Commit 64b36075 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: split elevator_switch 



Split an elevator_disable helper from elevator_switch for the case where
we want to switch to no scheduler at all.  This includes removing the
pointless elevator_switch_mq helper and removing the switch to no
schedule logic from blk_mq_init_sched.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221030100714.876891-8-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent ffb86425

block/blk-mq-sched.c

+0 −7
Original line number Diff line number Diff line
@@ -564,13 +564,6 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e) 
	unsigned long i;

	int ret;



	if (!e) {

		blk_queue_flag_clear(QUEUE_FLAG_SQ_SCHED, q);

		q->elevator = NULL;

		q->nr_requests = q->tag_set->queue_depth;

		return 0;

	}



	/*

	 * Default to double of smaller one between hw queue_depth and 128,

	 * since we don't split into sync/async like the old code did.

block/blk-mq.c

+1 −1
Original line number Diff line number Diff line
@@ -4588,7 +4588,7 @@ static bool blk_mq_elv_switch_none(struct list_head *head, 
	__elevator_get(qe->type);

	qe->type = q->elevator->type;

	list_add(&qe->node, head);

	elevator_switch(q, NULL);

	elevator_disable(q);

	mutex_unlock(&q->sysfs_lock);



	return true;

block/blk.h

+1 −0
Original line number Diff line number Diff line
@@ -278,6 +278,7 @@ bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, 
void blk_insert_flush(struct request *rq);



int elevator_switch(struct request_queue *q, struct elevator_type *new_e);

void elevator_disable(struct request_queue *q);

void elevator_exit(struct request_queue *q);

int elv_register_queue(struct request_queue *q, bool uevent);

void elv_unregister_queue(struct request_queue *q);

block/elevator.c

+38 −39
Original line number Diff line number Diff line
@@ -554,39 +554,6 @@ void elv_unregister(struct elevator_type *e) 
}

EXPORT_SYMBOL_GPL(elv_unregister);



static int elevator_switch_mq(struct request_queue *q,

			      struct elevator_type *new_e)

{

	int ret;



	lockdep_assert_held(&q->sysfs_lock);



	if (q->elevator) {

		elv_unregister_queue(q);

		elevator_exit(q);

	}



	ret = blk_mq_init_sched(q, new_e);

	if (ret)

		goto out;



	if (new_e) {

		ret = elv_register_queue(q, true);

		if (ret) {

			elevator_exit(q);

			goto out;

		}

	}



	if (new_e)

		blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);

	else

		blk_add_trace_msg(q, "elv switch: none");



out:

	return ret;

}



static inline bool elv_support_iosched(struct request_queue *q)

{

	if (!queue_is_mq(q) ||
@@ -691,19 +658,51 @@ void elevator_init_mq(struct request_queue *q) 
 */

int elevator_switch(struct request_queue *q, struct elevator_type *new_e)

{

	int err;

	int ret;



	lockdep_assert_held(&q->sysfs_lock);



	blk_mq_freeze_queue(q);

	blk_mq_quiesce_queue(q);



	err = elevator_switch_mq(q, new_e);

	if (q->elevator) {

		elv_unregister_queue(q);

		elevator_exit(q);

	}



	ret = blk_mq_init_sched(q, new_e);

	if (ret)

		goto out_unfreeze;



	ret = elv_register_queue(q, true);

	if (ret) {

		elevator_exit(q);

		goto out_unfreeze;

	}

	blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);



out_unfreeze:

	blk_mq_unquiesce_queue(q);

	blk_mq_unfreeze_queue(q);

	return ret;

}



	return err;

void elevator_disable(struct request_queue *q)

{

	lockdep_assert_held(&q->sysfs_lock);



	blk_mq_freeze_queue(q);

	blk_mq_quiesce_queue(q);



	elv_unregister_queue(q);

	elevator_exit(q);

	blk_queue_flag_clear(QUEUE_FLAG_SQ_SCHED, q);

	q->elevator = NULL;

	q->nr_requests = q->tag_set->queue_depth;

	blk_add_trace_msg(q, "elv switch: none");



	blk_mq_unquiesce_queue(q);

	blk_mq_unfreeze_queue(q);

}



/*
@@ -722,9 +721,9 @@ static int elevator_change(struct request_queue *q, const char *elevator_name) 
	 * Special case for mq, turn off scheduling

	 */

	if (!strncmp(elevator_name, "none", 4)) {

		if (!q->elevator)

		if (q->elevator)

			elevator_disable(q);

		return 0;

		return elevator_switch(q, NULL);

	}



	if (q->elevator && elevator_match(q->elevator->type, elevator_name))