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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext4/fsync.c
4 *
5 * Copyright (C) 1993 Stephen Tweedie (sct@redhat.com)
6 * from
7 * Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
8 * Laboratoire MASI - Institut Blaise Pascal
9 * Universite Pierre et Marie Curie (Paris VI)
10 * from
11 * linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds
12 *
13 * ext4fs fsync primitive
14 *
15 * Big-endian to little-endian byte-swapping/bitmaps by
16 * David S. Miller (davem@caip.rutgers.edu), 1995
17 *
18 * Removed unnecessary code duplication for little endian machines
19 * and excessive __inline__s.
20 * Andi Kleen, 1997
21 *
22 * Major simplications and cleanup - we only need to do the metadata, because
23 * we can depend on generic_block_fdatasync() to sync the data blocks.
24 */
25
26#include <linux/time.h>
27#include <linux/fs.h>
28#include <linux/sched.h>
29#include <linux/writeback.h>
30#include <linux/blkdev.h>
31
32#include "ext4.h"
33#include "ext4_jbd2.h"
34
35#include <trace/events/ext4.h>
36
37/*
38 * If we're not journaling and this is a just-created file, we have to
39 * sync our parent directory (if it was freshly created) since
40 * otherwise it will only be written by writeback, leaving a huge
41 * window during which a crash may lose the file. This may apply for
42 * the parent directory's parent as well, and so on recursively, if
43 * they are also freshly created.
44 */
45static int ext4_sync_parent(struct inode *inode)
46{
47 struct dentry *dentry, *next;
48 int ret = 0;
49
50 if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))
51 return 0;
52 dentry = d_find_any_alias(inode);
53 if (!dentry)
54 return 0;
55 while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
56 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
57
58 next = dget_parent(dentry);
59 dput(dentry);
60 dentry = next;
61 inode = dentry->d_inode;
62
63 /*
64 * The directory inode may have gone through rmdir by now. But
65 * the inode itself and its blocks are still allocated (we hold
66 * a reference to the inode via its dentry), so it didn't go
67 * through ext4_evict_inode()) and so we are safe to flush
68 * metadata blocks and the inode.
69 */
70 ret = sync_mapping_buffers(inode->i_mapping);
71 if (ret)
72 break;
73 ret = sync_inode_metadata(inode, 1);
74 if (ret)
75 break;
76 }
77 dput(dentry);
78 return ret;
79}
80
81static int ext4_fsync_nojournal(struct inode *inode, bool datasync,
82 bool *needs_barrier)
83{
84 int ret, err;
85
86 ret = sync_mapping_buffers(inode->i_mapping);
87 if (!(inode->i_state & I_DIRTY_ALL))
88 return ret;
89 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
90 return ret;
91
92 err = sync_inode_metadata(inode, 1);
93 if (!ret)
94 ret = err;
95
96 if (!ret)
97 ret = ext4_sync_parent(inode);
98 if (test_opt(inode->i_sb, BARRIER))
99 *needs_barrier = true;
100
101 return ret;
102}
103
104static int ext4_fsync_journal(struct inode *inode, bool datasync,
105 bool *needs_barrier)
106{
107 struct ext4_inode_info *ei = EXT4_I(inode);
108 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
109 tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
110
111 /*
112 * Fastcommit does not really support fsync on directories or other
113 * special files. Force a full commit.
114 */
115 if (!S_ISREG(inode->i_mode))
116 return ext4_force_commit(inode->i_sb);
117
118 if (journal->j_flags & JBD2_BARRIER &&
119 !jbd2_trans_will_send_data_barrier(journal, commit_tid))
120 *needs_barrier = true;
121
122 return ext4_fc_commit(journal, commit_tid);
123}
124
125/*
126 * akpm: A new design for ext4_sync_file().
127 *
128 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
129 * There cannot be a transaction open by this task.
130 * Another task could have dirtied this inode. Its data can be in any
131 * state in the journalling system.
132 *
133 * What we do is just kick off a commit and wait on it. This will snapshot the
134 * inode to disk.
135 */
136int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
137{
138 int ret = 0, err;
139 bool needs_barrier = false;
140 struct inode *inode = file->f_mapping->host;
141 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
142
143 if (unlikely(ext4_forced_shutdown(sbi)))
144 return -EIO;
145
146 ASSERT(ext4_journal_current_handle() == NULL);
147
148 trace_ext4_sync_file_enter(file, datasync);
149
150 if (sb_rdonly(inode->i_sb)) {
151 /* Make sure that we read updated s_mount_flags value */
152 smp_rmb();
153 if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FS_ABORTED))
154 ret = -EROFS;
155 goto out;
156 }
157
158 ret = file_write_and_wait_range(file, start, end);
159 if (ret)
160 goto out;
161
162 /*
163 * The caller's filemap_fdatawrite()/wait will sync the data.
164 * Metadata is in the journal, we wait for proper transaction to
165 * commit here.
166 */
167 if (!sbi->s_journal)
168 ret = ext4_fsync_nojournal(inode, datasync, &needs_barrier);
169 else
170 ret = ext4_fsync_journal(inode, datasync, &needs_barrier);
171
172 if (needs_barrier) {
173 err = blkdev_issue_flush(inode->i_sb->s_bdev);
174 if (!ret)
175 ret = err;
176 }
177out:
178 err = file_check_and_advance_wb_err(file);
179 if (ret == 0)
180 ret = err;
181 trace_ext4_sync_file_exit(inode, ret);
182 return ret;
183}