Commit b90cfaed authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

blk-mq: cleanup and rename __blk_mq_alloc_request 



The newly added loop for the cached requests in __blk_mq_alloc_request
is a little too convoluted for my taste, so unwind it a bit.  Also
rename the function to __blk_mq_alloc_requests now that it can allocate
more than a single request.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012104045.658051-2-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 47c122e3

block/blk-mq.c

+28 −28
Original line number Diff line number Diff line
@@ -354,7 +354,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, 
	return rq;

}



static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data)

static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)

{

	struct request_queue *q = data->q;

	struct elevator_queue *e = q->elevator;
@@ -395,38 +395,38 @@ static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data) 
	 */

	do {

		tag = blk_mq_get_tag(data);

		if (tag != BLK_MQ_NO_TAG) {

			rq = blk_mq_rq_ctx_init(data, tag, alloc_time_ns);

			if (!--data->nr_tags)

				return rq;

			if (e || data->hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)

				return rq;

			rq->rq_next = *data->cached_rq;

			*data->cached_rq = rq;

			data->flags |= BLK_MQ_REQ_NOWAIT;

			continue;

		}

		if (tag == BLK_MQ_NO_TAG) {

			if (data->flags & BLK_MQ_REQ_NOWAIT)

				break;



			/*

		 * Give up the CPU and sleep for a random short time to ensure

		 * that thread using a realtime scheduling class are migrated

		 * off the CPU, and thus off the hctx that is going away.

			 * Give up the CPU and sleep for a random short time to

			 * ensure that thread using a realtime scheduling class

			 * are migrated off the CPU, and thus off the hctx that

			 * is going away.

			 */

			msleep(3);

			goto retry;

		}



		rq = blk_mq_rq_ctx_init(data, tag, alloc_time_ns);

		if (!--data->nr_tags || e ||

		    (data->hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))

			return rq;



		/* link into the cached list */

		rq->rq_next = *data->cached_rq;

		*data->cached_rq = rq;

		data->flags |= BLK_MQ_REQ_NOWAIT;

	} while (1);



	if (data->cached_rq) {

	if (!data->cached_rq)

		return NULL;



	rq = *data->cached_rq;

	*data->cached_rq = rq->rq_next;

	return rq;

}



	return NULL;

}



struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,

		blk_mq_req_flags_t flags)

{
@@ -443,7 +443,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, 
	if (ret)

		return ERR_PTR(ret);



	rq = __blk_mq_alloc_request(&data);

	rq = __blk_mq_alloc_requests(&data);

	if (!rq)

		goto out_queue_exit;

	rq->__data_len = 0;
@@ -2258,7 +2258,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio) 
			plug->nr_ios = 1;

			data.cached_rq = &plug->cached_rq;

		}

		rq = __blk_mq_alloc_request(&data);

		rq = __blk_mq_alloc_requests(&data);

		if (unlikely(!rq)) {

			rq_qos_cleanup(q, bio);

			if (bio->bi_opf & REQ_NOWAIT)