From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65FCCC04ABB for ; Tue, 11 Sep 2018 18:41:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E9AD2087F for ; Tue, 11 Sep 2018 18:41:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HJ798DPP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1E9AD2087F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728177AbeIKXmW (ORCPT ); Tue, 11 Sep 2018 19:42:22 -0400 Received: from mail-yw1-f68.google.com ([209.85.161.68]:37531 "EHLO mail-yw1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727838AbeIKXmV (ORCPT ); Tue, 11 Sep 2018 19:42:21 -0400 Received: by mail-yw1-f68.google.com with SMTP id x83-v6so9626404ywd.4; Tue, 11 Sep 2018 11:41:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=Eiy8jfjFxZHKC78nIxR0T2ImKwTJro98JlpbbKeKMRI=; b=HJ798DPPWplZmJZHKHsOW0+OYclb38wIF2w+ETObMy2xRpsvJJV77fOn7PNoon9lTJ FFQyi197w65ow/gFMbpVIlEYlKl74C9zN9RFNL3LSaSmru9twJVejPcPhoPDRLWjiLAy ZokjYpjiESf+hZyWYkCYFeTj/ZL9RcRfb8vjjqBx5iNoXxKFiPn28DIxejIP+4l+DVQF O+Jh8WB59ucN4WgaNC0f9Y5UUFIVH/U1eJOl7BwwHBFDR0veFhJww4WhUP3X4EusF05q K6TCWZSdiaK1MbJG7ytOSTduro16l74zwAo/lCpyZLSUKP4xStZFt1PPZNuSJ96KAtd7 JEPg== 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=Eiy8jfjFxZHKC78nIxR0T2ImKwTJro98JlpbbKeKMRI=; b=KMPigE63GWPScyBaWdinZrIJvZ48p29Y+XUr/VelS1RmeT32lLYX8Dzl7B1sI9RsK2 T8a3tBi1gzbMpoyaTcuhUwAKtazboliYp9J12vTxNtQuRwWhi21yhMbmxT41wheR0Cfh 7rFQ6hYa+SbdL6K8Mh49oWOBIuWMrtVv4V1KQdV2I30c+aUzienni/BUtw2ch48XLR5e BtE7gP60tN4h0SqwSk6y+w5uFltTTtemGH2KNj0GT9t+JB+5V9HjYw57IEk3M8v3QqaL SpRt8IOqpCvOUxBGmLZ6hF8K8j0pGFng/jjV6Rwhzl6RRgB6/C6EDSLVJdR6AAx2h7G0 gcBA== X-Gm-Message-State: APzg51DevicAzoLweGVY2jeviJhNmzx0crKs86lVwKHXVOFGwtKT6ORW Xb/CP9thfRt2gvvlRiXTyds= X-Google-Smtp-Source: ANB0Vdb/7npWEgKReVeB4e7g1GJwW4RbwTE/AjF+rh2C1Bz3DYdqTBn8tutH+a6WpZ1Dt7fQlsolwQ== X-Received: by 2002:a81:7a4b:: with SMTP id v72-v6mr12980077ywc.438.1536691304663; Tue, 11 Sep 2018 11:41:44 -0700 (PDT) Received: from dennisz-mbp.thefacebook.com ([199.201.65.129]) by smtp.gmail.com with ESMTPSA id i123-v6sm7902875ywe.14.2018.09.11.11.41.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Sep 2018 11:41:43 -0700 (PDT) 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 (Facebook)" Subject: [PATCH 02/12] blkcg: update blkg_lookup_create to do locking Date: Tue, 11 Sep 2018 14:41:27 -0400 Message-Id: <20180911184137.35897-3-dennisszhou@gmail.com> X-Mailer: git-send-email 2.13.5 In-Reply-To: <20180911184137.35897-1-dennisszhou@gmail.com> References: <20180911184137.35897-1-dennisszhou@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Dennis Zhou (Facebook)" To know when to create a blkg, the general pattern is to do a blkg_lookup and if that fails, lock and then do a 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 | 31 ++++++++++++++++++++++++++++--- block/blk-iolatency.c | 2 +- include/linux/blk-cgroup.h | 4 +++- 3 files changed, 32 insertions(+), 5 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index c19f9078da1e..cd0d97bed83d 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -259,7 +259,7 @@ 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 * @@ -272,8 +272,8 @@ 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; @@ -310,6 +310,31 @@ 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); + unsigned long flags; + + if (unlikely(!blkg)) { + spin_lock_irqsave(q->queue_lock, flags); + + blkg = __blkg_lookup_create(blkcg, q); + + spin_unlock_irqrestore(q->queue_lock, flags); + } + + 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 62fdd9002c29..22b2ff0440cc 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -410,7 +410,7 @@ static void blkcg_iolatency_throttle(struct rq_qos *rqos, struct bio *bio, if (unlikely(!blkg)) { if (!lock) spin_lock_irq(q->queue_lock); - blkg = blkg_lookup_create(blkcg, q); + blkg = __blkg_lookup_create(blkcg, q); if (IS_ERR(blkg)) blkg = NULL; if (!lock) diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 24067a1f8b36..cc0f238530f6 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -184,6 +184,8 @@ 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); @@ -897,7 +899,7 @@ 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); -- 2.17.1