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blk-wbt: don't enable throttling if default elevator is bfq 

Commit b5dc5d4d1f ("block,bfq: Disable writeback throttling") tries to
disable wbt for bfq, it's done by calling wbt_disable_default() in
bfq_init_queue(). However, wbt is still enabled if default elevator is
bfq:

device_add_disk
 elevator_init_mq
  bfq_init_queue
   wbt_disable_default -> done nothing

 blk_register_queue
  wbt_enable_default -> wbt is enabled

Fix the problem by adding a new flag ELEVATOR_FLAG_DISBALE_WBT, bfq
will set the flag in bfq_init_queue, and following wbt_enable_default()
won't enable wbt while the flag is set.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221019121518.3865235-7-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Yu Kuai 2022-10-19 20:15:18 +08:00 committed by Jens Axboe
parent 181d066374
commit 671fae5e51
3 changed files with 12 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
block/bfq-iosched.c
View File

@ -7045,6 +7045,7 @@ static void bfq_exit_queue(struct elevator_queue *e)
#endif
blk_stat_disable_accounting(bfqd->queue);
clear_bit(ELEVATOR_FLAG_DISABLE_WBT, &e->flags);
wbt_enable_default(bfqd->queue);
kfree(bfqd);
@ -7190,6 +7191,7 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
/* We dispatch from request queue wide instead of hw queue */
blk_queue_flag_set(QUEUE_FLAG_SQ_SCHED, q);
set_bit(ELEVATOR_FLAG_DISABLE_WBT, &eq->flags);
wbt_disable_default(q);
blk_stat_enable_accounting(q);

11
block/blk-wbt.c
View File

@ -27,6 +27,7 @@
#include "blk-wbt.h"
#include "blk-rq-qos.h"
#include "elevator.h"
#define CREATE_TRACE_POINTS
#include <trace/events/wbt.h>
@ -651,11 +652,15 @@ void wbt_set_write_cache(struct request_queue *q, bool write_cache_on)
*/
void wbt_enable_default(struct request_queue *q)
{
struct rq_qos *rqos = wbt_rq_qos(q);
struct rq_qos *rqos;
bool disable_flag = q->elevator &&
test_bit(ELEVATOR_FLAG_DISABLE_WBT, &q->elevator->flags);
/* Throttling already enabled? */
rqos = wbt_rq_qos(q);
if (rqos) {
if (RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT)
if (!disable_flag &&
RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT)
RQWB(rqos)->enable_state = WBT_STATE_ON_DEFAULT;
return;
}
@ -664,7 +669,7 @@ void wbt_enable_default(struct request_queue *q)
if (!blk_queue_registered(q))
return;
if (queue_is_mq(q))
if (queue_is_mq(q) && !disable_flag)
wbt_init(q);
}
EXPORT_SYMBOL_GPL(wbt_enable_default);

3
block/elevator.h
View File

@ -104,7 +104,8 @@ struct elevator_queue
DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
};
#define ELEVATOR_FLAG_REGISTERED 0
#define ELEVATOR_FLAG_REGISTERED 0
#define ELEVATOR_FLAG_DISABLE_WBT 1
/*
* block elevator interface