[PATCH] btrfs: make sure SB_I_VERSION doesn't get unset by remount

[Josef Bacik <josef@toxicpanda.com>]

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.

Reported-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/super.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 5bcdad3ee258..0a9d8b7664f7 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 S_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);
-- 
2.24.1