md/linear: shutup lockdep warnning

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

Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Shaohua Li <shli@fb.com>

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 789008b..5b06b0d 100644 (file)
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -224,7 +224,8 @@ static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
         * 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");