From patchwork Tue May 10 09:08:42 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Valente X-Patchwork-Id: 67406 Delivered-To: patch@linaro.org Received: by 10.140.92.199 with SMTP id b65csp2017437qge; Tue, 10 May 2016 02:09:26 -0700 (PDT) X-Received: by 10.66.250.132 with SMTP id zc4mr57771930pac.130.1462871366427; Tue, 10 May 2016 02:09:26 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 13si1740861pfn.148.2016.05.10.02.09.26; Tue, 10 May 2016 02:09:26 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751350AbcEJJJX (ORCPT + 29 others); Tue, 10 May 2016 05:09:23 -0400 Received: from spostino.sms.unimo.it ([155.185.44.3]:39832 "EHLO spostino.sms.unimo.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750951AbcEJJJW (ORCPT ); Tue, 10 May 2016 05:09:22 -0400 Received: from [185.14.10.204] (port=41240 helo=localhost.localdomain) by spostino.sms.unimo.it with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA256:128) (Exim 4.80) (envelope-from ) id 1b03fH-0002oS-Hs; Tue, 10 May 2016 11:09:16 +0200 From: Paolo Valente To: Jens Axboe , Tejun Heo Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, linus.walleij@linaro.org, broonie@kernel.org, Paolo Valente Subject: [PATCH BUGFIX] block: add missing group association in bio_split Date: Tue, 10 May 2016 11:08:42 +0200 Message-Id: <1462871322-13217-1-git-send-email-paolo.valente@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <5730CFC5.80201@kernel.dk> References: <5730CFC5.80201@kernel.dk> UNIMORE-X-SA-Score: -2.9 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When a bio is split, the newly created bio must be associated with the same blkcg as the original bio (if BLK_CGROUP is enabled). If this operation is not performed, then the new bio is not associated with any group, and the group of the current task is returned when the group of the bio is requested. Depending on the frequency of splits, this may cause a large percentage of the bios belonging to a given group to be treated as if belonging to other groups (in most cases as if belonging to the root group). The expected group isolation may thereby be then broken. This commit adds the missing association in bio_split. Signed-off-by: Paolo Valente --- block/bio.c | 15 +++++++++++++++ include/linux/bio.h | 2 ++ 2 files changed, 17 insertions(+) -- 1.9.1 diff --git a/block/bio.c b/block/bio.c index 807d25e..20795eb 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1811,6 +1811,8 @@ struct bio *bio_split(struct bio *bio, int sectors, bio_advance(bio, split->bi_iter.bi_size); + bio_clone_blkcg_association(split, bio); + return split; } EXPORT_SYMBOL(bio_split); @@ -2016,6 +2018,19 @@ void bio_disassociate_task(struct bio *bio) } } +/** + * bio_clone_blkcg_association - clone blkcg association from src to dst bio + * @dst: destination bio + * @src: source bio + */ +int bio_clone_blkcg_association(struct bio *dst, struct bio *src) +{ + if (src->bi_css) + return bio_associate_blkcg(dst, src->bi_css); + + return 0; +} + #endif /* CONFIG_BLK_CGROUP */ static void __init biovec_init_slabs(void) diff --git a/include/linux/bio.h b/include/linux/bio.h index 6b7481f..8535f81 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -527,11 +527,13 @@ extern unsigned int bvec_nr_vecs(unsigned short idx); int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css); int bio_associate_current(struct bio *bio); void bio_disassociate_task(struct bio *bio); +int bio_clone_blkcg_association(struct bio *dst, struct bio *src); #else /* CONFIG_BLK_CGROUP */ static inline int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css) { return 0; } static inline int bio_associate_current(struct bio *bio) { return -ENOENT; } static inline void bio_disassociate_task(struct bio *bio) { } +int bio_clone_blkcg_association(struct bio *dst, struct bio *src) { return 0; } #endif /* CONFIG_BLK_CGROUP */ #ifdef CONFIG_HIGHMEM