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Commit 1f5bd336 authored by Ming Lin's avatar Ming Lin Committed by Jens Axboe
Browse files

blk-mq: add blk_mq_alloc_request_hctx 



For some protocols like NVMe over Fabrics we need to be able to send
initialization commands to a specific queue.

Based on an earlier patch from Christoph Hellwig <hch@lst.de>.

Signed-off-by: default avatarMing Lin <ming.l@ssi.samsung.com>
[hch: disallow sleeping allocation, req_op fixes]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarKeith Busch <keith.busch@intel.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 9e2d23f1

block/blk-mq.c

+39 −0
Original line number Diff line number Diff line
@@ -267,6 +267,45 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, 
}

EXPORT_SYMBOL(blk_mq_alloc_request);



struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,

		unsigned int flags, unsigned int hctx_idx)

{

	struct blk_mq_hw_ctx *hctx;

	struct blk_mq_ctx *ctx;

	struct request *rq;

	struct blk_mq_alloc_data alloc_data;

	int ret;



	/*

	 * If the tag allocator sleeps we could get an allocation for a

	 * different hardware context.  No need to complicate the low level

	 * allocator for this for the rare use case of a command tied to

	 * a specific queue.

	 */

	if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))

		return ERR_PTR(-EINVAL);



	if (hctx_idx >= q->nr_hw_queues)

		return ERR_PTR(-EIO);



	ret = blk_queue_enter(q, true);

	if (ret)

		return ERR_PTR(ret);



	hctx = q->queue_hw_ctx[hctx_idx];

	ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));



	blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);

	rq = __blk_mq_alloc_request(&alloc_data, rw, 0);

	if (!rq) {

		blk_queue_exit(q);

		return ERR_PTR(-EWOULDBLOCK);

	}



	return rq;

}

EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);



static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,

				  struct blk_mq_ctx *ctx, struct request *rq)

{

include/linux/blk-mq.h

+2 −0
Original line number Diff line number Diff line
@@ -196,6 +196,8 @@ enum { 


struct request *blk_mq_alloc_request(struct request_queue *q, int rw,

		unsigned int flags);

struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int op,

		unsigned int flags, unsigned int hctx_idx);

struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag);

struct cpumask *blk_mq_tags_cpumask(struct blk_mq_tags *tags);