From: Josef Bacik josef@toxicpanda.com
commit faa008899a4db21a2df99833cb4ff6fa67009a20 upstream.
There's some inconsistency around SB_I_VERSION handling with mount and remount. Since we don't really want it to be off ever just work around this by making sure we don't get the flag cleared on remount.
There's a tiny cpu cost of setting the bit, otherwise all changes to i_version also change some of the times (ctime/mtime) so the inode needs to be synced. We wouldn't save anything by disabling it.
Reported-by: Eric Sandeen sandeen@redhat.com CC: stable@vger.kernel.org # 5.4+ Signed-off-by: Josef Bacik josef@toxicpanda.com Reviewed-by: David Sterba dsterba@suse.com [ add perf impact analysis ] Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/super.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1895,6 +1895,12 @@ static int btrfs_remount(struct super_bl set_bit(BTRFS_FS_OPEN, &fs_info->flags); } out: + /* + * We need to set SB_I_VERSION here otherwise it'll get cleared by VFS, + * since the absence of the flag means it can be toggled off by remount. + */ + *flags |= SB_I_VERSION; + wake_up_process(fs_info->transaction_kthread); btrfs_remount_cleanup(fs_info, old_opts); return 0;