Commit 4eb44d10 authored by Li Lingfeng's avatar Li Lingfeng Committed by Jens Axboe
Browse files

block: remove init_mutex and open-code blk_iolatency_try_init 



Commit a13696b8 ("blk-iolatency: Make initialization lazy") adds
a mutex named "init_mutex" in blk_iolatency_try_init for the race
condition of initializing RQ_QOS_LATENCY.
Now a new lock has been add to struct request_queue by commit a13bd91b
("block/rq_qos: protect rq_qos apis with a new lock"). And it has been
held in blkg_conf_open_bdev before calling blk_iolatency_init.
So it's not necessary to keep init_mutex in blk_iolatency_try_init, just
remove it.

Since init_mutex has been removed, blk_iolatency_try_init can be
open-coded back to iolatency_set_limit() like ioc_qos_write().

Signed-off-by: default avatarLi Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: default avatarMichal Koutný <mkoutny@suse.com>
Link: https://lore.kernel.org/r/20230810035111.2236335-1-lilingfeng@huaweicloud.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c8659bbb

block/blk-iolatency.c

+11 −24
Original line number Diff line number Diff line
@@ -824,29 +824,6 @@ static void iolatency_clear_scaling(struct blkcg_gq *blkg) 
	}

}



static int blk_iolatency_try_init(struct blkg_conf_ctx *ctx)

{

	static DEFINE_MUTEX(init_mutex);

	int ret;



	ret = blkg_conf_open_bdev(ctx);

	if (ret)

		return ret;



	/*

	 * blk_iolatency_init() may fail after rq_qos_add() succeeds which can

	 * confuse iolat_rq_qos() test. Make the test and init atomic.

	 */

	mutex_lock(&init_mutex);



	if (!iolat_rq_qos(ctx->bdev->bd_queue))

		ret = blk_iolatency_init(ctx->bdev->bd_disk);



	mutex_unlock(&init_mutex);



	return ret;

}



static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf,

			     size_t nbytes, loff_t off)

{
@@ -861,7 +838,17 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf, 


	blkg_conf_init(&ctx, buf);



	ret = blk_iolatency_try_init(&ctx);

	ret = blkg_conf_open_bdev(&ctx);

	if (ret)

		goto out;



	/*

	 * blk_iolatency_init() may fail after rq_qos_add() succeeds which can

	 * confuse iolat_rq_qos() test. Make the test and init atomic.

	 */

	lockdep_assert_held(ctx.bdev->bd_queue->rq_qos_mutex);

	if (!iolat_rq_qos(ctx.bdev->bd_queue))

		ret = blk_iolatency_init(ctx.bdev->bd_disk);

	if (ret)

		goto out;