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1/*
2 * linux/fs/ext3/fsync.c
3 *
4 * Copyright (C) 1993 Stephen Tweedie (sct@redhat.com)
5 * from
6 * Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 * from
10 * linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds
11 *
12 * ext3fs fsync primitive
13 *
14 * Big-endian to little-endian byte-swapping/bitmaps by
15 * David S. Miller (davem@caip.rutgers.edu), 1995
16 *
17 * Removed unnecessary code duplication for little endian machines
18 * and excessive __inline__s.
19 * Andi Kleen, 1997
20 *
21 * Major simplications and cleanup - we only need to do the metadata, because
22 * we can depend on generic_block_fdatasync() to sync the data blocks.
23 */
24
25#include <linux/time.h>
26#include <linux/blkdev.h>
27#include <linux/fs.h>
28#include <linux/sched.h>
29#include <linux/writeback.h>
30#include <linux/jbd.h>
31#include <linux/ext3_fs.h>
32#include <linux/ext3_jbd.h>
33
34/*
35 * akpm: A new design for ext3_sync_file().
36 *
37 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
38 * There cannot be a transaction open by this task.
39 * Another task could have dirtied this inode. Its data can be in any
40 * state in the journalling system.
41 *
42 * What we do is just kick off a commit and wait on it. This will snapshot the
43 * inode to disk.
44 */
45
46int ext3_sync_file(struct file * file, struct dentry *dentry, int datasync)
47{
48 struct inode *inode = dentry->d_inode;
49 int ret = 0;
50
51 J_ASSERT(ext3_journal_current_handle() == NULL);
52
53 /*
54 * data=writeback:
55 * The caller's filemap_fdatawrite()/wait will sync the data.
56 * sync_inode() will sync the metadata
57 *
58 * data=ordered:
59 * The caller's filemap_fdatawrite() will write the data and
60 * sync_inode() will write the inode if it is dirty. Then the caller's
61 * filemap_fdatawait() will wait on the pages.
62 *
63 * data=journal:
64 * filemap_fdatawrite won't do anything (the buffers are clean).
65 * ext3_force_commit will write the file data into the journal and
66 * will wait on that.
67 * filemap_fdatawait() will encounter a ton of newly-dirtied pages
68 * (they were dirtied by commit). But that's OK - the blocks are
69 * safe in-journal, which is all fsync() needs to ensure.
70 */
71 if (ext3_should_journal_data(inode)) {
72 ret = ext3_force_commit(inode->i_sb);
73 goto out;
74 }
75
76 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
77 goto flush;
78
79 /*
80 * The VFS has written the file data. If the inode is unaltered
81 * then we need not start a commit.
82 */
83 if (inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC)) {
84 struct writeback_control wbc = {
85 .sync_mode = WB_SYNC_ALL,
86 .nr_to_write = 0, /* sys_fsync did this */
87 };
88 ret = sync_inode(inode, &wbc);
89 goto out;
90 }
91flush:
92 /*
93 * In case we didn't commit a transaction, we have to flush
94 * disk caches manually so that data really is on persistent
95 * storage
96 */
97 if (test_opt(inode->i_sb, BARRIER))
98 blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
99out:
100 return ret;
101}