From mboxrd@z Thu Jan  1 00:00:00 1970
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Sender: Tejun Heo <htejun@gmail.com>
Date: Fri, 31 Aug 2018 16:16:09 -0700
From: Tejun Heo <tj@kernel.org>
To: Dennis Zhou <dennisszhou@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>, Johannes Weiner <hannes@cmpxchg.org>,
	Josef Bacik <josef@toxicpanda.com>, kernel-team@fb.com,
	linux-block@vger.kernel.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 06/15] blkcg: always associate a bio with a blkg
Message-ID: <20180831231609.GD1488037@devbig004.ftw2.facebook.com>
References: <20180831015356.69796-1-dennisszhou@gmail.com>
 <20180831015356.69796-7-dennisszhou@gmail.com>
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In-Reply-To: <20180831015356.69796-7-dennisszhou@gmail.com>
List-ID: <linux-block@vger.kernel.org>

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