From 166f66d0bc94a14ec4bc6ee6ab079532df4a8d9e Mon Sep 17 00:00:00 2001 From: Zhaolei Date: Thu, 6 Aug 2015 22:39:36 +0800 Subject: [PATCH] btrfs: Add WARN_ON() for double lock in btrfs_tree_lock() When a task trying to double lock a extent buffer, there are no lockdep warning about it because this lock may be in "blocking_lock" state, and make us hard to debug. This patch add a WARN_ON() for above condition, it can not report all deadlock cases(as lock between tasks), but at least helps us some. Signed-off-by: Zhao Lei Signed-off-by: Chris Mason --- fs/btrfs/locking.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index f8229ef1b46d..d7e6baf1b205 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -241,6 +241,7 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb) */ void btrfs_tree_lock(struct extent_buffer *eb) { + WARN_ON(eb->lock_owner == current->pid); again: wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0); wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0); -- 2.20.1