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Date:   Thu, 26 Dec 2019 17:54:09 -0800 (PST)
From:   Christian Kujau <lists@nerdbynature.de>
To:     Deepa Dinamani <deepa.kernel@gmail.com>,
        Jeff Layton <jlayton@kernel.org>
cc:     LKML <linux-kernel@vger.kernel.org>,
        Eric Biggers <ebiggers@google.com>,
        torvalds@linux-foundation.org
Subject: [PATCH] Re: filesystem being remounted supports timestamps until
 2038
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On Fri, 20 Dec 2019, Christian Kujau wrote:
> I noticed the following messages in my dmesg:
> 
>  xfs filesystem being remounted at /mnt/disk supports imestamps until 2038 (0x7fffffff)
> 
> These messages get printed over and over again because /mnt/disk is 
> usually a read-only mount that is remounted (rw) a couple of times a day 
> for backup purposes.
> 
> I see that these messages have been introduced with f8b92ba67c5d ("mount: 
> Add mount warning for impending timestamp expiry") resp. 0ecee6699064 
> ("fix use-after-free of mount in mnt_warn_timestamp_expiry()") and I was 
> wondering if there is any chance to either adjust this to pr_debug (but 
> then it would still show up in dmesg, right?) or to only warn once when 
> it's mounted, but not on re-mount?

I realize that "it's the holidays", but it'd be a shame if this gets 
forgotten :(


# uptime; dmesg | grep -c 2038
 14:45:15 up 6 days, 21:16,  1 user,  load average: 0.20, 0.22, 0.27
350

Attached is a "fix" that changes pr_warn into pr_debug, but that's maybe 
not what was intended here.


Thanks,
Christian.


commit c9a5338b4930cdf99073042de0717db43d7b75be
Author: Christian Kujau <lists@nerdbynature.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@nerdbynature.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,


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