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blk-mq-sched: unify request prepare methods

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This patch makes sure we always allocate requests in the core blk-mq
code and use a common prepare_request method to initialize them for
both mq I/O schedulers.  For Kyber and additional limit_depth method
is added that is called before allocating the request.

Also because none of the intializations can really fail the new method
does not return an error - instead the bfq finish method is hardened
to deal with the no-IOC case.

Last but not least this removes the abuse of RQF_QUEUE by the blk-mq
scheduling code as RQF_ELFPRIV is all that is needed now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2017-06-16 18:15:26 +02:00 committed by Jens Axboe
parent 44e8c2bff8
commit 5bbf4e5a8e
4 changed files with 32 additions and 38 deletions
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19
block/bfq-iosched.c
View File

@ -4292,8 +4292,14 @@ static void bfq_put_rq_priv_body(struct bfq_queue *bfqq)
static void bfq_finish_request(struct request *rq)
{
struct bfq_queue *bfqq = RQ_BFQQ(rq);
struct bfq_data *bfqd = bfqq->bfqd;
struct bfq_queue *bfqq;
struct bfq_data *bfqd;
if (!rq->elv.icq)
return;
bfqq = RQ_BFQQ(rq);
bfqd = bfqq->bfqd;
if (rq->rq_flags & RQF_STARTED)
bfqg_stats_update_completion(bfqq_group(bfqq),
@ -4394,9 +4400,9 @@ static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
/*
* Allocate bfq data structures associated with this request.
*/
static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
struct bio *bio)
static void bfq_prepare_request(struct request *rq, struct bio *bio)
{
struct request_queue *q = rq->q;
struct bfq_data *bfqd = q->elevator->elevator_data;
struct bfq_io_cq *bic;
const int is_sync = rq_is_sync(rq);
@ -4405,7 +4411,7 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
bool split = false;
if (!rq->elv.icq)
return 1;
return;
bic = icq_to_bic(rq->elv.icq);
spin_lock_irq(&bfqd->lock);
@ -4466,7 +4472,6 @@ static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
bfq_handle_burst(bfqd, bfqq);
spin_unlock_irq(&bfqd->lock);
return 0;
}
static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
@ -4945,7 +4950,7 @@ static struct elv_fs_entry bfq_attrs[] = {
static struct elevator_type iosched_bfq_mq = {
.ops.mq = {
.get_rq_priv = bfq_get_rq_private,
.prepare_request = bfq_prepare_request,
.finish_request = bfq_finish_request,
.exit_icq = bfq_exit_icq,
.insert_requests = bfq_insert_requests,

22
block/blk-mq.c
View File

@ -298,16 +298,11 @@ static struct request *blk_mq_get_request(struct request_queue *q,
* Flush requests are special and go directly to the
* dispatch list.
*/
if (!op_is_flush(op) && e->type->ops.mq.get_request) {
rq = e->type->ops.mq.get_request(q, op, data);
if (rq)
rq->rq_flags |= RQF_QUEUED;
goto allocated;
}
if (!op_is_flush(op) && e->type->ops.mq.limit_depth)
e->type->ops.mq.limit_depth(op, data);
}
rq = __blk_mq_alloc_request(data, op);
allocated:
if (!rq) {
blk_queue_exit(q);
return NULL;
@ -315,17 +310,12 @@ allocated:
if (!op_is_flush(op)) {
rq->elv.icq = NULL;
if (e && e->type->ops.mq.get_rq_priv) {
if (e && e->type->ops.mq.prepare_request) {
if (e->type->icq_cache && rq_ioc(bio))
blk_mq_sched_assign_ioc(rq, bio);
if (e->type->ops.mq.get_rq_priv(q, rq, bio)) {
if (rq->elv.icq)
put_io_context(rq->elv.icq->ioc);
rq->elv.icq = NULL;
} else {
rq->rq_flags |= RQF_ELVPRIV;
}
e->type->ops.mq.prepare_request(rq, bio);
rq->rq_flags |= RQF_ELVPRIV;
}
}
data->hctx->queued++;
@ -413,7 +403,7 @@ void blk_mq_free_request(struct request *rq)
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
const int sched_tag = rq->internal_tag;
if (rq->rq_flags & (RQF_ELVPRIV | RQF_QUEUED)) {
if (rq->rq_flags & RQF_ELVPRIV) {
if (e && e->type->ops.mq.finish_request)
e->type->ops.mq.finish_request(rq);
if (rq->elv.icq) {

25
block/kyber-iosched.c
View File

@ -426,24 +426,22 @@ static void rq_clear_domain_token(struct kyber_queue_data *kqd,
}
}
static struct request *kyber_get_request(struct request_queue *q,
unsigned int op,
struct blk_mq_alloc_data *data)
static void kyber_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
{
struct kyber_queue_data *kqd = q->elevator->elevator_data;
struct request *rq;
/*
* We use the scheduler tags as per-hardware queue queueing tokens.
* Async requests can be limited at this stage.
*/
if (!op_is_sync(op))
data->shallow_depth = kqd->async_depth;
if (!op_is_sync(op)) {
struct kyber_queue_data *kqd = data->q->elevator->elevator_data;
rq = __blk_mq_alloc_request(data, op);
if (rq)
rq_set_domain_token(rq, -1);
return rq;
data->shallow_depth = kqd->async_depth;
}
}
static void kyber_prepare_request(struct request *rq, struct bio *bio)
{
rq_set_domain_token(rq, -1);
}
static void kyber_finish_request(struct request *rq)
@ -813,7 +811,8 @@ static struct elevator_type kyber_sched = {
.exit_sched = kyber_exit_sched,
.init_hctx = kyber_init_hctx,
.exit_hctx = kyber_exit_hctx,
.get_request = kyber_get_request,
.limit_depth = kyber_limit_depth,
.prepare_request = kyber_prepare_request,
.finish_request = kyber_finish_request,
.completed_request = kyber_completed_request,
.dispatch_request = kyber_dispatch_request,

4
include/linux/elevator.h
View File

@ -104,7 +104,8 @@ struct elevator_mq_ops {
int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
void (*requests_merged)(struct request_queue *, struct request *, struct request *);
struct request *(*get_request)(struct request_queue *, unsigned int, struct blk_mq_alloc_data *);
void (*limit_depth)(unsigned int, struct blk_mq_alloc_data *);
void (*prepare_request)(struct request *, struct bio *bio);
void (*finish_request)(struct request *);
void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
@ -114,7 +115,6 @@ struct elevator_mq_ops {
void (*requeue_request)(struct request *);
struct request *(*former_request)(struct request_queue *, struct request *);
struct request *(*next_request)(struct request_queue *, struct request *);
int (*get_rq_priv)(struct request_queue *, struct request *, struct bio *);
void (*init_icq)(struct io_cq *);
void (*exit_icq)(struct io_cq *);
};