On Thu, Sep 21, 2017 at 10:43:26PM +0000, Bart Van Assche wrote:

On Fri, 2017-09-22 at 06:06 +0800, Ming Lei wrote:

quoted

On Thu, Sep 21, 2017 at 02:22:55PM -0700, Bart Van Assche wrote:

quoted

+	} else {
 		scsi_run_queue(q);
+		while (atomic_read(&sdev->device_busy)) {
+			msleep_interruptible(200);
+			scsi_run_queue(q);
+		}

Are you sure only blk-mq need to drain queue? We need
to do that for block legacy too.

The code above your comment drains the queue for the legacy block layer.

That is just draining the requests dispatched to SCSI layer, and there
might be lots of requests in block I/O scheduler queue or requeue or
whatever.

-- 
Ming