Commit 88022d72 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

blk-mq: don't handle failure in .get_budget 



It is enough to just check if we can get the budget via .get_budget().
And we don't need to deal with device state change in .get_budget().

For SCSI, one issue to be fixed is that we have to call
scsi_mq_uninit_cmd() to free allocated ressources if SCSI device fails
to handle the request. And it isn't enough to simply call
blk_mq_end_request() to do that if this request is marked as
RQF_DONTPREP.

Fixes: 0df21c86(scsi: implement .get_budget and .put_budget for blk-mq)
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 826a70a0

block/blk-mq-sched.c

+2 −12
Original line number Diff line number Diff line
@@ -94,23 +94,18 @@ static void blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx) 


	do {

		struct request *rq;

		blk_status_t ret;



		if (e->type->ops.mq.has_work &&

				!e->type->ops.mq.has_work(hctx))

			break;



		ret = blk_mq_get_dispatch_budget(hctx);

		if (ret == BLK_STS_RESOURCE)

		if (!blk_mq_get_dispatch_budget(hctx))

			break;



		rq = e->type->ops.mq.dispatch_request(hctx);

		if (!rq) {

			blk_mq_put_dispatch_budget(hctx);

			break;

		} else if (ret != BLK_STS_OK) {

			blk_mq_end_request(rq, ret);

			continue;

		}



		/*
@@ -146,22 +141,17 @@ static void blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx) 


	do {

		struct request *rq;

		blk_status_t ret;



		if (!sbitmap_any_bit_set(&hctx->ctx_map))

			break;



		ret = blk_mq_get_dispatch_budget(hctx);

		if (ret == BLK_STS_RESOURCE)

		if (!blk_mq_get_dispatch_budget(hctx))

			break;



		rq = blk_mq_dequeue_from_ctx(hctx, ctx);

		if (!rq) {

			blk_mq_put_dispatch_budget(hctx);

			break;

		} else if (ret != BLK_STS_OK) {

			blk_mq_end_request(rq, ret);

			continue;

		}



		/*

block/blk-mq.c

+4 −13
Original line number Diff line number Diff line
@@ -1137,13 +1137,8 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list, 
			}

		}



		if (!got_budget) {

			ret = blk_mq_get_dispatch_budget(hctx);

			if (ret == BLK_STS_RESOURCE)

		if (!got_budget && !blk_mq_get_dispatch_budget(hctx))

			break;

			if (ret != BLK_STS_OK)

				goto fail_rq;

		}



		list_del_init(&rq->queuelist);
@@ -1170,7 +1165,6 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list, 
			break;

		}



 fail_rq:

		if (unlikely(ret != BLK_STS_OK)) {

			errors++;

			blk_mq_end_request(rq, BLK_STS_IOERR);
@@ -1642,12 +1636,10 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, 
	if (!blk_mq_get_driver_tag(rq, NULL, false))

		goto insert;



	ret = blk_mq_get_dispatch_budget(hctx);

	if (ret == BLK_STS_RESOURCE) {

	if (!blk_mq_get_dispatch_budget(hctx)) {

		blk_mq_put_driver_tag(rq);

		goto insert;

	} else if (ret != BLK_STS_OK)

		goto fail_rq;

	}



	new_cookie = request_to_qc_t(hctx, rq);
@@ -1665,7 +1657,6 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, 
		__blk_mq_requeue_request(rq);

		goto insert;

	default:

 fail_rq:

		*cookie = BLK_QC_T_NONE;

		blk_mq_end_request(rq, ret);

		return;

block/blk-mq.h

+2 −3
Original line number Diff line number Diff line
@@ -147,14 +147,13 @@ static inline void blk_mq_put_dispatch_budget(struct blk_mq_hw_ctx *hctx) 
		q->mq_ops->put_budget(hctx);

}



static inline blk_status_t blk_mq_get_dispatch_budget(

		struct blk_mq_hw_ctx *hctx)

static inline bool blk_mq_get_dispatch_budget(struct blk_mq_hw_ctx *hctx)

{

	struct request_queue *q = hctx->queue;



	if (q->mq_ops->get_budget)

		return q->mq_ops->get_budget(hctx);

	return BLK_STS_OK;

	return true;

}



#endif

drivers/scsi/scsi_lib.c

+3 −8
Original line number Diff line number Diff line
@@ -1955,27 +1955,22 @@ static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx) 
	put_device(&sdev->sdev_gendev);

}



static blk_status_t scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx)

static bool scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx)

{

	struct request_queue *q = hctx->queue;

	struct scsi_device *sdev = q->queuedata;

	blk_status_t ret;



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

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

		return ret;



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

		goto out;

	if (!scsi_dev_queue_ready(q, sdev))

		goto out_put_device;



	return BLK_STS_OK;

	return true;



out_put_device:

	put_device(&sdev->sdev_gendev);

out:

	return BLK_STS_RESOURCE;

	return false;

}



static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,

include/linux/blk-mq.h

+1 −1
Original line number Diff line number Diff line
@@ -92,7 +92,7 @@ struct blk_mq_queue_data { 


typedef blk_status_t (queue_rq_fn)(struct blk_mq_hw_ctx *,

		const struct blk_mq_queue_data *);

typedef blk_status_t (get_budget_fn)(struct blk_mq_hw_ctx *);

typedef bool (get_budget_fn)(struct blk_mq_hw_ctx *);

typedef void (put_budget_fn)(struct blk_mq_hw_ctx *);

typedef enum blk_eh_timer_return (timeout_fn)(struct request *, bool);

typedef int (init_hctx_fn)(struct blk_mq_hw_ctx *, void *, unsigned int);

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