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block: move queue freezing & elevator_lock into elevator_change() 

Move queue freezing & elevator_lock into elevator_change(), and prepare
for using elevator_change() for setting up & tearing down default elevator
too.

Also add lockdep_assert_held() in __elevator_change() because either
read or write lock is required for changing elevator.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250505141805.2751237-15-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2025-05-05 22:17:52 +08:00 committed by Jens Axboe
parent 596dce110b
commit 20117b5a4b
1 changed files with 12 additions and 8 deletions
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20
block/elevator.c
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@ -676,10 +676,19 @@ out_unfreeze:
*/
static int elevator_change(struct request_queue *q, const char *elevator_name)
{
if (q->elevator && elevator_match(q->elevator->type, elevator_name))
return 0;
unsigned int memflags;
int ret = 0;
return elevator_switch(q, elevator_name);
lockdep_assert_held(&q->tag_set->update_nr_hwq_lock);
memflags = blk_mq_freeze_queue(q);
mutex_lock(&q->elevator_lock);
if (!(q->elevator && elevator_match(q->elevator->type,
elevator_name)))
ret = elevator_switch(q, elevator_name);
mutex_unlock(&q->elevator_lock);
blk_mq_unfreeze_queue(q, memflags);
return ret;
}
/*
@ -718,7 +727,6 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf,
char elevator_name[ELV_NAME_MAX];
char *name;
int ret;
unsigned int memflags;
struct request_queue *q = disk->queue;
struct blk_mq_tag_set *set = q->tag_set;
@ -737,13 +745,9 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf,
elv_iosched_load_module(name);
down_read(&set->update_nr_hwq_lock);
memflags = blk_mq_freeze_queue(q);
mutex_lock(&q->elevator_lock);
ret = elevator_change(q, name);
if (!ret)
ret = count;
mutex_unlock(&q->elevator_lock);
blk_mq_unfreeze_queue(q, memflags);
up_read(&set->update_nr_hwq_lock);
return ret;
}