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Commit 0df21c86 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

scsi: implement .get_budget and .put_budget for blk-mq 



We need to tell blk-mq to reserve resources before queuing one request,
so implement these two callbacks. Then blk-mq can avoid to dequeue
request too early, and IO merging can be improved a lot.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent aeec7762

drivers/scsi/scsi_lib.c

+52 −23
Original line number Diff line number Diff line
@@ -1946,25 +1946,32 @@ static void scsi_mq_done(struct scsi_cmnd *cmd) 
	blk_mq_complete_request(cmd->request);

}



static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,

			 const struct blk_mq_queue_data *bd)

static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx)

{

	struct request *req = bd->rq;

	struct request_queue *q = req->q;

	struct request_queue *q = hctx->queue;

	struct scsi_device *sdev = q->queuedata;

	struct Scsi_Host *shost = sdev->host;



	atomic_dec(&shost->host_busy);

	if (scsi_target(sdev)->can_queue > 0)

		atomic_dec(&scsi_target(sdev)->target_busy);

	atomic_dec(&sdev->device_busy);

	put_device(&sdev->sdev_gendev);

}



static blk_status_t scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx)

{

	struct request_queue *q = hctx->queue;

	struct scsi_device *sdev = q->queuedata;

	struct Scsi_Host *shost = sdev->host;

	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);

	blk_status_t ret;

	int reason;



	ret = prep_to_mq(scsi_prep_state_check(sdev, req));

	if (ret != BLK_STS_OK)

		goto out;

	ret = prep_to_mq(scsi_prep_state_check(sdev, NULL));

	if (ret == BLK_STS_RESOURCE || ret != BLK_STS_OK)

		return ret;



	ret = BLK_STS_RESOURCE;

	if (!get_device(&sdev->sdev_gendev))

		goto out;



	if (!scsi_dev_queue_ready(q, sdev))

		goto out_put_device;

	if (!scsi_target_queue_ready(shost, sdev))
@@ -1972,10 +1979,38 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, 
	if (!scsi_host_queue_ready(q, shost, sdev))

		goto out_dec_target_busy;



	return BLK_STS_OK;



out_dec_target_busy:

	if (scsi_target(sdev)->can_queue > 0)

		atomic_dec(&scsi_target(sdev)->target_busy);

out_dec_device_busy:

	atomic_dec(&sdev->device_busy);

out_put_device:

	put_device(&sdev->sdev_gendev);

out:

	return BLK_STS_RESOURCE;

}



static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,

			 const struct blk_mq_queue_data *bd)

{

	struct request *req = bd->rq;

	struct request_queue *q = req->q;

	struct scsi_device *sdev = q->queuedata;

	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);

	blk_status_t ret;

	int reason;



	ret = prep_to_mq(scsi_prep_state_check(sdev, req));

	if (ret != BLK_STS_OK)

		goto out_put_budget;



	ret = BLK_STS_RESOURCE;

	if (!(req->rq_flags & RQF_DONTPREP)) {

		ret = prep_to_mq(scsi_mq_prep_fn(req));

		if (ret != BLK_STS_OK)

			goto out_dec_host_busy;

			goto out_put_budget;

		req->rq_flags |= RQF_DONTPREP;

	} else {

		blk_mq_start_request(req);
@@ -1993,21 +2028,13 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, 
	if (reason) {

		scsi_set_blocked(cmd, reason);

		ret = BLK_STS_RESOURCE;

		goto out_dec_host_busy;

		goto out_put_budget;

	}



	return BLK_STS_OK;



out_dec_host_busy:

	atomic_dec(&shost->host_busy);

out_dec_target_busy:

	if (scsi_target(sdev)->can_queue > 0)

		atomic_dec(&scsi_target(sdev)->target_busy);

out_dec_device_busy:

	atomic_dec(&sdev->device_busy);

out_put_device:

	put_device(&sdev->sdev_gendev);

out:

out_put_budget:

	scsi_mq_put_budget(hctx);

	switch (ret) {

	case BLK_STS_OK:

		break;
@@ -2211,6 +2238,8 @@ struct request_queue *scsi_old_alloc_queue(struct scsi_device *sdev) 
}



static const struct blk_mq_ops scsi_mq_ops = {

	.get_budget	= scsi_mq_get_budget,

	.put_budget	= scsi_mq_put_budget,

	.queue_rq	= scsi_queue_rq,

	.complete	= scsi_softirq_done,

	.timeout	= scsi_timeout,