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block: split elevator_switch

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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: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221030100714.876891-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2022-10-30 11:07:14 +01:00 committed by Jens Axboe
parent ffb86425ee
commit 64b36075eb
4 changed files with 41 additions and 48 deletions
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7
block/blk-mq-sched.c
View File

@ -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.

2
block/blk-mq.c
View File

@ -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;

1
block/blk.h
View File

@ -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);

79
block/elevator.c
View File

@ -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;
}
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);
return err;
}
/*
@ -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)
return 0;
return elevator_switch(q, NULL);
if (q->elevator)
elevator_disable(q);
return 0;
}
if (q->elevator && elevator_match(q->elevator->type, elevator_name))