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
45int 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	}
86out:
87	return ret;
88}
89