From: Zhaolei Date: Thu, 6 Aug 2015 14:39:36 +0000 (+0800) Subject: btrfs: Add WARN_ON() for double lock in btrfs_tree_lock() X-Git-Tag: v4.3-rc1~72^2~18 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=166f66d0bc94a14ec4bc6ee6ab079532df4a8d9e;p=linux.git 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 --- 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);