block/rnbd: Kill destroy_device_cb

We can use destroy_device directly since destroy_device_cb is just the
wrapper of destroy_device.

Signed-off-by: Guoqing Jiang <guoqing.jiang@ionos.com>
Reviewed-by: Danil Kipnis <danil.kipnis@ionos.com>
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Link: https://lore.kernel.org/r/20210419073722.15351-8-gi-oh.kim@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/rnbd/rnbd-srv.c

@@ -178,8 +178,10 @@ static int process_rdma(struct rtrs_srv *sess,
 	return err;
 }
 
-static void destroy_device(struct rnbd_srv_dev *dev)
+static void destroy_device(struct kref *kref)
 {
+	struct rnbd_srv_dev *dev = container_of(kref, struct rnbd_srv_dev, kref);
+
 	WARN_ONCE(!list_empty(&dev->sess_dev_list),
 		  "Device %s is being destroyed but still in use!\n",
 		  dev->id);
@@ -198,18 +200,9 @@ static void destroy_device(struct rnbd_srv_dev *dev)
 		kfree(dev);
 }
 
-static void destroy_device_cb(struct kref *kref)
-{
-	struct rnbd_srv_dev *dev;
-
-	dev = container_of(kref, struct rnbd_srv_dev, kref);
-
-	destroy_device(dev);
-}
-
 static void rnbd_put_srv_dev(struct rnbd_srv_dev *dev)
 {
-	kref_put(&dev->kref, destroy_device_cb);
+	kref_put(&dev->kref, destroy_device);
 }
 
 void rnbd_destroy_sess_dev(struct rnbd_srv_sess_dev *sess_dev, bool keep_id)