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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3A48C433FE for ; Fri, 25 Mar 2022 07:38:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354302AbiCYHkS (ORCPT ); Fri, 25 Mar 2022 03:40:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354245AbiCYHkP (ORCPT ); Fri, 25 Mar 2022 03:40:15 -0400 Received: from mail-ej1-x629.google.com (mail-ej1-x629.google.com [IPv6:2a00:1450:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06EC14C43C for ; Fri, 25 Mar 2022 00:38:42 -0700 (PDT) Received: by mail-ej1-x629.google.com with SMTP id p15so13648509ejc.7 for ; Fri, 25 Mar 2022 00:38:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=DiHXaOQKxgjJgR8FzYG0VW2c/gysd7B3sO8yEiSnp68=; b=j/OgKK9a/MpEwVPN4u69s2eJczNmOvkwscW8bzCVLv78HmxdsYX7X7jbHgtIgF97A9 w57W9Nljd7jQu9hzHcGLDWE8og4lj+XVi0qHG/fp9jPhDz5mm207hoF8E8P3gn08pXhe 4km1s2r9wfPR5Q7ppia5Ln5rCg8bE/uRCMwaIggJYROS5AQjHfiCYS5WGlCFdsxs4O1G 4uCi/ExPkuaMETF3CBI1NkdFb2NSxifMqmcS3Y6FmReticDT6U5pacPflu0g49lHYcKG rnFFtWjBNl28t20j6DPoxATK1WMLb6Jxl2DJ2NwUMFGy++UW5p7MKPb4Ub8rtZBoqSBN jKxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=DiHXaOQKxgjJgR8FzYG0VW2c/gysd7B3sO8yEiSnp68=; b=QrNR43K6cbgp8J9OiI30SDQWHESv+GIjnSqOqPA5rBjZp+GJrLcfhZseZtpMu3s0E9 w6Mhkd+apFT8mGYepzOC8/W+2nmcZwWASD7vnuHepWZ3QlPgjpaP2ks+lfwXTrNiz4fE /fn1XA7FU5EMulcv2SZEpgkZmOtqhMoZjAz1J5o9jksmiSHgLLEhwQK78B5euBZaYnPX biNLSr5dk6o8D43DCuxl7wWLZMUHet9Rd5m8qFzem6n7yKRWQOVjYmV16ghC2t/KrOsC H4cE3/CYeEh1dqgy+HQ5noqlKQXd4WfR0j+LmA3xoyx8irJPjdJ5J9/0vcR2R2nuzZvS 6lUw== X-Gm-Message-State: AOAM5312+DbmRztbbEzGNiEBOYjkm5KG8GbkAzHDNohgpKsnMA91rP8X 4LflWfh2pSGEK9LD6cCyLtm4g3apSQB77UUTXz8= X-Google-Smtp-Source: ABdhPJx/ZG6wSCbB1Yy/ImTT5JyWZnjoGJMZCccUQdUNol+H6ual7pZBJzX4EMORUrrfeWGs4ZsVKLmi04PGgCR40V4= X-Received: by 2002:a17:907:7849:b0:6d5:87bd:5602 with SMTP id lb9-20020a170907784900b006d587bd5602mr9999030ejc.349.1648193920270; Fri, 25 Mar 2022 00:38:40 -0700 (PDT) MIME-Version: 1.0 References: <20220321095814.175891-1-cccheng@synology.com> <20220321095814.175891-2-cccheng@synology.com> <87lex2e91h.fsf@mail.parknet.co.jp> <87sfr917hr.fsf@mail.parknet.co.jp> <87o81x0wdv.fsf@mail.parknet.co.jp> In-Reply-To: <87o81x0wdv.fsf@mail.parknet.co.jp> From: Chung-Chiang Cheng Date: Fri, 25 Mar 2022 15:38:29 +0800 Message-ID: Subject: Re: [PATCH 2/2] fat: introduce creation time To: OGAWA Hirofumi Cc: Chung-Chiang Cheng , linux-fsdevel@vger.kernel.org, kernel@cccheng.net Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Mar 23, 2022 at 6:57 PM OGAWA Hirofumi wrote: > > No, a user can change the ctime to arbitrary time, and after the your > patch, the changed ctime only hold on a memory inode. So a user sees > ctime jump backward and forward when a memory inode is expired. (Of > course, this happens just by "cp -a" in real world use case.) > > I'm pointing about this introduced new behavior by your patch. > As you mentioned, there are still some cases to consider that ctime isn't identical to mtime. If so, ctime won't be consistent after inode is expired because it will be filled with the value of on-disk mtime, which is weird and confusing. To solve the issue, I propose to keep ctime and mtime always the same in memory. If you agree with this approach, I'll send a v2 patch for it. Thanks.