On Mon, Mar 13, 2017 at 09:01:08PM +0000, Bart Van Assche wrote:

quoted

+		/*
+		 * @request_count may become stale because of schedule
+		 * out, so check the list again.
+		 */

The above comment was relevant as long as there was a request_count assignment
above blk_mq_sched_get_request(). This patch moves that assignment inside if
(plug && q->nr_hw_queues == 1). Does that mean that the above comment should be
removed entirely?

I don't think so - for the !blk_queue_nomerges cases we still rely
on blk_attempt_plug_merge calculatіng request_count, so the comment
still applies.