From 5a3e5cb8e08bd876e2542c1451c9a93dab1b0e39 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 27 Apr 2009 16:43:48 +0200 Subject: 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 Signed-off-by: Al Viro --- fs/internal.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'fs/internal.h') diff --git a/fs/internal.h b/fs/internal.h index 6d4ef208ef6..343a537ab80 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -71,3 +71,12 @@ extern void chroot_fs_refs(struct path *, struct path *); * file_table.c */ extern void mark_files_ro(struct super_block *); + +/* + * super.c + */ +#ifdef CONFIG_BLOCK +extern void sync_blockdevs(void); +#else +static inline void sync_blockdevs(void) { } +#endif -- cgit v1.2.3