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/blkdev.h>
26#include <linux/writeback.h>
27#include "ext3.h"
28
29/*
30 * akpm: A new design for ext3_sync_file().
31 *
32 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
33 * There cannot be a transaction open by this task.
34 * Another task could have dirtied this inode.  Its data can be in any
35 * state in the journalling system.
36 *
37 * What we do is just kick off a commit and wait on it.  This will snapshot the
38 * inode to disk.
39 */
40
41int ext3_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
42{
43	struct inode *inode = file->f_mapping->host;
44	struct ext3_inode_info *ei = EXT3_I(inode);
45	journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
46	int ret, needs_barrier = 0;
47	tid_t commit_tid;
48
49	trace_ext3_sync_file_enter(file, datasync);
50
51	if (inode->i_sb->s_flags & MS_RDONLY) {
52		/* Make sure that we read updated state */
53		smp_rmb();
54		if (EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ERROR_FS)
55			return -EROFS;
56		return 0;
57	}
58	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
59	if (ret)
60		goto out;
61
62	J_ASSERT(ext3_journal_current_handle() == NULL);
63
64	/*
65	 * data=writeback,ordered:
66	 *  The caller's filemap_fdatawrite()/wait will sync the data.
67	 *  Metadata is in the journal, we wait for a proper transaction
68	 *  to commit here.
69	 *
70	 * data=journal:
71	 *  filemap_fdatawrite won't do anything (the buffers are clean).
72	 *  ext3_force_commit will write the file data into the journal and
73	 *  will wait on that.
74	 *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
75	 *  (they were dirtied by commit).  But that's OK - the blocks are
76	 *  safe in-journal, which is all fsync() needs to ensure.
77	 */
78	if (ext3_should_journal_data(inode)) {
79		ret = ext3_force_commit(inode->i_sb);
80		goto out;
81	}
82
83	if (datasync)
84		commit_tid = atomic_read(&ei->i_datasync_tid);
85	else
86		commit_tid = atomic_read(&ei->i_sync_tid);
87
88	if (test_opt(inode->i_sb, BARRIER) &&
89	    !journal_trans_will_send_data_barrier(journal, commit_tid))
90		needs_barrier = 1;
91	log_start_commit(journal, commit_tid);
92	ret = log_wait_commit(journal, commit_tid);
93
94	/*
95	 * In case we didn't commit a transaction, we have to flush
96	 * disk caches manually so that data really is on persistent
97	 * storage
98	 */
99	if (needs_barrier) {
100		int err;
101
102		err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
103		if (!ret)
104			ret = err;
105	}
106out:
107	trace_ext3_sync_file_exit(inode, ret);
108	return ret;
109}
110