).
+ */
+int get_dnode_of_data(struct dnode_of_data *dn, pgoff_t index, int ro)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
+	struct page *npage[4];
+	struct page *parent;
+	int offset[4];
+	unsigned int noffset[4];
+	nid_t nids[4];
+	int level, i;
+	int err = 0;
+
+	level = get_node_path(index, offset, noffset);
+
+	nids[0] = dn->inode->i_ino;
+	npage[0] = get_node_page(sbi, nids[0]);
+	if (IS_ERR(npage[0]))
+		return PTR_ERR(npage[0]);
+
+	parent = npage[0];
+	nids[1] = get_nid(parent, offset[0], true);
+	dn->inode_page = npage[0];
+	dn->inode_page_locked = true;
+
+	/* get indirect or direct nodes */
+	for (i = 1; i <= level; i++) {
+		bool done = false;
+
+		if (!nids[i] && !ro) {
+			mutex_lock_op(sbi, NODE_NEW);
+
+			/* alloc new node */
+			if (!alloc_nid(sbi, &(nids[i]))) {
+				mutex_unlock_op(sbi, NODE_NEW);
+				err = -ENOSPC;
+				goto release_pages;
+			}
+
+			dn->nid = nids[i];
+			npage[i] = new_node_page(dn, noffset[i]);
+			if (IS_ERR(npage[i])) {
+				alloc_nid_failed(sbi, nids[i]);
+				mutex_unlock_op(sbi, NODE_NEW);
+				err = PTR_ERR(npage[i]);
+				goto release_pages;
+			}
+
+			set_nid(parent, offset[i - 1], nids[i], i == 1);
+			alloc_nid_done(sbi, nids[i]);
+			mutex_unlock_op(sbi, NODE_NEW);
+			done = true;
+		} else if (ro && i == level && level > 1) {
+			npage[i] = get_node_page_ra(parent, offset[i - 1]);
+			if (IS_ERR(npage[i])) {
+				err = PTR_ERR(npage[i]);
+				goto release_pages;
+			}
+			done = true;
+		}
+		if (i == 1) {
+			dn->inode_page_locked = false;
+			unlock_page(parent);
+		} else {
+			f2fs_put_page(parent, 1);
+		}
+
+		if (!done) {
+			npage[i] = get_node_page(sbi, nids[i]);
+			if (IS_ERR(npage[i])) {
+				err = PTR_ERR(npage[i]);
+				f2fs_put_page(npage[0], 0);
+				goto release_out;
+			}
+		}
+		if (i < level) {
+			parent = npage[i];
+			nids[i + 1] = get_nid(parent, offset[i], false);
+		}
+	}
+	dn->nid = nids[level];
+	dn->ofs_in_node = offset[level];
+	dn->node_page = npage[level];
+	dn->data_blkaddr = datablock_addr(dn->node_page, dn->ofs_in_node);
+	return 0;
+
+release_pages:
+	f2fs_put_page(parent, 1);
+	if (i > 1)
+		f2fs_put_page(npage[0], 0);
+release_out:
+	dn->inode_page = NULL;
+	dn->node_page = NULL;
+	return err;
+}
+
+static void truncate_node(struct dnode_of_data *dn)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
+	struct node_info ni;
+
+	get_node_info(sbi, dn->nid, &ni);
+	BUG_ON(ni.blk_addr == NULL_ADDR);
+
+	if (ni.blk_addr != NULL_ADDR)
+		invalidate_blocks(sbi, ni.blk_addr);
+
+	/* Deallocate node address */
+	dec_valid_node_count(sbi, dn->inode, 1);
+	set_node_addr(sbi, &ni, NULL_ADDR);
+
+	if (dn->nid == dn->inode->i_ino) {
+		remove_orphan_inode(sbi, dn->nid);
+		dec_valid_inode_count(sbi);
+	} else {
+		sync_inode_page(dn);
+	}
+
+	clear_node_page_dirty(dn->node_page);
+	F2FS_SET_SB_DIRT(sbi);
+
+	f2fs_put_page(dn->node_page, 1);
+	dn->node_page = NULL;
+}
+
+static int truncate_dnode(struct dnode_of_data *dn)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
+	struct page *page;
+
+	if (dn->nid == 0)
+		return 1;
+
+	/* get direct node */
+	page = get_node_page(sbi, dn->nid);
+	if (IS_ERR(page) && PTR_ERR(page) == -ENOENT)
+		return 1;
+	else if (IS_ERR(page))
+		return PTR_ERR(page);
+
+	/* Make dnode_of_data for parameter */
+	dn->node_page = page;
+	dn->ofs_in_node = 0;
+	truncate_data_blocks(dn);
+	truncate_node(dn);
+	return 1;
+}
+
+static int truncate_nodes(struct dnode_of_data *dn, unsigned int nofs,
+						int ofs, int depth)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
+	struct dnode_of_data rdn = *dn;
+	struct page *page;
+	struct f2fs_node *rn;
+	nid_t child_nid;
+	unsigned int child_nofs;
+	int freed = 0;
+	int i, ret;
+
+	if (dn->nid == 0)
+		return NIDS_PER_BLOCK + 1;
+
+	page = get_node_page(sbi, dn->nid);
+	if (IS_ERR(page))
+		return PTR_ERR(page);
+
+	rn = (struct f2fs_node *)page_address(page);
+	if (depth < 3) {
+		for (i = ofs; i < NIDS_PER_BLOCK; i++, freed++) {
+			child_nid = le32_to_cpu(rn->in.nid[i]);
+			if (child_nid == 0)
+				continue;
+			rdn.nid = child_nid;
+			ret = truncate_dnode(&rdn);
+			if (ret < 0)
+				goto out_err;
+			set_nid(page, i, 0, false);
+		}
+	} else {
+		child_nofs = nofs + ofs * (NIDS_PER_BLOCK + 1) + 1;
+		for (i = ofs; i < NIDS_PER_BLOCK; i++) {
+			child_nid = le32_to_cpu(rn->in.nid[i]);
+			if (child_nid == 0) {
+				child_nofs += NIDS_PER_BLOCK + 1;
+				continue;
+			}
+			rdn.nid = child_nid;
+			ret = truncate_nodes(&rdn, child_nofs, 0, depth - 1);
+			if (ret == (NIDS_PER_BLOCK + 1)) {
+				set_nid(page, i, 0, false);
+				child_nofs += ret;
+			} else if (ret < 0 && ret != -ENOENT) {
+				goto out_err;
+			}
+		}
+		freed = child_nofs;
+	}
+
+	if (!ofs) {
+		/* remove current indirect node */
+		dn->node_page = page;
+		truncate_node(dn);
+		freed++;
+	} else {
+		f2fs_put_page(page, 1);
+	}
+	return freed;
+
+out_err:
+	f2fs_put_page(page, 1);
+	return ret;
+}
+
+static int truncate_partial_nodes(struct dnode_of_data *dn,
+			struct f2fs_inode *ri, int *offset, int depth)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
+	struct page *pages[2];
+	nid_t nid[3];
+	nid_t child_nid;
+	int err = 0;
+	int i;
+	int idx = depth - 2;
+
+	nid[0] = le32_to_cpu(ri->i_nid[offset[0] - NODE_DIR1_BLOCK]);
+	if (!nid[0])
+		return 0;
+
+	/* get indirect nodes in the path */
+	for (i = 0; i < depth - 1; i++) {
+		/* refernece count'll be increased */
+		pages[i] = get_node_page(sbi, nid[i]);
+		if (IS_ERR(pages[i])) {
+			depth = i + 1;
+			err = PTR_ERR(pages[i]);
+			goto fail;
+		}
+		nid[i + 1] = get_nid(pages[i], offset[i + 1], false);
+	}
+
+	/* free direct nodes linked to a partial indirect node */
+	for (i = offset[depth - 1]; i < NIDS_PER_BLOCK; i++) {
+		child_nid = get_nid(pages[idx], i, false);
+		if (!child_nid)
+			continue;
+		dn->nid = child_nid;
+		err = truncate_dnode(dn);
+		if (err < 0)
+			goto fail;
+		set_nid(pages[idx], i, 0, false);
+	}
+
+	if (offset[depth - 1] == 0) {
+		dn->node_page = pages[idx];
+		dn->nid = nid[idx];
+		truncate_node(dn);
+	} else {
+		f2fs_put_page(pages[idx], 1);
+	}
+	offset[idx]++;
+	offset[depth - 1] = 0;
+fail:
+	for (i = depth - 3; i >= 0; i--)
+		f2fs_put_page(pages[i], 1);
+	return err;
+}
+
+/*
+ * All the block addresses of data and nodes should be nullified.
+ */
+int truncate_inode_blocks(struct inode *inode, pgoff_t from)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	int err = 0, cont = 1;
+	int level, offset[4], noffset[4];
+	unsigned int nofs;
+	struct f2fs_node *rn;
+	struct dnode_of_data dn;
+	struct page *page;
+
+	level = get_node_path(from, offset, noffset);
+
+	page = get_node_page(sbi, inode->i_ino);
+	if (IS_ERR(page))
+		return PTR_ERR(page);
+
+	set_new_dnode(&dn, inode, page, NULL, 0);
+	unlock_page(page);
+
+	rn = page_address(page);
+	switch (level) {
+	case 0:
+	case 1:
+		nofs = noffset[1];
+		break;
+	case 2:
+		nofs = noffset[1];
+		if (!offset[level - 1])
+			goto skip_partial;
+		err = truncate_partial_nodes(&dn, &rn->i, offset, level);
+		if (err < 0 && err != -ENOENT)
+			goto fail;
+		nofs += 1 + NIDS_PER_BLOCK;
+		break;
+	case 3:
+		nofs = 5 + 2 * NIDS_PER_BLOCK;
+		if (!offset[level - 1])
+			goto skip_partial;
+		err = truncate_partial_nodes(&dn, &rn->i, offset, level);
+		if (err < 0 && err != -ENOENT)
+			goto fail;
+		break;
+	default:
+		BUG();
+	}
+
+skip_partial:
+	while (cont) {
+		dn.nid = le32_to_cpu(rn->i.i_nid[offset[0] - NODE_DIR1_BLOCK]);
+		switch (offset[0]) {
+		case NODE_DIR1_BLOCK:
+		case NODE_DIR2_BLOCK:
+			err = truncate_dnode(&dn);
+			break;
+
+		case NODE_IND1_BLOCK:
+		case NODE_IND2_BLOCK:
+			err = truncate_nodes(&dn, nofs, offset[1], 2);
+			break;
+
+		case NODE_DIND_BLOCK:
+			err = truncate_nodes(&dn, nofs, offset[1], 3);
+			cont = 0;
+			break;
+
+		default:
+			BUG();
+		}
+		if (err < 0 && err != -ENOENT)
+			goto fail;
+		if (offset[1] == 0 &&
+				rn->i.i_nid[offset[0] - NODE_DIR1_BLOCK]) {
+			lock_page(page);
+			wait_on_page_writeback(page);
+			rn->i.i_nid[offset[0] - NODE_DIR1_BLOCK] = 0;
+			set_page_dirty(page);
+			unlock_page(page);
+		}
+		offset[1] = 0;
+		offset[0]++;
+		nofs += err;
+	}
+fail:
+	f2fs_put_page(page, 0);
+	return err > 0 ? 0 : err;
+}
+
+int remove_inode_page(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct page *page;
+	nid_t ino = inode->i_ino;
+	struct dnode_of_data dn;
+
+	mutex_lock_op(sbi, NODE_TRUNC);
+	page = get_node_page(sbi, ino);
+	if (IS_ERR(page)) {
+		mutex_unlock_op(sbi, NODE_TRUNC);
+		return PTR_ERR(page);
+	}
+
+	if (F2FS_I(inode)->i_xattr_nid) {
+		nid_t nid = F2FS_I(inode)->i_xattr_nid;
+		struct page *npage = get_node_page(sbi, nid);
+
+		if (IS_ERR(npage)) {
+			mutex_unlock_op(sbi, NODE_TRUNC);
+			return PTR_ERR(npage);
+		}
+
+		F2FS_I(inode)->i_xattr_nid = 0;
+		set_new_dnode(&dn, inode, page, npage, nid);
+		dn.inode_page_locked = 1;
+		truncate_node(&dn);
+	}
+	if (inode->i_blocks == 1) {
+		/* inernally call f2fs_put_page() */
+		set_new_dnode(&dn, inode, page, page, ino);
+		truncate_node(&dn);
+	} else if (inode->i_blocks == 0) {
+		struct node_info ni;
+		get_node_info(sbi, inode->i_ino, &ni);
+
+		/* called after f2fs_new_inode() is failed */
+		BUG_ON(ni.blk_addr != NULL_ADDR);
+		f2fs_put_page(page, 1);
+	} else {
+		BUG();
+	}
+	mutex_unlock_op(sbi, NODE_TRUNC);
+	return 0;
+}
+
+int new_inode_page(struct inode *inode, struct dentry *dentry)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct page *page;
+	struct dnode_of_data dn;
+
+	/* allocate inode page for new inode */
+	set_new_dnode(&dn, inode, NULL, NULL, inode->i_ino);
+	mutex_lock_op(sbi, NODE_NEW);
+	page = new_node_page(&dn, 0);
+	init_dent_inode(dentry, page);
+	mutex_unlock_op(sbi, NODE_NEW);
+	if (IS_ERR(page))
+		return PTR_ERR(page);
+	f2fs_put_page(page, 1);
+	return 0;
+}
+
+struct page *new_node_page(struct dnode_of_data *dn, unsigned int ofs)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
+	struct address_space *mapping = sbi->node_inode->i_mapping;
+	struct node_info old_ni, new_ni;
+	struct page *page;
+	int err;
+
+	if (is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC))
+		return ERR_PTR(-EPERM);
+
+	page = grab_cache_page(mapping, dn->nid);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	get_node_info(sbi, dn->nid, &old_ni);
+
+	SetPageUptodate(page);
+	fill_node_footer(page, dn->nid, dn->inode->i_ino, ofs, true);
+
+	/* Reinitialize old_ni with new node page */
+	BUG_ON(old_ni.blk_addr != NULL_ADDR);
+	new_ni = old_ni;
+	new_ni.ino = dn->inode->i_ino;
+
+	if (!inc_valid_node_count(sbi, dn->inode, 1)) {
+		err = -ENOSPC;
+		goto fail;
+	}
+	set_node_addr(sbi, &new_ni, NEW_ADDR);
+
+	dn->node_page = page;
+	sync_inode_page(dn);
+	set_page_dirty(page);
+	set_cold_node(dn->inode, page);
+	if (ofs == 0)
+		inc_valid_inode_count(sbi);
+
+	return page;
+
+fail:
+	f2fs_put_page(page, 1);
+	return ERR_PTR(err);
+}
+
+static int read_node_page(struct page *page, int type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb);
+	struct node_info ni;
+
+	get_node_info(sbi, page->index, &ni);
+
+	if (ni.blk_addr == NULL_ADDR)
+		return -ENOENT;
+	return f2fs_readpage(sbi, page, ni.blk_addr, type);
+}
+
+/*
+ * Readahead a node page
+ */
+void ra_node_page(struct f2fs_sb_info *sbi, nid_t nid)
+{
+	struct address_space *mapping = sbi->node_inode->i_mapping;
+	struct page *apage;
+
+	apage = find_get_page(mapping, nid);
+	if (apage && PageUptodate(apage))
+		goto release_out;
+	f2fs_put_page(apage, 0);
+
+	apage = grab_cache_page(mapping, nid);
+	if (!apage)
+		return;
+
+	if (read_node_page(apage, READA))
+		goto unlock_out;
+
+	page_cache_release(apage);
+	return;
+
+unlock_out:
+	unlock_page(apage);
+release_out:
+	page_cache_release(apage);
+}
+
+struct page *get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid)
+{
+	int err;
+	struct page *page;
+	struct address_space *mapping = sbi->node_inode->i_mapping;
+
+	page = grab_cache_page(mapping, nid);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	err = read_node_page(page, READ_SYNC);
+	if (err) {
+		f2fs_put_page(page, 1);
+		return ERR_PTR(err);
+	}
+
+	BUG_ON(nid != nid_of_node(page));
+	mark_page_accessed(page);
+	return page;
+}
+
+/*
+ * Return a locked page for the desired node page.
+ * And, readahead MAX_RA_NODE number of node pages.
+ */
+struct page *get_node_page_ra(struct page *parent, int start)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(parent->mapping->host->i_sb);
+	struct address_space *mapping = sbi->node_inode->i_mapping;
+	int i, end;
+	int err = 0;
+	nid_t nid;
+	struct page *page;
+
+	/* First, try getting the desired direct node. */
+	nid = get_nid(parent, start, false);
+	if (!nid)
+		return ERR_PTR(-ENOENT);
+
+	page = find_get_page(mapping, nid);
+	if (page && PageUptodate(page))
+		goto page_hit;
+	f2fs_put_page(page, 0);
+
+repeat:
+	page = grab_cache_page(mapping, nid);
+	if (!page)
+		return ERR_PTR(-ENOMEM);
+
+	err = read_node_page(page, READA);
+	if (err) {
+		f2fs_put_page(page, 1);
+		return ERR_PTR(err);
+	}
+
+	/* Then, try readahead for siblings of the desired node */
+	end = start + MAX_RA_NODE;
+	end = min(end, NIDS_PER_BLOCK);
+	for (i = start + 1; i < end; i++) {
+		nid = get_nid(parent, i, false);
+		if (!nid)
+			continue;
+		ra_node_page(sbi, nid);
+	}
+
+page_hit:
+	lock_page(page);
+	if (PageError(page)) {
+		f2fs_put_page(page, 1);
+		return ERR_PTR(-EIO);
+	}
+
+	/* Has the page been truncated? */
+	if (page->mapping != mapping) {
+		f2fs_put_page(page, 1);
+		goto repeat;
+	}
+	return page;
+}
+
+void sync_inode_page(struct dnode_of_data *dn)
+{
+	if (IS_INODE(dn->node_page) || dn->inode_page == dn->node_page) {
+		update_inode(dn->inode, dn->node_page);
+	} else if (dn->inode_page) {
+		if (!dn->inode_page_locked)
+			lock_page(dn->inode_page);
+		update_inode(dn->inode, dn->inode_page);
+		if (!dn->inode_page_locked)
+			unlock_page(dn->inode_page);
+	} else {
+		f2fs_write_inode(dn->inode, NULL);
+	}
+}
+
+int sync_node_pages(struct f2fs_sb_info *sbi, nid_t ino,
+					struct writeback_control *wbc)
+{
+	struct address_space *mapping = sbi->node_inode->i_mapping;
+	pgoff_t index, end;
+	struct pagevec pvec;
+	int step = ino ? 2 : 0;
+	int nwritten = 0, wrote = 0;
+
+	pagevec_init(&pvec, 0);
+
+next_step:
+	index = 0;
+	end = LONG_MAX;
+
+	while (index <= end) {
+		int i, nr_pages;
+		nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+				PAGECACHE_TAG_DIRTY,
+				min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
+		if (nr_pages == 0)
+			break;
+
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+
+			/*
+			 * flushing sequence with step:
+			 * 0. indirect nodes
+			 * 1. dentry dnodes
+			 * 2. file dnodes
+			 */
+			if (step == 0 && IS_DNODE(page))
+				continue;
+			if (step == 1 && (!IS_DNODE(page) ||
+						is_cold_node(page)))
+				continue;
+			if (step == 2 && (!IS_DNODE(page) ||
+						!is_cold_node(page)))
+				continue;
+
+			/*
+			 * If an fsync mode,
+			 * we should not skip writing node pages.
+			 */
+			if (ino && ino_of_node(page) == ino)
+				lock_page(page);
+			else if (!trylock_page(page))
+				continue;
+
+			if (unlikely(page->mapping != mapping)) {
+continue_unlock:
+				unlock_page(page);
+				continue;
+			}
+			if (ino && ino_of_node(page) != ino)
+				goto continue_unlock;
+
+			if (!PageDirty(page)) {
+				/* someone wrote it for us */
+				goto continue_unlock;
+			}
+
+			if (!clear_page_dirty_for_io(page))
+				goto continue_unlock;
+
+			/* called by fsync() */
+			if (ino && IS_DNODE(page)) {
+				int mark = !is_checkpointed_node(sbi, ino);
+				set_fsync_mark(page, 1);
+				if (IS_INODE(page))
+					set_dentry_mark(page, mark);
+				nwritten++;
+			} else {
+				set_fsync_mark(page, 0);
+				set_dentry_mark(page, 0);
+			}
+			mapping->a_ops->writepage(page, wbc);
+			wrote++;
+
+			if (--wbc->nr_to_write == 0)
+				break;
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+
+		if (wbc->nr_to_write == 0) {
+			step = 2;
+			break;
+		}
+	}
+
+	if (step < 2) {
+		step++;
+		goto next_step;
+	}
+
+	if (wrote)
+		f2fs_submit_bio(sbi, NODE, wbc->sync_mode == WB_SYNC_ALL);
+
+	return nwritten;
+}
+
+static int f2fs_write_node_page(struct page *page,
+				struct writeback_control *wbc)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb);
+	nid_t nid;
+	unsigned int nofs;
+	block_t new_addr;
+	struct node_info ni;
+
+	if (wbc->for_reclaim) {
+		dec_page_count(sbi, F2FS_DIRTY_NODES);
+		wbc->pages_skipped++;
+		set_page_dirty(page);
+		return AOP_WRITEPAGE_ACTIVATE;
+	}
+
+	wait_on_page_writeback(page);
+
+	mutex_lock_op(sbi, NODE_WRITE);
+
+	/* get old block addr of this node page */
+	nid = nid_of_node(page);
+	nofs = ofs_of_node(page);
+	BUG_ON(page->index != nid);
+
+	get_node_info(sbi, nid, &ni);
+
+	/* This page is already truncated */
+	if (ni.blk_addr == NULL_ADDR)
+		return 0;
+
+	set_page_writeback(page);
+
+	/* insert node offset */
+	write_node_page(sbi, page, nid, ni.blk_addr, &new_addr);
+	set_node_addr(sbi, &ni, new_addr);
+	dec_page_count(sbi, F2FS_DIRTY_NODES);
+
+	mutex_unlock_op(sbi, NODE_WRITE);
+	unlock_page(page);
+	return 0;
+}
+
+static int f2fs_write_node_pages(struct address_space *mapping,
+			    struct writeback_control *wbc)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(mapping->host->i_sb);
+	struct block_device *bdev = sbi->sb->s_bdev;
+	long nr_to_write = wbc->nr_to_write;
+
+	if (wbc->for_kupdate)
+		return 0;
+
+	if (get_pages(sbi, F2FS_DIRTY_NODES) == 0)
+		return 0;
+
+	if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK)) {
+		write_checkpoint(sbi, false, false);
+		return 0;
+	}
+
+	/* if mounting is failed, skip writing node pages */
+	wbc->nr_to_write = bio_get_nr_vecs(bdev);
+	sync_node_pages(sbi, 0, wbc);
+	wbc->nr_to_write = nr_to_write -
+		(bio_get_nr_vecs(bdev) - wbc->nr_to_write);
+	return 0;
+}
+
+static int f2fs_set_node_page_dirty(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct f2fs_sb_info *sbi = F2FS_SB(mapping->host->i_sb);
+
+	SetPageUptodate(page);
+	if (!PageDirty(page)) {
+		__set_page_dirty_nobuffers(page);
+		inc_page_count(sbi, F2FS_DIRTY_NODES);
+		SetPagePrivate(page);
+		return 1;
+	}
+	return 0;
+}
+
+static void f2fs_invalidate_node_page(struct page *page, unsigned long offset)
+{
+	struct inode *inode = page->mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	if (PageDirty(page))
+		dec_page_count(sbi, F2FS_DIRTY_NODES);
+	ClearPagePrivate(page);
+}
+
+static int f2fs_release_node_page(struct page *page, gfp_t wait)
+{
+	ClearPagePrivate(page);
+	return 0;
+}
+
+/*
+ * Structure of the f2fs node operations
+ */
+const struct address_space_operations f2fs_node_aops = {
+	.writepage	= f2fs_write_node_page,
+	.writepages	= f2fs_write_node_pages,
+	.set_page_dirty	= f2fs_set_node_page_dirty,
+	.invalidatepage	= f2fs_invalidate_node_page,
+	.releasepage	= f2fs_release_node_page,
+};
+
+static struct free_nid *__lookup_free_nid_list(nid_t n, struct list_head *head)
+{
+	struct list_head *this;
+	struct free_nid *i = NULL;
+	list_for_each(this, head) {
+		i = list_entry(this, struct free_nid, list);
+		if (i->nid == n)
+			break;
+		i = NULL;
+	}
+	return i;
+}
+
+static void __del_from_free_nid_list(struct free_nid *i)
+{
+	list_del(&i->list);
+	kmem_cache_free(free_nid_slab, i);
+}
+
+static int add_free_nid(struct f2fs_nm_info *nm_i, nid_t nid)
+{
+	struct free_nid *i;
+
+	if (nm_i->fcnt > 2 * MAX_FREE_NIDS)
+		return 0;
+retry:
+	i = kmem_cache_alloc(free_nid_slab, GFP_NOFS);
+	if (!i) {
+		cond_resched();
+		goto retry;
+	}
+	i->nid = nid;
+	i->state = NID_NEW;
+
+	spin_lock(&nm_i->free_nid_list_lock);
+	if (__lookup_free_nid_list(nid, &nm_i->free_nid_list)) {
+		spin_unlock(&nm_i->free_nid_list_lock);
+		kmem_cache_free(free_nid_slab, i);
+		return 0;
+	}
+	list_add_tail(&i->list, &nm_i->free_nid_list);
+	nm_i->fcnt++;
+	spin_unlock(&nm_i->free_nid_list_lock);
+	return 1;
+}
+
+static void remove_free_nid(struct f2fs_nm_info *nm_i, nid_t nid)
+{
+	struct free_nid *i;
+	spin_lock(&nm_i->free_nid_list_lock);
+	i = __lookup_free_nid_list(nid, &nm_i->free_nid_list);
+	if (i && i->state == NID_NEW) {
+		__del_from_free_nid_list(i);
+		nm_i->fcnt--;
+	}
+	spin_unlock(&nm_i->free_nid_list_lock);
+}
+
+static int scan_nat_page(struct f2fs_nm_info *nm_i,
+			struct page *nat_page, nid_t start_nid)
+{
+	struct f2fs_nat_block *nat_blk = page_address(nat_page);
+	block_t blk_addr;
+	int fcnt = 0;
+	int i;
+
+	/* 0 nid should not be used */
+	if (start_nid == 0)
+		++start_nid;
+
+	i = start_nid % NAT_ENTRY_PER_BLOCK;
+
+	for (; i < NAT_ENTRY_PER_BLOCK; i++, start_nid++) {
+		blk_addr  = le32_to_cpu(nat_blk->entries[i].block_addr);
+		BUG_ON(blk_addr == NEW_ADDR);
+		if (blk_addr == NULL_ADDR)
+			fcnt += add_free_nid(nm_i, start_nid);
+	}
+	return fcnt;
+}
+
+static void build_free_nids(struct f2fs_sb_info *sbi)
+{
+	struct free_nid *fnid, *next_fnid;
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
+	struct f2fs_summary_block *sum = curseg->sum_blk;
+	nid_t nid = 0;
+	bool is_cycled = false;
+	int fcnt = 0;
+	int i;
+
+	nid = nm_i->next_scan_nid;
+	nm_i->init_scan_nid = nid;
+
+	ra_nat_pages(sbi, nid);
+
+	while (1) {
+		struct page *page = get_current_nat_page(sbi, nid);
+
+		fcnt += scan_nat_page(nm_i, page, nid);
+		f2fs_put_page(page, 1);
+
+		nid += (NAT_ENTRY_PER_BLOCK - (nid % NAT_ENTRY_PER_BLOCK));
+
+		if (nid >= nm_i->max_nid) {
+			nid = 0;
+			is_cycled = true;
+		}
+		if (fcnt > MAX_FREE_NIDS)
+			break;
+		if (is_cycled && nm_i->init_scan_nid <= nid)
+			break;
+	}
+
+	nm_i->next_scan_nid = nid;
+
+	/* find free nids from current sum_pages */
+	mutex_lock(&curseg->curseg_mutex);
+	for (i = 0; i < nats_in_cursum(sum); i++) {
+		block_t addr = le32_to_cpu(nat_in_journal(sum, i).block_addr);
+		nid = le32_to_cpu(nid_in_journal(sum, i));
+		if (addr == NULL_ADDR)
+			add_free_nid(nm_i, nid);
+		else
+			remove_free_nid(nm_i, nid);
+	}
+	mutex_unlock(&curseg->curseg_mutex);
+
+	/* remove the free nids from current allocated nids */
+	list_for_each_entry_safe(fnid, next_fnid, &nm_i->free_nid_list, list) {
+		struct nat_entry *ne;
+
+		read_lock(&nm_i->nat_tree_lock);
+		ne = __lookup_nat_cache(nm_i, fnid->nid);
+		if (ne && nat_get_blkaddr(ne) != NULL_ADDR)
+			remove_free_nid(nm_i, fnid->nid);
+		read_unlock(&nm_i->nat_tree_lock);
+	}
+}
+
+/*
+ * If this function returns success, caller can obtain a new nid
+ * from second parameter of this function.
+ * The returned nid could be used ino as well as nid when inode is created.
+ */
+bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct free_nid *i = NULL;
+	struct list_head *this;
+retry:
+	mutex_lock(&nm_i->build_lock);
+	if (!nm_i->fcnt) {
+		/* scan NAT in order to build free nid list */
+		build_free_nids(sbi);
+		if (!nm_i->fcnt) {
+			mutex_unlock(&nm_i->build_lock);
+			return false;
+		}
+	}
+	mutex_unlock(&nm_i->build_lock);
+
+	/*
+	 * We check fcnt again since previous check is racy as
+	 * we didn't hold free_nid_list_lock. So other thread
+	 * could consume all of free nids.
+	 */
+	spin_lock(&nm_i->free_nid_list_lock);
+	if (!nm_i->fcnt) {
+		spin_unlock(&nm_i->free_nid_list_lock);
+		goto retry;
+	}
+
+	BUG_ON(list_empty(&nm_i->free_nid_list));
+	list_for_each(this, &nm_i->free_nid_list) {
+		i = list_entry(this, struct free_nid, list);
+		if (i->state == NID_NEW)
+			break;
+	}
+
+	BUG_ON(i->state != NID_NEW);
+	*nid = i->nid;
+	i->state = NID_ALLOC;
+	nm_i->fcnt--;
+	spin_unlock(&nm_i->free_nid_list_lock);
+	return true;
+}
+
+/*
+ * alloc_nid() should be called prior to this function.
+ */
+void alloc_nid_done(struct f2fs_sb_info *sbi, nid_t nid)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct free_nid *i;
+
+	spin_lock(&nm_i->free_nid_list_lock);
+	i = __lookup_free_nid_list(nid, &nm_i->free_nid_list);
+	if (i) {
+		BUG_ON(i->state != NID_ALLOC);
+		__del_from_free_nid_list(i);
+	}
+	spin_unlock(&nm_i->free_nid_list_lock);
+}
+
+/*
+ * alloc_nid() should be called prior to this function.
+ */
+void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
+{
+	alloc_nid_done(sbi, nid);
+	add_free_nid(NM_I(sbi), nid);
+}
+
+void recover_node_page(struct f2fs_sb_info *sbi, struct page *page,
+		struct f2fs_summary *sum, struct node_info *ni,
+		block_t new_blkaddr)
+{
+	rewrite_node_page(sbi, page, sum, ni->blk_addr, new_blkaddr);
+	set_node_addr(sbi, ni, new_blkaddr);
+	clear_node_page_dirty(page);
+}
+
+int recover_inode_page(struct f2fs_sb_info *sbi, struct page *page)
+{
+	struct address_space *mapping = sbi->node_inode->i_mapping;
+	struct f2fs_node *src, *dst;
+	nid_t ino = ino_of_node(page);
+	struct node_info old_ni, new_ni;
+	struct page *ipage;
+
+	ipage = grab_cache_page(mapping, ino);
+	if (!ipage)
+		return -ENOMEM;
+
+	/* Should not use this inode  from free nid list */
+	remove_free_nid(NM_I(sbi), ino);
+
+	get_node_info(sbi, ino, &old_ni);
+	SetPageUptodate(ipage);
+	fill_node_footer(ipage, ino, ino, 0, true);
+
+	src = (struct f2fs_node *)page_address(page);
+	dst = (struct f2fs_node *)page_address(ipage);
+
+	memcpy(dst, src, (unsigned long)&src->i.i_ext - (unsigned long)&src->i);
+	dst->i.i_size = 0;
+	dst->i.i_blocks = cpu_to_le64(1);
+	dst->i.i_links = cpu_to_le32(1);
+	dst->i.i_xattr_nid = 0;
+
+	new_ni = old_ni;
+	new_ni.ino = ino;
+
+	set_node_addr(sbi, &new_ni, NEW_ADDR);
+	inc_valid_inode_count(sbi);
+
+	f2fs_put_page(ipage, 1);
+	return 0;
+}
+
+int restore_node_summary(struct f2fs_sb_info *sbi,
+			unsigned int segno, struct f2fs_summary_block *sum)
+{
+	struct f2fs_node *rn;
+	struct f2fs_summary *sum_entry;
+	struct page *page;
+	block_t addr;
+	int i, last_offset;
+
+	/* alloc temporal page for read node */
+	page = alloc_page(GFP_NOFS | __GFP_ZERO);
+	if (IS_ERR(page))
+		return PTR_ERR(page);
+	lock_page(page);
+
+	/* scan the node segment */
+	last_offset = sbi->blocks_per_seg;
+	addr = START_BLOCK(sbi, segno);
+	sum_entry = &sum->entries[0];
+
+	for (i = 0; i < last_offset; i++, sum_entry++) {
+		if (f2fs_readpage(sbi, page, addr, READ_SYNC))
+			goto out;
+
+		rn = (struct f2fs_node *)page_address(page);
+		sum_entry->nid = rn->footer.nid;
+		sum_entry->version = 0;
+		sum_entry->ofs_in_node = 0;
+		addr++;
+
+		/*
+		 * In order to read next node page,
+		 * we must clear PageUptodate flag.
+		 */
+		ClearPageUptodate(page);
+	}
+out:
+	unlock_page(page);
+	__free_pages(page, 0);
+	return 0;
+}
+
+static bool flush_nats_in_journal(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
+	struct f2fs_summary_block *sum = curseg->sum_blk;
+	int i;
+
+	mutex_lock(&curseg->curseg_mutex);
+
+	if (nats_in_cursum(sum) < NAT_JOURNAL_ENTRIES) {
+		mutex_unlock(&curseg->curseg_mutex);
+		return false;
+	}
+
+	for (i = 0; i < nats_in_cursum(sum); i++) {
+		struct nat_entry *ne;
+		struct f2fs_nat_entry raw_ne;
+		nid_t nid = le32_to_cpu(nid_in_journal(sum, i));
+
+		raw_ne = nat_in_journal(sum, i);
+retry:
+		write_lock(&nm_i->nat_tree_lock);
+		ne = __lookup_nat_cache(nm_i, nid);
+		if (ne) {
+			__set_nat_cache_dirty(nm_i, ne);
+			write_unlock(&nm_i->nat_tree_lock);
+			continue;
+		}
+		ne = grab_nat_entry(nm_i, nid);
+		if (!ne) {
+			write_unlock(&nm_i->nat_tree_lock);
+			goto retry;
+		}
+		nat_set_blkaddr(ne, le32_to_cpu(raw_ne.block_addr));
+		nat_set_ino(ne, le32_to_cpu(raw_ne.ino));
+		nat_set_version(ne, raw_ne.version);
+		__set_nat_cache_dirty(nm_i, ne);
+		write_unlock(&nm_i->nat_tree_lock);
+	}
+	update_nats_in_cursum(sum, -i);
+	mutex_unlock(&curseg->curseg_mutex);
+	return true;
+}
+
+/*
+ * This function is called during the checkpointing process.
+ */
+void flush_nat_entries(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
+	struct f2fs_summary_block *sum = curseg->sum_blk;
+	struct list_head *cur, *n;
+	struct page *page = NULL;
+	struct f2fs_nat_block *nat_blk = NULL;
+	nid_t start_nid = 0, end_nid = 0;
+	bool flushed;
+
+	flushed = flush_nats_in_journal(sbi);
+
+	if (!flushed)
+		mutex_lock(&curseg->curseg_mutex);
+
+	/* 1) flush dirty nat caches */
+	list_for_each_safe(cur, n, &nm_i->dirty_nat_entries) {
+		struct nat_entry *ne;
+		nid_t nid;
+		struct f2fs_nat_entry raw_ne;
+		int offset = -1;
+		block_t old_blkaddr, new_blkaddr;
+
+		ne = list_entry(cur, struct nat_entry, list);
+		nid = nat_get_nid(ne);
+
+		if (nat_get_blkaddr(ne) == NEW_ADDR)
+			continue;
+		if (flushed)
+			goto to_nat_page;
+
+		/* if there is room for nat enries in curseg->sumpage */
+		offset = lookup_journal_in_cursum(sum, NAT_JOURNAL, nid, 1);
+		if (offset >= 0) {
+			raw_ne = nat_in_journal(sum, offset);
+			old_blkaddr = le32_to_cpu(raw_ne.block_addr);
+			goto flush_now;
+		}
+to_nat_page:
+		if (!page || (start_nid > nid || nid > end_nid)) {
+			if (page) {
+				f2fs_put_page(page, 1);
+				page = NULL;
+			}
+			start_nid = START_NID(nid);
+			end_nid = start_nid + NAT_ENTRY_PER_BLOCK - 1;
+
+			/*
+			 * get nat block with dirty flag, increased reference
+			 * count, mapped and lock
+			 */
+			page = get_next_nat_page(sbi, start_nid);
+			nat_blk = page_address(page);
+		}
+
+		BUG_ON(!nat_blk);
+		raw_ne = nat_blk->entries[nid - start_nid];
+		old_blkaddr = le32_to_cpu(raw_ne.block_addr);
+flush_now:
+		new_blkaddr = nat_get_blkaddr(ne);
+
+		raw_ne.ino = cpu_to_le32(nat_get_ino(ne));
+		raw_ne.block_addr = cpu_to_le32(new_blkaddr);
+		raw_ne.version = nat_get_version(ne);
+
+		if (offset < 0) {
+			nat_blk->entries[nid - start_nid] = raw_ne;
+		} else {
+			nat_in_journal(sum, offset) = raw_ne;
+			nid_in_journal(sum, offset) = cpu_to_le32(nid);
+		}
+
+		if (nat_get_blkaddr(ne) == NULL_ADDR) {
+			write_lock(&nm_i->nat_tree_lock);
+			__del_from_nat_cache(nm_i, ne);
+			write_unlock(&nm_i->nat_tree_lock);
+
+			/* We can reuse this freed nid at this point */
+			add_free_nid(NM_I(sbi), nid);
+		} else {
+			write_lock(&nm_i->nat_tree_lock);
+			__clear_nat_cache_dirty(nm_i, ne);
+			ne->checkpointed = true;
+			write_unlock(&nm_i->nat_tree_lock);
+		}
+	}
+	if (!flushed)
+		mutex_unlock(&curseg->curseg_mutex);
+	f2fs_put_page(page, 1);
+
+	/* 2) shrink nat caches if necessary */
+	try_to_free_nats(sbi, nm_i->nat_cnt - NM_WOUT_THRESHOLD);
+}
+
+static int init_node_manager(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_super_block *sb_raw = F2FS_RAW_SUPER(sbi);
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	unsigned char *version_bitmap;
+	unsigned int nat_segs, nat_blocks;
+
+	nm_i->nat_blkaddr = le32_to_cpu(sb_raw->nat_blkaddr);
+
+	/* segment_count_nat includes pair segment so divide to 2. */
+	nat_segs = le32_to_cpu(sb_raw->segment_count_nat) >> 1;
+	nat_blocks = nat_segs << le32_to_cpu(sb_raw->log_blocks_per_seg);
+	nm_i->max_nid = NAT_ENTRY_PER_BLOCK * nat_blocks;
+	nm_i->fcnt = 0;
+	nm_i->nat_cnt = 0;
+
+	INIT_LIST_HEAD(&nm_i->free_nid_list);
+	INIT_RADIX_TREE(&nm_i->nat_root, GFP_ATOMIC);
+	INIT_LIST_HEAD(&nm_i->nat_entries);
+	INIT_LIST_HEAD(&nm_i->dirty_nat_entries);
+
+	mutex_init(&nm_i->build_lock);
+	spin_lock_init(&nm_i->free_nid_list_lock);
+	rwlock_init(&nm_i->nat_tree_lock);
+
+	nm_i->bitmap_size = __bitmap_size(sbi, NAT_BITMAP);
+	nm_i->init_scan_nid = le32_to_cpu(sbi->ckpt->next_free_nid);
+	nm_i->next_scan_nid = le32_to_cpu(sbi->ckpt->next_free_nid);
+
+	nm_i->nat_bitmap = kzalloc(nm_i->bitmap_size, GFP_KERNEL);
+	if (!nm_i->nat_bitmap)
+		return -ENOMEM;
+	version_bitmap = __bitmap_ptr(sbi, NAT_BITMAP);
+	if (!version_bitmap)
+		return -EFAULT;
+
+	/* copy version bitmap */
+	memcpy(nm_i->nat_bitmap, version_bitmap, nm_i->bitmap_size);
+	return 0;
+}
+
+int build_node_manager(struct f2fs_sb_info *sbi)
+{
+	int err;
+
+	sbi->nm_info = kzalloc(sizeof(struct f2fs_nm_info), GFP_KERNEL);
+	if (!sbi->nm_info)
+		return -ENOMEM;
+
+	err = init_node_manager(sbi);
+	if (err)
+		return err;
+
+	build_free_nids(sbi);
+	return 0;
+}
+
+void destroy_node_manager(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct free_nid *i, *next_i;
+	struct nat_entry *natvec[NATVEC_SIZE];
+	nid_t nid = 0;
+	unsigned int found;
+
+	if (!nm_i)
+		return;
+
+	/* destroy free nid list */
+	spin_lock(&nm_i->free_nid_list_lock);
+	list_for_each_entry_safe(i, next_i, &nm_i->free_nid_list, list) {
+		BUG_ON(i->state == NID_ALLOC);
+		__del_from_free_nid_list(i);
+		nm_i->fcnt--;
+	}
+	BUG_ON(nm_i->fcnt);
+	spin_unlock(&nm_i->free_nid_list_lock);
+
+	/* destroy nat cache */
+	write_lock(&nm_i->nat_tree_lock);
+	while ((found = __gang_lookup_nat_cache(nm_i,
+					nid, NATVEC_SIZE, natvec))) {
+		unsigned idx;
+		for (idx = 0; idx < found; idx++) {
+			struct nat_entry *e = natvec[idx];
+			nid = nat_get_nid(e) + 1;
+			__del_from_nat_cache(nm_i, e);
+		}
+	}
+	BUG_ON(nm_i->nat_cnt);
+	write_unlock(&nm_i->nat_tree_lock);
+
+	kfree(nm_i->nat_bitmap);
+	sbi->nm_info = NULL;
+	kfree(nm_i);
+}
+
+int create_node_manager_caches(void)
+{
+	nat_entry_slab = f2fs_kmem_cache_create("nat_entry",
+			sizeof(struct nat_entry), NULL);
+	if (!nat_entry_slab)
+		return -ENOMEM;
+
+	free_nid_slab = f2fs_kmem_cache_create("free_nid",
+			sizeof(struct free_nid), NULL);
+	if (!free_nid_slab) {
+		kmem_cache_destroy(nat_entry_slab);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void destroy_node_manager_caches(void)
+{
+	kmem_cache_destroy(free_nid_slab);
+	kmem_cache_destroy(nat_entry_slab);
+}

