2 * linux/fs/ext4/fsync.c
4 * Copyright (C) 1993 Stephen Tweedie (sct@redhat.com)
6 * Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
10 * linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds
12 * ext4fs fsync primitive
14 * Big-endian to little-endian byte-swapping/bitmaps by
15 * David S. Miller (davem@caip.rutgers.edu), 1995
17 * Removed unnecessary code duplication for little endian machines
18 * and excessive __inline__s.
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.
25 #include <linux/time.h>
27 #include <linux/sched.h>
28 #include <linux/writeback.h>
29 #include <linux/jbd2.h>
30 #include <linux/blkdev.h>
33 #include "ext4_jbd2.h"
35 #include <trace/events/ext4.h>
38 * akpm: A new design for ext4_sync_file().
40 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
41 * There cannot be a transaction open by this task.
42 * Another task could have dirtied this inode. Its data can be in any
43 * state in the journalling system.
45 * What we do is just kick off a commit and wait on it. This will snapshot the
49 int ext4_sync_file(struct file
*file
, struct dentry
*dentry
, int datasync
)
51 struct inode
*inode
= dentry
->d_inode
;
52 journal_t
*journal
= EXT4_SB(inode
->i_sb
)->s_journal
;
55 J_ASSERT(ext4_journal_current_handle() == NULL
);
57 trace_ext4_sync_file(file
, dentry
, datasync
);
61 * The caller's filemap_fdatawrite()/wait will sync the data.
62 * sync_inode() will sync the metadata
65 * The caller's filemap_fdatawrite() will write the data and
66 * sync_inode() will write the inode if it is dirty. Then the caller's
67 * filemap_fdatawait() will wait on the pages.
70 * filemap_fdatawrite won't do anything (the buffers are clean).
71 * ext4_force_commit will write the file data into the journal and
73 * filemap_fdatawait() will encounter a ton of newly-dirtied pages
74 * (they were dirtied by commit). But that's OK - the blocks are
75 * safe in-journal, which is all fsync() needs to ensure.
77 if (ext4_should_journal_data(inode
)) {
78 ret
= ext4_force_commit(inode
->i_sb
);
82 if (datasync
&& !(inode
->i_state
& I_DIRTY_DATASYNC
))
86 * The VFS has written the file data. If the inode is unaltered
87 * then we need not start a commit.
89 if (inode
->i_state
& (I_DIRTY_SYNC
|I_DIRTY_DATASYNC
)) {
90 struct writeback_control wbc
= {
91 .sync_mode
= WB_SYNC_ALL
,
92 .nr_to_write
= 0, /* sys_fsync did this */
94 ret
= sync_inode(inode
, &wbc
);
95 if (journal
&& (journal
->j_flags
& JBD2_BARRIER
))
96 blkdev_issue_flush(inode
->i_sb
->s_bdev
, NULL
);
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