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blk-mq: remove blk_mq_wait_for_tags 

The current logic for blocking tag allocation is rather confusing, as we
first allocated and then free again a tag in blk_mq_wait_for_tags, just
to attempt a non-blocking allocation and then repeat if someone else
managed to grab the tag before us.

Instead change blk_mq_alloc_request_pinned to simply do a blocking tag
allocation itself and use the request we get back from it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
hifive-unleashed-5.1
Christoph Hellwig 2014-05-27 20:59:48 +02:00 committed by Jens Axboe
parent 5dee857720
commit a3bd77567c
3 changed files with 6 additions and 16 deletions
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8
block/blk-mq-tag.c
View File

@ -7,14 +7,6 @@
#include "blk-mq.h"
#include "blk-mq-tag.h"
void blk_mq_wait_for_tags(struct blk_mq_hw_ctx *hctx, bool reserved)
{
int tag, zero = 0;
tag = blk_mq_get_tag(hctx, &zero, __GFP_WAIT, reserved);
blk_mq_put_tag(hctx, tag, &zero);
}
static bool bt_has_free_tags(struct blk_mq_bitmap_tags *bt)
{
int i;

1
block/blk-mq-tag.h
View File

@ -49,7 +49,6 @@ extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int r
extern void blk_mq_free_tags(struct blk_mq_tags *tags);
extern unsigned int blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, unsigned int *last_tag, gfp_t gfp, bool reserved);
extern void blk_mq_wait_for_tags(struct blk_mq_hw_ctx *hctx, bool reserved);
extern void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag, unsigned int *last_tag);
extern bool blk_mq_has_free_tags(struct blk_mq_tags *tags);
extern ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page);

13
block/blk-mq.c
View File

@ -264,31 +264,30 @@ __blk_mq_alloc_request(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
return NULL;
}
static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
int rw, gfp_t gfp,
bool reserved)
{
bool gfp_mask = gfp & ~__GFP_WAIT;
struct request *rq;
do {
struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
rq = __blk_mq_alloc_request(q, hctx, ctx, rw, gfp & ~__GFP_WAIT,
rq = __blk_mq_alloc_request(q, hctx, ctx, rw, gfp_mask,
reserved);
if (rq)
break;
if (gfp & __GFP_WAIT) {
__blk_mq_run_hw_queue(hctx);
blk_mq_put_ctx(ctx);
} else {
if (!(gfp & __GFP_WAIT)) {
blk_mq_put_ctx(ctx);
break;
}
blk_mq_wait_for_tags(hctx, reserved);
__blk_mq_run_hw_queue(hctx);
blk_mq_put_ctx(ctx);
gfp_mask = gfp;
} while (1);
return rq;