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List:       linux-block
Subject:    Re: [PATCH 06/15] blkcg: always associate a bio with a blkg
From:       Tejun Heo <tj () kernel ! org>
Date:       2018-08-31 23:16:09
Message-ID: 20180831231609.GD1488037 () devbig004 ! ftw2 ! facebook ! com
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Hello,

On Thu, Aug 30, 2018 at 09:53:47PM -0400, Dennis Zhou wrote:
> From: "Dennis Zhou (Facebook)" <dennisszhou@gmail.com>
> 
> Previously, blkg's were only assigned as needed by blk-iolatency and
> blk-throttle. bio->css was also always being associated while blkg was
> being looked up and then thrown away in blkcg_bio_issue_check.
> 
> This patch beings the cleanup of bio->css and bio->bi_blkg by always
             ^
	     begins

> +int bio_associate_create_blkg(struct request_queue *q, struct bio *bio)
> +{
> +	struct blkcg *blkcg;
> +	struct blkcg_gq *blkg;
> +	int ret = 0;
> +
> +	/* someone has already associated this bio with a blkg */
> +	if (bio->bi_blkg)
> +		return ret;
> +
> +	rcu_read_lock();
> +
> +	bio_associate_blkcg(bio, NULL);
> +	blkcg = bio_blkcg(bio);
> +
> +	if (!blkcg->css.parent) {
> +		ret = bio_associate_blkg(bio, q->root_blkg);
> +		goto assoc_out;
> +	}
> +
> +	blkg = blkg_lookup_create(blkcg, q);
> +	if (IS_ERR(blkg))
> +		blkg = q->root_blkg;
> +
> +	ret = bio_associate_blkg(bio, blkg);
> +assoc_out:

Maybe if/else instead of goto?

Other than that,

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun
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