From 1e9db5c42730e9ffd32cb922775de4873ec1d8ee Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Mon, 5 May 2025 22:17:53 +0800 Subject: [PATCH] block: add `struct elv_change_ctx` for unifying elevator change Add `struct elv_change_ctx` and prepare for unifying elevator change by elevator_change(). With this way, any input & output parameter can be provided & observed in top helper. This way helps to move kobject add/delete & debugfs register/unregister out of ->elevator_lock & freezing queue. Reviewed-by: Hannes Reinecke Reviewed-by: Nilay Shroff Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20250505141805.2751237-16-ming.lei@redhat.com Signed-off-by: Jens Axboe --- block/elevator.c | 39 +++++++++++++++++++++++---------------- 1 file changed, 23 insertions(+), 16 deletions(-) diff --git a/block/elevator.c b/block/elevator.c index cb54a3791fe5..6cfac8f77d9f 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -45,6 +45,12 @@ #include "blk-wbt.h" #include "blk-cgroup.h" +/* Holding context data for changing elevator */ +struct elv_change_ctx { + const char *name; + bool no_uevent; +}; + static DEFINE_SPINLOCK(elv_list_lock); static LIST_HEAD(elv_list); @@ -621,7 +627,7 @@ void elevator_init_mq(struct request_queue *q) * If switching fails, we are most likely running out of memory and not able * to restore the old io scheduler, so leaving the io scheduler being none. */ -static int elevator_switch(struct request_queue *q, const char *name) +static int elevator_switch(struct request_queue *q, struct elv_change_ctx *ctx) { struct elevator_type *new_e = NULL; int ret = 0; @@ -629,8 +635,8 @@ static int elevator_switch(struct request_queue *q, const char *name) WARN_ON_ONCE(q->mq_freeze_depth == 0); lockdep_assert_held(&q->elevator_lock); - if (strncmp(name, "none", 4)) { - new_e = elevator_find_get(name); + if (strncmp(ctx->name, "none", 4)) { + new_e = elevator_find_get(ctx->name); if (!new_e) return -EINVAL; } @@ -646,7 +652,7 @@ static int elevator_switch(struct request_queue *q, const char *name) ret = blk_mq_init_sched(q, new_e); if (ret) goto out_unfreeze; - ret = elv_register_queue(q, true); + ret = elv_register_queue(q, !ctx->no_uevent); if (ret) { elevator_exit(q); goto out_unfreeze; @@ -656,7 +662,7 @@ static int elevator_switch(struct request_queue *q, const char *name) q->elevator = NULL; q->nr_requests = q->tag_set->queue_depth; } - blk_add_trace_msg(q, "elv switch: %s", name); + blk_add_trace_msg(q, "elv switch: %s", ctx->name); out_unfreeze: blk_mq_unquiesce_queue(q); @@ -674,7 +680,7 @@ out_unfreeze: /* * Switch this queue to the given IO scheduler. */ -static int elevator_change(struct request_queue *q, const char *elevator_name) +static int elevator_change(struct request_queue *q, struct elv_change_ctx *ctx) { unsigned int memflags; int ret = 0; @@ -683,9 +689,8 @@ static int elevator_change(struct request_queue *q, const char *elevator_name) 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); + if (!(q->elevator && elevator_match(q->elevator->type, ctx->name))) + ret = elevator_switch(q, ctx); mutex_unlock(&q->elevator_lock); blk_mq_unfreeze_queue(q, memflags); return ret; @@ -701,15 +706,17 @@ void elv_update_nr_hw_queues(struct request_queue *q) mutex_lock(&q->elevator_lock); if (q->elevator && !blk_queue_dying(q) && !blk_queue_registered(q)) { - const char *name = q->elevator->type->elevator_name; + struct elv_change_ctx ctx = { + .name = q->elevator->type->elevator_name, + }; /* force to reattach elevator after nr_hw_queue is updated */ - elevator_switch(q, name); + elevator_switch(q, &ctx); } mutex_unlock(&q->elevator_lock); } -static void elv_iosched_load_module(char *elevator_name) +static void elv_iosched_load_module(const char *elevator_name) { struct elevator_type *found; @@ -725,7 +732,7 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, size_t count) { char elevator_name[ELV_NAME_MAX]; - char *name; + struct elv_change_ctx ctx = {}; int ret; struct request_queue *q = disk->queue; struct blk_mq_tag_set *set = q->tag_set; @@ -740,12 +747,12 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, * queue is the one for the device storing the module file. */ strscpy(elevator_name, buf, sizeof(elevator_name)); - name = strstrip(elevator_name); + ctx.name = strstrip(elevator_name); - elv_iosched_load_module(name); + elv_iosched_load_module(ctx.name); down_read(&set->update_nr_hwq_lock); - ret = elevator_change(q, name); + ret = elevator_change(q, &ctx); if (!ret) ret = count; up_read(&set->update_nr_hwq_lock); -- 2.50.1