new mount is broken w/regard to devnames in /etc/fstab

new mount is broken w/regard to devnames in /etc/fstab

[Linda Walsh]

There are 2 problems -- they are unlikely to be
directly related, but are in so much as they are in the new version
of mount.

1) How is one supposed to get the real root device?
It's not /dev/root -- and on my system /dev/root doesn't even exist.
(though to be fair, it has in the past -- udev musta got sloppy this time,
and did point to the real root device).  But how can I get /proc to display
the real root device instead of some fake name.   

It's insecure the way it is -- as /dev/root could be "anything"...

2) I'd like lvm's naming to be available through mount.  Ideally, lvm's
naming would be available in /proc/mounts...  At least, though
in going from /dev/VG/LV => /dev/mapper/VG-LV, that can be
scripted reliably to get the mount device name. 

But /dev/root?... How to script that, *reliably*...
And why the bogus name?

Re: new mount is broken w/regard to devnames in /etc/fstab

[Karel Zak]

On Sat, May 18, 2013 at 04:02:02PM -0700, Linda Walsh wrote:
> 1) How is one supposed to get the real root device?
> It's not /dev/root -- and on my system /dev/root doesn't even exist.
> (though to be fair, it has in the past -- udev musta got sloppy this time,
> and did point to the real root device).  But how can I get /proc to display
> the real root device instead of some fake name.   
> 
> It's insecure the way it is -- as /dev/root could be "anything"...

I don't think this is util-linux issue. It's more distro specific and 
related to kernel & initramfs & udevd.

For example my Fedora 18:

$ findmnt /                                                                 
TARGET SOURCE    FSTYPE OPTIONS
/      /dev/sda4 ext4   rw,relatime,data=ordered

$ df /
Filesystem     1K-blocks     Used Available Use% Mounted on
/dev/sda4       35146488 16233036  17121452  49% /

$ grep ' / ' /proc/mounts                                
rootfs / rootfs rw 0 0
/dev/sda4 / ext4 rw,relatime,data=ordered 0 0


> 2) I'd like lvm's naming to be available through mount.  Ideally, lvm's
> naming would be available in /proc/mounts...  At least, though
> in going from /dev/VG/LV => /dev/mapper/VG-LV, that can be
> scripted reliably to get the mount device name. 

For example lsblk(8) should be able to convert to the /dev/mapper
format

   lsblk -rno NAME /dev/VG/LV

you can also use /dev/VG/LV for findmnt(8), it should be able to
convert the names for /dev/mapper/VG-LV to search for mountpoint.

.. or use /dev/mapper/<name> in your /etc/fstab ;-)

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: new mount is broken w/regard to devnames in /etc/fstab

[Helmut Hullen]

Hallo, Linda,

Du meintest am 18.05.13:



> There are 2 problems -- they are unlikely to be
> directly related, but are in so much as they are in the new version
> of mount.

> 1) How is one supposed to get the real root device?
> It's not /dev/root -- and on my system /dev/root doesn't even exist.
> (though to be fair, it has in the past -- udev musta got sloppy this
> time, and did point to the real root device).  But how can I get
> /proc to display the real root device instead of some fake name.

        rdev

should do the job.

Viele Gruesse!
Helmut

Re: new mount is broken w/regard to devnames in /etc/fstab

[Helmut Hullen]

Hallo, Linda,

Du meintest am 18.05.13:

> 1) How is one supposed to get the real root device?

        rdev

> It's not /dev/root -- and on my system /dev/root doesn't even exist.
> (though to be fair, it has in the past -- udev musta got sloppy this
> time, and did point to the real root device).

My system doesn't use "udev", it has no "/dev/root" entry, and it shows  
since some (few) years "/dev/root" when I invoke "df". No problem.

Viele Gruesse!
Helmut