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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#include <trace/events/ext3.h>
34
35/*
36 * akpm: A new design for ext3_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
47int ext3_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
48{
49 struct inode *inode = file->f_mapping->host;
50 struct ext3_inode_info *ei = EXT3_I(inode);
51 journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
52 int ret, needs_barrier = 0;
53 tid_t commit_tid;
54
55 trace_ext3_sync_file_enter(file, datasync);
56
57 if (inode->i_sb->s_flags & MS_RDONLY)
58 return 0;
59
60 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
61 if (ret)
62 goto out;
63
64 J_ASSERT(ext3_journal_current_handle() == NULL);
65
66 /*
67 * data=writeback,ordered:
68 * The caller's filemap_fdatawrite()/wait will sync the data.
69 * Metadata is in the journal, we wait for a proper transaction
70 * to commit here.
71 *
72 * data=journal:
73 * filemap_fdatawrite won't do anything (the buffers are clean).
74 * ext3_force_commit will write the file data into the journal and
75 * will wait on that.
76 * filemap_fdatawait() will encounter a ton of newly-dirtied pages
77 * (they were dirtied by commit). But that's OK - the blocks are
78 * safe in-journal, which is all fsync() needs to ensure.
79 */
80 if (ext3_should_journal_data(inode)) {
81 ret = ext3_force_commit(inode->i_sb);
82 goto out;
83 }
84
85 if (datasync)
86 commit_tid = atomic_read(&ei->i_datasync_tid);
87 else
88 commit_tid = atomic_read(&ei->i_sync_tid);
89
90 if (test_opt(inode->i_sb, BARRIER) &&
91 !journal_trans_will_send_data_barrier(journal, commit_tid))
92 needs_barrier = 1;
93 log_start_commit(journal, commit_tid);
94 ret = log_wait_commit(journal, commit_tid);
95
96 /*
97 * In case we didn't commit a transaction, we have to flush
98 * disk caches manually so that data really is on persistent
99 * storage
100 */
101 if (needs_barrier)
102 blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
103out:
104 trace_ext3_sync_file_exit(inode, ret);
105 return ret;
106}