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/fs.h>
27 #include <linux/sched.h>
28 #include <linux/writeback.h>
29 #include <linux/jbd.h>
30 #include <linux/ext3_fs.h>
31 #include <linux/ext3_jbd.h>
32
33 /*
34 * akpm: A new design for ext3_sync_file().
35 *
36 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
37 * There cannot be a transaction open by this task.
38 * Another task could have dirtied this inode. Its data can be in any
39 * state in the journalling system.
40 *
41 * What we do is just kick off a commit and wait on it. This will snapshot the
42 * inode to disk.
43 */
44
45 int ext3_sync_file(struct file * file, struct dentry *dentry, int datasync)
46 {
47 struct inode *inode = dentry->d_inode;
48 int ret = 0;
49
50 J_ASSERT(ext3_journal_current_handle() == 0);
51
52 /*
53 * data=writeback:
54 * The caller's filemap_fdatawrite()/wait will sync the data.
55 * sync_inode() will sync the metadata
56 *
57 * data=ordered:
58 * The caller's filemap_fdatawrite() will write the data and
59 * sync_inode() will write the inode if it is dirty. Then the caller's
60 * filemap_fdatawait() will wait on the pages.
61 *
62 * data=journal:
63 * filemap_fdatawrite won't do anything (the buffers are clean).
64 * ext3_force_commit will write the file data into the journal and
65 * will wait on that.
66 * filemap_fdatawait() will encounter a ton of newly-dirtied pages
67 * (they were dirtied by commit). But that's OK - the blocks are
68 * safe in-journal, which is all fsync() needs to ensure.
69 */
70 if (ext3_should_journal_data(inode)) {
71 ret = ext3_force_commit(inode->i_sb);
72 goto out;
73 }
74
75 /*
76 * The VFS has written the file data. If the inode is unaltered
77 * then we need not start a commit.
78 */
79 if (inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC)) {
80 struct writeback_control wbc = {
81 .sync_mode = WB_SYNC_ALL,
82 .nr_to_write = 0, /* sys_fsync did this */
83 };
84 ret = sync_inode(inode, &wbc);
85 }
86 out:
87 return ret;
88 }
89
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