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

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Date:   Tue, 23 Jun 2020 17:26:49 -0700 (PDT)
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 Sat, 4 Jan 2020, Christian Kujau wrote:
> 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.

Is there any chance that this can be revisited perhaps? This is still 
flooding my dmesg just because I have that (curde?) mechanism in place to 
remount the backup device after the hourly backup-run to read-only. Sure, 
I could omit that ("Doc, it hurts when I do that", as Al would comment), 
but that's really the only repeating message that gets triggered because 
of this. 1067 messages in ~60 days of uptime :-|

Does the patch below make any sense, would that work?

Please reconsider,
Christian.

> 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.

commit c9a5338b4930cdf99073042de0717db43d7b75be
Author: Christian Kujau <lists@...dbynature.de>
Date:   Thu Dec 26 17:39:57 2019 -0800

    Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp expiry") resp.
    0ecee6699064 ("fix use-after-free of mount in mnt_warn_timestamp_expiry()") introduced
    a pr_warn message and the following gets sent to dmesg on every remount:
    
     [...] filesystem being remounted at /mnt supports timestamps until 2038 (0x7fffffff)
    
    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.
    
    Signed-off-by: Christian Kujau <lists@...dbynature.de>

diff --git a/fs/namespace.c b/fs/namespace.c
index be601d3a8008..afc6a13e7316 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2478,7 +2478,7 @@ static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *
 
 		time64_to_tm(sb->s_time_max, 0, &tm);
 
-		pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n",
+		pr_debug("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n",
 			sb->s_type->name,
 			is_mounted(mnt) ? "remounted" : "mounted",
 			mntpath,




-- 
BOFH excuse #66:

bit bucket overflow