Commit 75383524 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

blk-mq: move getting driver tag and budget into one helper 



Move code for getting driver tag and budget into one helper, so
blk_mq_dispatch_rq_list gets a bit simplified, and easier to read.

Meantime move updating of 'no_tag' and 'no_budget_available' into
the branch for handling partial dispatch because that is exactly
consumer of the two local variables.

Also rename the parameter of 'got_budget' as 'ask_budget'.

No functional change.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Tested-by: default avatarBaolin Wang <baolin.wang7@gmail.com>
Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
Reviewed-by: default avatarChristoph Hellwig <hch@infradead.org>
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 445874e8

block/blk-mq.c

+40 −26
Original line number Diff line number Diff line
@@ -1255,18 +1255,50 @@ static void blk_mq_handle_zone_resource(struct request *rq, 
	__blk_mq_requeue_request(rq);

}



enum prep_dispatch {

	PREP_DISPATCH_OK,

	PREP_DISPATCH_NO_TAG,

	PREP_DISPATCH_NO_BUDGET,

};



static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,

						  bool need_budget)

{

	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;



	if (need_budget && !blk_mq_get_dispatch_budget(rq->q)) {

		blk_mq_put_driver_tag(rq);

		return PREP_DISPATCH_NO_BUDGET;

	}



	if (!blk_mq_get_driver_tag(rq)) {

		/*

		 * The initial allocation attempt failed, so we need to

		 * rerun the hardware queue when a tag is freed. The

		 * waitqueue takes care of that. If the queue is run

		 * before we add this entry back on the dispatch list,

		 * we'll re-run it below.

		 */

		if (!blk_mq_mark_tag_wait(hctx, rq)) {

			blk_mq_put_dispatch_budget(rq->q);

			return PREP_DISPATCH_NO_TAG;

		}

	}



	return PREP_DISPATCH_OK;

}



/*

 * Returns true if we did some work AND can potentially do more.

 */

bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,

			     bool got_budget)

{

	enum prep_dispatch prep;

	struct request_queue *q = hctx->queue;

	struct request *rq, *nxt;

	bool no_tag = false;

	int errors, queued;

	blk_status_t ret = BLK_STS_OK;

	bool no_budget_avail = false;

	LIST_HEAD(zone_list);



	if (list_empty(list))
@@ -1284,31 +1316,9 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, 
		rq = list_first_entry(list, struct request, queuelist);



		WARN_ON_ONCE(hctx != rq->mq_hctx);

		if (!got_budget && !blk_mq_get_dispatch_budget(q)) {

			blk_mq_put_driver_tag(rq);

			no_budget_avail = true;

			break;

		}



		if (!blk_mq_get_driver_tag(rq)) {

			/*

			 * The initial allocation attempt failed, so we need to

			 * rerun the hardware queue when a tag is freed. The

			 * waitqueue takes care of that. If the queue is run

			 * before we add this entry back on the dispatch list,

			 * we'll re-run it below.

			 */

			if (!blk_mq_mark_tag_wait(hctx, rq)) {

				blk_mq_put_dispatch_budget(q);

				/*

				 * For non-shared tags, the RESTART check

				 * will suffice.

				 */

				if (hctx->flags & BLK_MQ_F_TAG_SHARED)

					no_tag = true;

		prep = blk_mq_prep_dispatch_rq(rq, !got_budget);

		if (prep != PREP_DISPATCH_OK)

			break;

			}

		}



		list_del_init(&rq->queuelist);
@@ -1361,6 +1371,10 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, 
	 */

	if (!list_empty(list)) {

		bool needs_restart;

		/* For non-shared tags, the RESTART check will suffice */

		bool no_tag = prep == PREP_DISPATCH_NO_TAG &&

                        (hctx->flags & BLK_MQ_F_TAG_SHARED);

		bool no_budget_avail = prep == PREP_DISPATCH_NO_BUDGET;



		/*

		 * If we didn't flush the entire list, we could have told