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=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 6ED4CC43381 for ; Wed, 6 Jan 2021 02:40:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 49FFC22D50 for ; Wed, 6 Jan 2021 02:40:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726606AbhAFCja (ORCPT ); Tue, 5 Jan 2021 21:39:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59216 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726371AbhAFCj3 (ORCPT ); Tue, 5 Jan 2021 21:39:29 -0500 Received: from mail-lf1-x136.google.com (mail-lf1-x136.google.com [IPv6:2a00:1450:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1157CC06134B for ; Tue, 5 Jan 2021 18:38:14 -0800 (PST) Received: by mail-lf1-x136.google.com with SMTP id o19so3384420lfo.1 for ; Tue, 05 Jan 2021 18:38:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Ury5f7F0ygdu/yondQUGmbZ3cq88GMLsTjmzvozFvjc=; b=JJTa/Tc+QXB7WTaTy03wXcVsiHCJ38bI/5PQU88HQ7YN4KMpPo+5MqlwDqB9HQdU4s +ffbgkc58Jd0iZCuDKXDzIQGz508oG5upwZRERod2tiZ1JDwovF24A9bNyAkovIsB0DF vQ5dhm6M/QrRyW2sUvMRUA8fA580S8vKFJifkqsq+biFxy1WYEC9GR3S8uLl402UtDGC 8+BMzLyqfGhxhyK18nkdQE2lGKcyTUxz20aGSs7EYR3LJx/Bh70Xel7XpEPeO1o75+dR tTMfb8mBfsjMHKptKJQv9ke1SSeQz2hTBc6aWrgTgKDd6Gucj4N6AKERsmxMfoBBgG5f D3qQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Ury5f7F0ygdu/yondQUGmbZ3cq88GMLsTjmzvozFvjc=; b=fxqa+pGBqGYq17gAKhavXbxlcLoO+xzAJRmjYrPIxxnJAdvcoihx4tj5LdWOqzGn3H R87hGM6NJGkf8Jl7ARVY1sxFyVmq1agVkS4qAKSCVZpd1pGYthIc6PavpRIRM0Idnbn0 yxGgBxuJLxiaA8MCSFJf5nVavJIF+CJGCNroqgQrZkFh28y5YSi1l+/R0KYEjfPH3a5D AyKHLl2TqenCddfRxOdBJS5FVaaryEivd8I2akHwcX1m554d15p9U//5sGFb3xt2IICd VyQRJqFuzcJZMWwwdvDkTopn2BfnPP+VWE5XFVwRw1BvkicEkD/xHvr2qmxTWd/7GU3O TDYw== X-Gm-Message-State: AOAM530MfNGnHa7Tw93Gwep+4+MN61J0Wmu/Yj1UiNK7IEdEEhSrZEaa fjsrVwM/Q5Is24gsEu8rk7Rw1UihH7TRaNlfgD0= X-Google-Smtp-Source: ABdhPJyhW9COAv+OxGK2kh2IIX00msmTRyXR26oD1Hjec8jnar2dkN9PRalz7nXQlp7ElJNqMzgTW0hTwXUYrMrWpTo= X-Received: by 2002:ac2:599e:: with SMTP id w30mr918546lfn.552.1609900692588; Tue, 05 Jan 2021 18:38:12 -0800 (PST) MIME-Version: 1.0 References: <160862320263.291330.9467216031366035418.stgit@mickey.themaw.net> <04675888088a088146e3ca00ca53099c95fbbad7.camel@themaw.net> In-Reply-To: <04675888088a088146e3ca00ca53099c95fbbad7.camel@themaw.net> From: Fox Chen Date: Wed, 6 Jan 2021 10:38:00 +0800 Message-ID: Subject: Re: [PATCH 0/6] kernfs: proposed locking and concurrency improvement To: Ian Kent Cc: Tejun Heo , Greg Kroah-Hartman , Rick Lindsley , Al Viro , David Howells , Miklos Szeredi , linux-fsdevel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi Ian, I am rethinking this problem. Can we simply use a global lock? In your original patch 5, you have a global mutex attr_mutex to protect attr, if we change it to a rwsem, is it enough to protect both inode and attr while having the concurrent read ability? like this patch I submitted. ( clearly, I missed __kernfs_iattrs part, but just about that idea ) https://lore.kernel.org/lkml/20201207084333.179132-1-foxhlchen@gmail.com/ thanks, fox