GNU bug report logs - #19491
/etc/mtab give wrong entries for early-mounted items.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: 宋文武 <iyzsong <at> gmail.com>
To: bug-guix <at> gnu.org
Subject: /etc/mtab give wrong entries for early-mounted items.
Date: Fri, 02 Jan 2015 20:13:48 +0800

Notably, I have:
  /dev/sda1 /root ext4 rw,relatime,data=ordered 0 0
  none /root//dev devtmpfs rw 0 0

Which should be:
  /dev/sda1 / ...
  none /dev ...

Why not make /etc/mtab a symlink to /proc/self/mounts?

Message #8 received at 19491 <at> debbugs.gnu.org (full text, mbox):

From: ludo <at> gnu.org (Ludovic Courtès)
To: 宋文武 <iyzsong <at> gmail.com>
Cc: 19491 <at> debbugs.gnu.org
Subject: Re: bug#19491: /etc/mtab give wrong entries for early-mounted items.
Date: Sat, 03 Jan 2015 19:57:40 +0100

宋文武 <iyzsong <at> gmail.com> skribis:

> Notably, I have:
>   /dev/sda1 /root ext4 rw,relatime,data=ordered 0 0
>   none /root//dev devtmpfs rw 0 0
>
> Which should be:
>   /dev/sda1 / ...
>   none /dev ...
>
> Why not make /etc/mtab a symlink to /proc/self/mounts?

This sounds appealing, but it seems that libmount in util-linux will
insist to update /etc/mtab.

Do you have evidence that it could cope with it?

Thanks,
Ludo’.

Message #11 received at 19491 <at> debbugs.gnu.org (full text, mbox):

From: 宋文武 <iyzsong <at> gmail.com>
To: Ludovic Courtès <ludo <at> gnu.org>
Cc: 19491 <at> debbugs.gnu.org
Subject: Re: bug#19491: /etc/mtab give wrong entries for early-mounted items.
Date: Sun, 04 Jan 2015 20:50:07 +0800

Ludovic Courtès <ludo <at> gnu.org> writes:

> 宋文武 <iyzsong <at> gmail.com> skribis:
>
>> Notably, I have:
>>   /dev/sda1 /root ext4 rw,relatime,data=ordered 0 0
>>   none /root//dev devtmpfs rw 0 0
>>
>> Which should be:
>>   /dev/sda1 / ...
>>   none /dev ...
>>
>> Why not make /etc/mtab a symlink to /proc/self/mounts?
>
> This sounds appealing, but it seems that libmount in util-linux will
> insist to update /etc/mtab.
>
> Do you have evidence that it could cope with it?
Not sure, but I think libmount should just work fine.

util-linux support this since 2.19:
  https://www.kernel.org/pub/linux/utils/util-linux/v2.19/v2.19-ReleaseNotes

Debian make this default at 2011:
  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=494001
>
> Thanks,
> Ludo’.

Message #14 received at 19491 <at> debbugs.gnu.org (full text, mbox):

From: ludo <at> gnu.org (Ludovic Courtès)
To: 宋文武 <iyzsong <at> gmail.com>
Cc: 19491 <at> debbugs.gnu.org
Subject: Re: bug#19491: /etc/mtab give wrong entries for early-mounted items.
Date: Sun, 04 Jan 2015 17:04:58 +0100

宋文武 <iyzsong <at> gmail.com> skribis:

> Ludovic Courtès <ludo <at> gnu.org> writes:
>
>> 宋文武 <iyzsong <at> gmail.com> skribis:
>>
>>> Notably, I have:
>>>   /dev/sda1 /root ext4 rw,relatime,data=ordered 0 0
>>>   none /root//dev devtmpfs rw 0 0
>>>
>>> Which should be:
>>>   /dev/sda1 / ...
>>>   none /dev ...
>>>
>>> Why not make /etc/mtab a symlink to /proc/self/mounts?
>>
>> This sounds appealing, but it seems that libmount in util-linux will
>> insist to update /etc/mtab.
>>
>> Do you have evidence that it could cope with it?
> Not sure, but I think libmount should just work fine.
>
> util-linux support this since 2.19:
>   https://www.kernel.org/pub/linux/utils/util-linux/v2.19/v2.19-ReleaseNotes
>
> Debian make this default at 2011:
>   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=494001

OK, it sounds like it’s safe, then.  :-)

Would you like to propose a patch?  There are changes to make around
linux-boot.scm, and also in (guix build syscalls) the #:update-mtab?
argument should default to #f.

Thanks,
Ludo’.

Message #19 received at 19491-done <at> debbugs.gnu.org (full text, mbox):

From: 宋文武 <iyzsong <at> gmail.com>
To: 19491-done <at> debbugs.gnu.org
Subject: bug#19491: Fixed
Date: Thu, 08 Jan 2015 21:11:02 +0800

Fixed in commit 9331ba5d
by make /etc/mtab a symlink to /proc/self/mounts.

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