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

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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: 0df21c86bdbf(scsi: implement .get_budget and .put_budget for blk-mq)
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2017-11-05 02:21:12 +08:00 committed by Jens Axboe
parent 826a70a08b
commit 88022d7201
5 changed files with 12 additions and 37 deletions
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14
block/blk-mq-sched.c
View File

@ -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;
}
/*

17
block/blk-mq.c
View File

@ -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)
break;
if (ret != BLK_STS_OK)
goto fail_rq;
}
if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
break;
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;

5
block/blk-mq.h
View File

@ -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

11
drivers/scsi/scsi_lib.c
View File

@ -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,

2
include/linux/blk-mq.h
View File

@ -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);