Staging: hv: Cleanup blkvsc_shutdown()

Use the newly introduced function to wait for draining I/Os to
cleanup blkvsc_shutdown().

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/blkvsc_drv.c

@@ -588,15 +588,13 @@ static void blkvsc_shutdown(struct hv_device *dev)
 
 	spin_unlock_irqrestore(&blkdev->lock, flags);
 
-	while (blkdev->num_outstanding_reqs) {
-		DPRINT_INFO(STORVSC, "waiting for %d requests to complete...",
-			    blkdev->num_outstanding_reqs);
-		udelay(100);
-	}
-
-
 	blkvsc_do_operation(blkdev, DO_FLUSH);
 
+	/*
+	 * Now wait for all outgoing I/O to be drained.
+	 */
+	storvsc_wait_to_drain((struct storvsc_device *)dev->ext);
+
 }
 
 static int blkvsc_release(struct gendisk *disk, fmode_t mode)