fs/f2fs/node.h

···
+/*
+ * fs/f2fs/node.h
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+/* start node id of a node block dedicated to the given node id */
+#define	START_NID(nid) ((nid / NAT_ENTRY_PER_BLOCK) * NAT_ENTRY_PER_BLOCK)
+
+/* node block offset on the NAT area dedicated to the given start node id */
+#define	NAT_BLOCK_OFFSET(start_nid) (start_nid / NAT_ENTRY_PER_BLOCK)
+
+/* # of pages to perform readahead before building free nids */
+#define FREE_NID_PAGES 4
+
+/* maximum # of free node ids to produce during build_free_nids */
+#define MAX_FREE_NIDS (NAT_ENTRY_PER_BLOCK * FREE_NID_PAGES)
+
+/* maximum readahead size for node during getting data blocks */
+#define MAX_RA_NODE		128
+
+/* maximum cached nat entries to manage memory footprint */
+#define NM_WOUT_THRESHOLD	(64 * NAT_ENTRY_PER_BLOCK)
+
+/* vector size for gang look-up from nat cache that consists of radix tree */
+#define NATVEC_SIZE	64
+
+/*
+ * For node information
+ */
+struct node_info {
+	nid_t nid;		/* node id */
+	nid_t ino;		/* inode number of the node's owner */
+	block_t	blk_addr;	/* block address of the node */
+	unsigned char version;	/* version of the node */
+};
+
+struct nat_entry {
+	struct list_head list;	/* for clean or dirty nat list */
+	bool checkpointed;	/* whether it is checkpointed or not */
+	struct node_info ni;	/* in-memory node information */
+};
+
+#define nat_get_nid(nat)		(nat->ni.nid)
+#define nat_set_nid(nat, n)		(nat->ni.nid = n)
+#define nat_get_blkaddr(nat)		(nat->ni.blk_addr)
+#define nat_set_blkaddr(nat, b)		(nat->ni.blk_addr = b)
+#define nat_get_ino(nat)		(nat->ni.ino)
+#define nat_set_ino(nat, i)		(nat->ni.ino = i)
+#define nat_get_version(nat)		(nat->ni.version)
+#define nat_set_version(nat, v)		(nat->ni.version = v)
+
+#define __set_nat_cache_dirty(nm_i, ne)					\
+	list_move_tail(&ne->list, &nm_i->dirty_nat_entries);
+#define __clear_nat_cache_dirty(nm_i, ne)				\
+	list_move_tail(&ne->list, &nm_i->nat_entries);
+#define inc_node_version(version)	(++version)
+
+static inline void node_info_from_raw_nat(struct node_info *ni,
+						struct f2fs_nat_entry *raw_ne)
+{
+	ni->ino = le32_to_cpu(raw_ne->ino);
+	ni->blk_addr = le32_to_cpu(raw_ne->block_addr);
+	ni->version = raw_ne->version;
+}
+
+/*
+ * For free nid mangement
+ */
+enum nid_state {
+	NID_NEW,	/* newly added to free nid list */
+	NID_ALLOC	/* it is allocated */
+};
+
+struct free_nid {
+	struct list_head list;	/* for free node id list */
+	nid_t nid;		/* node id */
+	int state;		/* in use or not: NID_NEW or NID_ALLOC */
+};
+
+static inline int next_free_nid(struct f2fs_sb_info *sbi, nid_t *nid)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct free_nid *fnid;
+
+	if (nm_i->fcnt <= 0)
+		return -1;
+	spin_lock(&nm_i->free_nid_list_lock);
+	fnid = list_entry(nm_i->free_nid_list.next, struct free_nid, list);
+	*nid = fnid->nid;
+	spin_unlock(&nm_i->free_nid_list_lock);
+	return 0;
+}
+
+/*
+ * inline functions
+ */
+static inline void get_nat_bitmap(struct f2fs_sb_info *sbi, void *addr)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	memcpy(addr, nm_i->nat_bitmap, nm_i->bitmap_size);
+}
+
+static inline pgoff_t current_nat_addr(struct f2fs_sb_info *sbi, nid_t start)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	pgoff_t block_off;
+	pgoff_t block_addr;
+	int seg_off;
+
+	block_off = NAT_BLOCK_OFFSET(start);
+	seg_off = block_off >> sbi->log_blocks_per_seg;
+
+	block_addr = (pgoff_t)(nm_i->nat_blkaddr +
+		(seg_off << sbi->log_blocks_per_seg << 1) +
+		(block_off & ((1 << sbi->log_blocks_per_seg) - 1)));
+
+	if (f2fs_test_bit(block_off, nm_i->nat_bitmap))
+		block_addr += sbi->blocks_per_seg;
+
+	return block_addr;
+}
+
+static inline pgoff_t next_nat_addr(struct f2fs_sb_info *sbi,
+						pgoff_t block_addr)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+
+	block_addr -= nm_i->nat_blkaddr;
+	if ((block_addr >> sbi->log_blocks_per_seg) % 2)
+		block_addr -= sbi->blocks_per_seg;
+	else
+		block_addr += sbi->blocks_per_seg;
+
+	return block_addr + nm_i->nat_blkaddr;
+}
+
+static inline void set_to_next_nat(struct f2fs_nm_info *nm_i, nid_t start_nid)
+{
+	unsigned int block_off = NAT_BLOCK_OFFSET(start_nid);
+
+	if (f2fs_test_bit(block_off, nm_i->nat_bitmap))
+		f2fs_clear_bit(block_off, nm_i->nat_bitmap);
+	else
+		f2fs_set_bit(block_off, nm_i->nat_bitmap);
+}
+
+static inline void fill_node_footer(struct page *page, nid_t nid,
+				nid_t ino, unsigned int ofs, bool reset)
+{
+	void *kaddr = page_address(page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	if (reset)
+		memset(rn, 0, sizeof(*rn));
+	rn->footer.nid = cpu_to_le32(nid);
+	rn->footer.ino = cpu_to_le32(ino);
+	rn->footer.flag = cpu_to_le32(ofs << OFFSET_BIT_SHIFT);
+}
+
+static inline void copy_node_footer(struct page *dst, struct page *src)
+{
+	void *src_addr = page_address(src);
+	void *dst_addr = page_address(dst);
+	struct f2fs_node *src_rn = (struct f2fs_node *)src_addr;
+	struct f2fs_node *dst_rn = (struct f2fs_node *)dst_addr;
+	memcpy(&dst_rn->footer, &src_rn->footer, sizeof(struct node_footer));
+}
+
+static inline void fill_node_footer_blkaddr(struct page *page, block_t blkaddr)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb);
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	void *kaddr = page_address(page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	rn->footer.cp_ver = ckpt->checkpoint_ver;
+	rn->footer.next_blkaddr = cpu_to_le32(blkaddr);
+}
+
+static inline nid_t ino_of_node(struct page *node_page)
+{
+	void *kaddr = page_address(node_page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	return le32_to_cpu(rn->footer.ino);
+}
+
+static inline nid_t nid_of_node(struct page *node_page)
+{
+	void *kaddr = page_address(node_page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	return le32_to_cpu(rn->footer.nid);
+}
+
+static inline unsigned int ofs_of_node(struct page *node_page)
+{
+	void *kaddr = page_address(node_page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	unsigned flag = le32_to_cpu(rn->footer.flag);
+	return flag >> OFFSET_BIT_SHIFT;
+}
+
+static inline unsigned long long cpver_of_node(struct page *node_page)
+{
+	void *kaddr = page_address(node_page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	return le64_to_cpu(rn->footer.cp_ver);
+}
+
+static inline block_t next_blkaddr_of_node(struct page *node_page)
+{
+	void *kaddr = page_address(node_page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	return le32_to_cpu(rn->footer.next_blkaddr);
+}
+
+/*
+ * f2fs assigns the following node offsets described as (num).
+ * N = NIDS_PER_BLOCK
+ *
+ *  Inode block (0)
+ *    |- direct node (1)
+ *    |- direct node (2)
+ *    |- indirect node (3)
+ *    |            `- direct node (4 => 4 + N - 1)
+ *    |- indirect node (4 + N)
+ *    |            `- direct node (5 + N => 5 + 2N - 1)
+ *    `- double indirect node (5 + 2N)
+ *                 `- indirect node (6 + 2N)
+ *                       `- direct node (x(N + 1))
+ */
+static inline bool IS_DNODE(struct page *node_page)
+{
+	unsigned int ofs = ofs_of_node(node_page);
+	if (ofs == 3 || ofs == 4 + NIDS_PER_BLOCK ||
+			ofs == 5 + 2 * NIDS_PER_BLOCK)
+		return false;
+	if (ofs >= 6 + 2 * NIDS_PER_BLOCK) {
+		ofs -= 6 + 2 * NIDS_PER_BLOCK;
+		if ((long int)ofs % (NIDS_PER_BLOCK + 1))
+			return false;
+	}
+	return true;
+}
+
+static inline void set_nid(struct page *p, int off, nid_t nid, bool i)
+{
+	struct f2fs_node *rn = (struct f2fs_node *)page_address(p);
+
+	wait_on_page_writeback(p);
+
+	if (i)
+		rn->i.i_nid[off - NODE_DIR1_BLOCK] = cpu_to_le32(nid);
+	else
+		rn->in.nid[off] = cpu_to_le32(nid);
+	set_page_dirty(p);
+}
+
+static inline nid_t get_nid(struct page *p, int off, bool i)
+{
+	struct f2fs_node *rn = (struct f2fs_node *)page_address(p);
+	if (i)
+		return le32_to_cpu(rn->i.i_nid[off - NODE_DIR1_BLOCK]);
+	return le32_to_cpu(rn->in.nid[off]);
+}
+
+/*
+ * Coldness identification:
+ *  - Mark cold files in f2fs_inode_info
+ *  - Mark cold node blocks in their node footer
+ *  - Mark cold data pages in page cache
+ */
+static inline int is_cold_file(struct inode *inode)
+{
+	return F2FS_I(inode)->i_advise & FADVISE_COLD_BIT;
+}
+
+static inline int is_cold_data(struct page *page)
+{
+	return PageChecked(page);
+}
+
+static inline void set_cold_data(struct page *page)
+{
+	SetPageChecked(page);
+}
+
+static inline void clear_cold_data(struct page *page)
+{
+	ClearPageChecked(page);
+}
+
+static inline int is_cold_node(struct page *page)
+{
+	void *kaddr = page_address(page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	unsigned int flag = le32_to_cpu(rn->footer.flag);
+	return flag & (0x1 << COLD_BIT_SHIFT);
+}
+
+static inline unsigned char is_fsync_dnode(struct page *page)
+{
+	void *kaddr = page_address(page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	unsigned int flag = le32_to_cpu(rn->footer.flag);
+	return flag & (0x1 << FSYNC_BIT_SHIFT);
+}
+
+static inline unsigned char is_dent_dnode(struct page *page)
+{
+	void *kaddr = page_address(page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	unsigned int flag = le32_to_cpu(rn->footer.flag);
+	return flag & (0x1 << DENT_BIT_SHIFT);
+}
+
+static inline void set_cold_node(struct inode *inode, struct page *page)
+{
+	struct f2fs_node *rn = (struct f2fs_node *)page_address(page);
+	unsigned int flag = le32_to_cpu(rn->footer.flag);
+
+	if (S_ISDIR(inode->i_mode))
+		flag &= ~(0x1 << COLD_BIT_SHIFT);
+	else
+		flag |= (0x1 << COLD_BIT_SHIFT);
+	rn->footer.flag = cpu_to_le32(flag);
+}
+
+static inline void set_fsync_mark(struct page *page, int mark)
+{
+	void *kaddr = page_address(page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	unsigned int flag = le32_to_cpu(rn->footer.flag);
+	if (mark)
+		flag |= (0x1 << FSYNC_BIT_SHIFT);
+	else
+		flag &= ~(0x1 << FSYNC_BIT_SHIFT);
+	rn->footer.flag = cpu_to_le32(flag);
+}
+
+static inline void set_dentry_mark(struct page *page, int mark)
+{
+	void *kaddr = page_address(page);
+	struct f2fs_node *rn = (struct f2fs_node *)kaddr;
+	unsigned int flag = le32_to_cpu(rn->footer.flag);
+	if (mark)
+		flag |= (0x1 << DENT_BIT_SHIFT);
+	else
+		flag &= ~(0x1 << DENT_BIT_SHIFT);
+	rn->footer.flag = cpu_to_le32(flag);
+}

