Commit 1e9db5c4 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

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: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarNilay Shroff <nilay@linux.ibm.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250505141805.2751237-16-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 20117b5a

block/elevator.c

+23 −16
Original line number Diff line number Diff line
@@ -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 @@ static int elevator_switch(struct request_queue *q, const char *name) 
/*

 * 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);