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| author | Jan Kara <jack@suse.cz> | 2009-04-27 18:43:48 +0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2009-06-12 05:36:03 +0400 |
| commit | 5a3e5cb8e08bd876e2542c1451c9a93dab1b0e39 (patch) | |
| tree | 3b792d21246f1001adeca8b67df24ca71593dd3f /fs/super.c | |
| parent | 876a9f76abbcb775f8d21cbc99fa161f9e5937f1 (diff) | |
| download | linux-5a3e5cb8e08bd876e2542c1451c9a93dab1b0e39.tar.xz | |
vfs: Fix sys_sync() and fsync_super() reliability (version 4)
So far, do_sync() called:
sync_inodes(0);
sync_supers();
sync_filesystems(0);
sync_filesystems(1);
sync_inodes(1);
This ordering makes it kind of hard for filesystems as sync_inodes(0) need not
submit all the IO (for example it skips inodes with I_SYNC set) so e.g. forcing
transaction to disk in ->sync_fs() is not really enough. Therefore sys_sync has
not been completely reliable on some filesystems (ext3, ext4, reiserfs, ocfs2
and others are hit by this) when racing e.g. with background writeback. A
similar problem hits also other filesystems (e.g. ext2) because of
write_supers() being called before the sync_inodes(1).
Change the ordering of calls in do_sync() - this requires a new function
sync_blockdevs() to preserve the property that block devices are always synced
after write_super() / sync_fs() call.
The same issue is fixed in __fsync_super() function used on umount /
remount read-only.
[AV: build fixes]
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/super.c')
| -rw-r--r-- | fs/super.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/fs/super.c b/fs/super.c index 3d9f117dd2a3..18d159dc1e40 100644 --- a/fs/super.c +++ b/fs/super.c @@ -293,6 +293,7 @@ void __fsync_super(struct super_block *sb) { sync_inodes_sb(sb, 0); vfs_dq_sync(sb); + sync_inodes_sb(sb, 1); lock_super(sb); if (sb->s_dirt && sb->s_op->write_super) sb->s_op->write_super(sb); @@ -300,7 +301,6 @@ void __fsync_super(struct super_block *sb) if (sb->s_op->sync_fs) sb->s_op->sync_fs(sb, 1); sync_blockdev(sb->s_bdev); - sync_inodes_sb(sb, 1); } /* @@ -522,6 +522,33 @@ restart: mutex_unlock(&mutex); } +#ifdef CONFIG_BLOCK +/* + * Sync all block devices underlying some superblock + */ +void sync_blockdevs(void) +{ + struct super_block *sb; + + spin_lock(&sb_lock); +restart: + list_for_each_entry(sb, &super_blocks, s_list) { + if (!sb->s_bdev) + continue; + sb->s_count++; + spin_unlock(&sb_lock); + down_read(&sb->s_umount); + if (sb->s_root) + sync_blockdev(sb->s_bdev); + up_read(&sb->s_umount); + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto restart; + } + spin_unlock(&sb_lock); +} +#endif + /** * get_super - get the superblock of a device * @bdev: device to get the superblock for |