Patch "Btrfs: use down_read_nested to make lockdep silent" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Btrfs: use down_read_nested to make lockdep silent

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     btrfs-use-down_read_nested-to-make-lockdep-silent.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Fri Aug  4 15:15:51 PDT 2017
From: Liu Bo <bo.li.liu@oracle.com>
Date: Wed, 30 Nov 2016 16:11:04 -0800
Subject: Btrfs: use down_read_nested to make lockdep silent

From: Liu Bo <bo.li.liu@oracle.com>


[ Upstream commit e321f8a801d7b4c40da8005257b05b9c2b51b072 ]

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 <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/btrfs/extent-tree.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e46e7fbe1b34..14a37ff0b9e3 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7401,7 +7401,8 @@ 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)
-- 
2.13.4



Patches currently in stable-queue which might be from bo.li.liu@oracle.com are

queue-4.4/btrfs-adjust-outstanding_extents-counter-properly-when-dio-write-is-split.patch
queue-4.4/btrfs-use-down_read_nested-to-make-lockdep-silent.patch