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 F3387C433EF for ; Fri, 25 Mar 2022 10:36:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349965AbiCYKiR (ORCPT ); Fri, 25 Mar 2022 06:38:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50360 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358922AbiCYKhw (ORCPT ); Fri, 25 Mar 2022 06:37:52 -0400 Received: from mail.parknet.co.jp (mail.parknet.co.jp [210.171.160.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id CC02EB6D33 for ; Fri, 25 Mar 2022 03:36:18 -0700 (PDT) Received: from ibmpc.myhome.or.jp (server.parknet.ne.jp [210.171.168.39]) by mail.parknet.co.jp (Postfix) with ESMTPSA id CE3CF15F939; Fri, 25 Mar 2022 19:36:17 +0900 (JST) Received: from devron.myhome.or.jp (foobar@devron.myhome.or.jp [192.168.0.3]) by ibmpc.myhome.or.jp (8.16.1/8.16.1/Debian-2) with ESMTPS id 22PAaGkh043315 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Fri, 25 Mar 2022 19:36:17 +0900 Received: from devron.myhome.or.jp (foobar@localhost [127.0.0.1]) by devron.myhome.or.jp (8.16.1/8.16.1/Debian-2) with ESMTPS id 22PAaGB5151513 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Fri, 25 Mar 2022 19:36:16 +0900 Received: (from hirofumi@localhost) by devron.myhome.or.jp (8.16.1/8.16.1/Submit) id 22PAaGWQ151512; Fri, 25 Mar 2022 19:36:16 +0900 From: OGAWA Hirofumi To: Chung-Chiang Cheng Cc: Chung-Chiang Cheng , linux-fsdevel@vger.kernel.org, kernel@cccheng.net Subject: Re: [PATCH 2/2] fat: introduce creation time 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> Date: Fri, 25 Mar 2022 19:36:16 +0900 In-Reply-To: (Chung-Chiang Cheng's message of "Fri, 25 Mar 2022 15:38:29 +0800") Message-ID: <87cziapbdr.fsf@mail.parknet.co.jp> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Chung-Chiang Cheng writes: > 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. Yes, exactly. Although I think it is better, in real world userspace, it may got actual compatibility issue and reported, then we may have to revert even if I personally think new is better. Thanks. -- OGAWA Hirofumi