linux-kernel - Re: [Y2038] [PATCH 04/20] mount: Add mount warning for impending timestamp expiry

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Message-ID: <53df9d81bfb4ee7ec64fabf1089f91d80dceb491.camel@codethink.co.uk>
Date:   Mon, 12 Aug 2019 14:25:38 +0100
From:   Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:     Deepa Dinamani <deepa.kernel@...il.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
        y2038 Mailman List <y2038@...ts.linaro.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [Y2038] [PATCH 04/20] mount: Add mount warning for impending
 timestamp expiry

On Sat, 2019-08-10 at 13:44 -0700, Deepa Dinamani wrote:
> On Mon, Aug 5, 2019 at 7:14 AM Ben Hutchings
> <ben.hutchings@...ethink.co.uk> 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.

Ben.

-- 
Ben Hutchings, Software Developer                         Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
                                     Manchester, M1 2HF, United Kingdom