[PATCH 4.9 20/51] md/linear: shutup lockdep warnning

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Shaohua Li <shli@xxxxxx>


[ Upstream commit d939cdfde34f50b95254b375f498447c82190b3e ]

Commit 03a9e24(md linear: fix a race between linear_add() and
linear_congested()) introduces the warnning.

Acked-by: Coly Li <colyli@xxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/md/linear.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -223,7 +223,8 @@ static int linear_add(struct mddev *mdde
 	 * oldconf until no one uses it anymore.
 	 */
 	mddev_suspend(mddev);
-	oldconf = rcu_dereference(mddev->private);
+	oldconf = rcu_dereference_protected(mddev->private,
+			lockdep_is_held(&mddev->reconfig_mutex));
 	mddev->raid_disks++;
 	WARN_ONCE(mddev->raid_disks != newconf->raid_disks,
 		"copied raid_disks doesn't match mddev->raid_disks");