From patchwork Wed Dec 5 17:10:27 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dennis Zhou X-Patchwork-Id: 10714665 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2C72A18A7 for ; Wed, 5 Dec 2018 17:12:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1D7212E158 for ; Wed, 5 Dec 2018 17:12:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1B56F2E17D; Wed, 5 Dec 2018 17:12:15 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7CC832E176 for ; Wed, 5 Dec 2018 17:12:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727852AbeLERMI (ORCPT ); Wed, 5 Dec 2018 12:12:08 -0500 Received: from mail-qt1-f194.google.com ([209.85.160.194]:37034 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727297AbeLERKr (ORCPT ); Wed, 5 Dec 2018 12:10:47 -0500 Received: by mail-qt1-f194.google.com with SMTP id z16so23112412qtq.4; Wed, 05 Dec 2018 09:10:46 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=vqrnr706mxcuTBSv4fGe89XMxxRx6O2pZFhgxbxRlLY=; b=HJ2K4OG/kp6nh2SaNx8R/HNPKcZq8FZ5zTc8WUfLbHQIum2mAaKZJMkGza5D4kHkhw R0YbNxnuNRpewUYG+QpVgLXBa6YV+GM7VP+oPObVfN8nC8dJ7DYxhTJEzCisJZ2p0/Ax ShBh1nYdhbpmD+M7s1ljX5xrxAkBiuMS82D6iAgukkG05wuBfAnCO48abUYJZjhVYBlR qHOUmXsCzJVGsl0z/yF+5UUEuKgEFnoYu5/luDYhxOXvIP8NY8HJcMXA/uFGDo7LpgVL tPRtu9Alo843zh4ZQs7uLmi0mAXEaCMSRBmSWKhu/hGgG9KlfJ4P04GdXjtJpK/b471t 01Mw== X-Gm-Message-State: AA+aEWZy/C60p0rHDEQ3RnGcT8euMv5Ak4vf5/+9yQJXjy92VbCsH+Nu fA6lLLBWpUX1ITSZP7gtGFc= X-Google-Smtp-Source: AFSGD/WOSiMR10JJCNI2QTdk+x4OzqvdnpvqKVPv63Kof9/sukSLAOXqBa4IB+5YO35skc7xUOtFCw== X-Received: by 2002:aed:3e49:: with SMTP id m9mr22360105qtf.99.1544029845858; Wed, 05 Dec 2018 09:10:45 -0800 (PST) Received: from dennisz-mbp.thefacebook.com ([199.201.65.135]) by smtp.gmail.com with ESMTPSA id q15sm12098751qkl.81.2018.12.05.09.10.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 05 Dec 2018 09:10:44 -0800 (PST) From: Dennis Zhou To: Jens Axboe , Tejun Heo , Johannes Weiner , Josef Bacik Cc: kernel-team@fb.com, linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Dennis Zhou Subject: [PATCH 02/14] blkcg: update blkg_lookup_create() to do locking Date: Wed, 5 Dec 2018 12:10:27 -0500 Message-Id: <20181205171039.73066-3-dennis@kernel.org> X-Mailer: git-send-email 2.13.5 In-Reply-To: <20181205171039.73066-1-dennis@kernel.org> References: <20181205171039.73066-1-dennis@kernel.org> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP To know when to create a blkg, the general pattern is to do a blkg_lookup() and if that fails, lock and do the lookup again, and if that fails finally create. It doesn't make much sense for everyone who wants to do creation to write this themselves. This changes blkg_lookup_create() to do locking and implement this pattern. The old blkg_lookup_create() is renamed to __blkg_lookup_create(). If a call site wants to do its own error handling or already owns the queue lock, they can use __blkg_lookup_create(). This will be used in upcoming patches. Signed-off-by: Dennis Zhou Reviewed-by: Josef Bacik Acked-by: Tejun Heo Reviewed-by: Liu Bo --- block/blk-cgroup.c | 28 +++++++++++++++++++++++++--- block/blk-iolatency.c | 2 +- include/linux/blk-cgroup.h | 4 +++- 3 files changed, 29 insertions(+), 5 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 63d226a084cd..b421a9457e05 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -249,7 +249,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, } /** - * blkg_lookup_create - lookup blkg, try to create one if not there + * __blkg_lookup_create - lookup blkg, try to create one if not there * @blkcg: blkcg of interest * @q: request_queue of interest * @@ -262,8 +262,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not * dead and bypassing, returns ERR_PTR(-EBUSY). */ -struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, - struct request_queue *q) +struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q) { struct blkcg_gq *blkg; @@ -293,6 +293,28 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, } } +/** + * blkg_lookup_create - find or create a blkg + * @blkcg: target block cgroup + * @q: target request_queue + * + * This looks up or creates the blkg representing the unique pair + * of the blkcg and the request_queue. + */ +struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q) +{ + struct blkcg_gq *blkg = blkg_lookup(blkcg, q); + + if (unlikely(!blkg)) { + spin_lock_irq(&q->queue_lock); + blkg = __blkg_lookup_create(blkcg, q); + spin_unlock_irq(&q->queue_lock); + } + + return blkg; +} + static void blkg_destroy(struct blkcg_gq *blkg) { struct blkcg *blkcg = blkg->blkcg; diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index fe0c4ca312ff..e6f68f15dee9 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -486,7 +486,7 @@ static void blkcg_iolatency_throttle(struct rq_qos *rqos, struct bio *bio) blkg = blkg_lookup(blkcg, q); if (unlikely(!blkg)) { spin_lock_irq(&q->queue_lock); - blkg = blkg_lookup_create(blkcg, q); + blkg = __blkg_lookup_create(blkcg, q); if (IS_ERR(blkg)) blkg = NULL; spin_unlock_irq(&q->queue_lock); diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index f619307171a6..b3b1a8187d23 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -181,6 +181,8 @@ extern struct cgroup_subsys_state * const blkcg_root_css; struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, struct request_queue *q, bool update_hint); +struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q); struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, struct request_queue *q); int blkcg_init_queue(struct request_queue *q); @@ -799,7 +801,7 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q, blkg = blkg_lookup(blkcg, q); if (unlikely(!blkg)) { spin_lock_irq(&q->queue_lock); - blkg = blkg_lookup_create(blkcg, q); + blkg = __blkg_lookup_create(blkcg, q); if (IS_ERR(blkg)) blkg = NULL; spin_unlock_irq(&q->queue_lock);