The BUG_ON verifies a condition that should be guaranteed by the correct
use of the path search (with keep_locks and lowest_level set), an
assertion is the suitable check.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>