Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1bc691d3 authored by Tejun Heo's avatar Tejun Heo Committed by Linus Torvalds
Browse files

[PATCH] fix queue stalling while barrier sequencing 



If ordered tag isn't supported, request ordering for barrier
sequencing is performed by queue draining, which basically hangs the
request queue until elv_completed_request() reports completion of all
previous fs requests.

The condition check in elv_completed_request() was only performed for
fs requests.  If a special request is queued between the last
to-be-drained request and the barrier sequence, draining is never
completed and the queue is stalled forever.

This patch moves the end-of-draining condition check such that it's
performed for all requests.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 593195f9

block/elevator.c

+10 −10
Original line number Original line Diff line number Diff line
@@ -610,23 +610,23 @@ void elv_completed_request(request_queue_t *q, struct request *rq) 
	 * request is released from the driver, io must be done

	 * request is released from the driver, io must be done

	 */

	 */

	if (blk_account_rq(rq)) {

	if (blk_account_rq(rq)) {

		struct request *first_rq = list_entry_rq(q->queue_head.next);



		q->in_flight--;

		q->in_flight--;

		if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)

			e->ops->elevator_completed_req_fn(q, rq);

	}





	/*

	/*

	 * Check if the queue is waiting for fs requests to be

	 * Check if the queue is waiting for fs requests to be

	 * drained for flush sequence.

	 * drained for flush sequence.

	 */

	 */

		if (q->ordseq && q->in_flight == 0 &&

	if (unlikely(q->ordseq)) {

		struct request *first_rq = list_entry_rq(q->queue_head.next);

		if (q->in_flight == 0 &&

		    blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&

		    blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&

		    blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) {

		    blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) {

			blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);

			blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);

			q->request_fn(q);

			q->request_fn(q);

		}

		}



		if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)

			e->ops->elevator_completed_req_fn(q, rq);

	}

	}

}

}