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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 A19AEC33CB1 for ; Wed, 15 Jan 2020 14:24:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76388214AF for ; Wed, 15 Jan 2020 14:24:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="bVvlc4q8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726562AbgAOOYc (ORCPT ); Wed, 15 Jan 2020 09:24:32 -0500 Received: from mail-wm1-f67.google.com ([209.85.128.67]:37481 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726440AbgAOOYc (ORCPT ); Wed, 15 Jan 2020 09:24:32 -0500 Received: by mail-wm1-f67.google.com with SMTP id f129so44831wmf.2; Wed, 15 Jan 2020 06:24:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=/cV4Dosms8WVB2oaAlg7z/oFwAecJU/lIwjN6rGAxM8=; b=bVvlc4q8m8fhK0Z9DySQFpKNp6uE8a9NG/bVO5p6RoTPSFGT18+CVCybpNpmxjkCRk DM8inpDxNv5gzVK8mV/ptdfNwHPjW8FJFSOIx+5nzWdGwdyC4u34KU+gfzSCM5yYQShp dT9Aj+aPX/wav9Wc8s2Bh6pH1gZYSGgwpnB8BPBnfdrNxS1Q7ZLDPIdXvcoKgeRZEKiq z7hha2oGjhjAMRotvZYt9gA8VuV8aK2qrxzA5bHWNPbA/KW8Bkcyz/PvLsEXzSOXFgNY hqsy8FfA+80kEu37WvXFFtkZk4gvZ0KZNYVSuifWRxO+N5gFe22oZGrW5HC7tgPQEZSq TPNQ== 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:content-transfer-encoding :in-reply-to:user-agent; bh=/cV4Dosms8WVB2oaAlg7z/oFwAecJU/lIwjN6rGAxM8=; b=crB4sbTOl5pl8kppQdXMJ6QU+oVi1Dcy1ciwg2I+YD3xxXLlrg1j4qI1lZakl1Ge1h 8Yvsi02j3/YoPPiwMAYH4lmmeY2JOZ61fTL6kDwVLf2pXnQPu9CbMQDhy6/8hup/ROaS A6wZBSwUIRvBhmZzSFKlrV7cgyUBOcL0R/a4Vk5WBvUD4oZWjoGihZr/F63cqMA/U9tv U4V1y/4D6E89cze+h4tN3BnZGygxVWI0YQQQLT87lqE0Z9aerLPbD74vOxFH8G55fvVF rVWKdRFOu78WtrSwv7Sc8ZQpeXxF3GDR8V6HZVIfiQJwIuQ9dxk6+T7e945uhfzcjA9U xGfg== X-Gm-Message-State: APjAAAW532U3sCC4GlPwBkKTznCOS1joA0NyOblFcMfl+tICWtX4Zk0k bIhBANk2VTs+hILWNuMD07g= X-Google-Smtp-Source: APXvYqxTwabGn05HpEh7ACRTNrjX9YrY1gcLlaH7ueZdUinow1DSehKVBJkyalyeYPRke/izr14LYg== X-Received: by 2002:a7b:cb0d:: with SMTP id u13mr35307563wmj.31.1579098269992; Wed, 15 Jan 2020 06:24:29 -0800 (PST) Received: from pali ([2a02:2b88:2:1::5cc6:2f]) by smtp.gmail.com with ESMTPSA id v8sm23733273wrw.2.2020.01.15.06.24.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jan 2020 06:24:29 -0800 (PST) Date: Wed, 15 Jan 2020 15:24:28 +0100 From: Pali =?utf-8?B?Um9ow6Fy?= To: Arnd Bergmann Cc: Namjae Jeon , Namjae Jeon , "linux-kernel@vger.kernel.org" , Linux FS-devel Mailing List , gregkh , Valdis Kletnieks , Christoph Hellwig , sj1557.seo@samsung.com Subject: Re: [PATCH v10 09/14] exfat: add misc operations Message-ID: <20200115142428.ugsp3binf2vuiarq@pali> References: <20200115082447.19520-1-namjae.jeon@samsung.com> <20200115082447.19520-10-namjae.jeon@samsung.com> <20200115133838.q33p5riihsinp6c4@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20180716 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wednesday 15 January 2020 14:50:10 Arnd Bergmann wrote: > On Wed, Jan 15, 2020 at 2:38 PM Pali Rohár wrote: > > On Wednesday 15 January 2020 22:30:59 Namjae Jeon wrote: > > > 2020-01-15 19:10 GMT+09:00, Arnd Bergmann : > > > > It is not described in the specification. I don't know exactly what > > > the problem is because sys_tz.tz_minuteswest seems to work fine to me. > > > It can be random garbage value ? > > > > > > > so if there is a choice, falling back to UTC would > > > > be nicer. > > > > > > Okay. > > > > Arnd, what is the default value of sys_tz.tz_minuteswest? What is the > > benefit of not using it? > > > > I though that timezone mount option is just an old hack when userspace > > does not correctly set kernel's timezone and that this timezone mount > > option should be in most cases avoided. > > The main problem is that it is system-wide and initialized at boot > time through settimeofday() to a timezone picked by the system > administrator. > > However, in user space, every user may set their own timezone with > the 'TZ' variable, and the default timezone may be different inside of a > container based on the contents of /etc/timezone in its root directory. So kernel timezone is shared across all containers, right? > > So also another question, what is benefit of having fs specific timezone > > mount option? As it is fs specific it means that it would be used so > > much. > > You can use it to access removable media that were written in > a different timezone or a partition that is shared with another OS > running on the same machine but with different timezone settings. So... basically all userspace <--> kernel API which works with timestamp do not have information about timezone right? creat(), utime() or utimensat() just pass timestamp without timezone information. Is this timestamp mean to be in UTC or in local user time zone (as specified by user's TZ= env variable)? -- Pali Rohár pali.rohar@gmail.com