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block: remove init_mutex and open-code blk_iolatency_try_init

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Commit a13696b83d ("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 a13bd91be2
("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: Li Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Link: https://lore.kernel.org/r/20230810035111.2236335-1-lilingfeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Li Lingfeng 2023-08-10 11:51:11 +08:00 committed by Jens Axboe
parent c8659bbb15
commit 4eb44d1076
1 changed files with 11 additions and 24 deletions
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35
block/blk-iolatency.c
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@ -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;