From faa008899a4db21a2df99833cb4ff6fa67009a20 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 30 Jul 2020 11:18:09 -0400 Subject: [PATCH] btrfs: make sure SB_I_VERSION doesn't get unset by remount 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 CC: stable@vger.kernel.org # 5.4+ Signed-off-by: Josef Bacik Reviewed-by: David Sterba [ add perf impact analysis ] Signed-off-by: David Sterba --- fs/btrfs/super.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 9b4e9c4..e529ddb 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1960,6 +1960,12 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data) 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); clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state); -- 2.7.4