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=-0.6 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, URIBL_BLOCKED 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 887FEC433FF for ; Mon, 12 Aug 2019 16:09:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DD6B20665 for ; Mon, 12 Aug 2019 16:09:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="RL/zKcoR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726916AbfHLQJs (ORCPT ); Mon, 12 Aug 2019 12:09:48 -0400 Received: from mail-ot1-f65.google.com ([209.85.210.65]:40866 "EHLO mail-ot1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725843AbfHLQJs (ORCPT ); Mon, 12 Aug 2019 12:09:48 -0400 Received: by mail-ot1-f65.google.com with SMTP id c34so20791384otb.7; Mon, 12 Aug 2019 09:09:47 -0700 (PDT) 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=xcEZapTx9gb37JnflSbAgedavIW6EzyB7mIFw5JH/4I=; b=RL/zKcoR3eseiuX8sGv2LyrWC/b4WTVuwxOEti92mbge9n/+BZjWUN09bSaUd5Yetp QfeDIuKE0L/Qtb12fk/DKfF7rFMTqZhe+gqgdZIXL5tFIIfaPVftPBGAK4lo5N9ScW9I /KOsv515ZKyKzjzzNqo5izPIdyhkSr1y3JwZEmR1MX7hoIlVb2mMNDdNeuKrHKZ685T0 gTkl9Lqr+rfY9q22jOqYUdw0SaUiGmNXHfG5uZ+0Vq4bOC1kWmMwzPYNQjQKOqxkgmj6 S5KwLEgtNPFjM0ToQJCl9J7jpNRIjq98QVy5B81zDLKQmdsYYxIxMHJkbFQtGT4LFmC0 OSuA== 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=xcEZapTx9gb37JnflSbAgedavIW6EzyB7mIFw5JH/4I=; b=GMLWA4XwvjrbSesDssIVSjGoTMrqfYFovuWqhZvcykMx74ngZd3AN4dbxOSjlmLrgP svT+eycdT9VnlgyzJSWrpzVIZyeUL1/lzJru7CCr78SmwYIFoqi1iIYXJogYHMpKUKLe kF+DROi2EC8GK1ZmYuOUtucZ2PswnkxNrbB0I3c6icvL7jZnf+7yhdOv4eFFyALvWTYm Wm8UnvRyMFQ6KBVsboqdIimCgVp4b6bu/nMmqlWvI8DerCk7FnD3Q8LPr5nMzS/Yppf1 H7z5YANm7bl7892R0oBBCF72HkXFMusdIONBjlKAMvnP/csHzMgBwz+U+mS7gliWObh4 2Ebw== X-Gm-Message-State: APjAAAXp24v2oglm9OWR6GdDm7hp3uVDIppiqbP7Ys8fKsP6gCmP3GLg CK+NZQlW+M5HUplxAh0TGk8Ro9hLH7pd49Z5ovdG7u8O X-Google-Smtp-Source: APXvYqzqWtEXtUQlBMqRX1uDe/YrNtqz5xPnjIc7b2b3dlEkqoGwt44wKdLkzm254HXxruY2qKjts8H3vyqtwIAme+E= X-Received: by 2002:a02:c012:: with SMTP id y18mr27966443jai.85.1565626187318; Mon, 12 Aug 2019 09:09:47 -0700 (PDT) MIME-Version: 1.0 References: <20190730014924.2193-1-deepa.kernel@gmail.com> <20190730014924.2193-5-deepa.kernel@gmail.com> <53df9d81bfb4ee7ec64fabf1089f91d80dceb491.camel@codethink.co.uk> In-Reply-To: From: Deepa Dinamani Date: Mon, 12 Aug 2019 09:09:35 -0700 Message-ID: Subject: Re: [Y2038] [PATCH 04/20] mount: Add mount warning for impending timestamp expiry To: Arnd Bergmann Cc: Ben Hutchings , Alexander Viro , Linux Kernel Mailing List , Linux FS-devel Mailing List , y2038 Mailman List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 12, 2019 at 7:11 AM Arnd Bergmann wrote: > > On Mon, Aug 12, 2019 at 3:25 PM Ben Hutchings > wrote: > > On Sat, 2019-08-10 at 13:44 -0700, Deepa Dinamani wrote: > > > On Mon, Aug 5, 2019 at 7:14 AM Ben Hutchings > > > wrote: > > > > On Mon, 2019-07-29 at 18:49 -0700, Deepa Dinamani wrote: > > > > > The warning reuses the uptime max of 30 years used by the > > > > > setitimeofday(). > > > > > > > > > > Note that the warning is only added for new filesystem mounts > > > > > through the mount syscall. Automounts do not have the same warning. > > > > [...] > > > > > > > > Another thing - perhaps this warning should be suppressed for read-only > > > > mounts? > > > > > > Many filesystems support read only mounts only. We do fill in right > > > granularities and limits for these filesystems as well. In keeping > > > with the trend, I have added the warning accordingly. I don't think I > > > have a preference either way. But, not warning for the red only mounts > > > adds another if case. If you have a strong preference, I could add it > > > in. > > > > It seems to me that the warning is needed if there is a possibility of > > data loss (incorrect timestamps, potentially leading to incorrect > > decisions about which files are newer). This can happen only when a > > filesystem is mounted read-write, or when a filesystem image is > > created. > > > > I think that warning for read-only mounts would be an annoyance to > > users retrieving files from old filesystems. > > I agree, the warning is not helpful for read-only mounts. An earlier > plan was to completely disallow writable mounts that might risk an > overflow (in some configurations at least). The warning replaces that > now, and I think it should also just warn for the cases that would > otherwise have been dangerous. Ok, I will make the change to exclude new read only mounts. I will use __mnt_is_readonly() so that it also exculdes filesystems that are readonly also. The diff looks like below: - if (!error && sb->s_time_max && + if (!error && !__mnt_is_readonly(mnt) && (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) { Note that we can get rid of checking for non zero sb->s_time_max now. -Deepa