Re: Problem with NFS and XEN

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Fri, 2009-05-08 at 15:11 +0200, Roger Marcus wrote:
> Hi Trond,
> 
> Thank you for your answer.
> 
> exportfs does not report the individual directories that are mounted
> on the exported directory, so I cannot use your script.
> 
> on the nfsserver exports file:
> /adir     192.168.11.129(rw,sync,no_subtree_check,crossmnt,no_root_squash)
> 
> on the same machine:
> mount -o loop virtual.iso virtualstuff
> so now I have /adir/virtualstuff
> 
> (which by the way, I can:  umount virtualstuff immediately without
> problem and it releases.
> however, if I run XEN on the client, then the directory is permanently
> locked, ie, umount virtualstuff
> DOESN'T work again unless I run exportfs -ua killing all connections
> to the server.)
> 
> the nfs-client sees /adir/virtualstuff, since parent /adir is mounted.
> When I run the virtualmachine within the virtualstuff directory (xm
> create /adir/virtualstuff/config.cfg)
> and then I destroy the virtualmachine (xm destroy /adir/virtualstuff/config.cfg)
> I can never 'umount virtualstuff' from the nfsserver, even though no
> one is accessing the directory
> any more.
> 
> So on the nfsserver I cannot umount virtualstuff. this is the bug.
> 
> exportfs -ua    kills nfs for everybody, and then I can run 'umount
> virtualstuff', but this is not what I want.
> exportfs -u nfsclient:/adir       doesn't even work. I don't want this
> variation because I might be running 2 virtual machines
>                                                  in two subdirectories.
> 
> question: is the fact that ;exportfs -u nfsclient:/adir' doesn't work a bug?
> 
> What I want to be able to do is from the nfsserver side, 'umount
> virtualstuff', which I can do if I
> 1) never run XEN, or
> 2) exportfs -ua. The latter command kills all clients attached to the server
> so I cannot use this second command.
> 3) the command 'exportfs -u nfsclient:/adir' doesn't work and this
> might be a bug. I do not
> want this variant since if I am running 2 virtual machines on the
> nfsclient I would kill the other machine.
> 
> In /proc/net/rpc/nfsd.export/content   I see my virtualstuff
> subdirectory referenced. Perhaps this
> tells you something.
> 
> Thank you in advance,
> 
> Roger Marcus
> 

Oh, you're using crossmnt to export the subdirectories? In that case,
why doesn't just 'exportfs -f' suffice to allow you to unmount them?

Trond