fs/f2fs/recovery.c

···
+/*
+ * fs/f2fs/recovery.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include "f2fs.h"
+#include "node.h"
+#include "segment.h"
+
+static struct kmem_cache *fsync_entry_slab;
+
+bool space_for_roll_forward(struct f2fs_sb_info *sbi)
+{
+	if (sbi->last_valid_block_count + sbi->alloc_valid_block_count
+			> sbi->user_block_count)
+		return false;
+	return true;
+}
+
+static struct fsync_inode_entry *get_fsync_inode(struct list_head *head,
+								nid_t ino)
+{
+	struct list_head *this;
+	struct fsync_inode_entry *entry;
+
+	list_for_each(this, head) {
+		entry = list_entry(this, struct fsync_inode_entry, list);
+		if (entry->inode->i_ino == ino)
+			return entry;
+	}
+	return NULL;
+}
+
+static int recover_dentry(struct page *ipage, struct inode *inode)
+{
+	struct f2fs_node *raw_node = (struct f2fs_node *)kmap(ipage);
+	struct f2fs_inode *raw_inode = &(raw_node->i);
+	struct dentry dent, parent;
+	struct f2fs_dir_entry *de;
+	struct page *page;
+	struct inode *dir;
+	int err = 0;
+
+	if (!is_dent_dnode(ipage))
+		goto out;
+
+	dir = f2fs_iget(inode->i_sb, le32_to_cpu(raw_inode->i_pino));
+	if (IS_ERR(dir)) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	parent.d_inode = dir;
+	dent.d_parent = &parent;
+	dent.d_name.len = le32_to_cpu(raw_inode->i_namelen);
+	dent.d_name.name = raw_inode->i_name;
+
+	de = f2fs_find_entry(dir, &dent.d_name, &page);
+	if (de) {
+		kunmap(page);
+		f2fs_put_page(page, 0);
+	} else {
+		f2fs_add_link(&dent, inode);
+	}
+	iput(dir);
+out:
+	kunmap(ipage);
+	return err;
+}
+
+static int recover_inode(struct inode *inode, struct page *node_page)
+{
+	void *kaddr = page_address(node_page);
+	struct f2fs_node *raw_node = (struct f2fs_node *)kaddr;
+	struct f2fs_inode *raw_inode = &(raw_node->i);
+
+	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
+	i_size_write(inode, le64_to_cpu(raw_inode->i_size));
+	inode->i_atime.tv_sec = le64_to_cpu(raw_inode->i_mtime);
+	inode->i_ctime.tv_sec = le64_to_cpu(raw_inode->i_ctime);
+	inode->i_mtime.tv_sec = le64_to_cpu(raw_inode->i_mtime);
+	inode->i_atime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);
+	inode->i_ctime.tv_nsec = le32_to_cpu(raw_inode->i_ctime_nsec);
+	inode->i_mtime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);
+
+	return recover_dentry(node_page, inode);
+}
+
+static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head)
+{
+	unsigned long long cp_ver = le64_to_cpu(sbi->ckpt->checkpoint_ver);
+	struct curseg_info *curseg;
+	struct page *page;
+	block_t blkaddr;
+	int err = 0;
+
+	/* get node pages in the current segment */
+	curseg = CURSEG_I(sbi, CURSEG_WARM_NODE);
+	blkaddr = START_BLOCK(sbi, curseg->segno) + curseg->next_blkoff;
+
+	/* read node page */
+	page = alloc_page(GFP_F2FS_ZERO);
+	if (IS_ERR(page))
+		return PTR_ERR(page);
+	lock_page(page);
+
+	while (1) {
+		struct fsync_inode_entry *entry;
+
+		if (f2fs_readpage(sbi, page, blkaddr, READ_SYNC))
+			goto out;
+
+		if (cp_ver != cpver_of_node(page))
+			goto out;
+
+		if (!is_fsync_dnode(page))
+			goto next;
+
+		entry = get_fsync_inode(head, ino_of_node(page));
+		if (entry) {
+			entry->blkaddr = blkaddr;
+			if (IS_INODE(page) && is_dent_dnode(page))
+				set_inode_flag(F2FS_I(entry->inode),
+							FI_INC_LINK);
+		} else {
+			if (IS_INODE(page) && is_dent_dnode(page)) {
+				if (recover_inode_page(sbi, page)) {
+					err = -ENOMEM;
+					goto out;
+				}
+			}
+
+			/* add this fsync inode to the list */
+			entry = kmem_cache_alloc(fsync_entry_slab, GFP_NOFS);
+			if (!entry) {
+				err = -ENOMEM;
+				goto out;
+			}
+
+			INIT_LIST_HEAD(&entry->list);
+			list_add_tail(&entry->list, head);
+
+			entry->inode = f2fs_iget(sbi->sb, ino_of_node(page));
+			if (IS_ERR(entry->inode)) {
+				err = PTR_ERR(entry->inode);
+				goto out;
+			}
+			entry->blkaddr = blkaddr;
+		}
+		if (IS_INODE(page)) {
+			err = recover_inode(entry->inode, page);
+			if (err)
+				goto out;
+		}
+next:
+		/* check next segment */
+		blkaddr = next_blkaddr_of_node(page);
+		ClearPageUptodate(page);
+	}
+out:
+	unlock_page(page);
+	__free_pages(page, 0);
+	return err;
+}
+
+static void destroy_fsync_dnodes(struct f2fs_sb_info *sbi,
+					struct list_head *head)
+{
+	struct list_head *this;
+	struct fsync_inode_entry *entry;
+	list_for_each(this, head) {
+		entry = list_entry(this, struct fsync_inode_entry, list);
+		iput(entry->inode);
+		list_del(&entry->list);
+		kmem_cache_free(fsync_entry_slab, entry);
+	}
+}
+
+static void check_index_in_prev_nodes(struct f2fs_sb_info *sbi,
+						block_t blkaddr)
+{
+	struct seg_entry *sentry;
+	unsigned int segno = GET_SEGNO(sbi, blkaddr);
+	unsigned short blkoff = GET_SEGOFF_FROM_SEG0(sbi, blkaddr) &
+					(sbi->blocks_per_seg - 1);
+	struct f2fs_summary sum;
+	nid_t ino;
+	void *kaddr;
+	struct inode *inode;
+	struct page *node_page;
+	block_t bidx;
+	int i;
+
+	sentry = get_seg_entry(sbi, segno);
+	if (!f2fs_test_bit(blkoff, sentry->cur_valid_map))
+		return;
+
+	/* Get the previous summary */
+	for (i = CURSEG_WARM_DATA; i <= CURSEG_COLD_DATA; i++) {
+		struct curseg_info *curseg = CURSEG_I(sbi, i);
+		if (curseg->segno == segno) {
+			sum = curseg->sum_blk->entries[blkoff];
+			break;
+		}
+	}
+	if (i > CURSEG_COLD_DATA) {
+		struct page *sum_page = get_sum_page(sbi, segno);
+		struct f2fs_summary_block *sum_node;
+		kaddr = page_address(sum_page);
+		sum_node = (struct f2fs_summary_block *)kaddr;
+		sum = sum_node->entries[blkoff];
+		f2fs_put_page(sum_page, 1);
+	}
+
+	/* Get the node page */
+	node_page = get_node_page(sbi, le32_to_cpu(sum.nid));
+	bidx = start_bidx_of_node(ofs_of_node(node_page)) +
+				le16_to_cpu(sum.ofs_in_node);
+	ino = ino_of_node(node_page);
+	f2fs_put_page(node_page, 1);
+
+	/* Deallocate previous index in the node page */
+	inode = f2fs_iget_nowait(sbi->sb, ino);
+	truncate_hole(inode, bidx, bidx + 1);
+	iput(inode);
+}
+
+static void do_recover_data(struct f2fs_sb_info *sbi, struct inode *inode,
+					struct page *page, block_t blkaddr)
+{
+	unsigned int start, end;
+	struct dnode_of_data dn;
+	struct f2fs_summary sum;
+	struct node_info ni;
+
+	start = start_bidx_of_node(ofs_of_node(page));
+	if (IS_INODE(page))
+		end = start + ADDRS_PER_INODE;
+	else
+		end = start + ADDRS_PER_BLOCK;
+
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
+	if (get_dnode_of_data(&dn, start, 0))
+		return;
+
+	wait_on_page_writeback(dn.node_page);
+
+	get_node_info(sbi, dn.nid, &ni);
+	BUG_ON(ni.ino != ino_of_node(page));
+	BUG_ON(ofs_of_node(dn.node_page) != ofs_of_node(page));
+
+	for (; start < end; start++) {
+		block_t src, dest;
+
+		src = datablock_addr(dn.node_page, dn.ofs_in_node);
+		dest = datablock_addr(page, dn.ofs_in_node);
+
+		if (src != dest && dest != NEW_ADDR && dest != NULL_ADDR) {
+			if (src == NULL_ADDR) {
+				int err = reserve_new_block(&dn);
+				/* We should not get -ENOSPC */
+				BUG_ON(err);
+			}
+
+			/* Check the previous node page having this index */
+			check_index_in_prev_nodes(sbi, dest);
+
+			set_summary(&sum, dn.nid, dn.ofs_in_node, ni.version);
+
+			/* write dummy data page */
+			recover_data_page(sbi, NULL, &sum, src, dest);
+			update_extent_cache(dest, &dn);
+		}
+		dn.ofs_in_node++;
+	}
+
+	/* write node page in place */
+	set_summary(&sum, dn.nid, 0, 0);
+	if (IS_INODE(dn.node_page))
+		sync_inode_page(&dn);
+
+	copy_node_footer(dn.node_page, page);
+	fill_node_footer(dn.node_page, dn.nid, ni.ino,
+					ofs_of_node(page), false);
+	set_page_dirty(dn.node_page);
+
+	recover_node_page(sbi, dn.node_page, &sum, &ni, blkaddr);
+	f2fs_put_dnode(&dn);
+}
+
+static void recover_data(struct f2fs_sb_info *sbi,
+				struct list_head *head, int type)
+{
+	unsigned long long cp_ver = le64_to_cpu(sbi->ckpt->checkpoint_ver);
+	struct curseg_info *curseg;
+	struct page *page;
+	block_t blkaddr;
+
+	/* get node pages in the current segment */
+	curseg = CURSEG_I(sbi, type);
+	blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
+
+	/* read node page */
+	page = alloc_page(GFP_NOFS | __GFP_ZERO);
+	if (IS_ERR(page))
+		return;
+	lock_page(page);
+
+	while (1) {
+		struct fsync_inode_entry *entry;
+
+		if (f2fs_readpage(sbi, page, blkaddr, READ_SYNC))
+			goto out;
+
+		if (cp_ver != cpver_of_node(page))
+			goto out;
+
+		entry = get_fsync_inode(head, ino_of_node(page));
+		if (!entry)
+			goto next;
+
+		do_recover_data(sbi, entry->inode, page, blkaddr);
+
+		if (entry->blkaddr == blkaddr) {
+			iput(entry->inode);
+			list_del(&entry->list);
+			kmem_cache_free(fsync_entry_slab, entry);
+		}
+next:
+		/* check next segment */
+		blkaddr = next_blkaddr_of_node(page);
+		ClearPageUptodate(page);
+	}
+out:
+	unlock_page(page);
+	__free_pages(page, 0);
+
+	allocate_new_segments(sbi);
+}
+
+void recover_fsync_data(struct f2fs_sb_info *sbi)
+{
+	struct list_head inode_list;
+
+	fsync_entry_slab = f2fs_kmem_cache_create("f2fs_fsync_inode_entry",
+			sizeof(struct fsync_inode_entry), NULL);
+	if (unlikely(!fsync_entry_slab))
+		return;
+
+	INIT_LIST_HEAD(&inode_list);
+
+	/* step #1: find fsynced inode numbers */
+	if (find_fsync_dnodes(sbi, &inode_list))
+		goto out;
+
+	if (list_empty(&inode_list))
+		goto out;
+
+	/* step #2: recover data */
+	sbi->por_doing = 1;
+	recover_data(sbi, &inode_list, CURSEG_WARM_NODE);
+	sbi->por_doing = 0;
+	BUG_ON(!list_empty(&inode_list));
+out:
+	destroy_fsync_dnodes(sbi, &inode_list);
+	kmem_cache_destroy(fsync_entry_slab);
+	write_checkpoint(sbi, false, false);
+}

