rbd: reacquire lock should update lock owner client id

Otherwise, future operations on this RBD using exclusive-lock are
going to require the lock from a non-existent client id.

Cc: stable@vger.kernel.org
Fixes: 14bb211 ("rbd: support updating the lock cookie without releasing the lock")
Link: http://tracker.ceph.com/issues/19929
Signed-off-by: Florian Margaine <florian@platform.sh>
[idryomov@gmail.com: rbd_set_owner_cid() call, __rbd_lock() helper]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

drivers/block/rbd.c

@@ -3047,13 +3047,21 @@ static void format_lock_cookie(struct rbd_device *rbd_dev, char *buf)
 	mutex_unlock(&rbd_dev->watch_mutex);
 }
 
+static void __rbd_lock(struct rbd_device *rbd_dev, const char *cookie)
+{
+	struct rbd_client_id cid = rbd_get_cid(rbd_dev);
+
+	strcpy(rbd_dev->lock_cookie, cookie);
+	rbd_set_owner_cid(rbd_dev, &cid);
+	queue_work(rbd_dev->task_wq, &rbd_dev->acquired_lock_work);
+}
+
 /*
  * lock_rwsem must be held for write
  */
 static int rbd_lock(struct rbd_device *rbd_dev)
 {
 	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
-	struct rbd_client_id cid = rbd_get_cid(rbd_dev);
 	char cookie[32];
 	int ret;
 
@@ -3068,9 +3076,7 @@ static int rbd_lock(struct rbd_device *rbd_dev)
 		return ret;
 
 	rbd_dev->lock_state = RBD_LOCK_STATE_LOCKED;
-	strcpy(rbd_dev->lock_cookie, cookie);
-	rbd_set_owner_cid(rbd_dev, &cid);
-	queue_work(rbd_dev->task_wq, &rbd_dev->acquired_lock_work);
+	__rbd_lock(rbd_dev, cookie);
 	return 0;
 }
 
@@ -3856,7 +3862,7 @@ static void rbd_reacquire_lock(struct rbd_device *rbd_dev)
 			queue_delayed_work(rbd_dev->task_wq,
 					   &rbd_dev->lock_dwork, 0);
 	} else {
-		strcpy(rbd_dev->lock_cookie, cookie);
+		__rbd_lock(rbd_dev, cookie);
 	}
 }