Mailinglist Archive: opensuse-kernel (75 mails)

[Petr Uzel <petr.uzel@xxxxxxx>]

On Sun, Mar 13, 2011 at 06:03:20PM +0100, richard -rw- weinberger wrote:
> Hi,
>
> bind mounts seem not to work as expected on OpenSUSE 11.4.

Yes, it behaves slightly different as a consequence of making
/etc/mtab a symlink to /proc/self/mounts.

It's documented in mount(8):
---------
Note that behavior of the remount operation depends on the
/etc/mtab file. The first command stores the 'bind' flag to the
/etc/mtab file and the  second  command reads  the  flag  from  the
file. If you  have a system without the /etc/mtab file or if you
explicitly define source and target for the remount command (then
mount(8) does not read /etc/mtab), then you have to use bind flag (or
option) for the remount command too.  For example:

mount --bind olddir newdir
mount -o remount,ro,bind olddir newdir
---------

> E.g:
> $ mount /home /mnt -o bind
> $ mount | grep mnt
> /dev/sda1 on /mnt type ext3
> (rw,relatime,errors=continue,user_xattr,acl,commit=600,barrier=0,data=ordered)
> $ mount | grep sda1
> /dev/sda1 on / type ext3
> (rw,relatime,errors=continue,user_xattr,acl,commit=600,barrier=0,data=ordered)
> /dev/sda1 on /mnt type ext3
> (rw,relatime,errors=continue,user_xattr,acl,commit=600,barrier=0,data=ordered)
>
> mount shows me the for both / and /mnt /dev/sda1 as device.

Information about bind mounts is missing in /proc/self/mounts and thus
also in /etc/mtab. AFAIK this should and will be resolved with new
util-linux, which will store the bind information into
/dev/.mount/utab or something similar.

> The expected output is:
> /home on /mnt type none (rw,bind)
>
> The read-only bind mount also does not work.
> $ mount -o bind,ro /home /mnt
> mount: warning: /mnt seems to be mounted read-write.
> $ mount | grep mnt
> /dev/sda1 on /mnt type ext3
> (rw,relatime,errors=continue,user_xattr,acl,commit=600,barrier=0,data=ordered)

Try this:
mount -o bind /home /mnt
mount -o remount,ro,bind /mnt


> I can reproduce this on OpenSUSE 11.4 using 
> kernel-desktop-2.6.37.1-1.2.2.i586,
> kernel-vanilla-2.6.37.1-1.2.2.i586 and
> kernel-vanilla-2.6.37.3-16.1.i586 (from tumbleweed repo)
>
> But, on a CentOS 5.5 box with a hand compiled 2.6.37.3 kernel
> everything works as expected.
>
> Now I'm confused, is this a OpenSUSE or a kernel issue?

util-linux (known) issue.

HTH,

        Petr

--
Petr Uzel
IRC: ptr_uzl @ freenode