fs/f2fs/segment.c

···
+/*
+ * fs/f2fs/segment.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/vmalloc.h>
+
+#include "f2fs.h"
+#include "segment.h"
+#include "node.h"
+
+static int need_to_flush(struct f2fs_sb_info *sbi)
+{
+	unsigned int pages_per_sec = (1 << sbi->log_blocks_per_seg) *
+			sbi->segs_per_sec;
+	int node_secs = ((get_pages(sbi, F2FS_DIRTY_NODES) + pages_per_sec - 1)
+		>> sbi->log_blocks_per_seg) / sbi->segs_per_sec;
+	int dent_secs = ((get_pages(sbi, F2FS_DIRTY_DENTS) + pages_per_sec - 1)
+		>> sbi->log_blocks_per_seg) / sbi->segs_per_sec;
+
+	if (sbi->por_doing)
+		return 0;
+
+	if (free_sections(sbi) <= (node_secs + 2 * dent_secs +
+						reserved_sections(sbi)))
+		return 1;
+	return 0;
+}
+
+/*
+ * This function balances dirty node and dentry pages.
+ * In addition, it controls garbage collection.
+ */
+void f2fs_balance_fs(struct f2fs_sb_info *sbi)
+{
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_ALL,
+		.nr_to_write = LONG_MAX,
+		.for_reclaim = 0,
+	};
+
+	if (sbi->por_doing)
+		return;
+
+	/*
+	 * We should do checkpoint when there are so many dirty node pages
+	 * with enough free segments. After then, we should do GC.
+	 */
+	if (need_to_flush(sbi)) {
+		sync_dirty_dir_inodes(sbi);
+		sync_node_pages(sbi, 0, &wbc);
+	}
+
+	if (has_not_enough_free_secs(sbi)) {
+		mutex_lock(&sbi->gc_mutex);
+		f2fs_gc(sbi, 1);
+	}
+}
+
+static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
+		enum dirty_type dirty_type)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+
+	/* need not be added */
+	if (IS_CURSEG(sbi, segno))
+		return;
+
+	if (!test_and_set_bit(segno, dirty_i->dirty_segmap[dirty_type]))
+		dirty_i->nr_dirty[dirty_type]++;
+
+	if (dirty_type == DIRTY) {
+		struct seg_entry *sentry = get_seg_entry(sbi, segno);
+		dirty_type = sentry->type;
+		if (!test_and_set_bit(segno, dirty_i->dirty_segmap[dirty_type]))
+			dirty_i->nr_dirty[dirty_type]++;
+	}
+}
+
+static void __remove_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
+		enum dirty_type dirty_type)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+
+	if (test_and_clear_bit(segno, dirty_i->dirty_segmap[dirty_type]))
+		dirty_i->nr_dirty[dirty_type]--;
+
+	if (dirty_type == DIRTY) {
+		struct seg_entry *sentry = get_seg_entry(sbi, segno);
+		dirty_type = sentry->type;
+		if (test_and_clear_bit(segno,
+					dirty_i->dirty_segmap[dirty_type]))
+			dirty_i->nr_dirty[dirty_type]--;
+		clear_bit(segno, dirty_i->victim_segmap[FG_GC]);
+		clear_bit(segno, dirty_i->victim_segmap[BG_GC]);
+	}
+}
+
+/*
+ * Should not occur error such as -ENOMEM.
+ * Adding dirty entry into seglist is not critical operation.
+ * If a given segment is one of current working segments, it won't be added.
+ */
+void locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	unsigned short valid_blocks;
+
+	if (segno == NULL_SEGNO || IS_CURSEG(sbi, segno))
+		return;
+
+	mutex_lock(&dirty_i->seglist_lock);
+
+	valid_blocks = get_valid_blocks(sbi, segno, 0);
+
+	if (valid_blocks == 0) {
+		__locate_dirty_segment(sbi, segno, PRE);
+		__remove_dirty_segment(sbi, segno, DIRTY);
+	} else if (valid_blocks < sbi->blocks_per_seg) {
+		__locate_dirty_segment(sbi, segno, DIRTY);
+	} else {
+		/* Recovery routine with SSR needs this */
+		__remove_dirty_segment(sbi, segno, DIRTY);
+	}
+
+	mutex_unlock(&dirty_i->seglist_lock);
+	return;
+}
+
+/*
+ * Should call clear_prefree_segments after checkpoint is done.
+ */
+static void set_prefree_as_free_segments(struct f2fs_sb_info *sbi)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	unsigned int segno, offset = 0;
+	unsigned int total_segs = TOTAL_SEGS(sbi);
+
+	mutex_lock(&dirty_i->seglist_lock);
+	while (1) {
+		segno = find_next_bit(dirty_i->dirty_segmap[PRE], total_segs,
+				offset);
+		if (segno >= total_segs)
+			break;
+		__set_test_and_free(sbi, segno);
+		offset = segno + 1;
+	}
+	mutex_unlock(&dirty_i->seglist_lock);
+}
+
+void clear_prefree_segments(struct f2fs_sb_info *sbi)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	unsigned int segno, offset = 0;
+	unsigned int total_segs = TOTAL_SEGS(sbi);
+
+	mutex_lock(&dirty_i->seglist_lock);
+	while (1) {
+		segno = find_next_bit(dirty_i->dirty_segmap[PRE], total_segs,
+				offset);
+		if (segno >= total_segs)
+			break;
+
+		offset = segno + 1;
+		if (test_and_clear_bit(segno, dirty_i->dirty_segmap[PRE]))
+			dirty_i->nr_dirty[PRE]--;
+
+		/* Let's use trim */
+		if (test_opt(sbi, DISCARD))
+			blkdev_issue_discard(sbi->sb->s_bdev,
+					START_BLOCK(sbi, segno) <<
+					sbi->log_sectors_per_block,
+					1 << (sbi->log_sectors_per_block +
+						sbi->log_blocks_per_seg),
+					GFP_NOFS, 0);
+	}
+	mutex_unlock(&dirty_i->seglist_lock);
+}
+
+static void __mark_sit_entry_dirty(struct f2fs_sb_info *sbi, unsigned int segno)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	if (!__test_and_set_bit(segno, sit_i->dirty_sentries_bitmap))
+		sit_i->dirty_sentries++;
+}
+
+static void __set_sit_entry_type(struct f2fs_sb_info *sbi, int type,
+					unsigned int segno, int modified)
+{
+	struct seg_entry *se = get_seg_entry(sbi, segno);
+	se->type = type;
+	if (modified)
+		__mark_sit_entry_dirty(sbi, segno);
+}
+
+static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
+{
+	struct seg_entry *se;
+	unsigned int segno, offset;
+	long int new_vblocks;
+
+	segno = GET_SEGNO(sbi, blkaddr);
+
+	se = get_seg_entry(sbi, segno);
+	new_vblocks = se->valid_blocks + del;
+	offset = GET_SEGOFF_FROM_SEG0(sbi, blkaddr) & (sbi->blocks_per_seg - 1);
+
+	BUG_ON((new_vblocks >> (sizeof(unsigned short) << 3) ||
+				(new_vblocks > sbi->blocks_per_seg)));
+
+	se->valid_blocks = new_vblocks;
+	se->mtime = get_mtime(sbi);
+	SIT_I(sbi)->max_mtime = se->mtime;
+
+	/* Update valid block bitmap */
+	if (del > 0) {
+		if (f2fs_set_bit(offset, se->cur_valid_map))
+			BUG();
+	} else {
+		if (!f2fs_clear_bit(offset, se->cur_valid_map))
+			BUG();
+	}
+	if (!f2fs_test_bit(offset, se->ckpt_valid_map))
+		se->ckpt_valid_blocks += del;
+
+	__mark_sit_entry_dirty(sbi, segno);
+
+	/* update total number of valid blocks to be written in ckpt area */
+	SIT_I(sbi)->written_valid_blocks += del;
+
+	if (sbi->segs_per_sec > 1)
+		get_sec_entry(sbi, segno)->valid_blocks += del;
+}
+
+static void refresh_sit_entry(struct f2fs_sb_info *sbi,
+			block_t old_blkaddr, block_t new_blkaddr)
+{
+	update_sit_entry(sbi, new_blkaddr, 1);
+	if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO)
+		update_sit_entry(sbi, old_blkaddr, -1);
+}
+
+void invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr)
+{
+	unsigned int segno = GET_SEGNO(sbi, addr);
+	struct sit_info *sit_i = SIT_I(sbi);
+
+	BUG_ON(addr == NULL_ADDR);
+	if (addr == NEW_ADDR)
+		return;
+
+	/* add it into sit main buffer */
+	mutex_lock(&sit_i->sentry_lock);
+
+	update_sit_entry(sbi, addr, -1);
+
+	/* add it into dirty seglist */
+	locate_dirty_segment(sbi, segno);
+
+	mutex_unlock(&sit_i->sentry_lock);
+}
+
+/*
+ * This function should be resided under the curseg_mutex lock
+ */
+static void __add_sum_entry(struct f2fs_sb_info *sbi, int type,
+		struct f2fs_summary *sum, unsigned short offset)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	void *addr = curseg->sum_blk;
+	addr += offset * sizeof(struct f2fs_summary);
+	memcpy(addr, sum, sizeof(struct f2fs_summary));
+	return;
+}
+
+/*
+ * Calculate the number of current summary pages for writing
+ */
+int npages_for_summary_flush(struct f2fs_sb_info *sbi)
+{
+	int total_size_bytes = 0;
+	int valid_sum_count = 0;
+	int i, sum_space;
+
+	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
+		if (sbi->ckpt->alloc_type[i] == SSR)
+			valid_sum_count += sbi->blocks_per_seg;
+		else
+			valid_sum_count += curseg_blkoff(sbi, i);
+	}
+
+	total_size_bytes = valid_sum_count * (SUMMARY_SIZE + 1)
+			+ sizeof(struct nat_journal) + 2
+			+ sizeof(struct sit_journal) + 2;
+	sum_space = PAGE_CACHE_SIZE - SUM_FOOTER_SIZE;
+	if (total_size_bytes < sum_space)
+		return 1;
+	else if (total_size_bytes < 2 * sum_space)
+		return 2;
+	return 3;
+}
+
+/*
+ * Caller should put this summary page
+ */
+struct page *get_sum_page(struct f2fs_sb_info *sbi, unsigned int segno)
+{
+	return get_meta_page(sbi, GET_SUM_BLOCK(sbi, segno));
+}
+
+static void write_sum_page(struct f2fs_sb_info *sbi,
+			struct f2fs_summary_block *sum_blk, block_t blk_addr)
+{
+	struct page *page = grab_meta_page(sbi, blk_addr);
+	void *kaddr = page_address(page);
+	memcpy(kaddr, sum_blk, PAGE_CACHE_SIZE);
+	set_page_dirty(page);
+	f2fs_put_page(page, 1);
+}
+
+static unsigned int check_prefree_segments(struct f2fs_sb_info *sbi,
+					int ofs_unit, int type)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	unsigned long *prefree_segmap = dirty_i->dirty_segmap[PRE];
+	unsigned int segno, next_segno, i;
+	int ofs = 0;
+
+	/*
+	 * If there is not enough reserved sections,
+	 * we should not reuse prefree segments.
+	 */
+	if (has_not_enough_free_secs(sbi))
+		return NULL_SEGNO;
+
+	/*
+	 * NODE page should not reuse prefree segment,
+	 * since those information is used for SPOR.
+	 */
+	if (IS_NODESEG(type))
+		return NULL_SEGNO;
+next:
+	segno = find_next_bit(prefree_segmap, TOTAL_SEGS(sbi), ofs++);
+	ofs = ((segno / ofs_unit) * ofs_unit) + ofs_unit;
+	if (segno < TOTAL_SEGS(sbi)) {
+		/* skip intermediate segments in a section */
+		if (segno % ofs_unit)
+			goto next;
+
+		/* skip if whole section is not prefree */
+		next_segno = find_next_zero_bit(prefree_segmap,
+						TOTAL_SEGS(sbi), segno + 1);
+		if (next_segno - segno < ofs_unit)
+			goto next;
+
+		/* skip if whole section was not free at the last checkpoint */
+		for (i = 0; i < ofs_unit; i++)
+			if (get_seg_entry(sbi, segno)->ckpt_valid_blocks)
+				goto next;
+		return segno;
+	}
+	return NULL_SEGNO;
+}
+
+/*
+ * Find a new segment from the free segments bitmap to right order
+ * This function should be returned with success, otherwise BUG
+ */
+static void get_new_segment(struct f2fs_sb_info *sbi,
+			unsigned int *newseg, bool new_sec, int dir)
+{
+	struct free_segmap_info *free_i = FREE_I(sbi);
+	unsigned int total_secs = sbi->total_sections;
+	unsigned int segno, secno, zoneno;
+	unsigned int total_zones = sbi->total_sections / sbi->secs_per_zone;
+	unsigned int hint = *newseg / sbi->segs_per_sec;
+	unsigned int old_zoneno = GET_ZONENO_FROM_SEGNO(sbi, *newseg);
+	unsigned int left_start = hint;
+	bool init = true;
+	int go_left = 0;
+	int i;
+
+	write_lock(&free_i->segmap_lock);
+
+	if (!new_sec && ((*newseg + 1) % sbi->segs_per_sec)) {
+		segno = find_next_zero_bit(free_i->free_segmap,
+					TOTAL_SEGS(sbi), *newseg + 1);
+		if (segno < TOTAL_SEGS(sbi))
+			goto got_it;
+	}
+find_other_zone:
+	secno = find_next_zero_bit(free_i->free_secmap, total_secs, hint);
+	if (secno >= total_secs) {
+		if (dir == ALLOC_RIGHT) {
+			secno = find_next_zero_bit(free_i->free_secmap,
+						total_secs, 0);
+			BUG_ON(secno >= total_secs);
+		} else {
+			go_left = 1;
+			left_start = hint - 1;
+		}
+	}
+	if (go_left == 0)
+		goto skip_left;
+
+	while (test_bit(left_start, free_i->free_secmap)) {
+		if (left_start > 0) {
+			left_start--;
+			continue;
+		}
+		left_start = find_next_zero_bit(free_i->free_secmap,
+						total_secs, 0);
+		BUG_ON(left_start >= total_secs);
+		break;
+	}
+	secno = left_start;
+skip_left:
+	hint = secno;
+	segno = secno * sbi->segs_per_sec;
+	zoneno = secno / sbi->secs_per_zone;
+
+	/* give up on finding another zone */
+	if (!init)
+		goto got_it;
+	if (sbi->secs_per_zone == 1)
+		goto got_it;
+	if (zoneno == old_zoneno)
+		goto got_it;
+	if (dir == ALLOC_LEFT) {
+		if (!go_left && zoneno + 1 >= total_zones)
+			goto got_it;
+		if (go_left && zoneno == 0)
+			goto got_it;
+	}
+	for (i = 0; i < NR_CURSEG_TYPE; i++)
+		if (CURSEG_I(sbi, i)->zone == zoneno)
+			break;
+
+	if (i < NR_CURSEG_TYPE) {
+		/* zone is in user, try another */
+		if (go_left)
+			hint = zoneno * sbi->secs_per_zone - 1;
+		else if (zoneno + 1 >= total_zones)
+			hint = 0;
+		else
+			hint = (zoneno + 1) * sbi->secs_per_zone;
+		init = false;
+		goto find_other_zone;
+	}
+got_it:
+	/* set it as dirty segment in free segmap */
+	BUG_ON(test_bit(segno, free_i->free_segmap));
+	__set_inuse(sbi, segno);
+	*newseg = segno;
+	write_unlock(&free_i->segmap_lock);
+}
+
+static void reset_curseg(struct f2fs_sb_info *sbi, int type, int modified)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	struct summary_footer *sum_footer;
+
+	curseg->segno = curseg->next_segno;
+	curseg->zone = GET_ZONENO_FROM_SEGNO(sbi, curseg->segno);
+	curseg->next_blkoff = 0;
+	curseg->next_segno = NULL_SEGNO;
+
+	sum_footer = &(curseg->sum_blk->footer);
+	memset(sum_footer, 0, sizeof(struct summary_footer));
+	if (IS_DATASEG(type))
+		SET_SUM_TYPE(sum_footer, SUM_TYPE_DATA);
+	if (IS_NODESEG(type))
+		SET_SUM_TYPE(sum_footer, SUM_TYPE_NODE);
+	__set_sit_entry_type(sbi, type, curseg->segno, modified);
+}
+
+/*
+ * Allocate a current working segment.
+ * This function always allocates a free segment in LFS manner.
+ */
+static void new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	unsigned int segno = curseg->segno;
+	int dir = ALLOC_LEFT;
+
+	write_sum_page(sbi, curseg->sum_blk,
+				GET_SUM_BLOCK(sbi, curseg->segno));
+	if (type == CURSEG_WARM_DATA || type == CURSEG_COLD_DATA)
+		dir = ALLOC_RIGHT;
+
+	if (test_opt(sbi, NOHEAP))
+		dir = ALLOC_RIGHT;
+
+	get_new_segment(sbi, &segno, new_sec, dir);
+	curseg->next_segno = segno;
+	reset_curseg(sbi, type, 1);
+	curseg->alloc_type = LFS;
+}
+
+static void __next_free_blkoff(struct f2fs_sb_info *sbi,
+			struct curseg_info *seg, block_t start)
+{
+	struct seg_entry *se = get_seg_entry(sbi, seg->segno);
+	block_t ofs;
+	for (ofs = start; ofs < sbi->blocks_per_seg; ofs++) {
+		if (!f2fs_test_bit(ofs, se->ckpt_valid_map)
+			&& !f2fs_test_bit(ofs, se->cur_valid_map))
+			break;
+	}
+	seg->next_blkoff = ofs;
+}
+
+/*
+ * If a segment is written by LFS manner, next block offset is just obtained
+ * by increasing the current block offset. However, if a segment is written by
+ * SSR manner, next block offset obtained by calling __next_free_blkoff
+ */
+static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
+				struct curseg_info *seg)
+{
+	if (seg->alloc_type == SSR)
+		__next_free_blkoff(sbi, seg, seg->next_blkoff + 1);
+	else
+		seg->next_blkoff++;
+}
+
+/*
+ * This function always allocates a used segment (from dirty seglist) by SSR
+ * manner, so it should recover the existing segment information of valid blocks
+ */
+static void change_curseg(struct f2fs_sb_info *sbi, int type, bool reuse)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	unsigned int new_segno = curseg->next_segno;
+	struct f2fs_summary_block *sum_node;
+	struct page *sum_page;
+
+	write_sum_page(sbi, curseg->sum_blk,
+				GET_SUM_BLOCK(sbi, curseg->segno));
+	__set_test_and_inuse(sbi, new_segno);
+
+	mutex_lock(&dirty_i->seglist_lock);
+	__remove_dirty_segment(sbi, new_segno, PRE);
+	__remove_dirty_segment(sbi, new_segno, DIRTY);
+	mutex_unlock(&dirty_i->seglist_lock);
+
+	reset_curseg(sbi, type, 1);
+	curseg->alloc_type = SSR;
+	__next_free_blkoff(sbi, curseg, 0);
+
+	if (reuse) {
+		sum_page = get_sum_page(sbi, new_segno);
+		sum_node = (struct f2fs_summary_block *)page_address(sum_page);
+		memcpy(curseg->sum_blk, sum_node, SUM_ENTRY_SIZE);
+		f2fs_put_page(sum_page, 1);
+	}
+}
+
+/*
+ * flush out current segment and replace it with new segment
+ * This function should be returned with success, otherwise BUG
+ */
+static void allocate_segment_by_default(struct f2fs_sb_info *sbi,
+						int type, bool force)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	unsigned int ofs_unit;
+
+	if (force) {
+		new_curseg(sbi, type, true);
+		goto out;
+	}
+
+	ofs_unit = need_SSR(sbi) ? 1 : sbi->segs_per_sec;
+	curseg->next_segno = check_prefree_segments(sbi, ofs_unit, type);
+
+	if (curseg->next_segno != NULL_SEGNO)
+		change_curseg(sbi, type, false);
+	else if (type == CURSEG_WARM_NODE)
+		new_curseg(sbi, type, false);
+	else if (need_SSR(sbi) && get_ssr_segment(sbi, type))
+		change_curseg(sbi, type, true);
+	else
+		new_curseg(sbi, type, false);
+out:
+	sbi->segment_count[curseg->alloc_type]++;
+}
+
+void allocate_new_segments(struct f2fs_sb_info *sbi)
+{
+	struct curseg_info *curseg;
+	unsigned int old_curseg;
+	int i;
+
+	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
+		curseg = CURSEG_I(sbi, i);
+		old_curseg = curseg->segno;
+		SIT_I(sbi)->s_ops->allocate_segment(sbi, i, true);
+		locate_dirty_segment(sbi, old_curseg);
+	}
+}
+
+static const struct segment_allocation default_salloc_ops = {
+	.allocate_segment = allocate_segment_by_default,
+};
+
+static void f2fs_end_io_write(struct bio *bio, int err)
+{
+	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+	struct bio_private *p = bio->bi_private;
+
+	do {
+		struct page *page = bvec->bv_page;
+
+		if (--bvec >= bio->bi_io_vec)
+			prefetchw(&bvec->bv_page->flags);
+		if (!uptodate) {
+			SetPageError(page);
+			if (page->mapping)
+				set_bit(AS_EIO, &page->mapping->flags);
+			set_ckpt_flags(p->sbi->ckpt, CP_ERROR_FLAG);
+			set_page_dirty(page);
+		}
+		end_page_writeback(page);
+		dec_page_count(p->sbi, F2FS_WRITEBACK);
+	} while (bvec >= bio->bi_io_vec);
+
+	if (p->is_sync)
+		complete(p->wait);
+	kfree(p);
+	bio_put(bio);
+}
+
+struct bio *f2fs_bio_alloc(struct block_device *bdev, int npages)
+{
+	struct bio *bio;
+	struct bio_private *priv;
+retry:
+	priv = kmalloc(sizeof(struct bio_private), GFP_NOFS);
+	if (!priv) {
+		cond_resched();
+		goto retry;
+	}
+
+	/* No failure on bio allocation */
+	bio = bio_alloc(GFP_NOIO, npages);
+	bio->bi_bdev = bdev;
+	bio->bi_private = priv;
+	return bio;
+}
+
+static void do_submit_bio(struct f2fs_sb_info *sbi,
+				enum page_type type, bool sync)
+{
+	int rw = sync ? WRITE_SYNC : WRITE;
+	enum page_type btype = type > META ? META : type;
+
+	if (type >= META_FLUSH)
+		rw = WRITE_FLUSH_FUA;
+
+	if (sbi->bio[btype]) {
+		struct bio_private *p = sbi->bio[btype]->bi_private;
+		p->sbi = sbi;
+		sbi->bio[btype]->bi_end_io = f2fs_end_io_write;
+		if (type == META_FLUSH) {
+			DECLARE_COMPLETION_ONSTACK(wait);
+			p->is_sync = true;
+			p->wait = &wait;
+			submit_bio(rw, sbi->bio[btype]);
+			wait_for_completion(&wait);
+		} else {
+			p->is_sync = false;
+			submit_bio(rw, sbi->bio[btype]);
+		}
+		sbi->bio[btype] = NULL;
+	}
+}
+
+void f2fs_submit_bio(struct f2fs_sb_info *sbi, enum page_type type, bool sync)
+{
+	down_write(&sbi->bio_sem);
+	do_submit_bio(sbi, type, sync);
+	up_write(&sbi->bio_sem);
+}
+
+static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
+				block_t blk_addr, enum page_type type)
+{
+	struct block_device *bdev = sbi->sb->s_bdev;
+
+	verify_block_addr(sbi, blk_addr);
+
+	down_write(&sbi->bio_sem);
+
+	inc_page_count(sbi, F2FS_WRITEBACK);
+
+	if (sbi->bio[type] && sbi->last_block_in_bio[type] != blk_addr - 1)
+		do_submit_bio(sbi, type, false);
+alloc_new:
+	if (sbi->bio[type] == NULL) {
+		sbi->bio[type] = f2fs_bio_alloc(bdev, bio_get_nr_vecs(bdev));
+		sbi->bio[type]->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
+		/*
+		 * The end_io will be assigned at the sumbission phase.
+		 * Until then, let bio_add_page() merge consecutive IOs as much
+		 * as possible.
+		 */
+	}
+
+	if (bio_add_page(sbi->bio[type], page, PAGE_CACHE_SIZE, 0) <
+							PAGE_CACHE_SIZE) {
+		do_submit_bio(sbi, type, false);
+		goto alloc_new;
+	}
+
+	sbi->last_block_in_bio[type] = blk_addr;
+
+	up_write(&sbi->bio_sem);
+}
+
+static bool __has_curseg_space(struct f2fs_sb_info *sbi, int type)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	if (curseg->next_blkoff < sbi->blocks_per_seg)
+		return true;
+	return false;
+}
+
+static int __get_segment_type_2(struct page *page, enum page_type p_type)
+{
+	if (p_type == DATA)
+		return CURSEG_HOT_DATA;
+	else
+		return CURSEG_HOT_NODE;
+}
+
+static int __get_segment_type_4(struct page *page, enum page_type p_type)
+{
+	if (p_type == DATA) {
+		struct inode *inode = page->mapping->host;
+
+		if (S_ISDIR(inode->i_mode))
+			return CURSEG_HOT_DATA;
+		else
+			return CURSEG_COLD_DATA;
+	} else {
+		if (IS_DNODE(page) && !is_cold_node(page))
+			return CURSEG_HOT_NODE;
+		else
+			return CURSEG_COLD_NODE;
+	}
+}
+
+static int __get_segment_type_6(struct page *page, enum page_type p_type)
+{
+	if (p_type == DATA) {
+		struct inode *inode = page->mapping->host;
+
+		if (S_ISDIR(inode->i_mode))
+			return CURSEG_HOT_DATA;
+		else if (is_cold_data(page) || is_cold_file(inode))
+			return CURSEG_COLD_DATA;
+		else
+			return CURSEG_WARM_DATA;
+	} else {
+		if (IS_DNODE(page))
+			return is_cold_node(page) ? CURSEG_WARM_NODE :
+						CURSEG_HOT_NODE;
+		else
+			return CURSEG_COLD_NODE;
+	}
+}
+
+static int __get_segment_type(struct page *page, enum page_type p_type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb);
+	switch (sbi->active_logs) {
+	case 2:
+		return __get_segment_type_2(page, p_type);
+	case 4:
+		return __get_segment_type_4(page, p_type);
+	case 6:
+		return __get_segment_type_6(page, p_type);
+	default:
+		BUG();
+	}
+}
+
+static void do_write_page(struct f2fs_sb_info *sbi, struct page *page,
+			block_t old_blkaddr, block_t *new_blkaddr,
+			struct f2fs_summary *sum, enum page_type p_type)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	struct curseg_info *curseg;
+	unsigned int old_cursegno;
+	int type;
+
+	type = __get_segment_type(page, p_type);
+	curseg = CURSEG_I(sbi, type);
+
+	mutex_lock(&curseg->curseg_mutex);
+
+	*new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
+	old_cursegno = curseg->segno;
+
+	/*
+	 * __add_sum_entry should be resided under the curseg_mutex
+	 * because, this function updates a summary entry in the
+	 * current summary block.
+	 */
+	__add_sum_entry(sbi, type, sum, curseg->next_blkoff);
+
+	mutex_lock(&sit_i->sentry_lock);
+	__refresh_next_blkoff(sbi, curseg);
+	sbi->block_count[curseg->alloc_type]++;
+
+	/*
+	 * SIT information should be updated before segment allocation,
+	 * since SSR needs latest valid block information.
+	 */
+	refresh_sit_entry(sbi, old_blkaddr, *new_blkaddr);
+
+	if (!__has_curseg_space(sbi, type))
+		sit_i->s_ops->allocate_segment(sbi, type, false);
+
+	locate_dirty_segment(sbi, old_cursegno);
+	locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
+	mutex_unlock(&sit_i->sentry_lock);
+
+	if (p_type == NODE)
+		fill_node_footer_blkaddr(page, NEXT_FREE_BLKADDR(sbi, curseg));
+
+	/* writeout dirty page into bdev */
+	submit_write_page(sbi, page, *new_blkaddr, p_type);
+
+	mutex_unlock(&curseg->curseg_mutex);
+}
+
+int write_meta_page(struct f2fs_sb_info *sbi, struct page *page,
+			struct writeback_control *wbc)
+{
+	if (wbc->for_reclaim)
+		return AOP_WRITEPAGE_ACTIVATE;
+
+	set_page_writeback(page);
+	submit_write_page(sbi, page, page->index, META);
+	return 0;
+}
+
+void write_node_page(struct f2fs_sb_info *sbi, struct page *page,
+		unsigned int nid, block_t old_blkaddr, block_t *new_blkaddr)
+{
+	struct f2fs_summary sum;
+	set_summary(&sum, nid, 0, 0);
+	do_write_page(sbi, page, old_blkaddr, new_blkaddr, &sum, NODE);
+}
+
+void write_data_page(struct inode *inode, struct page *page,
+		struct dnode_of_data *dn, block_t old_blkaddr,
+		block_t *new_blkaddr)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct f2fs_summary sum;
+	struct node_info ni;
+
+	BUG_ON(old_blkaddr == NULL_ADDR);
+	get_node_info(sbi, dn->nid, &ni);
+	set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);
+
+	do_write_page(sbi, page, old_blkaddr,
+			new_blkaddr, &sum, DATA);
+}
+
+void rewrite_data_page(struct f2fs_sb_info *sbi, struct page *page,
+					block_t old_blk_addr)
+{
+	submit_write_page(sbi, page, old_blk_addr, DATA);
+}
+
+void recover_data_page(struct f2fs_sb_info *sbi,
+			struct page *page, struct f2fs_summary *sum,
+			block_t old_blkaddr, block_t new_blkaddr)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	struct curseg_info *curseg;
+	unsigned int segno, old_cursegno;
+	struct seg_entry *se;
+	int type;
+
+	segno = GET_SEGNO(sbi, new_blkaddr);
+	se = get_seg_entry(sbi, segno);
+	type = se->type;
+
+	if (se->valid_blocks == 0 && !IS_CURSEG(sbi, segno)) {
+		if (old_blkaddr == NULL_ADDR)
+			type = CURSEG_COLD_DATA;
+		else
+			type = CURSEG_WARM_DATA;
+	}
+	curseg = CURSEG_I(sbi, type);
+
+	mutex_lock(&curseg->curseg_mutex);
+	mutex_lock(&sit_i->sentry_lock);
+
+	old_cursegno = curseg->segno;
+
+	/* change the current segment */
