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

Commit 49f5baa5 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

blk-mq: pair blk_mq_start_request / blk_mq_requeue_request 



Make sure we have a proper pairing between starting and requeueing
requests.  Move the dma drain and REQ_END setup into blk_mq_start_request,
and make sure blk_mq_requeue_request properly undoes them, giving us
a pair of function to prepare and unprepare a request without leaving
side effects.

Together this ensures we always clean up properly after
BLK_MQ_RQ_QUEUE_BUSY returns from ->queue_rq.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 1e93b8c2

block/blk-mq.c

+26 −23
Original line number Diff line number Diff line
@@ -377,7 +377,7 @@ void blk_mq_complete_request(struct request *rq) 
}

EXPORT_SYMBOL(blk_mq_complete_request);



static void blk_mq_start_request(struct request *rq)

static void blk_mq_start_request(struct request *rq, bool last)

{

	struct request_queue *q = rq->q;
@@ -390,6 +390,25 @@ static void blk_mq_start_request(struct request *rq) 
	 */

	rq->deadline = jiffies + q->rq_timeout;

	set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);



	if (q->dma_drain_size && blk_rq_bytes(rq)) {

		/*

		 * Make sure space for the drain appears.  We know we can do

		 * this because max_hw_segments has been adjusted to be one

		 * fewer than the device can handle.

		 */

		rq->nr_phys_segments++;

	}



	/*

	 * Flag the last request in the series so that drivers know when IO

	 * should be kicked off, if they don't do it on a per-request basis.

	 *

	 * Note: the flag isn't the only condition drivers should do kick off.

	 * If drive is busy, the last request might not have the bit set.

	 */

	if (last)

		rq->cmd_flags |= REQ_END;

}



static void blk_mq_requeue_request(struct request *rq)
@@ -398,6 +417,11 @@ static void blk_mq_requeue_request(struct request *rq) 


	trace_block_rq_requeue(q, rq);

	clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);



	rq->cmd_flags &= ~REQ_END;



	if (q->dma_drain_size && blk_rq_bytes(rq))

		rq->nr_phys_segments--;

}



struct blk_mq_timeout_data {
@@ -565,29 +589,8 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) 


		rq = list_first_entry(&rq_list, struct request, queuelist);

		list_del_init(&rq->queuelist);

		blk_mq_start_request(rq);



		if (q->dma_drain_size && blk_rq_bytes(rq)) {

			/*

			 * make sure space for the drain appears we

			 * know we can do this because max_hw_segments

			 * has been adjusted to be one fewer than the

			 * device can handle

			 */

			rq->nr_phys_segments++;

		}



		/*

		 * Last request in the series. Flag it as such, this

		 * enables drivers to know when IO should be kicked off,

		 * if they don't do it on a per-request basis.

		 *

		 * Note: the flag isn't the only condition drivers

		 * should do kick off. If drive is busy, the last

		 * request might not have the bit set.

		 */

		if (list_empty(&rq_list))

			rq->cmd_flags |= REQ_END;

		blk_mq_start_request(rq, list_empty(&rq_list));



		ret = q->mq_ops->queue_rq(hctx, rq);

		switch (ret) {