From 64b36075eb0e50af6f59047b5f698a9f2bb2b4fd Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sun, 30 Oct 2022 11:07:14 +0100 Subject: [PATCH] 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: Christoph Hellwig Link: https://lore.kernel.org/r/20221030100714.876891-8-hch@lst.de Signed-off-by: Jens Axboe --- block/blk-mq-sched.c | 7 ----- block/blk-mq.c | 2 +- block/blk.h | 1 + block/elevator.c | 77 ++++++++++++++++++++++++++-------------------------- 4 files changed, 40 insertions(+), 47 deletions(-) diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 6822724..23d1a90 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -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. diff --git a/block/blk-mq.c b/block/blk-mq.c index 623e8a50..a785385 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -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; diff --git a/block/blk.h b/block/blk.h index 7f9e089..f1398fb 100644 --- a/block/blk.h +++ b/block/blk.h @@ -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); diff --git a/block/elevator.c b/block/elevator.c index 5781f5d..800e003 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -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); - return err; + 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) - 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)) -- 2.7.4