+	if (segno != curseg->segno) {
+		curseg->next_segno = segno;
+		change_curseg(sbi, type, true);
+	}
+
+	curseg->next_blkoff = GET_SEGOFF_FROM_SEG0(sbi, new_blkaddr) &
+					(sbi->blocks_per_seg - 1);
+	__add_sum_entry(sbi, type, sum, curseg->next_blkoff);
+
+	refresh_sit_entry(sbi, old_blkaddr, new_blkaddr);
+
+	locate_dirty_segment(sbi, old_cursegno);
+	locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
+
+	mutex_unlock(&sit_i->sentry_lock);
+	mutex_unlock(&curseg->curseg_mutex);
+}
+
+void rewrite_node_page(struct f2fs_sb_info *sbi,
+			struct page *page, struct f2fs_summary *sum,
+			block_t old_blkaddr, block_t new_blkaddr)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	int type = CURSEG_WARM_NODE;
+	struct curseg_info *curseg;
+	unsigned int segno, old_cursegno;
+	block_t next_blkaddr = next_blkaddr_of_node(page);
+	unsigned int next_segno = GET_SEGNO(sbi, next_blkaddr);
+
+	curseg = CURSEG_I(sbi, type);
+
+	mutex_lock(&curseg->curseg_mutex);
+	mutex_lock(&sit_i->sentry_lock);
+
+	segno = GET_SEGNO(sbi, new_blkaddr);
+	old_cursegno = curseg->segno;
+
+	/* change the current segment */
+	if (segno != curseg->segno) {
+		curseg->next_segno = segno;
+		change_curseg(sbi, type, true);
+	}
+	curseg->next_blkoff = GET_SEGOFF_FROM_SEG0(sbi, new_blkaddr) &
+					(sbi->blocks_per_seg - 1);
+	__add_sum_entry(sbi, type, sum, curseg->next_blkoff);
+
+	/* change the current log to the next block addr in advance */
+	if (next_segno != segno) {
+		curseg->next_segno = next_segno;
+		change_curseg(sbi, type, true);
+	}
+	curseg->next_blkoff = GET_SEGOFF_FROM_SEG0(sbi, next_blkaddr) &
+					(sbi->blocks_per_seg - 1);
+
+	/* rewrite node page */
+	set_page_writeback(page);
+	submit_write_page(sbi, page, new_blkaddr, NODE);
+	f2fs_submit_bio(sbi, NODE, true);
+	refresh_sit_entry(sbi, old_blkaddr, new_blkaddr);
+
+	locate_dirty_segment(sbi, old_cursegno);
+	locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
+
+	mutex_unlock(&sit_i->sentry_lock);
+	mutex_unlock(&curseg->curseg_mutex);
+}
+
+static int read_compacted_summaries(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	struct curseg_info *seg_i;
+	unsigned char *kaddr;
+	struct page *page;
+	block_t start;
+	int i, j, offset;
+
+	start = start_sum_block(sbi);
+
+	page = get_meta_page(sbi, start++);
+	kaddr = (unsigned char *)page_address(page);
+
+	/* Step 1: restore nat cache */
+	seg_i = CURSEG_I(sbi, CURSEG_HOT_DATA);
+	memcpy(&seg_i->sum_blk->n_nats, kaddr, SUM_JOURNAL_SIZE);
+
+	/* Step 2: restore sit cache */
+	seg_i = CURSEG_I(sbi, CURSEG_COLD_DATA);
+	memcpy(&seg_i->sum_blk->n_sits, kaddr + SUM_JOURNAL_SIZE,
+						SUM_JOURNAL_SIZE);
+	offset = 2 * SUM_JOURNAL_SIZE;
+
+	/* Step 3: restore summary entries */
+	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
+		unsigned short blk_off;
+		unsigned int segno;
+
+		seg_i = CURSEG_I(sbi, i);
+		segno = le32_to_cpu(ckpt->cur_data_segno[i]);
+		blk_off = le16_to_cpu(ckpt->cur_data_blkoff[i]);
+		seg_i->next_segno = segno;
+		reset_curseg(sbi, i, 0);
+		seg_i->alloc_type = ckpt->alloc_type[i];
+		seg_i->next_blkoff = blk_off;
+
+		if (seg_i->alloc_type == SSR)
+			blk_off = sbi->blocks_per_seg;
+
+		for (j = 0; j < blk_off; j++) {
+			struct f2fs_summary *s;
+			s = (struct f2fs_summary *)(kaddr + offset);
+			seg_i->sum_blk->entries[j] = *s;
+			offset += SUMMARY_SIZE;
+			if (offset + SUMMARY_SIZE <= PAGE_CACHE_SIZE -
+						SUM_FOOTER_SIZE)
+				continue;
+
+			f2fs_put_page(page, 1);
+			page = NULL;
+
+			page = get_meta_page(sbi, start++);
+			kaddr = (unsigned char *)page_address(page);
+			offset = 0;
+		}
+	}
+	f2fs_put_page(page, 1);
+	return 0;
+}
+
+static int read_normal_summaries(struct f2fs_sb_info *sbi, int type)
+{
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	struct f2fs_summary_block *sum;
+	struct curseg_info *curseg;
+	struct page *new;
+	unsigned short blk_off;
+	unsigned int segno = 0;
+	block_t blk_addr = 0;
+
+	/* get segment number and block addr */
+	if (IS_DATASEG(type)) {
+		segno = le32_to_cpu(ckpt->cur_data_segno[type]);
+		blk_off = le16_to_cpu(ckpt->cur_data_blkoff[type -
+							CURSEG_HOT_DATA]);
+		if (is_set_ckpt_flags(ckpt, CP_UMOUNT_FLAG))
+			blk_addr = sum_blk_addr(sbi, NR_CURSEG_TYPE, type);
+		else
+			blk_addr = sum_blk_addr(sbi, NR_CURSEG_DATA_TYPE, type);
+	} else {
+		segno = le32_to_cpu(ckpt->cur_node_segno[type -
+							CURSEG_HOT_NODE]);
+		blk_off = le16_to_cpu(ckpt->cur_node_blkoff[type -
+							CURSEG_HOT_NODE]);
+		if (is_set_ckpt_flags(ckpt, CP_UMOUNT_FLAG))
+			blk_addr = sum_blk_addr(sbi, NR_CURSEG_NODE_TYPE,
+							type - CURSEG_HOT_NODE);
+		else
+			blk_addr = GET_SUM_BLOCK(sbi, segno);
+	}
+
+	new = get_meta_page(sbi, blk_addr);
+	sum = (struct f2fs_summary_block *)page_address(new);
+
+	if (IS_NODESEG(type)) {
+		if (is_set_ckpt_flags(ckpt, CP_UMOUNT_FLAG)) {
+			struct f2fs_summary *ns = &sum->entries[0];
+			int i;
+			for (i = 0; i < sbi->blocks_per_seg; i++, ns++) {
+				ns->version = 0;
+				ns->ofs_in_node = 0;
+			}
+		} else {
+			if (restore_node_summary(sbi, segno, sum)) {
+				f2fs_put_page(new, 1);
+				return -EINVAL;
+			}
+		}
+	}
+
+	/* set uncompleted segment to curseg */
+	curseg = CURSEG_I(sbi, type);
+	mutex_lock(&curseg->curseg_mutex);
+	memcpy(curseg->sum_blk, sum, PAGE_CACHE_SIZE);
+	curseg->next_segno = segno;
+	reset_curseg(sbi, type, 0);
+	curseg->alloc_type = ckpt->alloc_type[type];
+	curseg->next_blkoff = blk_off;
+	mutex_unlock(&curseg->curseg_mutex);
+	f2fs_put_page(new, 1);
+	return 0;
+}
+
+static int restore_curseg_summaries(struct f2fs_sb_info *sbi)
+{
+	int type = CURSEG_HOT_DATA;
+
+	if (is_set_ckpt_flags(F2FS_CKPT(sbi), CP_COMPACT_SUM_FLAG)) {
+		/* restore for compacted data summary */
+		if (read_compacted_summaries(sbi))
+			return -EINVAL;
+		type = CURSEG_HOT_NODE;
+	}
+
+	for (; type <= CURSEG_COLD_NODE; type++)
+		if (read_normal_summaries(sbi, type))
+			return -EINVAL;
+	return 0;
+}
+
+static void write_compacted_summaries(struct f2fs_sb_info *sbi, block_t blkaddr)
+{
+	struct page *page;
+	unsigned char *kaddr;
+	struct f2fs_summary *summary;
+	struct curseg_info *seg_i;
+	int written_size = 0;
+	int i, j;
+
+	page = grab_meta_page(sbi, blkaddr++);
+	kaddr = (unsigned char *)page_address(page);
+
+	/* Step 1: write nat cache */
+	seg_i = CURSEG_I(sbi, CURSEG_HOT_DATA);
+	memcpy(kaddr, &seg_i->sum_blk->n_nats, SUM_JOURNAL_SIZE);
+	written_size += SUM_JOURNAL_SIZE;
+
+	/* Step 2: write sit cache */
+	seg_i = CURSEG_I(sbi, CURSEG_COLD_DATA);
+	memcpy(kaddr + written_size, &seg_i->sum_blk->n_sits,
+						SUM_JOURNAL_SIZE);
+	written_size += SUM_JOURNAL_SIZE;
+
+	set_page_dirty(page);
+
+	/* Step 3: write summary entries */
+	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
+		unsigned short blkoff;
+		seg_i = CURSEG_I(sbi, i);
+		if (sbi->ckpt->alloc_type[i] == SSR)
+			blkoff = sbi->blocks_per_seg;
+		else
+			blkoff = curseg_blkoff(sbi, i);
+
+		for (j = 0; j < blkoff; j++) {
+			if (!page) {
+				page = grab_meta_page(sbi, blkaddr++);
+				kaddr = (unsigned char *)page_address(page);
+				written_size = 0;
+			}
+			summary = (struct f2fs_summary *)(kaddr + written_size);
+			*summary = seg_i->sum_blk->entries[j];
+			written_size += SUMMARY_SIZE;
+			set_page_dirty(page);
+
+			if (written_size + SUMMARY_SIZE <= PAGE_CACHE_SIZE -
+							SUM_FOOTER_SIZE)
+				continue;
+
+			f2fs_put_page(page, 1);
+			page = NULL;
+		}
+	}
+	if (page)
+		f2fs_put_page(page, 1);
+}
+
+static void write_normal_summaries(struct f2fs_sb_info *sbi,
+					block_t blkaddr, int type)
+{
+	int i, end;
+	if (IS_DATASEG(type))
+		end = type + NR_CURSEG_DATA_TYPE;
+	else
+		end = type + NR_CURSEG_NODE_TYPE;
+
+	for (i = type; i < end; i++) {
+		struct curseg_info *sum = CURSEG_I(sbi, i);
+		mutex_lock(&sum->curseg_mutex);
+		write_sum_page(sbi, sum->sum_blk, blkaddr + (i - type));
+		mutex_unlock(&sum->curseg_mutex);
+	}
+}
+
+void write_data_summaries(struct f2fs_sb_info *sbi, block_t start_blk)
+{
+	if (is_set_ckpt_flags(F2FS_CKPT(sbi), CP_COMPACT_SUM_FLAG))
+		write_compacted_summaries(sbi, start_blk);
+	else
+		write_normal_summaries(sbi, start_blk, CURSEG_HOT_DATA);
+}
+
+void write_node_summaries(struct f2fs_sb_info *sbi, block_t start_blk)
+{
+	if (is_set_ckpt_flags(F2FS_CKPT(sbi), CP_UMOUNT_FLAG))
+		write_normal_summaries(sbi, start_blk, CURSEG_HOT_NODE);
+	return;
+}
+
+int lookup_journal_in_cursum(struct f2fs_summary_block *sum, int type,
+					unsigned int val, int alloc)
+{
+	int i;
+
+	if (type == NAT_JOURNAL) {
+		for (i = 0; i < nats_in_cursum(sum); i++) {
+			if (le32_to_cpu(nid_in_journal(sum, i)) == val)
+				return i;
+		}
+		if (alloc && nats_in_cursum(sum) < NAT_JOURNAL_ENTRIES)
+			return update_nats_in_cursum(sum, 1);
+	} else if (type == SIT_JOURNAL) {
+		for (i = 0; i < sits_in_cursum(sum); i++)
+			if (le32_to_cpu(segno_in_journal(sum, i)) == val)
+				return i;
+		if (alloc && sits_in_cursum(sum) < SIT_JOURNAL_ENTRIES)
+			return update_sits_in_cursum(sum, 1);
+	}
+	return -1;
+}
+
+static struct page *get_current_sit_page(struct f2fs_sb_info *sbi,
+					unsigned int segno)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	unsigned int offset = SIT_BLOCK_OFFSET(sit_i, segno);
+	block_t blk_addr = sit_i->sit_base_addr + offset;
+
+	check_seg_range(sbi, segno);
+
+	/* calculate sit block address */
+	if (f2fs_test_bit(offset, sit_i->sit_bitmap))
+		blk_addr += sit_i->sit_blocks;
+
+	return get_meta_page(sbi, blk_addr);
+}
+
+static struct page *get_next_sit_page(struct f2fs_sb_info *sbi,
+					unsigned int start)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	struct page *src_page, *dst_page;
+	pgoff_t src_off, dst_off;
+	void *src_addr, *dst_addr;
+
+	src_off = current_sit_addr(sbi, start);
+	dst_off = next_sit_addr(sbi, src_off);
+
+	/* get current sit block page without lock */
+	src_page = get_meta_page(sbi, src_off);
+	dst_page = grab_meta_page(sbi, dst_off);
+	BUG_ON(PageDirty(src_page));
+
+	src_addr = page_address(src_page);
+	dst_addr = page_address(dst_page);
+	memcpy(dst_addr, src_addr, PAGE_CACHE_SIZE);
+
+	set_page_dirty(dst_page);
+	f2fs_put_page(src_page, 1);
+
+	set_to_next_sit(sit_i, start);
+
+	return dst_page;
+}
+
+static bool flush_sits_in_journal(struct f2fs_sb_info *sbi)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
+	struct f2fs_summary_block *sum = curseg->sum_blk;
+	int i;
+
+	/*
+	 * If the journal area in the current summary is full of sit entries,
+	 * all the sit entries will be flushed. Otherwise the sit entries
+	 * are not able to replace with newly hot sit entries.
+	 */
+	if (sits_in_cursum(sum) >= SIT_JOURNAL_ENTRIES) {
+		for (i = sits_in_cursum(sum) - 1; i >= 0; i--) {
+			unsigned int segno;
+			segno = le32_to_cpu(segno_in_journal(sum, i));
+			__mark_sit_entry_dirty(sbi, segno);
+		}
+		update_sits_in_cursum(sum, -sits_in_cursum(sum));
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * CP calls this function, which flushes SIT entries including sit_journal,
+ * and moves prefree segs to free segs.
+ */
+void flush_sit_entries(struct f2fs_sb_info *sbi)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	unsigned long *bitmap = sit_i->dirty_sentries_bitmap;
+	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
+	struct f2fs_summary_block *sum = curseg->sum_blk;
+	unsigned long nsegs = TOTAL_SEGS(sbi);
+	struct page *page = NULL;
+	struct f2fs_sit_block *raw_sit = NULL;
+	unsigned int start = 0, end = 0;
+	unsigned int segno = -1;
+	bool flushed;
+
+	mutex_lock(&curseg->curseg_mutex);
+	mutex_lock(&sit_i->sentry_lock);
+
+	/*
+	 * "flushed" indicates whether sit entries in journal are flushed
+	 * to the SIT area or not.
+	 */
+	flushed = flush_sits_in_journal(sbi);
+
+	while ((segno = find_next_bit(bitmap, nsegs, segno + 1)) < nsegs) {
+		struct seg_entry *se = get_seg_entry(sbi, segno);
+		int sit_offset, offset;
+
+		sit_offset = SIT_ENTRY_OFFSET(sit_i, segno);
+
+		if (flushed)
+			goto to_sit_page;
+
+		offset = lookup_journal_in_cursum(sum, SIT_JOURNAL, segno, 1);
+		if (offset >= 0) {
+			segno_in_journal(sum, offset) = cpu_to_le32(segno);
+			seg_info_to_raw_sit(se, &sit_in_journal(sum, offset));
+			goto flush_done;
+		}
+to_sit_page:
+		if (!page || (start > segno) || (segno > end)) {
+			if (page) {
+				f2fs_put_page(page, 1);
+				page = NULL;
+			}
+
+			start = START_SEGNO(sit_i, segno);
+			end = start + SIT_ENTRY_PER_BLOCK - 1;
+
+			/* read sit block that will be updated */
+			page = get_next_sit_page(sbi, start);
+			raw_sit = page_address(page);
+		}
+
+		/* udpate entry in SIT block */
+		seg_info_to_raw_sit(se, &raw_sit->entries[sit_offset]);
+flush_done:
+		__clear_bit(segno, bitmap);
+		sit_i->dirty_sentries--;
+	}
+	mutex_unlock(&sit_i->sentry_lock);
+	mutex_unlock(&curseg->curseg_mutex);
+
+	/* writeout last modified SIT block */
+	f2fs_put_page(page, 1);
+
+	set_prefree_as_free_segments(sbi);
+}
+
+static int build_sit_info(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	struct sit_info *sit_i;
+	unsigned int sit_segs, start;
+	char *src_bitmap, *dst_bitmap;
+	unsigned int bitmap_size;
+
+	/* allocate memory for SIT information */
+	sit_i = kzalloc(sizeof(struct sit_info), GFP_KERNEL);
+	if (!sit_i)
+		return -ENOMEM;
+
+	SM_I(sbi)->sit_info = sit_i;
+
+	sit_i->sentries = vzalloc(TOTAL_SEGS(sbi) * sizeof(struct seg_entry));
+	if (!sit_i->sentries)
+		return -ENOMEM;
+
+	bitmap_size = f2fs_bitmap_size(TOTAL_SEGS(sbi));
+	sit_i->dirty_sentries_bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+	if (!sit_i->dirty_sentries_bitmap)
+		return -ENOMEM;
+
+	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
+		sit_i->sentries[start].cur_valid_map
+			= kzalloc(SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
+		sit_i->sentries[start].ckpt_valid_map
+			= kzalloc(SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
+		if (!sit_i->sentries[start].cur_valid_map
+				|| !sit_i->sentries[start].ckpt_valid_map)
+			return -ENOMEM;
+	}
+
+	if (sbi->segs_per_sec > 1) {
+		sit_i->sec_entries = vzalloc(sbi->total_sections *
+					sizeof(struct sec_entry));
+		if (!sit_i->sec_entries)
+			return -ENOMEM;
+	}
+
+	/* get information related with SIT */
+	sit_segs = le32_to_cpu(raw_super->segment_count_sit) >> 1;
+
+	/* setup SIT bitmap from ckeckpoint pack */
+	bitmap_size = __bitmap_size(sbi, SIT_BITMAP);
+	src_bitmap = __bitmap_ptr(sbi, SIT_BITMAP);
+
+	dst_bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+	if (!dst_bitmap)
+		return -ENOMEM;
+	memcpy(dst_bitmap, src_bitmap, bitmap_size);
+
+	/* init SIT information */
+	sit_i->s_ops = &default_salloc_ops;
+
+	sit_i->sit_base_addr = le32_to_cpu(raw_super->sit_blkaddr);
+	sit_i->sit_blocks = sit_segs << sbi->log_blocks_per_seg;
+	sit_i->written_valid_blocks = le64_to_cpu(ckpt->valid_block_count);
+	sit_i->sit_bitmap = dst_bitmap;
+	sit_i->bitmap_size = bitmap_size;
+	sit_i->dirty_sentries = 0;
+	sit_i->sents_per_block = SIT_ENTRY_PER_BLOCK;
+	sit_i->elapsed_time = le64_to_cpu(sbi->ckpt->elapsed_time);
+	sit_i->mounted_time = CURRENT_TIME_SEC.tv_sec;
+	mutex_init(&sit_i->sentry_lock);
+	return 0;
+}
+
+static int build_free_segmap(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_sm_info *sm_info = SM_I(sbi);
+	struct free_segmap_info *free_i;
+	unsigned int bitmap_size, sec_bitmap_size;
+
+	/* allocate memory for free segmap information */
+	free_i = kzalloc(sizeof(struct free_segmap_info), GFP_KERNEL);
+	if (!free_i)
+		return -ENOMEM;
+
+	SM_I(sbi)->free_info = free_i;
+
+	bitmap_size = f2fs_bitmap_size(TOTAL_SEGS(sbi));
+	free_i->free_segmap = kmalloc(bitmap_size, GFP_KERNEL);
+	if (!free_i->free_segmap)
+		return -ENOMEM;
+
+	sec_bitmap_size = f2fs_bitmap_size(sbi->total_sections);
+	free_i->free_secmap = kmalloc(sec_bitmap_size, GFP_KERNEL);
+	if (!free_i->free_secmap)
+		return -ENOMEM;
+
+	/* set all segments as dirty temporarily */
+	memset(free_i->free_segmap, 0xff, bitmap_size);
+	memset(free_i->free_secmap, 0xff, sec_bitmap_size);
+
+	/* init free segmap information */
+	free_i->start_segno =
+		(unsigned int) GET_SEGNO_FROM_SEG0(sbi, sm_info->main_blkaddr);
+	free_i->free_segments = 0;
+	free_i->free_sections = 0;
+	rwlock_init(&free_i->segmap_lock);
+	return 0;
+}
+
+static int build_curseg(struct f2fs_sb_info *sbi)
+{
+	struct curseg_info *array;
+	int i;
+
+	array = kzalloc(sizeof(*array) * NR_CURSEG_TYPE, GFP_KERNEL);
+	if (!array)
+		return -ENOMEM;
+
+	SM_I(sbi)->curseg_array = array;
+
+	for (i = 0; i < NR_CURSEG_TYPE; i++) {
+		mutex_init(&array[i].curseg_mutex);
+		array[i].sum_blk = kzalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
+		if (!array[i].sum_blk)
+			return -ENOMEM;
+		array[i].segno = NULL_SEGNO;
+		array[i].next_blkoff = 0;
+	}
+	return restore_curseg_summaries(sbi);
+}
+
+static void build_sit_entries(struct f2fs_sb_info *sbi)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
+	struct f2fs_summary_block *sum = curseg->sum_blk;
+	unsigned int start;
+
+	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
+		struct seg_entry *se = &sit_i->sentries[start];
+		struct f2fs_sit_block *sit_blk;
+		struct f2fs_sit_entry sit;
+		struct page *page;
+		int i;
+
+		mutex_lock(&curseg->curseg_mutex);
+		for (i = 0; i < sits_in_cursum(sum); i++) {
+			if (le32_to_cpu(segno_in_journal(sum, i)) == start) {
+				sit = sit_in_journal(sum, i);
+				mutex_unlock(&curseg->curseg_mutex);
+				goto got_it;
+			}
+		}
+		mutex_unlock(&curseg->curseg_mutex);
+		page = get_current_sit_page(sbi, start);
+		sit_blk = (struct f2fs_sit_block *)page_address(page);
+		sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
+		f2fs_put_page(page, 1);
+got_it:
+		check_block_count(sbi, start, &sit);
+		seg_info_from_raw_sit(se, &sit);
+		if (sbi->segs_per_sec > 1) {
+			struct sec_entry *e = get_sec_entry(sbi, start);
+			e->valid_blocks += se->valid_blocks;
+		}
+	}
+}
+
+static void init_free_segmap(struct f2fs_sb_info *sbi)
+{
+	unsigned int start;
+	int type;
+
+	for (start = 0; start < TOTAL_SEGS(sbi); start++) {
+		struct seg_entry *sentry = get_seg_entry(sbi, start);
+		if (!sentry->valid_blocks)
+			__set_free(sbi, start);
+	}
+
+	/* set use the current segments */
+	for (type = CURSEG_HOT_DATA; type <= CURSEG_COLD_NODE; type++) {
+		struct curseg_info *curseg_t = CURSEG_I(sbi, type);
+		__set_test_and_inuse(sbi, curseg_t->segno);
+	}
+}
+
+static void init_dirty_segmap(struct f2fs_sb_info *sbi)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	struct free_segmap_info *free_i = FREE_I(sbi);
+	unsigned int segno = 0, offset = 0;
+	unsigned short valid_blocks;
+
+	while (segno < TOTAL_SEGS(sbi)) {
+		/* find dirty segment based on free segmap */
+		segno = find_next_inuse(free_i, TOTAL_SEGS(sbi), offset);
+		if (segno >= TOTAL_SEGS(sbi))
+			break;
+		offset = segno + 1;
+		valid_blocks = get_valid_blocks(sbi, segno, 0);
+		if (valid_blocks >= sbi->blocks_per_seg || !valid_blocks)
+			continue;
+		mutex_lock(&dirty_i->seglist_lock);
+		__locate_dirty_segment(sbi, segno, DIRTY);
+		mutex_unlock(&dirty_i->seglist_lock);
+	}
+}
+
+static int init_victim_segmap(struct f2fs_sb_info *sbi)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	unsigned int bitmap_size = f2fs_bitmap_size(TOTAL_SEGS(sbi));
+
+	dirty_i->victim_segmap[FG_GC] = kzalloc(bitmap_size, GFP_KERNEL);
+	dirty_i->victim_segmap[BG_GC] = kzalloc(bitmap_size, GFP_KERNEL);
+	if (!dirty_i->victim_segmap[FG_GC] || !dirty_i->victim_segmap[BG_GC])
+		return -ENOMEM;
+	return 0;
+}
+
+static int build_dirty_segmap(struct f2fs_sb_info *sbi)
+{
+	struct dirty_seglist_info *dirty_i;
+	unsigned int bitmap_size, i;
+
+	/* allocate memory for dirty segments list information */
+	dirty_i = kzalloc(sizeof(struct dirty_seglist_info), GFP_KERNEL);
+	if (!dirty_i)
+		return -ENOMEM;
+
+	SM_I(sbi)->dirty_info = dirty_i;
+	mutex_init(&dirty_i->seglist_lock);
+
+	bitmap_size = f2fs_bitmap_size(TOTAL_SEGS(sbi));
+
+	for (i = 0; i < NR_DIRTY_TYPE; i++) {
+		dirty_i->dirty_segmap[i] = kzalloc(bitmap_size, GFP_KERNEL);
+		dirty_i->nr_dirty[i] = 0;
+		if (!dirty_i->dirty_segmap[i])
+			return -ENOMEM;
+	}
+
+	init_dirty_segmap(sbi);
+	return init_victim_segmap(sbi);
+}
+
+/*
+ * Update min, max modified time for cost-benefit GC algorithm
+ */
+static void init_min_max_mtime(struct f2fs_sb_info *sbi)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	unsigned int segno;
+
+	mutex_lock(&sit_i->sentry_lock);
+
+	sit_i->min_mtime = LLONG_MAX;
+
+	for (segno = 0; segno < TOTAL_SEGS(sbi); segno += sbi->segs_per_sec) {
+		unsigned int i;
+		unsigned long long mtime = 0;
+
+		for (i = 0; i < sbi->segs_per_sec; i++)
+			mtime += get_seg_entry(sbi, segno + i)->mtime;
+
+		mtime = div_u64(mtime, sbi->segs_per_sec);
+
+		if (sit_i->min_mtime > mtime)
+			sit_i->min_mtime = mtime;
+	}
+	sit_i->max_mtime = get_mtime(sbi);
+	mutex_unlock(&sit_i->sentry_lock);
+}
+
+int build_segment_manager(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
+	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
+	struct f2fs_sm_info *sm_info;
+	int err;
+
+	sm_info = kzalloc(sizeof(struct f2fs_sm_info), GFP_KERNEL);
+	if (!sm_info)
+		return -ENOMEM;
+
+	/* init sm info */
+	sbi->sm_info = sm_info;
+	INIT_LIST_HEAD(&sm_info->wblist_head);
+	spin_lock_init(&sm_info->wblist_lock);
+	sm_info->seg0_blkaddr = le32_to_cpu(raw_super->segment0_blkaddr);
+	sm_info->main_blkaddr = le32_to_cpu(raw_super->main_blkaddr);
+	sm_info->segment_count = le32_to_cpu(raw_super->segment_count);
+	sm_info->reserved_segments = le32_to_cpu(ckpt->rsvd_segment_count);
+	sm_info->ovp_segments = le32_to_cpu(ckpt->overprov_segment_count);
+	sm_info->main_segments = le32_to_cpu(raw_super->segment_count_main);
+	sm_info->ssa_blkaddr = le32_to_cpu(raw_super->ssa_blkaddr);
+
+	err = build_sit_info(sbi);
+	if (err)
+		return err;
+	err = build_free_segmap(sbi);
+	if (err)
+		return err;
+	err = build_curseg(sbi);
+	if (err)
+		return err;
+
+	/* reinit free segmap based on SIT */
+	build_sit_entries(sbi);
+
+	init_free_segmap(sbi);
+	err = build_dirty_segmap(sbi);
+	if (err)
+		return err;
+
+	init_min_max_mtime(sbi);
+	return 0;
+}
+
+static void discard_dirty_segmap(struct f2fs_sb_info *sbi,
+		enum dirty_type dirty_type)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+
+	mutex_lock(&dirty_i->seglist_lock);
+	kfree(dirty_i->dirty_segmap[dirty_type]);
+	dirty_i->nr_dirty[dirty_type] = 0;
+	mutex_unlock(&dirty_i->seglist_lock);
+}
+
+void reset_victim_segmap(struct f2fs_sb_info *sbi)
+{
+	unsigned int bitmap_size = f2fs_bitmap_size(TOTAL_SEGS(sbi));
+	memset(DIRTY_I(sbi)->victim_segmap[FG_GC], 0, bitmap_size);
+}
+
+static void destroy_victim_segmap(struct f2fs_sb_info *sbi)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+
+	kfree(dirty_i->victim_segmap[FG_GC]);
+	kfree(dirty_i->victim_segmap[BG_GC]);
+}
+
+static void destroy_dirty_segmap(struct f2fs_sb_info *sbi)
+{
+	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
+	int i;
+
+	if (!dirty_i)
+		return;
+
+	/* discard pre-free/dirty segments list */
+	for (i = 0; i < NR_DIRTY_TYPE; i++)
+		discard_dirty_segmap(sbi, i);
+
+	destroy_victim_segmap(sbi);
+	SM_I(sbi)->dirty_info = NULL;
+	kfree(dirty_i);
+}
+
+static void destroy_curseg(struct f2fs_sb_info *sbi)
+{
+	struct curseg_info *array = SM_I(sbi)->curseg_array;
+	int i;
+
+	if (!array)
+		return;
+	SM_I(sbi)->curseg_array = NULL;
+	for (i = 0; i < NR_CURSEG_TYPE; i++)
+		kfree(array[i].sum_blk);
+	kfree(array);
+}
+
+static void destroy_free_segmap(struct f2fs_sb_info *sbi)
+{
+	struct free_segmap_info *free_i = SM_I(sbi)->free_info;
+	if (!free_i)
+		return;
+	SM_I(sbi)->free_info = NULL;
+	kfree(free_i->free_segmap);
+	kfree(free_i->free_secmap);
+	kfree(free_i);
+}
+
+static void destroy_sit_info(struct f2fs_sb_info *sbi)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	unsigned int start;
+
+	if (!sit_i)
+		return;
+
+	if (sit_i->sentries) {
+		for (start = 0; start < TOTAL_SEGS(sbi); start++) {
+			kfree(sit_i->sentries[start].cur_valid_map);
+			kfree(sit_i->sentries[start].ckpt_valid_map);
+		}
+	}
+	vfree(sit_i->sentries);
+	vfree(sit_i->sec_entries);
+	kfree(sit_i->dirty_sentries_bitmap);
+
+	SM_I(sbi)->sit_info = NULL;
+	kfree(sit_i->sit_bitmap);
+	kfree(sit_i);
+}
+
+void destroy_segment_manager(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_sm_info *sm_info = SM_I(sbi);
+	destroy_dirty_segmap(sbi);
+	destroy_curseg(sbi);
+	destroy_free_segmap(sbi);
+	destroy_sit_info(sbi);
+	sbi->sm_info = NULL;
+	kfree(sm_info);
+}

