From: Liu Bo Date: Thu, 1 Dec 2016 00:11:04 +0000 (-0800) Subject: Btrfs: use down_read_nested to make lockdep silent X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e321f8a801d7b4c40da8005257b05b9c2b51b072;p=linux-beck.git Btrfs: use down_read_nested to make lockdep silent If @block_group is not @used_bg, it'll try to get @used_bg's lock without droping @block_group 's lock and lockdep has throwed a scary deadlock warning about it. Fix it by using down_read_nested. Signed-off-by: Liu Bo Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index ac7e6713033c..dcd2e798767e 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -7387,7 +7387,8 @@ btrfs_lock_cluster(struct btrfs_block_group_cache *block_group, spin_unlock(&cluster->refill_lock); - down_read(&used_bg->data_rwsem); + /* We should only have one-level nested. */ + down_read_nested(&used_bg->data_rwsem, SINGLE_DEPTH_NESTING); spin_lock(&cluster->refill_lock); if (used_bg == cluster->block_group)