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Commit e4f36b24 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: fix peeking requests during PM 



We need to look for an active PM request until the next softbarrier
instead of looking for the first non-PM request.  Otherwise any cause
of request reordering might starve the PM request(s).

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 21e768b4

block/blk-core.c

+18 −17
Original line number Diff line number Diff line
@@ -2511,20 +2511,22 @@ void blk_account_io_done(struct request *req) 
 * Don't process normal requests when queue is suspended

 * or in the process of suspending/resuming

 */

static struct request *blk_pm_peek_request(struct request_queue *q,

					   struct request *rq)

static bool blk_pm_allow_request(struct request *rq)

{

	if (q->dev && (q->rpm_status == RPM_SUSPENDED ||

	    (q->rpm_status != RPM_ACTIVE && !(rq->rq_flags & RQF_PM))))

		return NULL;

	else

		return rq;

	switch (rq->q->rpm_status) {

	case RPM_RESUMING:

	case RPM_SUSPENDING:

		return rq->rq_flags & RQF_PM;

	case RPM_SUSPENDED:

		return false;

	}



	return true;

}

#else

static inline struct request *blk_pm_peek_request(struct request_queue *q,

						  struct request *rq)

static bool blk_pm_allow_request(struct request *rq)

{

	return rq;

	return true;

}

#endif
@@ -2572,9 +2574,12 @@ static struct request *elv_next_request(struct request_queue *q) 
	WARN_ON_ONCE(q->mq_ops);



	while (1) {

		if (!list_empty(&q->queue_head)) {

			rq = list_entry_rq(q->queue_head.next);

		list_for_each_entry(rq, &q->queue_head, queuelist) {

			if (blk_pm_allow_request(rq))

				return rq;



			if (rq->rq_flags & RQF_SOFTBARRIER)

				break;

		}



		/*
@@ -2625,10 +2630,6 @@ struct request *blk_peek_request(struct request_queue *q) 
	WARN_ON_ONCE(q->mq_ops);



	while ((rq = elv_next_request(q)) != NULL) {

		rq = blk_pm_peek_request(q, rq);

		if (!rq)

			break;



		if (!(rq->rq_flags & RQF_STARTED)) {

			/*

			 * This is the first time the device driver