block: have ->poll_fn() return number of entries polled

We currently only really support sync poll, ie poll with 1 IO in flight. This prepares us for supporting async poll. Note that the returned value isn't necessarily 100% accurate. If poll races with IRQ completion, we assume that the fact that the task is now runnable means we found at least one entry. In reality it could be more than 1, or not even 1. This is fine, the caller will just need to take this into account.

Jens Axboe committed 8 years ago

Commit 85f4d4b1 parent 849a3703 files · +12 −12Browse files

Unified · Split

3 files

block/blk-mq.c +9 −9
drivers/nvme/host/multipath.c +2 −2
include/linux/blkdev.h +1 −1

block/blk-mq.c+9−9

@@ -38,7 +38,7 @@ · 37 unmodified lines
38	#include "blk-mq-sched.h"	38	#include "blk-mq-sched.h"
39	#include "blk-rq-qos.h"	39	#include "blk-rq-qos.h"
40		40
41	static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie);	41	static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie);
42	static void blk_mq_poll_stats_start(struct request_queue *q);	42	static void blk_mq_poll_stats_start(struct request_queue *q);
43	static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);	43	static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
44		44
@@ -3305,7 +3305,7 @@ static bool blk_mq_poll_hybrid_sleep(struct request_queue *q, · 3260 unmodified lines
3305	return true;	3305	return true;
3306	}	3306	}
3307		3307
3308	static bool __blk_mq_poll(struct blk_mq_hw_ctx hctx, struct request rq)	3308	static int __blk_mq_poll(struct blk_mq_hw_ctx hctx, struct request rq)
3309	{	3309	{
3310	struct request_queue *q = hctx->queue;	3310	struct request_queue *q = hctx->queue;
3311	long state;	3311	long state;
@@ -3318,7 +3318,7 @@ static bool __blk_mq_poll(struct blk_mq_hw_ctx hctx, struct request rq) · 6 unmodified lines
3318	* straight to the busy poll loop.	3318	* straight to the busy poll loop.
3319	*/	3319	*/
3320	if (blk_mq_poll_hybrid_sleep(q, hctx, rq))	3320	if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
3321	return true;	3321	return 1;
3322		3322
3323	hctx->poll_considered++;	3323	hctx->poll_considered++;
3324		3324
@@ -3332,30 +3332,30 @@ static bool __blk_mq_poll(struct blk_mq_hw_ctx hctx, struct request rq) · 7 unmodified lines
3332	if (ret > 0) {	3332	if (ret > 0) {
3333	hctx->poll_success++;	3333	hctx->poll_success++;
3334	__set_current_state(TASK_RUNNING);	3334	__set_current_state(TASK_RUNNING);
3335	return true;	3335	return ret;
3336	}	3336	}
3337		3337
3338	if (signal_pending_state(state, current))	3338	if (signal_pending_state(state, current))
3339	__set_current_state(TASK_RUNNING);	3339	__set_current_state(TASK_RUNNING);
3340		3340
3341	if (current->state == TASK_RUNNING)	3341	if (current->state == TASK_RUNNING)
3342	return true;	3342	return 1;
3343	if (ret < 0)	3343	if (ret < 0)
3344	break;	3344	break;
3345	cpu_relax();	3345	cpu_relax();
3346	}	3346	}
3347		3347
3348	__set_current_state(TASK_RUNNING);	3348	__set_current_state(TASK_RUNNING);
3349	return false;	3349	return 0;
3350	}	3350	}
3351		3351
3352	static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)	3352	static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
3353	{	3353	{
3354	struct blk_mq_hw_ctx *hctx;	3354	struct blk_mq_hw_ctx *hctx;
3355	struct request *rq;	3355	struct request *rq;
3356		3356
3357	if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))	3357	if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3358	return false;	3358	return 0;
3359		3359
3360	hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];	3360	hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3361	if (!blk_qc_t_is_internal(cookie))	3361	if (!blk_qc_t_is_internal(cookie))
@@ -3369,7 +3369,7 @@ static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie) · 7 unmodified lines
3369	* so we should be safe with just the NULL check.	3369	* so we should be safe with just the NULL check.
3370	*/	3370	*/
3371	if (!rq)	3371	if (!rq)
3372	return false;	3372	return 0;
3373	}	3373	}
3374		3374
3375	return __blk_mq_poll(hctx, rq);	3375	return __blk_mq_poll(hctx, rq);

drivers/nvme/host/multipath.c+2−2

@@ -220,11 +220,11 @@ static blk_qc_t nvme_ns_head_make_request(struct request_queue *q, · 219 unmodified lines
220	return ret;	220	return ret;
221	}	221	}
222		222
223	static bool nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc)	223	static int nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc)
224	{	224	{
225	struct nvme_ns_head *head = q->queuedata;	225	struct nvme_ns_head *head = q->queuedata;
226	struct nvme_ns *ns;	226	struct nvme_ns *ns;
227	bool found = false;	227	int found = 0;
228	int srcu_idx;	228	int srcu_idx;
229		229
230	srcu_idx = srcu_read_lock(&head->srcu);	230	srcu_idx = srcu_read_lock(&head->srcu);

include/linux/blkdev.h+1−1

@@ -283,7 +283,7 @@ static inline unsigned short req_get_ioprio(struct request *req) · 282 unmodified lines
283	struct blk_queue_ctx;	283	struct blk_queue_ctx;
284		284
285	typedef blk_qc_t (make_request_fn) (struct request_queue q, struct bio bio);	285	typedef blk_qc_t (make_request_fn) (struct request_queue q, struct bio bio);
286	typedef bool (poll_q_fn) (struct request_queue *q, blk_qc_t);	286	typedef int (poll_q_fn) (struct request_queue *q, blk_qc_t);
287		287
288	struct bio_vec;	288	struct bio_vec;
289	typedef int (dma_drain_needed_fn)(struct request *);	289	typedef int (dma_drain_needed_fn)(struct request *);