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
ext3_sync_file(struct file * file,loff_t start,loff_t end,int datasync)41 int 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 return 0;
53
54 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
55 if (ret)
56 goto out;
57
58 J_ASSERT(ext3_journal_current_handle() == NULL);
59
60 /*
61 * data=writeback,ordered:
62 * The caller's filemap_fdatawrite()/wait will sync the data.
63 * Metadata is in the journal, we wait for a proper transaction
64 * to commit here.
65 *
66 * data=journal:
67 * filemap_fdatawrite won't do anything (the buffers are clean).
68 * ext3_force_commit will write the file data into the journal and
69 * will wait on that.
70 * filemap_fdatawait() will encounter a ton of newly-dirtied pages
71 * (they were dirtied by commit). But that's OK - the blocks are
72 * safe in-journal, which is all fsync() needs to ensure.
73 */
74 if (ext3_should_journal_data(inode)) {
75 ret = ext3_force_commit(inode->i_sb);
76 goto out;
77 }
78
79 if (datasync)
80 commit_tid = atomic_read(&ei->i_datasync_tid);
81 else
82 commit_tid = atomic_read(&ei->i_sync_tid);
83
84 if (test_opt(inode->i_sb, BARRIER) &&
85 !journal_trans_will_send_data_barrier(journal, commit_tid))
86 needs_barrier = 1;
87 log_start_commit(journal, commit_tid);
88 ret = log_wait_commit(journal, commit_tid);
89
90 /*
91 * In case we didn't commit a transaction, we have to flush
92 * disk caches manually so that data really is on persistent
93 * storage
94 */
95 if (needs_barrier)
96 blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
97 out:
98 trace_ext3_sync_file_exit(inode, ret);
99 return ret;
100 }
101