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[209.132.180.67]) by mx.google.com with ESMTP id g3-v6si6578001pgu.248.2018.09.06.14.41.59; Thu, 06 Sep 2018 14:42:14 -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; dkim=pass header.i=@gmail.com header.s=20161025 header.b=tisRTJJs; 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=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729861AbeIGBth (ORCPT + 99 others); Thu, 6 Sep 2018 21:49:37 -0400 Received: from mail-yb1-f193.google.com ([209.85.219.193]:38690 "EHLO mail-yb1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727952AbeIGBsR (ORCPT ); Thu, 6 Sep 2018 21:48:17 -0400 Received: by mail-yb1-f193.google.com with SMTP id e18-v6so4694777ybq.5; Thu, 06 Sep 2018 14:10:59 -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=ElWDl0f7yaVkieg8dsiiyfInoiRyXp3U8BvsQtSTbKs=; b=tisRTJJs/93AbzNxeq7Ak2SO6dKqyeOAdLDj4iU1p+9jLS6w40xlWxCzOeu+QQOjP+ bk/nCf5vIK//2ynQAG0WtMJyTYA02u7Tv6jp3F8vJGz+SLo3Ojpju8jRDvxB+htuMIdd VYKiMWFX6cZfOwYLrrs/zokOqWAljBWvstbrHYgYGGN0qZwGmIv26/v2eSi9u4+LZhz7 JMT1ChKynlzNRFcNeKsdrqL8Xtg3iw1wbA94d23JFr+zpNhAqYCnnsuoXjxHYaVztLRW mL0jb7P6hC7gybZsxhag1f2B+fWMOMEkUVU0vngSlTlS4OzqrOXCdcBXgcjilqJNIl4W blBA== 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=ElWDl0f7yaVkieg8dsiiyfInoiRyXp3U8BvsQtSTbKs=; b=ckCrunPxh1GBloavMA3Y/8GVIAVwx8eWhNQuhCvXZd3i4zs+tV54/oPFlmyrZyrqU7 /Q5kgieE1hGvbvy/yNDkan3KOj+s5wJC0tYO1LpAv3Ewa8sh6lsWrSOtuuC21G+5LbT9 oi2AmF8JLapZeRsSJ3yU6oJOvGpQ1Rtz2mtuKq0ESPSyfuepryog6CEcOR7U/gB4Q9JC 6BB4Hj0sJIN1yiE4s/A7zrG3Br3C79y4lKlpzo+zs/gHwO14T+T0OCc6+PE4ZfjOTUuK tx7WrbcLHD+4lTnQ/TBTd72aJVX+n09JXjaJWvJALQfXZ8n/olqN3Mggjc1AY1smeIwi pnsg== X-Gm-Message-State: APzg51BJA3VeAQL1k5c0wmW7JhxeE2FOhjGUzMeWxSz2lzX4PtmauNQX iPttjdbYLcHZ4jU4tO66sKI= X-Received: by 2002:a25:3b96:: with SMTP id i144-v6mr2564653yba.366.1536268259560; Thu, 06 Sep 2018 14:10:59 -0700 (PDT) Received: from dennisz-mbp.thefacebook.com ([199.201.65.129]) by smtp.gmail.com with ESMTPSA id u67-v6sm2032802ywa.56.2018.09.06.14.10.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Sep 2018 14:10:58 -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: Thu, 6 Sep 2018 17:10:35 -0400 Message-Id: <20180906211045.29055-3-dennisszhou@gmail.com> X-Mailer: git-send-email 2.13.5 In-Reply-To: <20180906211045.29055-1-dennisszhou@gmail.com> References: <20180906211045.29055-1-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 --- 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