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 03/12] blkcg: convert blkg_lookup_create to find closest blkg
Date: Fri, 7 Sep 2018 10:27:30 -0700 [thread overview]
Message-ID: <20180907172730.GB1100574@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20180906211045.29055-4-dennisszhou@gmail.com>
Hello,
On Thu, Sep 06, 2018 at 05:10:36PM -0400, Dennis Zhou wrote:
> @@ -2021,9 +2021,7 @@ int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
> {
> if (unlikely(bio->bi_blkg))
> return -EBUSY;
> + bio->bi_blkg = blkg_try_get_closest(blkg);
> return 0;
It prolly would be a good idea to point out that the associated blkg
might not be the same one passed in. Maybe this gets cleared up later
in the series?
> @@ -298,14 +297,23 @@ struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
> while (true) {
> struct blkcg *pos = blkcg;
> struct blkcg *parent = blkcg_parent(blkcg);
> -
> - while (parent && !__blkg_lookup(parent, q, false)) {
> + struct blkcg_gq *ret_blkg = NULL;
> +
> + while (parent) {
> + blkg = __blkg_lookup(parent, q, false);
> + if (blkg) {
> + /* remember closest blkg */
> + ret_blkg = blkg;
> + break;
> + }
> pos = parent;
> parent = blkcg_parent(parent);
> }
>
> blkg = blkg_create(pos, q, NULL);
> - if (pos == blkcg || IS_ERR(blkg))
> + if (IS_ERR(blkg))
> + return ret_blkg ?: q->root_blkg;
Why not ret_blkg here?
Thanks.
--
tejun
next prev parent reply other threads:[~2018-09-07 17:27 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 21:10 [PATCH 00/12] block: always associate blkg and refcount cleanup Dennis Zhou
2018-09-06 21:10 ` [PATCH 01/12] blkcg: fix ref count issue with bio_blkcg using task_css Dennis Zhou
2018-09-07 16:52 ` Tejun Heo
2018-09-06 21:10 ` [PATCH 02/12] blkcg: update blkg_lookup_create to do locking Dennis Zhou
2018-09-07 6:17 ` Liu Bo
2018-09-06 21:10 ` [PATCH 03/12] blkcg: convert blkg_lookup_create to find closest blkg Dennis Zhou
2018-09-07 17:27 ` Tejun Heo [this message]
2018-09-07 20:33 ` Dennis Zhou
2018-09-06 21:10 ` [PATCH 04/12] blkcg: always associate a bio with a blkg Dennis Zhou
2018-09-06 21:10 ` [PATCH 05/12] blkcg: consolidate bio_issue_init to be a part of core Dennis Zhou
2018-09-07 19:18 ` Liu Bo
2018-09-06 21:10 ` [PATCH 06/12] blkcg: associate a blkg for pages being evicted by swap Dennis Zhou
2018-09-06 21:10 ` [PATCH 07/12] blkcg: associate writeback bios with a blkg Dennis Zhou
2018-09-06 21:10 ` [PATCH 08/12] blkcg: remove bio->bi_css and instead use bio->bi_blkg Dennis Zhou
2018-09-06 21:10 ` [PATCH 09/12] blkcg: remove additional reference to the css Dennis Zhou
2018-09-07 17:54 ` Tejun Heo
2018-09-07 20:24 ` Dennis Zhou
2018-09-06 21:10 ` [PATCH 10/12] blkcg: cleanup and make blk_get_rl use blkg_lookup_create Dennis Zhou
2018-09-11 5:11 ` [LKP] [blkcg] 1d0e59f90b: BUG:unable_to_handle_kernel kernel test robot
2018-09-06 21:10 ` [PATCH 11/12] blkcg: change blkg reference counting to use percpu_ref Dennis Zhou
2018-09-07 17:59 ` Tejun Heo
2018-09-06 21:10 ` [PATCH 12/12] blkcg: rename blkg_try_get to blkg_tryget Dennis Zhou
2018-09-11 18:41 [PATCH v3 00/12] block: always associate blkg and refcount cleanup Dennis Zhou
2018-09-11 18:41 ` [PATCH 03/12] blkcg: convert blkg_lookup_create to find closest blkg Dennis Zhou
2018-09-11 23:50 ` Tejun Heo
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