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, int datasync)
47{
48	struct inode *inode = file->f_mapping->host;
49	struct ext3_inode_info *ei = EXT3_I(inode);
50	journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
51	int ret, needs_barrier = 0;
52	tid_t commit_tid;
53
54	if (inode->i_sb->s_flags & MS_RDONLY)
55		return 0;
56
57	J_ASSERT(ext3_journal_current_handle() == NULL);
58
59	/*
60	 * data=writeback,ordered:
61	 *  The caller's filemap_fdatawrite()/wait will sync the data.
62	 *  Metadata is in the journal, we wait for a proper transaction
63	 *  to commit here.
64	 *
65	 * data=journal:
66	 *  filemap_fdatawrite won't do anything (the buffers are clean).
67	 *  ext3_force_commit will write the file data into the journal and
68	 *  will wait on that.
69	 *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
70	 *  (they were dirtied by commit).  But that's OK - the blocks are
71	 *  safe in-journal, which is all fsync() needs to ensure.
72	 */
73	if (ext3_should_journal_data(inode))
74		return ext3_force_commit(inode->i_sb);
75
76	if (datasync)
77		commit_tid = atomic_read(&ei->i_datasync_tid);
78	else
79		commit_tid = atomic_read(&ei->i_sync_tid);
80
81	if (test_opt(inode->i_sb, BARRIER) &&
82	    !journal_trans_will_send_data_barrier(journal, commit_tid))
83		needs_barrier = 1;
84	log_start_commit(journal, commit_tid);
85	ret = log_wait_commit(journal, commit_tid);
86
87	/*
88	 * In case we didn't commit a transaction, we have to flush
89	 * disk caches manually so that data really is on persistent
90	 * storage
91	 */
92	if (needs_barrier)
93		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL,
94				BLKDEV_IFL_WAIT);
95	return ret;
96}
97