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, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_MED, URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 DDD7AC433F4 for ; Fri, 31 Aug 2018 15:38:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D6382077C for ; Fri, 31 Aug 2018 15:38:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=toxicpanda-com.20150623.gappssmtp.com header.i=@toxicpanda-com.20150623.gappssmtp.com header.b="ZIR6D0IY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7D6382077C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=toxicpanda.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 S1729099AbeHaTqE (ORCPT ); Fri, 31 Aug 2018 15:46:04 -0400 Received: from mail-qt0-f195.google.com ([209.85.216.195]:33809 "EHLO mail-qt0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728872AbeHaTqE (ORCPT ); Fri, 31 Aug 2018 15:46:04 -0400 Received: by mail-qt0-f195.google.com with SMTP id m13-v6so15033185qth.1 for ; Fri, 31 Aug 2018 08:38:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=4horjyeJc+AP18U1mdCUwawf1Q45fUOIo0sacVoEYXQ=; b=ZIR6D0IYHg6u+A+5s8aeDh8kd8lRi8BapEmyS73g4N7SiM6QgrZdfo64z1j4F4NZsa Y22ROBc/3jomOQ9feMbV9cWEDmdaT3rXFmm9I72rjJfOVrPGc8MM/W3QpP+wFWRK7fTw fGEsGrYZ26w6YmTF50Qr24SUZz1rCQNSgwPOAsE3SroC9QVxI4e1/r2H2MYThYuQSz3B OM7MU6Z0Fyq6xk/t/jzXyNMQsvcPQ8yI/8oyWy5EnmmyWE7Rr0AvSkYUXtIBRSVvQROr KeNmGWK8UsUwBiwVCg/60hlrKh6x0N91ZJ1XDYKbOyKW/sb0g+/YoZ8RWgJydscCXa98 Y5Sw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=4horjyeJc+AP18U1mdCUwawf1Q45fUOIo0sacVoEYXQ=; b=psMFaM0L6MARAb9DPXqMuYx1qjm2IvyuxVXpxE3+MCId5ncsCONJjA9FJLO0Q+S2vL eXglJF2yUzrcIqwvPetEIy7vLo9C/Cuk1gbGeSJ7I5Nlckc4il3DzK+E2OPK9IrpjduA Oqhi127ObmhVsapzqlGgcQ3nLmVquRDD4P/q5/0Sn/rkTp2pzFjq3BhssN02DPdeOVbo rUrI/Ks3FrO6nysBl0bt7z9/HQNd5ipNWNO5LCWYgD57xcQZ/3jj6uDd34jL4zVgLRv6 oqAv7qbTELAUSpID6hjChyJmlGx+dulFKlu3iXUaTT+YahpiDdh6cRDCgCexTOKXIE+y WA+Q== X-Gm-Message-State: APzg51Avp8qcw+Rdw2MNmOUjBeLlbAzVzwCTGf3unb25HGB5n7T6bF4Q FyEzGnb1xSaQ4S5nDWuZQgHQJg== X-Google-Smtp-Source: ANB0VdZEs5zgD+bM4hP7hhWMzuqdoov/JToYy0XwB4A2LO2PErzxk4Y7wubMmUUKbPM3+J4ROtzOiA== X-Received: by 2002:aed:2524:: with SMTP id v33-v6mr16672444qtc.319.1535729880835; Fri, 31 Aug 2018 08:38:00 -0700 (PDT) Received: from localhost ([107.15.81.208]) by smtp.gmail.com with ESMTPSA id o124-v6sm6183968qkd.61.2018.08.31.08.37.59 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 31 Aug 2018 08:37:59 -0700 (PDT) Date: Fri, 31 Aug 2018 11:37:59 -0400 From: Josef Bacik To: Dennis Zhou Cc: Jens Axboe , Tejun Heo , Johannes Weiner , Josef Bacik , kernel-team@fb.com, linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 05/15] blkcg: update blkg_lookup_create to do locking Message-ID: <20180831153757.ztep3tw5j4zmlatm@destiny> References: <20180831015356.69796-1-dennisszhou@gmail.com> <20180831015356.69796-6-dennisszhou@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180831015356.69796-6-dennisszhou@gmail.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 30, 2018 at 09:53:46PM -0400, Dennis Zhou wrote: > 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. > > Signed-off-by: Dennis Zhou Reviewed-by: Josef Bacik Thanks, Josef