fs/f2fs/segment.h

···
+/*
+ * fs/f2fs/segment.h
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+/* constant macro */
+#define NULL_SEGNO			((unsigned int)(~0))
+
+/* V: Logical segment # in volume, R: Relative segment # in main area */
+#define GET_L2R_SEGNO(free_i, segno)	(segno - free_i->start_segno)
+#define GET_R2L_SEGNO(free_i, segno)	(segno + free_i->start_segno)
+
+#define IS_DATASEG(t)							\
+	((t == CURSEG_HOT_DATA) || (t == CURSEG_COLD_DATA) ||		\
+	(t == CURSEG_WARM_DATA))
+
+#define IS_NODESEG(t)							\
+	((t == CURSEG_HOT_NODE) || (t == CURSEG_COLD_NODE) ||		\
+	(t == CURSEG_WARM_NODE))
+
+#define IS_CURSEG(sbi, segno)						\
+	((segno == CURSEG_I(sbi, CURSEG_HOT_DATA)->segno) ||	\
+	 (segno == CURSEG_I(sbi, CURSEG_WARM_DATA)->segno) ||	\
+	 (segno == CURSEG_I(sbi, CURSEG_COLD_DATA)->segno) ||	\
+	 (segno == CURSEG_I(sbi, CURSEG_HOT_NODE)->segno) ||	\
+	 (segno == CURSEG_I(sbi, CURSEG_WARM_NODE)->segno) ||	\
+	 (segno == CURSEG_I(sbi, CURSEG_COLD_NODE)->segno))
+
+#define IS_CURSEC(sbi, secno)						\
+	((secno == CURSEG_I(sbi, CURSEG_HOT_DATA)->segno /		\
+	  sbi->segs_per_sec) ||	\
+	 (secno == CURSEG_I(sbi, CURSEG_WARM_DATA)->segno /		\
+	  sbi->segs_per_sec) ||	\
+	 (secno == CURSEG_I(sbi, CURSEG_COLD_DATA)->segno /		\
+	  sbi->segs_per_sec) ||	\
+	 (secno == CURSEG_I(sbi, CURSEG_HOT_NODE)->segno /		\
+	  sbi->segs_per_sec) ||	\
+	 (secno == CURSEG_I(sbi, CURSEG_WARM_NODE)->segno /		\
+	  sbi->segs_per_sec) ||	\
+	 (secno == CURSEG_I(sbi, CURSEG_COLD_NODE)->segno /		\
+	  sbi->segs_per_sec))	\
+
+#define START_BLOCK(sbi, segno)						\
+	(SM_I(sbi)->seg0_blkaddr +					\
+	 (GET_R2L_SEGNO(FREE_I(sbi), segno) << sbi->log_blocks_per_seg))
+#define NEXT_FREE_BLKADDR(sbi, curseg)					\
+	(START_BLOCK(sbi, curseg->segno) + curseg->next_blkoff)
+
+#define MAIN_BASE_BLOCK(sbi)	(SM_I(sbi)->main_blkaddr)
+
+#define GET_SEGOFF_FROM_SEG0(sbi, blk_addr)				\
+	((blk_addr) - SM_I(sbi)->seg0_blkaddr)
+#define GET_SEGNO_FROM_SEG0(sbi, blk_addr)				\
+	(GET_SEGOFF_FROM_SEG0(sbi, blk_addr) >> sbi->log_blocks_per_seg)
+#define GET_SEGNO(sbi, blk_addr)					\
+	(((blk_addr == NULL_ADDR) || (blk_addr == NEW_ADDR)) ?		\
+	NULL_SEGNO : GET_L2R_SEGNO(FREE_I(sbi),			\
+		GET_SEGNO_FROM_SEG0(sbi, blk_addr)))
+#define GET_SECNO(sbi, segno)					\
+	((segno) / sbi->segs_per_sec)
+#define GET_ZONENO_FROM_SEGNO(sbi, segno)				\
+	((segno / sbi->segs_per_sec) / sbi->secs_per_zone)
+
+#define GET_SUM_BLOCK(sbi, segno)				\
+	((sbi->sm_info->ssa_blkaddr) + segno)
+
+#define GET_SUM_TYPE(footer) ((footer)->entry_type)
+#define SET_SUM_TYPE(footer, type) ((footer)->entry_type = type)
+
+#define SIT_ENTRY_OFFSET(sit_i, segno)					\
+	(segno % sit_i->sents_per_block)
+#define SIT_BLOCK_OFFSET(sit_i, segno)					\
+	(segno / SIT_ENTRY_PER_BLOCK)
+#define	START_SEGNO(sit_i, segno)		\
+	(SIT_BLOCK_OFFSET(sit_i, segno) * SIT_ENTRY_PER_BLOCK)
+#define f2fs_bitmap_size(nr)			\
+	(BITS_TO_LONGS(nr) * sizeof(unsigned long))
+#define TOTAL_SEGS(sbi)	(SM_I(sbi)->main_segments)
+
+#define SECTOR_FROM_BLOCK(sbi, blk_addr)				\
+	(blk_addr << ((sbi)->log_blocksize - F2FS_LOG_SECTOR_SIZE))
+
+/* during checkpoint, bio_private is used to synchronize the last bio */
+struct bio_private {
+	struct f2fs_sb_info *sbi;
+	bool is_sync;
+	void *wait;
+};
+
+/*
+ * indicate a block allocation direction: RIGHT and LEFT.
+ * RIGHT means allocating new sections towards the end of volume.
+ * LEFT means the opposite direction.
+ */
+enum {
+	ALLOC_RIGHT = 0,
+	ALLOC_LEFT
+};
+
+/*
+ * In the victim_sel_policy->alloc_mode, there are two block allocation modes.
+ * LFS writes data sequentially with cleaning operations.
+ * SSR (Slack Space Recycle) reuses obsolete space without cleaning operations.
+ */
+enum {
+	LFS = 0,
+	SSR
+};
+
+/*
+ * In the victim_sel_policy->gc_mode, there are two gc, aka cleaning, modes.
+ * GC_CB is based on cost-benefit algorithm.
+ * GC_GREEDY is based on greedy algorithm.
+ */
+enum {
+	GC_CB = 0,
+	GC_GREEDY
+};
+
+/*
+ * BG_GC means the background cleaning job.
+ * FG_GC means the on-demand cleaning job.
+ */
+enum {
+	BG_GC = 0,
+	FG_GC
+};
+
+/* for a function parameter to select a victim segment */
+struct victim_sel_policy {
+	int alloc_mode;			/* LFS or SSR */
+	int gc_mode;			/* GC_CB or GC_GREEDY */
+	unsigned long *dirty_segmap;	/* dirty segment bitmap */
+	unsigned int offset;		/* last scanned bitmap offset */
+	unsigned int ofs_unit;		/* bitmap search unit */
+	unsigned int min_cost;		/* minimum cost */
+	unsigned int min_segno;		/* segment # having min. cost */
+};
+
+struct seg_entry {
+	unsigned short valid_blocks;	/* # of valid blocks */
+	unsigned char *cur_valid_map;	/* validity bitmap of blocks */
+	/*
+	 * # of valid blocks and the validity bitmap stored in the the last
+	 * checkpoint pack. This information is used by the SSR mode.
+	 */
+	unsigned short ckpt_valid_blocks;
+	unsigned char *ckpt_valid_map;
+	unsigned char type;		/* segment type like CURSEG_XXX_TYPE */
+	unsigned long long mtime;	/* modification time of the segment */
+};
+
+struct sec_entry {
+	unsigned int valid_blocks;	/* # of valid blocks in a section */
+};
+
+struct segment_allocation {
+	void (*allocate_segment)(struct f2fs_sb_info *, int, bool);
+};
+
+struct sit_info {
+	const struct segment_allocation *s_ops;
+
+	block_t sit_base_addr;		/* start block address of SIT area */
+	block_t sit_blocks;		/* # of blocks used by SIT area */
+	block_t written_valid_blocks;	/* # of valid blocks in main area */
+	char *sit_bitmap;		/* SIT bitmap pointer */
+	unsigned int bitmap_size;	/* SIT bitmap size */
+
+	unsigned long *dirty_sentries_bitmap;	/* bitmap for dirty sentries */
+	unsigned int dirty_sentries;		/* # of dirty sentries */
+	unsigned int sents_per_block;		/* # of SIT entries per block */
+	struct mutex sentry_lock;		/* to protect SIT cache */
+	struct seg_entry *sentries;		/* SIT segment-level cache */
+	struct sec_entry *sec_entries;		/* SIT section-level cache */
+
+	/* for cost-benefit algorithm in cleaning procedure */
+	unsigned long long elapsed_time;	/* elapsed time after mount */
+	unsigned long long mounted_time;	/* mount time */
+	unsigned long long min_mtime;		/* min. modification time */
+	unsigned long long max_mtime;		/* max. modification time */
+};
+
+struct free_segmap_info {
+	unsigned int start_segno;	/* start segment number logically */
+	unsigned int free_segments;	/* # of free segments */
+	unsigned int free_sections;	/* # of free sections */
+	rwlock_t segmap_lock;		/* free segmap lock */
+	unsigned long *free_segmap;	/* free segment bitmap */
+	unsigned long *free_secmap;	/* free section bitmap */
+};
+
+/* Notice: The order of dirty type is same with CURSEG_XXX in f2fs.h */
+enum dirty_type {
+	DIRTY_HOT_DATA,		/* dirty segments assigned as hot data logs */
+	DIRTY_WARM_DATA,	/* dirty segments assigned as warm data logs */
+	DIRTY_COLD_DATA,	/* dirty segments assigned as cold data logs */
+	DIRTY_HOT_NODE,		/* dirty segments assigned as hot node logs */
+	DIRTY_WARM_NODE,	/* dirty segments assigned as warm node logs */
+	DIRTY_COLD_NODE,	/* dirty segments assigned as cold node logs */
+	DIRTY,			/* to count # of dirty segments */
+	PRE,			/* to count # of entirely obsolete segments */
+	NR_DIRTY_TYPE
+};
+
+struct dirty_seglist_info {
+	const struct victim_selection *v_ops;	/* victim selction operation */
+	unsigned long *dirty_segmap[NR_DIRTY_TYPE];
+	struct mutex seglist_lock;		/* lock for segment bitmaps */
+	int nr_dirty[NR_DIRTY_TYPE];		/* # of dirty segments */
+	unsigned long *victim_segmap[2];	/* BG_GC, FG_GC */
+};
+
+/* victim selection function for cleaning and SSR */
+struct victim_selection {
+	int (*get_victim)(struct f2fs_sb_info *, unsigned int *,
+							int, int, char);
+};
+
+/* for active log information */
+struct curseg_info {
+	struct mutex curseg_mutex;		/* lock for consistency */
+	struct f2fs_summary_block *sum_blk;	/* cached summary block */
+	unsigned char alloc_type;		/* current allocation type */
+	unsigned int segno;			/* current segment number */
+	unsigned short next_blkoff;		/* next block offset to write */
+	unsigned int zone;			/* current zone number */
+	unsigned int next_segno;		/* preallocated segment */
+};
+
+/*
+ * inline functions
+ */
+static inline struct curseg_info *CURSEG_I(struct f2fs_sb_info *sbi, int type)
+{
+	return (struct curseg_info *)(SM_I(sbi)->curseg_array + type);
+}
+
+static inline struct seg_entry *get_seg_entry(struct f2fs_sb_info *sbi,
+						unsigned int segno)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	return &sit_i->sentries[segno];
+}
+
+static inline struct sec_entry *get_sec_entry(struct f2fs_sb_info *sbi,
+						unsigned int segno)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	return &sit_i->sec_entries[GET_SECNO(sbi, segno)];
+}
+
+static inline unsigned int get_valid_blocks(struct f2fs_sb_info *sbi,
+				unsigned int segno, int section)
+{
+	/*
+	 * In order to get # of valid blocks in a section instantly from many
+	 * segments, f2fs manages two counting structures separately.
+	 */
+	if (section > 1)
+		return get_sec_entry(sbi, segno)->valid_blocks;
+	else
+		return get_seg_entry(sbi, segno)->valid_blocks;
+}
+
+static inline void seg_info_from_raw_sit(struct seg_entry *se,
+					struct f2fs_sit_entry *rs)
+{
+	se->valid_blocks = GET_SIT_VBLOCKS(rs);
+	se->ckpt_valid_blocks = GET_SIT_VBLOCKS(rs);
+	memcpy(se->cur_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
+	memcpy(se->ckpt_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
+	se->type = GET_SIT_TYPE(rs);
+	se->mtime = le64_to_cpu(rs->mtime);
+}
+
+static inline void seg_info_to_raw_sit(struct seg_entry *se,
+					struct f2fs_sit_entry *rs)
+{
+	unsigned short raw_vblocks = (se->type << SIT_VBLOCKS_SHIFT) |
+					se->valid_blocks;
+	rs->vblocks = cpu_to_le16(raw_vblocks);
+	memcpy(rs->valid_map, se->cur_valid_map, SIT_VBLOCK_MAP_SIZE);
+	memcpy(se->ckpt_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
+	se->ckpt_valid_blocks = se->valid_blocks;
+	rs->mtime = cpu_to_le64(se->mtime);
+}
+
+static inline unsigned int find_next_inuse(struct free_segmap_info *free_i,
+		unsigned int max, unsigned int segno)
+{
+	unsigned int ret;
+	read_lock(&free_i->segmap_lock);
+	ret = find_next_bit(free_i->free_segmap, max, segno);
+	read_unlock(&free_i->segmap_lock);
+	return ret;
+}
+
+static inline void __set_free(struct f2fs_sb_info *sbi, unsigned int segno)
+{
+	struct free_segmap_info *free_i = FREE_I(sbi);
+	unsigned int secno = segno / sbi->segs_per_sec;
+	unsigned int start_segno = secno * sbi->segs_per_sec;
+	unsigned int next;
+
+	write_lock(&free_i->segmap_lock);
+	clear_bit(segno, free_i->free_segmap);
+	free_i->free_segments++;
+
+	next = find_next_bit(free_i->free_segmap, TOTAL_SEGS(sbi), start_segno);
+	if (next >= start_segno + sbi->segs_per_sec) {
+		clear_bit(secno, free_i->free_secmap);
+		free_i->free_sections++;
+	}
+	write_unlock(&free_i->segmap_lock);
+}
+
+static inline void __set_inuse(struct f2fs_sb_info *sbi,
+		unsigned int segno)
+{
+	struct free_segmap_info *free_i = FREE_I(sbi);
+	unsigned int secno = segno / sbi->segs_per_sec;
+	set_bit(segno, free_i->free_segmap);
+	free_i->free_segments--;
+	if (!test_and_set_bit(secno, free_i->free_secmap))
+		free_i->free_sections--;
+}
+
+static inline void __set_test_and_free(struct f2fs_sb_info *sbi,
+		unsigned int segno)
+{
+	struct free_segmap_info *free_i = FREE_I(sbi);
+	unsigned int secno = segno / sbi->segs_per_sec;
+	unsigned int start_segno = secno * sbi->segs_per_sec;
+	unsigned int next;
+
+	write_lock(&free_i->segmap_lock);
+	if (test_and_clear_bit(segno, free_i->free_segmap)) {
+		free_i->free_segments++;
+
+		next = find_next_bit(free_i->free_segmap, TOTAL_SEGS(sbi),
+								start_segno);
+		if (next >= start_segno + sbi->segs_per_sec) {
+			if (test_and_clear_bit(secno, free_i->free_secmap))
+				free_i->free_sections++;
+		}
+	}
+	write_unlock(&free_i->segmap_lock);
+}
+
+static inline void __set_test_and_inuse(struct f2fs_sb_info *sbi,
+		unsigned int segno)
+{
+	struct free_segmap_info *free_i = FREE_I(sbi);
+	unsigned int secno = segno / sbi->segs_per_sec;
+	write_lock(&free_i->segmap_lock);
+	if (!test_and_set_bit(segno, free_i->free_segmap)) {
+		free_i->free_segments--;
+		if (!test_and_set_bit(secno, free_i->free_secmap))
+			free_i->free_sections--;
+	}
+	write_unlock(&free_i->segmap_lock);
+}
+
+static inline void get_sit_bitmap(struct f2fs_sb_info *sbi,
+		void *dst_addr)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	memcpy(dst_addr, sit_i->sit_bitmap, sit_i->bitmap_size);
+}
+
+static inline block_t written_block_count(struct f2fs_sb_info *sbi)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	block_t vblocks;
+
+	mutex_lock(&sit_i->sentry_lock);
+	vblocks = sit_i->written_valid_blocks;
+	mutex_unlock(&sit_i->sentry_lock);
+
+	return vblocks;
+}
+
+static inline unsigned int free_segments(struct f2fs_sb_info *sbi)
+{
+	struct free_segmap_info *free_i = FREE_I(sbi);
+	unsigned int free_segs;
+
+	read_lock(&free_i->segmap_lock);
+	free_segs = free_i->free_segments;
+	read_unlock(&free_i->segmap_lock);
+
+	return free_segs;
+}
+
+static inline int reserved_segments(struct f2fs_sb_info *sbi)
+{
+	return SM_I(sbi)->reserved_segments;
+}
+
+static inline unsigned int free_sections(struct f2fs_sb_info *sbi)
+{
+	struct free_segmap_info *free_i = FREE_I(sbi);
+	unsigned int free_secs;
+
+	read_lock(&free_i->segmap_lock);
+	free_secs = free_i->free_sections;
+	read_unlock(&free_i->segmap_lock);
+
+	return free_secs;
+}
+
+static inline unsigned int prefree_segments(struct f2fs_sb_info *sbi)
+{
+	return DIRTY_I(sbi)->nr_dirty[PRE];
+}
+
+static inline unsigned int dirty_segments(struct f2fs_sb_info *sbi)
+{
+	return DIRTY_I(sbi)->nr_dirty[DIRTY_HOT_DATA] +
+		DIRTY_I(sbi)->nr_dirty[DIRTY_WARM_DATA] +
+		DIRTY_I(sbi)->nr_dirty[DIRTY_COLD_DATA] +
+		DIRTY_I(sbi)->nr_dirty[DIRTY_HOT_NODE] +
+		DIRTY_I(sbi)->nr_dirty[DIRTY_WARM_NODE] +
+		DIRTY_I(sbi)->nr_dirty[DIRTY_COLD_NODE];
+}
+
+static inline int overprovision_segments(struct f2fs_sb_info *sbi)
+{
+	return SM_I(sbi)->ovp_segments;
+}
+
+static inline int overprovision_sections(struct f2fs_sb_info *sbi)
+{
+	return ((unsigned int) overprovision_segments(sbi)) / sbi->segs_per_sec;
+}
+
+static inline int reserved_sections(struct f2fs_sb_info *sbi)
+{
+	return ((unsigned int) reserved_segments(sbi)) / sbi->segs_per_sec;
+}
+
+static inline bool need_SSR(struct f2fs_sb_info *sbi)
+{
+	return (free_sections(sbi) < overprovision_sections(sbi));
+}
+
+static inline int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	return DIRTY_I(sbi)->v_ops->get_victim(sbi,
+				&(curseg)->next_segno, BG_GC, type, SSR);
+}
+
+static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi)
+{
+	return free_sections(sbi) <= reserved_sections(sbi);
+}
+
+static inline int utilization(struct f2fs_sb_info *sbi)
+{
+	return (long int)valid_user_blocks(sbi) * 100 /
+			(long int)sbi->user_block_count;
+}
+
+/*
+ * Sometimes f2fs may be better to drop out-of-place update policy.
+ * So, if fs utilization is over MIN_IPU_UTIL, then f2fs tries to write
+ * data in the original place likewise other traditional file systems.
+ * But, currently set 100 in percentage, which means it is disabled.
+ * See below need_inplace_update().
+ */
+#define MIN_IPU_UTIL		100
+static inline bool need_inplace_update(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	if (S_ISDIR(inode->i_mode))
+		return false;
+	if (need_SSR(sbi) && utilization(sbi) > MIN_IPU_UTIL)
+		return true;
+	return false;
+}
+
+static inline unsigned int curseg_segno(struct f2fs_sb_info *sbi,
+		int type)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	return curseg->segno;
+}
+
+static inline unsigned char curseg_alloc_type(struct f2fs_sb_info *sbi,
+		int type)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	return curseg->alloc_type;
+}
+
+static inline unsigned short curseg_blkoff(struct f2fs_sb_info *sbi, int type)
+{
+	struct curseg_info *curseg = CURSEG_I(sbi, type);
+	return curseg->next_blkoff;
+}
+
+static inline void check_seg_range(struct f2fs_sb_info *sbi, unsigned int segno)
+{
+	unsigned int end_segno = SM_I(sbi)->segment_count - 1;
+	BUG_ON(segno > end_segno);
+}
+
+/*
+ * This function is used for only debugging.
+ * NOTE: In future, we have to remove this function.
+ */
+static inline void verify_block_addr(struct f2fs_sb_info *sbi, block_t blk_addr)
+{
+	struct f2fs_sm_info *sm_info = SM_I(sbi);
+	block_t total_blks = sm_info->segment_count << sbi->log_blocks_per_seg;
+	block_t start_addr = sm_info->seg0_blkaddr;
+	block_t end_addr = start_addr + total_blks - 1;
+	BUG_ON(blk_addr < start_addr);
+	BUG_ON(blk_addr > end_addr);
+}
+
+/*
+ * Summary block is always treated as invalid block
+ */
+static inline void check_block_count(struct f2fs_sb_info *sbi,
+		int segno, struct f2fs_sit_entry *raw_sit)
+{
+	struct f2fs_sm_info *sm_info = SM_I(sbi);
+	unsigned int end_segno = sm_info->segment_count - 1;
+	int valid_blocks = 0;
+	int i;
+
+	/* check segment usage */
+	BUG_ON(GET_SIT_VBLOCKS(raw_sit) > sbi->blocks_per_seg);
+
+	/* check boundary of a given segment number */
+	BUG_ON(segno > end_segno);
+
+	/* check bitmap with valid block count */
+	for (i = 0; i < sbi->blocks_per_seg; i++)
+		if (f2fs_test_bit(i, raw_sit->valid_map))
+			valid_blocks++;
+	BUG_ON(GET_SIT_VBLOCKS(raw_sit) != valid_blocks);
+}
+
+static inline pgoff_t current_sit_addr(struct f2fs_sb_info *sbi,
+						unsigned int start)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	unsigned int offset = SIT_BLOCK_OFFSET(sit_i, start);
+	block_t blk_addr = sit_i->sit_base_addr + offset;
+
+	check_seg_range(sbi, start);
+
+	/* calculate sit block address */
+	if (f2fs_test_bit(offset, sit_i->sit_bitmap))
+		blk_addr += sit_i->sit_blocks;
+
+	return blk_addr;
+}
+
+static inline pgoff_t next_sit_addr(struct f2fs_sb_info *sbi,
+						pgoff_t block_addr)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	block_addr -= sit_i->sit_base_addr;
+	if (block_addr < sit_i->sit_blocks)
+		block_addr += sit_i->sit_blocks;
+	else
+		block_addr -= sit_i->sit_blocks;
+
+	return block_addr + sit_i->sit_base_addr;
+}
+
+static inline void set_to_next_sit(struct sit_info *sit_i, unsigned int start)
+{
+	unsigned int block_off = SIT_BLOCK_OFFSET(sit_i, start);
+
+	if (f2fs_test_bit(block_off, sit_i->sit_bitmap))
+		f2fs_clear_bit(block_off, sit_i->sit_bitmap);
+	else
+		f2fs_set_bit(block_off, sit_i->sit_bitmap);
+}
+
+static inline unsigned long long get_mtime(struct f2fs_sb_info *sbi)
+{
+	struct sit_info *sit_i = SIT_I(sbi);
+	return sit_i->elapsed_time + CURRENT_TIME_SEC.tv_sec -
+						sit_i->mounted_time;
+}
+
+static inline void set_summary(struct f2fs_summary *sum, nid_t nid,
+			unsigned int ofs_in_node, unsigned char version)
+{
+	sum->nid = cpu_to_le32(nid);
+	sum->ofs_in_node = cpu_to_le16(ofs_in_node);
+	sum->version = version;
+}
+
+static inline block_t start_sum_block(struct f2fs_sb_info *sbi)
+{
+	return __start_cp_addr(sbi) +
+		le32_to_cpu(F2FS_CKPT(sbi)->cp_pack_start_sum);
+}
+
+static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
+{
+	return __start_cp_addr(sbi) +
+		le32_to_cpu(F2FS_CKPT(sbi)->cp_pack_total_block_count)
+				- (base + 1) + type;
+}

