Commit 2751b900 authored by Yu Kuai's avatar Yu Kuai Committed by Jens Axboe
Browse files

blk-wbt: factor out a helper wbt_set_lat() 



To move implementation details inside blk-wbt.c, prepare to fix possible
deadlock to call wbt_init() while queue is frozen in the next patch.

Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarNilay Shroff <nilay@linux.ibm.com>
Signed-off-by: default avatarYu Kuai <yukuai@fnnas.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 06564bae

block/blk-sysfs.c

+2 −37
Original line number Diff line number Diff line
@@ -636,11 +636,8 @@ static ssize_t queue_wb_lat_show(struct gendisk *disk, char *page) 
static ssize_t queue_wb_lat_store(struct gendisk *disk, const char *page,

				  size_t count)

{

	struct request_queue *q = disk->queue;

	struct rq_qos *rqos;

	ssize_t ret;

	s64 val;

	unsigned int memflags;



	ret = queue_var_store64(&val, page);

	if (ret < 0)
@@ -648,40 +645,8 @@ static ssize_t queue_wb_lat_store(struct gendisk *disk, const char *page, 
	if (val < -1)

		return -EINVAL;



	/*

	 * Ensure that the queue is idled, in case the latency update

	 * ends up either enabling or disabling wbt completely. We can't

	 * have IO inflight if that happens.

	 */

	memflags = blk_mq_freeze_queue(q);



	rqos = wbt_rq_qos(q);

	if (!rqos) {

		ret = wbt_init(disk);

		if (ret)

			goto out;

	}



	ret = count;

	if (val == -1)

		val = wbt_default_latency_nsec(q);

	else if (val >= 0)

		val *= 1000ULL;



	if (wbt_get_min_lat(q) == val)

		goto out;



	blk_mq_quiesce_queue(q);



	mutex_lock(&disk->rqos_state_mutex);

	wbt_set_min_lat(q, val);

	mutex_unlock(&disk->rqos_state_mutex);



	blk_mq_unquiesce_queue(q);

out:

	blk_mq_unfreeze_queue(q, memflags);



	return ret;

	ret = wbt_set_lat(disk, val);

	return ret ? ret : count;

}



QUEUE_RW_ENTRY(queue_wb_lat, "wbt_lat_usec");

block/blk-wbt.c

+47 −3
Original line number Diff line number Diff line
@@ -93,6 +93,8 @@ struct rq_wb { 
	struct rq_depth rq_depth;

};



static int wbt_init(struct gendisk *disk);



static inline struct rq_wb *RQWB(struct rq_qos *rqos)

{

	return container_of(rqos, struct rq_wb, rqos);
@@ -506,7 +508,7 @@ u64 wbt_get_min_lat(struct request_queue *q) 
	return RQWB(rqos)->min_lat_nsec;

}



void wbt_set_min_lat(struct request_queue *q, u64 val)

static void wbt_set_min_lat(struct request_queue *q, u64 val)

{

	struct rq_qos *rqos = wbt_rq_qos(q);

	if (!rqos)
@@ -741,7 +743,7 @@ void wbt_init_enable_default(struct gendisk *disk) 
		WARN_ON_ONCE(wbt_init(disk));

}



u64 wbt_default_latency_nsec(struct request_queue *q)

static u64 wbt_default_latency_nsec(struct request_queue *q)

{

	/*

	 * We default to 2msec for non-rotational storage, and 75msec
@@ -901,7 +903,7 @@ static const struct rq_qos_ops wbt_rqos_ops = { 
#endif

};



int wbt_init(struct gendisk *disk)

static int wbt_init(struct gendisk *disk)

{

	struct request_queue *q = disk->queue;

	struct rq_wb *rwb;
@@ -948,3 +950,45 @@ int wbt_init(struct gendisk *disk) 
	return ret;



}



int wbt_set_lat(struct gendisk *disk, s64 val)

{

	struct request_queue *q = disk->queue;

	unsigned int memflags;

	struct rq_qos *rqos;

	int ret = 0;



	/*

	 * Ensure that the queue is idled, in case the latency update

	 * ends up either enabling or disabling wbt completely. We can't

	 * have IO inflight if that happens.

	 */

	memflags = blk_mq_freeze_queue(q);



	rqos = wbt_rq_qos(q);

	if (!rqos) {

		ret = wbt_init(disk);

		if (ret)

			goto out;

	}



	if (val == -1)

		val = wbt_default_latency_nsec(q);

	else if (val >= 0)

		val *= 1000ULL;



	if (wbt_get_min_lat(q) == val)

		goto out;



	blk_mq_quiesce_queue(q);



	mutex_lock(&disk->rqos_state_mutex);

	wbt_set_min_lat(q, val);

	mutex_unlock(&disk->rqos_state_mutex);



	blk_mq_unquiesce_queue(q);

out:

	blk_mq_unfreeze_queue(q, memflags);



	return ret;

}

block/blk-wbt.h

+2 −5
Original line number Diff line number Diff line
@@ -4,16 +4,13 @@ 


#ifdef CONFIG_BLK_WBT



int wbt_init(struct gendisk *disk);

void wbt_init_enable_default(struct gendisk *disk);

void wbt_disable_default(struct gendisk *disk);

void wbt_enable_default(struct gendisk *disk);



u64 wbt_get_min_lat(struct request_queue *q);

void wbt_set_min_lat(struct request_queue *q, u64 val);

bool wbt_disabled(struct request_queue *);



u64 wbt_default_latency_nsec(struct request_queue *);

bool wbt_disabled(struct request_queue *q);

int wbt_set_lat(struct gendisk *disk, s64 val);



#else