Commit 671fae5e authored by Yu Kuai's avatar Yu Kuai Committed by Jens Axboe
Browse files

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



Commit b5dc5d4d ("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: default avatarYu Kuai <yukuai3@huawei.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221019121518.3865235-7-yukuai1@huaweicloud.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 181d0663

block/bfq-iosched.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

block/blk-wbt.c

+8 −3
Original line number Diff line number Diff line
@@ -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);

block/elevator.h

+2 −1
Original line number Diff line number Diff line
@@ -105,6 +105,7 @@ struct elevator_queue 
};



#define ELEVATOR_FLAG_REGISTERED	0

#define ELEVATOR_FLAG_DISABLE_WBT	1



/*

 * block elevator interface