fs/f2fs/super.c

···
+/*
+ * fs/f2fs/super.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/statfs.h>
+#include <linux/proc_fs.h>
+#include <linux/buffer_head.h>
+#include <linux/backing-dev.h>
+#include <linux/kthread.h>
+#include <linux/parser.h>
+#include <linux/mount.h>
+#include <linux/seq_file.h>
+#include <linux/random.h>
+#include <linux/exportfs.h>
+#include <linux/f2fs_fs.h>
+
+#include "f2fs.h"
+#include "node.h"
+#include "xattr.h"
+
+static struct kmem_cache *f2fs_inode_cachep;
+
+enum {
+	Opt_gc_background_off,
+	Opt_disable_roll_forward,
+	Opt_discard,
+	Opt_noheap,
+	Opt_nouser_xattr,
+	Opt_noacl,
+	Opt_active_logs,
+	Opt_disable_ext_identify,
+	Opt_err,
+};
+
+static match_table_t f2fs_tokens = {
+	{Opt_gc_background_off, "background_gc_off"},
+	{Opt_disable_roll_forward, "disable_roll_forward"},
+	{Opt_discard, "discard"},
+	{Opt_noheap, "no_heap"},
+	{Opt_nouser_xattr, "nouser_xattr"},
+	{Opt_noacl, "noacl"},
+	{Opt_active_logs, "active_logs=%u"},
+	{Opt_disable_ext_identify, "disable_ext_identify"},
+	{Opt_err, NULL},
+};
+
+static void init_once(void *foo)
+{
+	struct f2fs_inode_info *fi = (struct f2fs_inode_info *) foo;
+
+	inode_init_once(&fi->vfs_inode);
+}
+
+static struct inode *f2fs_alloc_inode(struct super_block *sb)
+{
+	struct f2fs_inode_info *fi;
+
+	fi = kmem_cache_alloc(f2fs_inode_cachep, GFP_NOFS | __GFP_ZERO);
+	if (!fi)
+		return NULL;
+
+	init_once((void *) fi);
+
+	/* Initilize f2fs-specific inode info */
+	fi->vfs_inode.i_version = 1;
+	atomic_set(&fi->dirty_dents, 0);
+	fi->i_current_depth = 1;
+	fi->i_advise = 0;
+	rwlock_init(&fi->ext.ext_lock);
+
+	set_inode_flag(fi, FI_NEW_INODE);
+
+	return &fi->vfs_inode;
+}
+
+static void f2fs_i_callback(struct rcu_head *head)
+{
+	struct inode *inode = container_of(head, struct inode, i_rcu);
+	kmem_cache_free(f2fs_inode_cachep, F2FS_I(inode));
+}
+
+static void f2fs_destroy_inode(struct inode *inode)
+{
+	call_rcu(&inode->i_rcu, f2fs_i_callback);
+}
+
+static void f2fs_put_super(struct super_block *sb)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+
+	f2fs_destroy_stats(sbi);
+	stop_gc_thread(sbi);
+
+	write_checkpoint(sbi, false, true);
+
+	iput(sbi->node_inode);
+	iput(sbi->meta_inode);
+
+	/* destroy f2fs internal modules */
+	destroy_node_manager(sbi);
+	destroy_segment_manager(sbi);
+
+	kfree(sbi->ckpt);
+
+	sb->s_fs_info = NULL;
+	brelse(sbi->raw_super_buf);
+	kfree(sbi);
+}
+
+int f2fs_sync_fs(struct super_block *sb, int sync)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	int ret = 0;
+
+	if (!sbi->s_dirty && !get_pages(sbi, F2FS_DIRTY_NODES))
+		return 0;
+
+	if (sync)
+		write_checkpoint(sbi, false, false);
+
+	return ret;
+}
+
+static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
+	block_t total_count, user_block_count, start_count, ovp_count;
+
+	total_count = le64_to_cpu(sbi->raw_super->block_count);
+	user_block_count = sbi->user_block_count;
+	start_count = le32_to_cpu(sbi->raw_super->segment0_blkaddr);
+	ovp_count = SM_I(sbi)->ovp_segments << sbi->log_blocks_per_seg;
+	buf->f_type = F2FS_SUPER_MAGIC;
+	buf->f_bsize = sbi->blocksize;
+
+	buf->f_blocks = total_count - start_count;
+	buf->f_bfree = buf->f_blocks - valid_user_blocks(sbi) - ovp_count;
+	buf->f_bavail = user_block_count - valid_user_blocks(sbi);
+
+	buf->f_files = valid_inode_count(sbi);
+	buf->f_ffree = sbi->total_node_count - valid_node_count(sbi);
+
+	buf->f_namelen = F2FS_MAX_NAME_LEN;
+	buf->f_fsid.val[0] = (u32)id;
+	buf->f_fsid.val[1] = (u32)(id >> 32);
+
+	return 0;
+}
+
+static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(root->d_sb);
+
+	if (test_opt(sbi, BG_GC))
+		seq_puts(seq, ",background_gc_on");
+	else
+		seq_puts(seq, ",background_gc_off");
+	if (test_opt(sbi, DISABLE_ROLL_FORWARD))
+		seq_puts(seq, ",disable_roll_forward");
+	if (test_opt(sbi, DISCARD))
+		seq_puts(seq, ",discard");
+	if (test_opt(sbi, NOHEAP))
+		seq_puts(seq, ",no_heap_alloc");
+#ifdef CONFIG_F2FS_FS_XATTR
+	if (test_opt(sbi, XATTR_USER))
+		seq_puts(seq, ",user_xattr");
+	else
+		seq_puts(seq, ",nouser_xattr");
+#endif
+#ifdef CONFIG_F2FS_FS_POSIX_ACL
+	if (test_opt(sbi, POSIX_ACL))
+		seq_puts(seq, ",acl");
+	else
+		seq_puts(seq, ",noacl");
+#endif
+	if (test_opt(sbi, DISABLE_EXT_IDENTIFY))
+		seq_puts(seq, ",disable_ext_indentify");
+
+	seq_printf(seq, ",active_logs=%u", sbi->active_logs);
+
+	return 0;
+}
+
+static struct super_operations f2fs_sops = {
+	.alloc_inode	= f2fs_alloc_inode,
+	.destroy_inode	= f2fs_destroy_inode,
+	.write_inode	= f2fs_write_inode,
+	.show_options	= f2fs_show_options,
+	.evict_inode	= f2fs_evict_inode,
+	.put_super	= f2fs_put_super,
+	.sync_fs	= f2fs_sync_fs,
+	.statfs		= f2fs_statfs,
+};
+
+static struct inode *f2fs_nfs_get_inode(struct super_block *sb,
+		u64 ino, u32 generation)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct inode *inode;
+
+	if (ino < F2FS_ROOT_INO(sbi))
+		return ERR_PTR(-ESTALE);
+
+	/*
+	 * f2fs_iget isn't quite right if the inode is currently unallocated!
+	 * However f2fs_iget currently does appropriate checks to handle stale
+	 * inodes so everything is OK.
+	 */
+	inode = f2fs_iget(sb, ino);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+	if (generation && inode->i_generation != generation) {
+		/* we didn't find the right inode.. */
+		iput(inode);
+		return ERR_PTR(-ESTALE);
+	}
+	return inode;
+}
+
+static struct dentry *f2fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
+		int fh_len, int fh_type)
+{
+	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+				    f2fs_nfs_get_inode);
+}
+
+static struct dentry *f2fs_fh_to_parent(struct super_block *sb, struct fid *fid,
+		int fh_len, int fh_type)
+{
+	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+				    f2fs_nfs_get_inode);
+}
+
+static const struct export_operations f2fs_export_ops = {
+	.fh_to_dentry = f2fs_fh_to_dentry,
+	.fh_to_parent = f2fs_fh_to_parent,
+	.get_parent = f2fs_get_parent,
+};
+
+static int parse_options(struct f2fs_sb_info *sbi, char *options)
+{
+	substring_t args[MAX_OPT_ARGS];
+	char *p;
+	int arg = 0;
+
+	if (!options)
+		return 0;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+		if (!*p)
+			continue;
+		/*
+		 * Initialize args struct so we know whether arg was
+		 * found; some options take optional arguments.
+		 */
+		args[0].to = args[0].from = NULL;
+		token = match_token(p, f2fs_tokens, args);
+
+		switch (token) {
+		case Opt_gc_background_off:
+			clear_opt(sbi, BG_GC);
+			break;
+		case Opt_disable_roll_forward:
+			set_opt(sbi, DISABLE_ROLL_FORWARD);
+			break;
+		case Opt_discard:
+			set_opt(sbi, DISCARD);
+			break;
+		case Opt_noheap:
+			set_opt(sbi, NOHEAP);
+			break;
+#ifdef CONFIG_F2FS_FS_XATTR
+		case Opt_nouser_xattr:
+			clear_opt(sbi, XATTR_USER);
+			break;
+#else
+		case Opt_nouser_xattr:
+			pr_info("nouser_xattr options not supported\n");
+			break;
+#endif
+#ifdef CONFIG_F2FS_FS_POSIX_ACL
+		case Opt_noacl:
+			clear_opt(sbi, POSIX_ACL);
+			break;
+#else
+		case Opt_noacl:
+			pr_info("noacl options not supported\n");
+			break;
+#endif
+		case Opt_active_logs:
+			if (args->from && match_int(args, &arg))
+				return -EINVAL;
+			if (arg != 2 && arg != 4 && arg != 6)
+				return -EINVAL;
+			sbi->active_logs = arg;
+			break;
+		case Opt_disable_ext_identify:
+			set_opt(sbi, DISABLE_EXT_IDENTIFY);
+			break;
+		default:
+			pr_err("Unrecognized mount option \"%s\" or missing value\n",
+					p);
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static loff_t max_file_size(unsigned bits)
+{
+	loff_t result = ADDRS_PER_INODE;
+	loff_t leaf_count = ADDRS_PER_BLOCK;
+
+	/* two direct node blocks */
+	result += (leaf_count * 2);
+
+	/* two indirect node blocks */
+	leaf_count *= NIDS_PER_BLOCK;
+	result += (leaf_count * 2);
+
+	/* one double indirect node block */
+	leaf_count *= NIDS_PER_BLOCK;
+	result += leaf_count;
+
+	result <<= bits;
+	return result;
+}
+
+static int sanity_check_raw_super(struct f2fs_super_block *raw_super)
+{
+	unsigned int blocksize;
+
+	if (F2FS_SUPER_MAGIC != le32_to_cpu(raw_super->magic))
+		return 1;
+
+	/* Currently, support only 4KB block size */
+	blocksize = 1 << le32_to_cpu(raw_super->log_blocksize);
+	if (blocksize != PAGE_CACHE_SIZE)
+		return 1;
+	if (le32_to_cpu(raw_super->log_sectorsize) !=
+					F2FS_LOG_SECTOR_SIZE)
+		return 1;
+	if (le32_to_cpu(raw_super->log_sectors_per_block) !=
+					F2FS_LOG_SECTORS_PER_BLOCK)
+		return 1;
+	return 0;
+}
+
+static int sanity_check_ckpt(struct f2fs_super_block *raw_super,
+				struct f2fs_checkpoint *ckpt)
+{
+	unsigned int total, fsmeta;
+
+	total = le32_to_cpu(raw_super->segment_count);
+	fsmeta = le32_to_cpu(raw_super->segment_count_ckpt);
+	fsmeta += le32_to_cpu(raw_super->segment_count_sit);
+	fsmeta += le32_to_cpu(raw_super->segment_count_nat);
+	fsmeta += le32_to_cpu(ckpt->rsvd_segment_count);
+	fsmeta += le32_to_cpu(raw_super->segment_count_ssa);
+
+	if (fsmeta >= total)
+		return 1;
+	return 0;
+}
+
+static void init_sb_info(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_super_block *raw_super = sbi->raw_super;
+	int i;
+
+	sbi->log_sectors_per_block =
+		le32_to_cpu(raw_super->log_sectors_per_block);
+	sbi->log_blocksize = le32_to_cpu(raw_super->log_blocksize);
+	sbi->blocksize = 1 << sbi->log_blocksize;
+	sbi->log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
+	sbi->blocks_per_seg = 1 << sbi->log_blocks_per_seg;
+	sbi->segs_per_sec = le32_to_cpu(raw_super->segs_per_sec);
+	sbi->secs_per_zone = le32_to_cpu(raw_super->secs_per_zone);
+	sbi->total_sections = le32_to_cpu(raw_super->section_count);
+	sbi->total_node_count =
+		(le32_to_cpu(raw_super->segment_count_nat) / 2)
+			* sbi->blocks_per_seg * NAT_ENTRY_PER_BLOCK;
+	sbi->root_ino_num = le32_to_cpu(raw_super->root_ino);
+	sbi->node_ino_num = le32_to_cpu(raw_super->node_ino);
+	sbi->meta_ino_num = le32_to_cpu(raw_super->meta_ino);
+
+	for (i = 0; i < NR_COUNT_TYPE; i++)
+		atomic_set(&sbi->nr_pages[i], 0);
+}
+
+static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct f2fs_sb_info *sbi;
+	struct f2fs_super_block *raw_super;
+	struct buffer_head *raw_super_buf;
+	struct inode *root;
+	long err = -EINVAL;
+	int i;
+
+	/* allocate memory for f2fs-specific super block info */
+	sbi = kzalloc(sizeof(struct f2fs_sb_info), GFP_KERNEL);
+	if (!sbi)
+		return -ENOMEM;
+
+	/* set a temporary block size */
+	if (!sb_set_blocksize(sb, F2FS_BLKSIZE))
+		goto free_sbi;
+
+	/* read f2fs raw super block */
+	raw_super_buf = sb_bread(sb, 0);
+	if (!raw_super_buf) {
+		err = -EIO;
+		goto free_sbi;
+	}
+	raw_super = (struct f2fs_super_block *)
+			((char *)raw_super_buf->b_data + F2FS_SUPER_OFFSET);
+
+	/* init some FS parameters */
+	sbi->active_logs = NR_CURSEG_TYPE;
+
+	set_opt(sbi, BG_GC);
+
+#ifdef CONFIG_F2FS_FS_XATTR
+	set_opt(sbi, XATTR_USER);
+#endif
+#ifdef CONFIG_F2FS_FS_POSIX_ACL
+	set_opt(sbi, POSIX_ACL);
+#endif
+	/* parse mount options */
+	if (parse_options(sbi, (char *)data))
+		goto free_sb_buf;
+
+	/* sanity checking of raw super */
+	if (sanity_check_raw_super(raw_super))
+		goto free_sb_buf;
+
+	sb->s_maxbytes = max_file_size(le32_to_cpu(raw_super->log_blocksize));
+	sb->s_max_links = F2FS_LINK_MAX;
+	get_random_bytes(&sbi->s_next_generation, sizeof(u32));
+
+	sb->s_op = &f2fs_sops;
+	sb->s_xattr = f2fs_xattr_handlers;
+	sb->s_export_op = &f2fs_export_ops;
+	sb->s_magic = F2FS_SUPER_MAGIC;
+	sb->s_fs_info = sbi;
+	sb->s_time_gran = 1;
+	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
+		(test_opt(sbi, POSIX_ACL) ? MS_POSIXACL : 0);
+	memcpy(sb->s_uuid, raw_super->uuid, sizeof(raw_super->uuid));
+
+	/* init f2fs-specific super block info */
+	sbi->sb = sb;
+	sbi->raw_super = raw_super;
+	sbi->raw_super_buf = raw_super_buf;
+	mutex_init(&sbi->gc_mutex);
+	mutex_init(&sbi->write_inode);
+	mutex_init(&sbi->writepages);
+	mutex_init(&sbi->cp_mutex);
+	for (i = 0; i < NR_LOCK_TYPE; i++)
+		mutex_init(&sbi->fs_lock[i]);
+	sbi->por_doing = 0;
+	spin_lock_init(&sbi->stat_lock);
+	init_rwsem(&sbi->bio_sem);
+	init_sb_info(sbi);
+
+	/* get an inode for meta space */
+	sbi->meta_inode = f2fs_iget(sb, F2FS_META_INO(sbi));
+	if (IS_ERR(sbi->meta_inode)) {
+		err = PTR_ERR(sbi->meta_inode);
+		goto free_sb_buf;
+	}
+
+	err = get_valid_checkpoint(sbi);
+	if (err)
+		goto free_meta_inode;
+
+	/* sanity checking of checkpoint */
+	err = -EINVAL;
+	if (sanity_check_ckpt(raw_super, sbi->ckpt))
+		goto free_cp;
+
+	sbi->total_valid_node_count =
+				le32_to_cpu(sbi->ckpt->valid_node_count);
+	sbi->total_valid_inode_count =
+				le32_to_cpu(sbi->ckpt->valid_inode_count);
+	sbi->user_block_count = le64_to_cpu(sbi->ckpt->user_block_count);
+	sbi->total_valid_block_count =
+				le64_to_cpu(sbi->ckpt->valid_block_count);
+	sbi->last_valid_block_count = sbi->total_valid_block_count;
+	sbi->alloc_valid_block_count = 0;
+	INIT_LIST_HEAD(&sbi->dir_inode_list);
+	spin_lock_init(&sbi->dir_inode_lock);
+
+	/* init super block */
+	if (!sb_set_blocksize(sb, sbi->blocksize))
+		goto free_cp;
+
+	init_orphan_info(sbi);
+
+	/* setup f2fs internal modules */
+	err = build_segment_manager(sbi);
+	if (err)
+		goto free_sm;
+	err = build_node_manager(sbi);
+	if (err)
+		goto free_nm;
+
+	build_gc_manager(sbi);
+
+	/* get an inode for node space */
+	sbi->node_inode = f2fs_iget(sb, F2FS_NODE_INO(sbi));
+	if (IS_ERR(sbi->node_inode)) {
+		err = PTR_ERR(sbi->node_inode);
+		goto free_nm;
+	}
+
+	/* if there are nt orphan nodes free them */
+	err = -EINVAL;
+	if (!is_set_ckpt_flags(F2FS_CKPT(sbi), CP_UMOUNT_FLAG) &&
+				recover_orphan_inodes(sbi))
+		goto free_node_inode;
+
+	/* read root inode and dentry */
+	root = f2fs_iget(sb, F2FS_ROOT_INO(sbi));
+	if (IS_ERR(root)) {
+		err = PTR_ERR(root);
+		goto free_node_inode;
+	}
+	if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size)
+		goto free_root_inode;
+
+	sb->s_root = d_make_root(root); /* allocate root dentry */
+	if (!sb->s_root) {
+		err = -ENOMEM;
+		goto free_root_inode;
+	}
+
+	/* recover fsynced data */
+	if (!is_set_ckpt_flags(F2FS_CKPT(sbi), CP_UMOUNT_FLAG) &&
+				!test_opt(sbi, DISABLE_ROLL_FORWARD))
+		recover_fsync_data(sbi);
+
+	/* After POR, we can run background GC thread */
+	err = start_gc_thread(sbi);
+	if (err)
+		goto fail;
+
+	err = f2fs_build_stats(sbi);
+	if (err)
+		goto fail;
+
+	return 0;
+fail:
+	stop_gc_thread(sbi);
+free_root_inode:
+	dput(sb->s_root);
+	sb->s_root = NULL;
+free_node_inode:
+	iput(sbi->node_inode);
+free_nm:
+	destroy_node_manager(sbi);
+free_sm:
+	destroy_segment_manager(sbi);
+free_cp:
+	kfree(sbi->ckpt);
+free_meta_inode:
+	make_bad_inode(sbi->meta_inode);
+	iput(sbi->meta_inode);
+free_sb_buf:
+	brelse(raw_super_buf);
+free_sbi:
+	kfree(sbi);
+	return err;
+}
+
+static struct dentry *f2fs_mount(struct file_system_type *fs_type, int flags,
+			const char *dev_name, void *data)
+{
+	return mount_bdev(fs_type, flags, dev_name, data, f2fs_fill_super);
+}
+
+static struct file_system_type f2fs_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "f2fs",
+	.mount		= f2fs_mount,
+	.kill_sb	= kill_block_super,
+	.fs_flags	= FS_REQUIRES_DEV,
+};
+
+static int init_inodecache(void)
+{
+	f2fs_inode_cachep = f2fs_kmem_cache_create("f2fs_inode_cache",
+			sizeof(struct f2fs_inode_info), NULL);
+	if (f2fs_inode_cachep == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+static void destroy_inodecache(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+	kmem_cache_destroy(f2fs_inode_cachep);
+}
+
+static int __init init_f2fs_fs(void)
+{
+	int err;
+
+	err = init_inodecache();
+	if (err)
+		goto fail;
+	err = create_node_manager_caches();
+	if (err)
+		goto fail;
+	err = create_gc_caches();
+	if (err)
+		goto fail;
+	err = create_checkpoint_caches();
+	if (err)
+		goto fail;
+	return register_filesystem(&f2fs_fs_type);
+fail:
+	return err;
+}
+
+static void __exit exit_f2fs_fs(void)
+{
+	destroy_root_stats();
+	unregister_filesystem(&f2fs_fs_type);
+	destroy_checkpoint_caches();
+	destroy_gc_caches();
+	destroy_node_manager_caches();
+	destroy_inodecache();
+}
+
+module_init(init_f2fs_fs)
+module_exit(exit_f2fs_fs)
+
+MODULE_AUTHOR("Samsung Electronics's Praesto Team");
+MODULE_DESCRIPTION("Flash Friendly File System");
+MODULE_LICENSE("GPL");

fs/f2fs/xattr.c

···
+/*
+ * fs/f2fs/xattr.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext2/xattr.c
+ *
+ * Copyright (C) 2001-2003 Andreas Gruenbacher <[e-mail]>
+ *
+ * Fix by Harrison Xing <[e-mail]>.
+ * Extended attributes for symlinks and special files added per
+ *  suggestion of Luka Renko <[e-mail]>.
+ * xattr consolidation Copyright (c) 2004 James Morris <[e-mail]>,
+ *  Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/rwsem.h>
+#include <linux/f2fs_fs.h>
+#include "f2fs.h"
+#include "xattr.h"
+
+static size_t f2fs_xattr_generic_list(struct dentry *dentry, char *list,
+		size_t list_size, const char *name, size_t name_len, int type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
+	int total_len, prefix_len = 0;
+	const char *prefix = NULL;
+
+	switch (type) {
+	case F2FS_XATTR_INDEX_USER:
+		if (!test_opt(sbi, XATTR_USER))
+			return -EOPNOTSUPP;
+		prefix = XATTR_USER_PREFIX;
+		prefix_len = XATTR_USER_PREFIX_LEN;
+		break;
+	case F2FS_XATTR_INDEX_TRUSTED:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		prefix = XATTR_TRUSTED_PREFIX;
+		prefix_len = XATTR_TRUSTED_PREFIX_LEN;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	total_len = prefix_len + name_len + 1;
+	if (list && total_len <= list_size) {
+		memcpy(list, prefix, prefix_len);
+		memcpy(list+prefix_len, name, name_len);
+		list[prefix_len + name_len] = '\0';
+	}
+	return total_len;
+}
+
+static int f2fs_xattr_generic_get(struct dentry *dentry, const char *name,
+		void *buffer, size_t size, int type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
+
+	switch (type) {
+	case F2FS_XATTR_INDEX_USER:
+		if (!test_opt(sbi, XATTR_USER))
+			return -EOPNOTSUPP;
+		break;
+	case F2FS_XATTR_INDEX_TRUSTED:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (strcmp(name, "") == 0)
+		return -EINVAL;
+	return f2fs_getxattr(dentry->d_inode, type, name,
+			buffer, size);
+}
+
+static int f2fs_xattr_generic_set(struct dentry *dentry, const char *name,
+		const void *value, size_t size, int flags, int type)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
+
+	switch (type) {
+	case F2FS_XATTR_INDEX_USER:
+		if (!test_opt(sbi, XATTR_USER))
+			return -EOPNOTSUPP;
+		break;
+	case F2FS_XATTR_INDEX_TRUSTED:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (strcmp(name, "") == 0)
+		return -EINVAL;
+
+	return f2fs_setxattr(dentry->d_inode, type, name, value, size);
+}
+
+static size_t f2fs_xattr_advise_list(struct dentry *dentry, char *list,
+		size_t list_size, const char *name, size_t name_len, int type)
+{
+	const char *xname = F2FS_SYSTEM_ADVISE_PREFIX;
+	size_t size;
+
+	if (type != F2FS_XATTR_INDEX_ADVISE)
+		return 0;
+
+	size = strlen(xname) + 1;
+	if (list && size <= list_size)
+		memcpy(list, xname, size);
+	return size;
+}
+
+static int f2fs_xattr_advise_get(struct dentry *dentry, const char *name,
+		void *buffer, size_t size, int type)
+{
+	struct inode *inode = dentry->d_inode;
+
+	if (strcmp(name, "") != 0)
+		return -EINVAL;
+
+	*((char *)buffer) = F2FS_I(inode)->i_advise;
+	return sizeof(char);
+}
+
+static int f2fs_xattr_advise_set(struct dentry *dentry, const char *name,
+		const void *value, size_t size, int flags, int type)
+{
+	struct inode *inode = dentry->d_inode;
+
+	if (strcmp(name, "") != 0)
+		return -EINVAL;
+	if (!inode_owner_or_capable(inode))
+		return -EPERM;
+	if (value == NULL)
+		return -EINVAL;
+
+	F2FS_I(inode)->i_advise |= *(char *)value;
+	return 0;
+}
+
+const struct xattr_handler f2fs_xattr_user_handler = {
+	.prefix	= XATTR_USER_PREFIX,
+	.flags	= F2FS_XATTR_INDEX_USER,
+	.list	= f2fs_xattr_generic_list,
+	.get	= f2fs_xattr_generic_get,
+	.set	= f2fs_xattr_generic_set,
+};
+
+const struct xattr_handler f2fs_xattr_trusted_handler = {
+	.prefix	= XATTR_TRUSTED_PREFIX,
+	.flags	= F2FS_XATTR_INDEX_TRUSTED,
+	.list	= f2fs_xattr_generic_list,
+	.get	= f2fs_xattr_generic_get,
+	.set	= f2fs_xattr_generic_set,
+};
+
+const struct xattr_handler f2fs_xattr_advise_handler = {
+	.prefix = F2FS_SYSTEM_ADVISE_PREFIX,
+	.flags	= F2FS_XATTR_INDEX_ADVISE,
+	.list   = f2fs_xattr_advise_list,
+	.get    = f2fs_xattr_advise_get,
+	.set    = f2fs_xattr_advise_set,
+};
+
+static const struct xattr_handler *f2fs_xattr_handler_map[] = {
+	[F2FS_XATTR_INDEX_USER] = &f2fs_xattr_user_handler,
+#ifdef CONFIG_F2FS_FS_POSIX_ACL
+	[F2FS_XATTR_INDEX_POSIX_ACL_ACCESS] = &f2fs_xattr_acl_access_handler,
+	[F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT] = &f2fs_xattr_acl_default_handler,
+#endif
+	[F2FS_XATTR_INDEX_TRUSTED] = &f2fs_xattr_trusted_handler,
+	[F2FS_XATTR_INDEX_ADVISE] = &f2fs_xattr_advise_handler,
+};
+
+const struct xattr_handler *f2fs_xattr_handlers[] = {
+	&f2fs_xattr_user_handler,
+#ifdef CONFIG_F2FS_FS_POSIX_ACL
+	&f2fs_xattr_acl_access_handler,
+	&f2fs_xattr_acl_default_handler,
+#endif
+	&f2fs_xattr_trusted_handler,
+	&f2fs_xattr_advise_handler,
+	NULL,
+};
+
+static inline const struct xattr_handler *f2fs_xattr_handler(int name_index)
+{
+	const struct xattr_handler *handler = NULL;
+
+	if (name_index > 0 && name_index < ARRAY_SIZE(f2fs_xattr_handler_map))
+		handler = f2fs_xattr_handler_map[name_index];
+	return handler;
+}
+
+int f2fs_getxattr(struct inode *inode, int name_index, const char *name,
+		void *buffer, size_t buffer_size)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	struct f2fs_xattr_entry *entry;
+	struct page *page;
+	void *base_addr;
+	int error = 0, found = 0;
+	int value_len, name_len;
+
+	if (name == NULL)
+		return -EINVAL;
+	name_len = strlen(name);
+
+	if (!fi->i_xattr_nid)
+		return -ENODATA;
+
+	page = get_node_page(sbi, fi->i_xattr_nid);
+	base_addr = page_address(page);
+
+	list_for_each_xattr(entry, base_addr) {
+		if (entry->e_name_index != name_index)
+			continue;
+		if (entry->e_name_len != name_len)
+			continue;
+		if (!memcmp(entry->e_name, name, name_len)) {
+			found = 1;
+			break;
+		}
+	}
+	if (!found) {
+		error = -ENODATA;
+		goto cleanup;
+	}
+
+	value_len = le16_to_cpu(entry->e_value_size);
+
+	if (buffer && value_len > buffer_size) {
+		error = -ERANGE;
+		goto cleanup;
+	}
+
+	if (buffer) {
+		char *pval = entry->e_name + entry->e_name_len;
+		memcpy(buffer, pval, value_len);
+	}
+	error = value_len;
+
+cleanup:
+	f2fs_put_page(page, 1);
+	return error;
+}
+
+ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
+{
+	struct inode *inode = dentry->d_inode;
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	struct f2fs_xattr_entry *entry;
+	struct page *page;
+	void *base_addr;
+	int error = 0;
+	size_t rest = buffer_size;
+
+	if (!fi->i_xattr_nid)
+		return 0;
+
+	page = get_node_page(sbi, fi->i_xattr_nid);
+	base_addr = page_address(page);
+
+	list_for_each_xattr(entry, base_addr) {
+		const struct xattr_handler *handler =
+			f2fs_xattr_handler(entry->e_name_index);
+		size_t size;
+
+		if (!handler)
+			continue;
+
+		size = handler->list(dentry, buffer, rest, entry->e_name,
+				entry->e_name_len, handler->flags);
+		if (buffer && size > rest) {
+			error = -ERANGE;
+			goto cleanup;
+		}
+
+		if (buffer)
+			buffer += size;
+		rest -= size;
+	}
+	error = buffer_size - rest;
+cleanup:
+	f2fs_put_page(page, 1);
+	return error;
+}
+
+int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
+					const void *value, size_t value_len)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	struct f2fs_xattr_header *header = NULL;
+	struct f2fs_xattr_entry *here, *last;
+	struct page *page;
+	void *base_addr;
+	int error, found, free, name_len, newsize;
+	char *pval;
+
+	if (name == NULL)
+		return -EINVAL;
+	name_len = strlen(name);
+
+	if (value == NULL)
+		value_len = 0;
+
+	if (name_len > 255 || value_len > MAX_VALUE_LEN)
+		return -ERANGE;
+
+	mutex_lock_op(sbi, NODE_NEW);
+	if (!fi->i_xattr_nid) {
+		/* Allocate new attribute block */
+		struct dnode_of_data dn;
+
+		if (!alloc_nid(sbi, &fi->i_xattr_nid)) {
+			mutex_unlock_op(sbi, NODE_NEW);
+			return -ENOSPC;
+		}
+		set_new_dnode(&dn, inode, NULL, NULL, fi->i_xattr_nid);
+		mark_inode_dirty(inode);
+
+		page = new_node_page(&dn, XATTR_NODE_OFFSET);
+		if (IS_ERR(page)) {
+			alloc_nid_failed(sbi, fi->i_xattr_nid);
+			fi->i_xattr_nid = 0;
+			mutex_unlock_op(sbi, NODE_NEW);
+			return PTR_ERR(page);
+		}
+
+		alloc_nid_done(sbi, fi->i_xattr_nid);
+		base_addr = page_address(page);
+		header = XATTR_HDR(base_addr);
+		header->h_magic = cpu_to_le32(F2FS_XATTR_MAGIC);
+		header->h_refcount = cpu_to_le32(1);
+	} else {
+		/* The inode already has an extended attribute block. */
+		page = get_node_page(sbi, fi->i_xattr_nid);
+		if (IS_ERR(page)) {
+			mutex_unlock_op(sbi, NODE_NEW);
+			return PTR_ERR(page);
+		}
+
+		base_addr = page_address(page);
+		header = XATTR_HDR(base_addr);
+	}
+
+	if (le32_to_cpu(header->h_magic) != F2FS_XATTR_MAGIC) {
+		error = -EIO;
+		goto cleanup;
+	}
+
+	/* find entry with wanted name. */
+	found = 0;
+	list_for_each_xattr(here, base_addr) {
+		if (here->e_name_index != name_index)
+			continue;
+		if (here->e_name_len != name_len)
+			continue;
+		if (!memcmp(here->e_name, name, name_len)) {
+			found = 1;
+			break;
+		}
+	}
+
+	last = here;
+
+	while (!IS_XATTR_LAST_ENTRY(last))
+		last = XATTR_NEXT_ENTRY(last);
+
+	newsize = XATTR_ALIGN(sizeof(struct f2fs_xattr_entry) +
+			name_len + value_len);
+
+	/* 1. Check space */
+	if (value) {
+		/* If value is NULL, it is remove operation.
+		 * In case of update operation, we caculate free.
+		 */
+		free = MIN_OFFSET - ((char *)last - (char *)header);
+		if (found)
+			free = free - ENTRY_SIZE(here);
+
+		if (free < newsize) {
+			error = -ENOSPC;
+			goto cleanup;
+		}
+	}
+
+	/* 2. Remove old entry */
+	if (found) {
+		/* If entry is found, remove old entry.
+		 * If not found, remove operation is not needed.
+		 */
+		struct f2fs_xattr_entry *next = XATTR_NEXT_ENTRY(here);
+		int oldsize = ENTRY_SIZE(here);
+
+		memmove(here, next, (char *)last - (char *)next);
+		last = (struct f2fs_xattr_entry *)((char *)last - oldsize);
+		memset(last, 0, oldsize);
+	}
+
+	/* 3. Write new entry */
+	if (value) {
+		/* Before we come here, old entry is removed.
+		 * We just write new entry. */
+		memset(last, 0, newsize);
+		last->e_name_index = name_index;
+		last->e_name_len = name_len;
+		memcpy(last->e_name, name, name_len);
+		pval = last->e_name + name_len;
+		memcpy(pval, value, value_len);
+		last->e_value_size = cpu_to_le16(value_len);
+	}
+
+	set_page_dirty(page);
+	f2fs_put_page(page, 1);
+
+	if (is_inode_flag_set(fi, FI_ACL_MODE)) {
+		inode->i_mode = fi->i_acl_mode;
+		inode->i_ctime = CURRENT_TIME;
+		clear_inode_flag(fi, FI_ACL_MODE);
+	}
+	f2fs_write_inode(inode, NULL);
+	mutex_unlock_op(sbi, NODE_NEW);
+
+	return 0;
+cleanup:
+	f2fs_put_page(page, 1);
+	mutex_unlock_op(sbi, NODE_NEW);
+	return error;
+}

