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blk-mq: remove blk_mq_put_ctx()

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No code that occurs between blk_mq_get_ctx() and blk_mq_put_ctx() depends
on preemption being disabled for its correctness. Since removing the CPU
preemption calls does not measurably affect performance, simplify the
blk-mq code by removing the blk_mq_put_ctx() function and also by not
disabling preemption in blk_mq_get_ctx().

Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Bart Van Assche 2019-07-01 08:47:29 -07:00 committed by Jens Axboe
parent 417232880c
commit c05f42206f
5 changed files with 5 additions and 32 deletions
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5
block/blk-mq-sched.c
View File

@ -330,10 +330,8 @@ bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
bool ret = false;
enum hctx_type type;
if (e && e->type->ops.bio_merge) {
blk_mq_put_ctx(ctx);
if (e && e->type->ops.bio_merge)
return e->type->ops.bio_merge(hctx, bio, nr_segs);
}
type = hctx->type;
if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
@ -344,7 +342,6 @@ bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
spin_unlock(&ctx->lock);
}
blk_mq_put_ctx(ctx);
return ret;
}

8
block/blk-mq-tag.c
View File

@ -113,7 +113,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
struct sbq_wait_state *ws;
DEFINE_SBQ_WAIT(wait);
unsigned int tag_offset;
bool drop_ctx;
int tag;
if (data->flags & BLK_MQ_REQ_RESERVED) {
@ -136,7 +135,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
return BLK_MQ_TAG_FAIL;
ws = bt_wait_ptr(bt, data->hctx);
drop_ctx = data->ctx == NULL;
do {
struct sbitmap_queue *bt_prev;
@ -161,9 +159,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
if (tag != -1)
break;
if (data->ctx)
blk_mq_put_ctx(data->ctx);
bt_prev = bt;
io_schedule();
@ -189,9 +184,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
ws = bt_wait_ptr(bt, data->hctx);
} while (1);
if (drop_ctx && data->ctx)
blk_mq_put_ctx(data->ctx);
sbitmap_finish_wait(bt, ws, &wait);
found_tag:

16
block/blk-mq.c
View File

@ -355,13 +355,13 @@ static struct request *blk_mq_get_request(struct request_queue *q,
struct elevator_queue *e = q->elevator;
struct request *rq;
unsigned int tag;
bool put_ctx_on_error = false;
bool clear_ctx_on_error = false;
blk_queue_enter_live(q);
data->q = q;
if (likely(!data->ctx)) {
data->ctx = blk_mq_get_ctx(q);
put_ctx_on_error = true;
clear_ctx_on_error = true;
}
if (likely(!data->hctx))
data->hctx = blk_mq_map_queue(q, data->cmd_flags,
@ -387,10 +387,8 @@ static struct request *blk_mq_get_request(struct request_queue *q,
tag = blk_mq_get_tag(data);
if (tag == BLK_MQ_TAG_FAIL) {
if (put_ctx_on_error) {
blk_mq_put_ctx(data->ctx);
if (clear_ctx_on_error)
data->ctx = NULL;
}
blk_queue_exit(q);
return NULL;
}
@ -427,8 +425,6 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
if (!rq)
return ERR_PTR(-EWOULDBLOCK);
blk_mq_put_ctx(alloc_data.ctx);
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
@ -1977,7 +1973,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
plug = current->plug;
if (unlikely(is_flush_fua)) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio, nr_segs);
/* bypass scheduler for flush rq */
@ -1991,7 +1986,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
unsigned int request_count = plug->rq_count;
struct request *last = NULL;
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio, nr_segs);
if (!request_count)
@ -2025,8 +2019,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
blk_add_rq_to_plug(plug, rq);
trace_block_plug(q);
blk_mq_put_ctx(data.ctx);
if (same_queue_rq) {
data.hctx = same_queue_rq->mq_hctx;
trace_block_unplug(q, 1, true);
@ -2035,11 +2027,9 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
}
} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
!data.hctx->dispatch_busy)) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio, nr_segs);
blk_mq_try_issue_directly(data.hctx, rq, &cookie);
} else {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio, nr_segs);
blk_mq_sched_insert_request(rq, false, true, true);
}

7
block/blk-mq.h
View File

@ -151,12 +151,7 @@ static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
*/
static inline struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
{
return __blk_mq_get_ctx(q, get_cpu());
}
static inline void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
{
put_cpu();
return __blk_mq_get_ctx(q, raw_smp_processor_id());
}
struct blk_mq_alloc_data {

1
block/kyber-iosched.c
View File

@ -575,7 +575,6 @@ static bool kyber_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio,
spin_lock(&kcq->lock);
merged = blk_mq_bio_list_merge(hctx->queue, rq_list, bio, nr_segs);
spin_unlock(&kcq->lock);
blk_mq_put_ctx(ctx);
return merged;
}