1 /*
2 * linux/fs/ext4/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 * ext4fs 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/jbd2.h>
30 #include <linux/blkdev.h>
31 #include <linux/marker.h>
32 #include "ext4.h"
33 #include "ext4_jbd2.h"
34
35 /*
36 * akpm: A new design for ext4_sync_file().
37 *
38 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
39 * There cannot be a transaction open by this task.
40 * Another task could have dirtied this inode. Its data can be in any
41 * state in the journalling system.
42 *
43 * What we do is just kick off a commit and wait on it. This will snapshot the
44 * inode to disk.
45 */
46
ext4_sync_file(struct file * file,struct dentry * dentry,int datasync)47 int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync)
48 {
49 struct inode *inode = dentry->d_inode;
50 journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
51 int ret = 0;
52
53 J_ASSERT(ext4_journal_current_handle() == NULL);
54
55 trace_mark(ext4_sync_file, "dev %s datasync %d ino %ld parent %ld",
56 inode->i_sb->s_id, datasync, inode->i_ino,
57 dentry->d_parent->d_inode->i_ino);
58
59 /*
60 * data=writeback:
61 * The caller's filemap_fdatawrite()/wait will sync the data.
62 * sync_inode() will sync the metadata
63 *
64 * data=ordered:
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.
68 *
69 * data=journal:
70 * filemap_fdatawrite won't do anything (the buffers are clean).
71 * ext4_force_commit will write the file data into the journal and
72 * will wait on that.
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.
76 */
77 if (ext4_should_journal_data(inode)) {
78 ret = ext4_force_commit(inode->i_sb);
79 goto out;
80 }
81
82 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
83 goto out;
84
85 /*
86 * The VFS has written the file data. If the inode is unaltered
87 * then we need not start a commit.
88 */
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 */
93 };
94 ret = sync_inode(inode, &wbc);
95 if (journal && (journal->j_flags & JBD2_BARRIER))
96 blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
97 }
98 out:
99 return ret;
100 }
101