fs/f2fs/xattr.h

···
+/*
+ * fs/f2fs/xattr.h
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext2/xattr.h
+ *
+ * On-disk format of extended attributes for the ext2 filesystem.
+ *
+ * (C) 2001 Andreas Gruenbacher, <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef __F2FS_XATTR_H__
+#define __F2FS_XATTR_H__
+
+#include <linux/init.h>
+#include <linux/xattr.h>
+
+/* Magic value in attribute blocks */
+#define F2FS_XATTR_MAGIC                0xF2F52011
+
+/* Maximum number of references to one attribute block */
+#define F2FS_XATTR_REFCOUNT_MAX         1024
+
+/* Name indexes */
+#define F2FS_SYSTEM_ADVISE_PREFIX		"system.advise"
+#define F2FS_XATTR_INDEX_USER			1
+#define F2FS_XATTR_INDEX_POSIX_ACL_ACCESS	2
+#define F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT	3
+#define F2FS_XATTR_INDEX_TRUSTED		4
+#define F2FS_XATTR_INDEX_LUSTRE			5
+#define F2FS_XATTR_INDEX_SECURITY		6
+#define F2FS_XATTR_INDEX_ADVISE			7
+
+struct f2fs_xattr_header {
+	__le32  h_magic;        /* magic number for identification */
+	__le32  h_refcount;     /* reference count */
+	__u32   h_reserved[4];  /* zero right now */
+};
+
+struct f2fs_xattr_entry {
+	__u8    e_name_index;
+	__u8    e_name_len;
+	__le16  e_value_size;   /* size of attribute value */
+	char    e_name[0];      /* attribute name */
+};
+
+#define XATTR_HDR(ptr)		((struct f2fs_xattr_header *)(ptr))
+#define XATTR_ENTRY(ptr)	((struct f2fs_xattr_entry *)(ptr))
+#define XATTR_FIRST_ENTRY(ptr)	(XATTR_ENTRY(XATTR_HDR(ptr)+1))
+#define XATTR_ROUND		(3)
+
+#define XATTR_ALIGN(size)	((size + XATTR_ROUND) & ~XATTR_ROUND)
+
+#define ENTRY_SIZE(entry) (XATTR_ALIGN(sizeof(struct f2fs_xattr_entry) + \
+			entry->e_name_len + le16_to_cpu(entry->e_value_size)))
+
+#define XATTR_NEXT_ENTRY(entry)	((struct f2fs_xattr_entry *)((char *)(entry) +\
+			ENTRY_SIZE(entry)))
+
+#define IS_XATTR_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
+
+#define list_for_each_xattr(entry, addr) \
+		for (entry = XATTR_FIRST_ENTRY(addr);\
+				!IS_XATTR_LAST_ENTRY(entry);\
+				entry = XATTR_NEXT_ENTRY(entry))
+
+
+#define MIN_OFFSET	XATTR_ALIGN(PAGE_SIZE - \
+			sizeof(struct node_footer) - \
+			sizeof(__u32))
+
+#define MAX_VALUE_LEN	(MIN_OFFSET - sizeof(struct f2fs_xattr_header) - \
+			sizeof(struct f2fs_xattr_entry))
+
+/*
+ * On-disk structure of f2fs_xattr
+ * We use only 1 block for xattr.
+ *
+ * +--------------------+
+ * | f2fs_xattr_header  |
+ * |                    |
+ * +--------------------+
+ * | f2fs_xattr_entry   |
+ * | .e_name_index = 1  |
+ * | .e_name_len = 3    |
+ * | .e_value_size = 14 |
+ * | .e_name = "foo"    |
+ * | "value_of_xattr"   |<- value_offs = e_name + e_name_len
+ * +--------------------+
+ * | f2fs_xattr_entry   |
+ * | .e_name_index = 4  |
+ * | .e_name = "bar"    |
+ * +--------------------+
+ * |                    |
+ * |        Free        |
+ * |                    |
+ * +--------------------+<- MIN_OFFSET
+ * |   node_footer      |
+ * | (nid, ino, offset) |
+ * +--------------------+
+ *
+ **/
+
+#ifdef CONFIG_F2FS_FS_XATTR
+extern const struct xattr_handler f2fs_xattr_user_handler;
+extern const struct xattr_handler f2fs_xattr_trusted_handler;
+extern const struct xattr_handler f2fs_xattr_acl_access_handler;
+extern const struct xattr_handler f2fs_xattr_acl_default_handler;
+extern const struct xattr_handler f2fs_xattr_advise_handler;
+
+extern const struct xattr_handler *f2fs_xattr_handlers[];
+
+extern int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
+		const void *value, size_t value_len);
+extern int f2fs_getxattr(struct inode *inode, int name_index, const char *name,
+		void *buffer, size_t buffer_size);
+extern ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer,
+		size_t buffer_size);
+
+#else
+
+#define f2fs_xattr_handlers	NULL
+static inline int f2fs_setxattr(struct inode *inode, int name_index,
+	const char *name, const void *value, size_t value_len)
+{
+	return -EOPNOTSUPP;
+}
+static inline int f2fs_getxattr(struct inode *inode, int name_index,
+		const char *name, void *buffer, size_t buffer_size)
+{
+	return -EOPNOTSUPP;
+}
+static inline ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer,
+		size_t buffer_size)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
+#endif /* __F2FS_XATTR_H__ */

include/linux/f2fs_fs.h

···
+/**
+ * include/linux/f2fs_fs.h
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef _LINUX_F2FS_FS_H
+#define _LINUX_F2FS_FS_H
+
+#include <linux/pagemap.h>
+#include <linux/types.h>
+
+#define F2FS_SUPER_OFFSET		1024	/* byte-size offset */
+#define F2FS_LOG_SECTOR_SIZE		9	/* 9 bits for 512 byte */
+#define F2FS_LOG_SECTORS_PER_BLOCK	3	/* 4KB: F2FS_BLKSIZE */
+#define F2FS_BLKSIZE			4096	/* support only 4KB block */
+#define F2FS_MAX_EXTENSION		64	/* # of extension entries */
+
+#define NULL_ADDR		0x0U
+#define NEW_ADDR		-1U
+
+#define F2FS_ROOT_INO(sbi)	(sbi->root_ino_num)
+#define F2FS_NODE_INO(sbi)	(sbi->node_ino_num)
+#define F2FS_META_INO(sbi)	(sbi->meta_ino_num)
+
+/* This flag is used by node and meta inodes, and by recovery */
+#define GFP_F2FS_ZERO	(GFP_NOFS | __GFP_ZERO)
+
+/*
+ * For further optimization on multi-head logs, on-disk layout supports maximum
+ * 16 logs by default. The number, 16, is expected to cover all the cases
+ * enoughly. The implementaion currently uses no more than 6 logs.
+ * Half the logs are used for nodes, and the other half are used for data.
+ */
+#define MAX_ACTIVE_LOGS	16
+#define MAX_ACTIVE_NODE_LOGS	8
+#define MAX_ACTIVE_DATA_LOGS	8
+
+/*
+ * For superblock
+ */
+struct f2fs_super_block {
+	__le32 magic;			/* Magic Number */
+	__le16 major_ver;		/* Major Version */
+	__le16 minor_ver;		/* Minor Version */
+	__le32 log_sectorsize;		/* log2 sector size in bytes */
+	__le32 log_sectors_per_block;	/* log2 # of sectors per block */
+	__le32 log_blocksize;		/* log2 block size in bytes */
+	__le32 log_blocks_per_seg;	/* log2 # of blocks per segment */
+	__le32 segs_per_sec;		/* # of segments per section */
+	__le32 secs_per_zone;		/* # of sections per zone */
+	__le32 checksum_offset;		/* checksum offset inside super block */
+	__le64 block_count;		/* total # of user blocks */
+	__le32 section_count;		/* total # of sections */
+	__le32 segment_count;		/* total # of segments */
+	__le32 segment_count_ckpt;	/* # of segments for checkpoint */
+	__le32 segment_count_sit;	/* # of segments for SIT */
+	__le32 segment_count_nat;	/* # of segments for NAT */
+	__le32 segment_count_ssa;	/* # of segments for SSA */
+	__le32 segment_count_main;	/* # of segments for main area */
+	__le32 segment0_blkaddr;	/* start block address of segment 0 */
+	__le32 cp_blkaddr;		/* start block address of checkpoint */
+	__le32 sit_blkaddr;		/* start block address of SIT */
+	__le32 nat_blkaddr;		/* start block address of NAT */
+	__le32 ssa_blkaddr;		/* start block address of SSA */
+	__le32 main_blkaddr;		/* start block address of main area */
+	__le32 root_ino;		/* root inode number */
+	__le32 node_ino;		/* node inode number */
+	__le32 meta_ino;		/* meta inode number */
+	__u8 uuid[16];			/* 128-bit uuid for volume */
+	__le16 volume_name[512];	/* volume name */
+	__le32 extension_count;		/* # of extensions below */
+	__u8 extension_list[F2FS_MAX_EXTENSION][8];	/* extension array */
+} __packed;
+
+/*
+ * For checkpoint
+ */
+#define CP_ERROR_FLAG		0x00000008
+#define CP_COMPACT_SUM_FLAG	0x00000004
+#define CP_ORPHAN_PRESENT_FLAG	0x00000002
+#define CP_UMOUNT_FLAG		0x00000001
+
+struct f2fs_checkpoint {
+	__le64 checkpoint_ver;		/* checkpoint block version number */
+	__le64 user_block_count;	/* # of user blocks */
+	__le64 valid_block_count;	/* # of valid blocks in main area */
+	__le32 rsvd_segment_count;	/* # of reserved segments for gc */
+	__le32 overprov_segment_count;	/* # of overprovision segments */
+	__le32 free_segment_count;	/* # of free segments in main area */
+
+	/* information of current node segments */
+	__le32 cur_node_segno[MAX_ACTIVE_NODE_LOGS];
+	__le16 cur_node_blkoff[MAX_ACTIVE_NODE_LOGS];
+	/* information of current data segments */
+	__le32 cur_data_segno[MAX_ACTIVE_DATA_LOGS];
+	__le16 cur_data_blkoff[MAX_ACTIVE_DATA_LOGS];
+	__le32 ckpt_flags;		/* Flags : umount and journal_present */
+	__le32 cp_pack_total_block_count;	/* total # of one cp pack */
+	__le32 cp_pack_start_sum;	/* start block number of data summary */
+	__le32 valid_node_count;	/* Total number of valid nodes */
+	__le32 valid_inode_count;	/* Total number of valid inodes */
+	__le32 next_free_nid;		/* Next free node number */
+	__le32 sit_ver_bitmap_bytesize;	/* Default value 64 */
+	__le32 nat_ver_bitmap_bytesize; /* Default value 256 */
+	__le32 checksum_offset;		/* checksum offset inside cp block */
+	__le64 elapsed_time;		/* mounted time */
+	/* allocation type of current segment */
+	unsigned char alloc_type[MAX_ACTIVE_LOGS];
+
+	/* SIT and NAT version bitmap */
+	unsigned char sit_nat_version_bitmap[1];
+} __packed;
+
+/*
+ * For orphan inode management
+ */
+#define F2FS_ORPHANS_PER_BLOCK	1020
+
+struct f2fs_orphan_block {
+	__le32 ino[F2FS_ORPHANS_PER_BLOCK];	/* inode numbers */
+	__le32 reserved;	/* reserved */
+	__le16 blk_addr;	/* block index in current CP */
+	__le16 blk_count;	/* Number of orphan inode blocks in CP */
+	__le32 entry_count;	/* Total number of orphan nodes in current CP */
+	__le32 check_sum;	/* CRC32 for orphan inode block */
+} __packed;
+
+/*
+ * For NODE structure
+ */
+struct f2fs_extent {
+	__le32 fofs;		/* start file offset of the extent */
+	__le32 blk_addr;	/* start block address of the extent */
+	__le32 len;		/* lengh of the extent */
+} __packed;
+
+#define F2FS_MAX_NAME_LEN	256
+#define ADDRS_PER_INODE         923	/* Address Pointers in an Inode */
+#define ADDRS_PER_BLOCK         1018	/* Address Pointers in a Direct Block */
+#define NIDS_PER_BLOCK          1018	/* Node IDs in an Indirect Block */
+
+struct f2fs_inode {
+	__le16 i_mode;			/* file mode */
+	__u8 i_advise;			/* file hints */
+	__u8 i_reserved;		/* reserved */
+	__le32 i_uid;			/* user ID */
+	__le32 i_gid;			/* group ID */
+	__le32 i_links;			/* links count */
+	__le64 i_size;			/* file size in bytes */
+	__le64 i_blocks;		/* file size in blocks */
+	__le64 i_atime;			/* access time */
+	__le64 i_ctime;			/* change time */
+	__le64 i_mtime;			/* modification time */
+	__le32 i_atime_nsec;		/* access time in nano scale */
+	__le32 i_ctime_nsec;		/* change time in nano scale */
+	__le32 i_mtime_nsec;		/* modification time in nano scale */
+	__le32 i_generation;		/* file version (for NFS) */
+	__le32 i_current_depth;		/* only for directory depth */
+	__le32 i_xattr_nid;		/* nid to save xattr */
+	__le32 i_flags;			/* file attributes */
+	__le32 i_pino;			/* parent inode number */
+	__le32 i_namelen;		/* file name length */
+	__u8 i_name[F2FS_MAX_NAME_LEN];	/* file name for SPOR */
+
+	struct f2fs_extent i_ext;	/* caching a largest extent */
+
+	__le32 i_addr[ADDRS_PER_INODE];	/* Pointers to data blocks */
+
+	__le32 i_nid[5];		/* direct(2), indirect(2),
+						double_indirect(1) node id */
+} __packed;
+
+struct direct_node {
+	__le32 addr[ADDRS_PER_BLOCK];	/* array of data block address */
+} __packed;
+
+struct indirect_node {
+	__le32 nid[NIDS_PER_BLOCK];	/* array of data block address */
+} __packed;
+
+enum {
+	COLD_BIT_SHIFT = 0,
+	FSYNC_BIT_SHIFT,
+	DENT_BIT_SHIFT,
+	OFFSET_BIT_SHIFT
+};
+
+struct node_footer {
+	__le32 nid;		/* node id */
+	__le32 ino;		/* inode nunmber */
+	__le32 flag;		/* include cold/fsync/dentry marks and offset */
+	__le64 cp_ver;		/* checkpoint version */
+	__le32 next_blkaddr;	/* next node page block address */
+} __packed;
+
+struct f2fs_node {
+	/* can be one of three types: inode, direct, and indirect types */
+	union {
+		struct f2fs_inode i;
+		struct direct_node dn;
+		struct indirect_node in;
+	};
+	struct node_footer footer;
+} __packed;
+
+/*
+ * For NAT entries
+ */
+#define NAT_ENTRY_PER_BLOCK (PAGE_CACHE_SIZE / sizeof(struct f2fs_nat_entry))
+
+struct f2fs_nat_entry {
+	__u8 version;		/* latest version of cached nat entry */
+	__le32 ino;		/* inode number */
+	__le32 block_addr;	/* block address */
+} __packed;
+
+struct f2fs_nat_block {
+	struct f2fs_nat_entry entries[NAT_ENTRY_PER_BLOCK];
+} __packed;
+
+/*
+ * For SIT entries
+ *
+ * Each segment is 2MB in size by default so that a bitmap for validity of
+ * there-in blocks should occupy 64 bytes, 512 bits.
+ * Not allow to change this.
+ */
+#define SIT_VBLOCK_MAP_SIZE 64
+#define SIT_ENTRY_PER_BLOCK (PAGE_CACHE_SIZE / sizeof(struct f2fs_sit_entry))
+
+/*
+ * Note that f2fs_sit_entry->vblocks has the following bit-field information.
+ * [15:10] : allocation type such as CURSEG_XXXX_TYPE
+ * [9:0] : valid block count
+ */
+#define SIT_VBLOCKS_SHIFT	10
+#define SIT_VBLOCKS_MASK	((1 << SIT_VBLOCKS_SHIFT) - 1)
+#define GET_SIT_VBLOCKS(raw_sit)				\
+	(le16_to_cpu((raw_sit)->vblocks) & SIT_VBLOCKS_MASK)
+#define GET_SIT_TYPE(raw_sit)					\
+	((le16_to_cpu((raw_sit)->vblocks) & ~SIT_VBLOCKS_MASK)	\
+	 >> SIT_VBLOCKS_SHIFT)
+
+struct f2fs_sit_entry {
+	__le16 vblocks;				/* reference above */
+	__u8 valid_map[SIT_VBLOCK_MAP_SIZE];	/* bitmap for valid blocks */
+	__le64 mtime;				/* segment age for cleaning */
+} __packed;
+
+struct f2fs_sit_block {
+	struct f2fs_sit_entry entries[SIT_ENTRY_PER_BLOCK];
+} __packed;
+
+/*
+ * For segment summary
+ *
+ * One summary block contains exactly 512 summary entries, which represents
+ * exactly 2MB segment by default. Not allow to change the basic units.
+ *
+ * NOTE: For initializing fields, you must use set_summary
+ *
+ * - If data page, nid represents dnode's nid
+ * - If node page, nid represents the node page's nid.
+ *
+ * The ofs_in_node is used by only data page. It represents offset
+ * from node's page's beginning to get a data block address.
+ * ex) data_blkaddr = (block_t)(nodepage_start_address + ofs_in_node)
+ */
+#define ENTRIES_IN_SUM		512
+#define	SUMMARY_SIZE		(7)	/* sizeof(struct summary) */
+#define	SUM_FOOTER_SIZE		(5)	/* sizeof(struct summary_footer) */
+#define SUM_ENTRY_SIZE		(SUMMARY_SIZE * ENTRIES_IN_SUM)
+
+/* a summary entry for a 4KB-sized block in a segment */
+struct f2fs_summary {
+	__le32 nid;		/* parent node id */
+	union {
+		__u8 reserved[3];
+		struct {
+			__u8 version;		/* node version number */
+			__le16 ofs_in_node;	/* block index in parent node */
+		} __packed;
+	};
+} __packed;
+
+/* summary block type, node or data, is stored to the summary_footer */
+#define SUM_TYPE_NODE		(1)
+#define SUM_TYPE_DATA		(0)
+
+struct summary_footer {
+	unsigned char entry_type;	/* SUM_TYPE_XXX */
+	__u32 check_sum;		/* summary checksum */
+} __packed;
+
+#define SUM_JOURNAL_SIZE	(F2FS_BLKSIZE - SUM_FOOTER_SIZE -\
+				SUM_ENTRY_SIZE)
+#define NAT_JOURNAL_ENTRIES	((SUM_JOURNAL_SIZE - 2) /\
+				sizeof(struct nat_journal_entry))
+#define NAT_JOURNAL_RESERVED	((SUM_JOURNAL_SIZE - 2) %\
+				sizeof(struct nat_journal_entry))
+#define SIT_JOURNAL_ENTRIES	((SUM_JOURNAL_SIZE - 2) /\
+				sizeof(struct sit_journal_entry))
+#define SIT_JOURNAL_RESERVED	((SUM_JOURNAL_SIZE - 2) %\
+				sizeof(struct sit_journal_entry))
+/*
+ * frequently updated NAT/SIT entries can be stored in the spare area in
+ * summary blocks
+ */
+enum {
+	NAT_JOURNAL = 0,
+	SIT_JOURNAL
+};
+
+struct nat_journal_entry {
+	__le32 nid;
+	struct f2fs_nat_entry ne;
+} __packed;
+
+struct nat_journal {
+	struct nat_journal_entry entries[NAT_JOURNAL_ENTRIES];
+	__u8 reserved[NAT_JOURNAL_RESERVED];
+} __packed;
+
+struct sit_journal_entry {
+	__le32 segno;
+	struct f2fs_sit_entry se;
+} __packed;
+
+struct sit_journal {
+	struct sit_journal_entry entries[SIT_JOURNAL_ENTRIES];
+	__u8 reserved[SIT_JOURNAL_RESERVED];
+} __packed;
+
+/* 4KB-sized summary block structure */
+struct f2fs_summary_block {
+	struct f2fs_summary entries[ENTRIES_IN_SUM];
+	union {
+		__le16 n_nats;
+		__le16 n_sits;
+	};
+	/* spare area is used by NAT or SIT journals */
+	union {
+		struct nat_journal nat_j;
+		struct sit_journal sit_j;
+	};
+	struct summary_footer footer;
+} __packed;
+
+/*
+ * For directory operations
+ */
+#define F2FS_DOT_HASH		0
+#define F2FS_DDOT_HASH		F2FS_DOT_HASH
+#define F2FS_MAX_HASH		(~((0x3ULL) << 62))
+#define F2FS_HASH_COL_BIT	((0x1ULL) << 63)
+
+typedef __le32	f2fs_hash_t;
+
+/* One directory entry slot covers 8bytes-long file name */
+#define F2FS_NAME_LEN		8
+#define F2FS_NAME_LEN_BITS	3
+
+#define GET_DENTRY_SLOTS(x)	((x + F2FS_NAME_LEN - 1) >> F2FS_NAME_LEN_BITS)
+
+/* the number of dentry in a block */
+#define NR_DENTRY_IN_BLOCK	214
+
+/* MAX level for dir lookup */
+#define MAX_DIR_HASH_DEPTH	63
+
+#define SIZE_OF_DIR_ENTRY	11	/* by byte */
+#define SIZE_OF_DENTRY_BITMAP	((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \
+					BITS_PER_BYTE)
+#define SIZE_OF_RESERVED	(PAGE_SIZE - ((SIZE_OF_DIR_ENTRY + \
+				F2FS_NAME_LEN) * \
+				NR_DENTRY_IN_BLOCK + SIZE_OF_DENTRY_BITMAP))
+
+/* One directory entry slot representing F2FS_NAME_LEN-sized file name */
+struct f2fs_dir_entry {
+	__le32 hash_code;	/* hash code of file name */
+	__le32 ino;		/* inode number */
+	__le16 name_len;	/* lengh of file name */
+	__u8 file_type;		/* file type */
+} __packed;
+
+/* 4KB-sized directory entry block */
+struct f2fs_dentry_block {
+	/* validity bitmap for directory entries in each block */
+	__u8 dentry_bitmap[SIZE_OF_DENTRY_BITMAP];
+	__u8 reserved[SIZE_OF_RESERVED];
+	struct f2fs_dir_entry dentry[NR_DENTRY_IN_BLOCK];
+	__u8 filename[NR_DENTRY_IN_BLOCK][F2FS_NAME_LEN];
+} __packed;
+
+/* file types used in inode_info->flags */
+enum {
+	F2FS_FT_UNKNOWN,
+	F2FS_FT_REG_FILE,
+	F2FS_FT_DIR,
+	F2FS_FT_CHRDEV,
+	F2FS_FT_BLKDEV,
+	F2FS_FT_FIFO,
+	F2FS_FT_SOCK,
+	F2FS_FT_SYMLINK,
+	F2FS_FT_MAX
+};
+
+#endif  /* _LINUX_F2FS_FS_H */

include/uapi/linux/magic.h

···
 #define EXT4_SUPER_MAGIC	0xEF53
 #define BTRFS_SUPER_MAGIC	0x9123683E
 #define NILFS_SUPER_MAGIC	0x3434
+#define F2FS_SUPER_MAGIC	0xF2F52010
 #define HPFS_SUPER_MAGIC	0xf995e849
 #define ISOFS_SUPER_MAGIC	0x9660
 #define JFFS2_SUPER_MAGIC	0x72b6