linux-kernel - Re: [PATCH] Re: filesystem being remounted supports timestamps until 2038

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Message-ID: <alpine.DEB.2.21.99999.375.2001041545350.21037@trent.utfs.org>
Date:   Sat, 4 Jan 2020 15:51:57 -0800 (PST)
From:   Christian Kujau <lists@...dbynature.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     Deepa Dinamani <deepa.kernel@...il.com>,
        Jeff Layton <jlayton@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Eric Biggers <ebiggers@...gle.com>
Subject: Re: [PATCH] Re: filesystem being remounted supports timestamps until
 2038

On Sun, 29 Dec 2019, Linus Torvalds wrote:
> >     When file systems are remounted a couple of times per day (e.g. rw/ro for backup
> >     purposes), dmesg gets flooded with these messages. Change pr_warn into pr_debug
> >     to make it stop.
> 
> How about just doing it once per mount?

Yes, once per mount would work, and maybe not print a warning on remounts 
at all.

Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp 
expiry") introduced:

   Mounted %s file system at %s supports timestamps until [...]

in mnt_warn_timestamp_expiry(), but then 0ecee6699064 ("fs/namespace.c: 
fix use-after-free of mount in mnt_warn_timestamp_expiry") changed this to

  %s filesystem being %s at %s supports timestamps until [...]

in order to fix a use-after-free.

> Of course, if you actually unmount and completely re-mount a
> filesystem, then that would still warn multiple times, but at that
> point I think it's reasonable to do.

Yes, of course. Umount/remount cycles should still issue a warning, but 
"-o remount" should not, IMHO.

Thanks,
Christian.
-- 
BOFH excuse #108:

The air conditioning water supply pipe ruptured over the machine room