drbd: Consider that bio->bi_bdev might be modified below DRBD

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_req.c

@@ -1154,7 +1154,6 @@ void request_timer_fn(unsigned long data)
 	struct drbd_conf *mdev = (struct drbd_conf *) data;
 	struct drbd_tconn *tconn = mdev->tconn;
 	struct drbd_request *req; /* oldest request */
-	struct block_device *bdev;
 	struct list_head *le;
 	struct net_conf *nc;
 	unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */
@@ -1165,7 +1164,6 @@ void request_timer_fn(unsigned long data)
 
 	if (get_ldev(mdev)) {
 		dt = rcu_dereference(mdev->ldev->disk_conf)->disk_timeout * HZ / 10;
-		bdev = mdev->ldev->backing_bdev;
 		put_ldev(mdev);
 	}
 	rcu_read_unlock();
@@ -1191,7 +1189,7 @@ void request_timer_fn(unsigned long data)
 			_drbd_set_state(_NS(mdev, conn, C_TIMEOUT), CS_VERBOSE | CS_HARD, NULL);
 		}
 	}
-	if (dt && req->rq_state & RQ_LOCAL_PENDING && req->private_bio->bi_bdev == bdev) {
+	if (dt && req->rq_state & RQ_LOCAL_PENDING && req->w.mdev == mdev) {
 		if (time_is_before_eq_jiffies(req->start_time + dt)) {
 			dev_warn(DEV, "Local backing device failed to meet the disk-timeout\n");
 			__drbd_chk_io_error(mdev, 1);