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Commit 9d74e257 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

blk-mq: do not initialize req->special 



Drivers can reach their private data easily using the blk_mq_rq_to_pdu
helper and don't need req->special.  By not initializing it code can
be simplified nicely, and we also shave off a few more instructions from
the I/O path.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 742ee69b

block/blk-flush.c

+2 −8
Original line number Diff line number Diff line
@@ -306,22 +306,16 @@ static bool blk_kick_flush(struct request_queue *q) 
	 */

	q->flush_pending_idx ^= 1;



	blk_rq_init(q, q->flush_rq);

	if (q->mq_ops) {

		struct blk_mq_ctx *ctx = first_rq->mq_ctx;

		struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);



		blk_mq_rq_init(hctx, q->flush_rq);

		q->flush_rq->mq_ctx = ctx;



		/*

		 * Reuse the tag value from the fist waiting request,

		 * with blk-mq the tag is generated during request

		 * allocation and drivers can rely on it being inside

		 * the range they asked for.

		 */

		q->flush_rq->mq_ctx = first_rq->mq_ctx;

		q->flush_rq->tag = first_rq->tag;

	} else {

		blk_rq_init(q, q->flush_rq);

	}



	q->flush_rq->cmd_type = REQ_TYPE_FS;

block/blk-mq.c

+2 −13
Original line number Diff line number Diff line
@@ -251,24 +251,13 @@ struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw, 
}

EXPORT_SYMBOL(blk_mq_alloc_reserved_request);



/*

 * Re-init and set pdu, if we have it

 */

void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)

{

	blk_rq_init(hctx->queue, rq);



	if (hctx->cmd_size)

		rq->special = blk_mq_rq_to_pdu(rq);

}



static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,

				  struct blk_mq_ctx *ctx, struct request *rq)

{

	const int tag = rq->tag;

	struct request_queue *q = rq->q;



	blk_mq_rq_init(hctx, rq);

	blk_rq_init(hctx->queue, rq);

	blk_mq_put_tag(hctx->tags, tag);



	blk_mq_queue_exit(q);
@@ -1165,7 +1154,7 @@ static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx, 
		left -= to_do * rq_size;

		for (j = 0; j < to_do; j++) {

			hctx->rqs[i] = p;

			blk_mq_rq_init(hctx, hctx->rqs[i]);

			blk_rq_init(hctx->queue, hctx->rqs[i]);

			p += rq_size;

			i++;

		}

block/blk-mq.h

+0 −1
Original line number Diff line number Diff line
@@ -27,7 +27,6 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async); 
void blk_mq_init_flush(struct request_queue *q);

void blk_mq_drain_queue(struct request_queue *q);

void blk_mq_free_queue(struct request_queue *q);

void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq);



/*

 * CPU hotplug helpers

drivers/block/null_blk.c

+2 −2
Original line number Diff line number Diff line
@@ -226,7 +226,7 @@ static void null_cmd_end_timer(struct nullb_cmd *cmd) 


static void null_softirq_done_fn(struct request *rq)

{

	end_cmd(rq->special);

	end_cmd(blk_mq_rq_to_pdu(rq));

}



static inline void null_handle_cmd(struct nullb_cmd *cmd)
@@ -311,7 +311,7 @@ static void null_request_fn(struct request_queue *q) 


static int null_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *rq)

{

	struct nullb_cmd *cmd = rq->special;

	struct nullb_cmd *cmd = blk_mq_rq_to_pdu(rq);



	cmd->rq = rq;

	cmd->nq = hctx->driver_data;

drivers/block/virtio_blk.c

+3 −3
Original line number Diff line number Diff line
@@ -112,7 +112,7 @@ static int __virtblk_add_req(struct virtqueue *vq, 


static inline void virtblk_request_done(struct request *req)

{

	struct virtblk_req *vbr = req->special;

	struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);

	int error = virtblk_result(vbr);



	if (req->cmd_type == REQ_TYPE_BLOCK_PC) {
@@ -154,7 +154,7 @@ static void virtblk_done(struct virtqueue *vq) 
static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)

{

	struct virtio_blk *vblk = hctx->queue->queuedata;

	struct virtblk_req *vbr = req->special;

	struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);

	unsigned long flags;

	unsigned int num;

	const bool last = (req->cmd_flags & REQ_END) != 0;
@@ -501,7 +501,7 @@ static int virtblk_init_vbr(void *data, struct blk_mq_hw_ctx *hctx, 
			     struct request *rq, unsigned int nr)

{

	struct virtio_blk *vblk = data;

	struct virtblk_req *vbr = rq->special;

	struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);



	sg_init_table(vbr->sg, vblk->sg_elems);

	return 0;