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block: add struct elv_change_ctx for unifying elevator change

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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 <hare@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250505141805.2751237-16-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei
2025-05-05 22:17:53 +08:00
committed by Jens Axboe
parent 20117b5a4b
commit 1e9db5c427
1 changed files with 23 additions and 16 deletions
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39
block/elevator.c
View File

@@ -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);