Re: [uml-devel] df -h and hostfs

[Blaisorblade <blaisorblade@yahoo.it>]

On Wednesday 12 January 2005 19:22, stian@nixia.no wrote:
> >> df -h inside UML: (/etc/mtab is symlinked to /proc/mounts)
> >>
> >> Filesystems           Size  Used Avail Use% Mounted on
> >> rootfs                496M   11M  460M   3% /
> >> /dev/root             496M   11M  460M   3% /
> >> /dev/ubd/disc1/part1  187G  146G   33G  82% /a
> >> a                     7.3G  6.2G  717M  90% /a/lost+found
> >> /root/UML/a           7.3G  6.2G  717M  90% /a/lost+found
> >
> > What has happened here? Why there are two entries on the same mount
> > point? One
> > mount over the other?

Well, there is a big question - is there in the patchset a "hostfs" or 
"externfs" patch? In that case, if you used the *new* hostfs code, everything 
I said disappears, because that's completely different code.

Only in the other case, you can find below my answer.

> I just used
> mount /root/UML/a /a/lost+found -t hostfs
Hmm, like I supposed. This is the wrong command line. To mount the 
host /root/UML/a, you need to use this syntax:

mount none /a/lost+found -t hostfs -o /root/UML/a

This is the correct syntax.
> why should you need an -o ? The mount-point works, and everything inside
> it looks like it should,

Well, do you claim that it contains only the content of /root/UML/a on the 
host?

I think that this is false, and I just tested this on my UML (2.6.9-bs5):

root@zion:~ (0)# umount /mnt/host/
root@zion:~ (0)# mount /bin/ -t hostfs /mnt/host/
root@zion:~ (0)# ls /mnt/host/
bin/   dev/   etc/   lib/  opt@   root/  sys/  usr/
boot/  disk@  home/  mnt/  proc/  sbin/  tmp/  var/
root@zion:~ (0)# umount /mnt/host/

root@zion:~ (0)# mount none  -t hostfs /mnt/host/ -o /bin
root@zion:~ (0)# ls /mnt/host/
Mail@          df*             install*        pidof@       tar*
root@zion:~ (0)# umount /mnt/host/

Satisfied? If that syntax works on your kernel, something *very* strange is 
happening.
> and files I put into it appears as they should (I 
> used that directory, since the uml-filesystem is just banged together som
> files from /bin so I could fix a disk, use /bin/sh as init for instance)

> An those entries as what likes in /proc/mounts, since I don't have a
> maintained /etc/mtab file in that filesystem. /etc/mtab is symlinked to
> /proc/mounts
Ok, understood, but the duplicate entry still seems a bit strange...

-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade


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