Can not read from ZFS exported over NFSv4 but write to it

[Yamagi Burmeister]

Hello

On Tue, 23 Oct 2012 17:55:15 -0400 (EDT)
Rick Macklem <rmacklem at uoguelph.ca> wrote:

> > # ZFS
> > /usr/home/yamagi
> > # UFS
> > /mnt
> > V4: / -sec=sys 192.168.0.13
> > 
> For ZFS, all volumes down to yamagi must be exported.
> You don't show what your ZFS setup is, but you either
> need to export "home" and "usr" if those are ZFS volumes.
> (The above /etc/exports would be ok, only if /, /usr and
> /home are all UFS volumes and /usr/home/yamagi is the root
> of a ZFS volume.) For UFS, non-exported volumes can be
> traversed by "mount", but for ZFS that is not the case.
> 
> The only way I know of to fix this inconsistency is to
> disable the traversal capability for UFS, but that would
> be a POLA violation, so the inconsistency (caused by ZFS
> checking exports itself instead of leaving to the VFS layer)
> remains.
> 
> OR
> you can specify the root of V4 in the exported volume.
> For example, you could:
> # ZFS
> /usr/home/yamagi
> V4: /usr/home/yamagi -sec=sys 192.168.0.13
> 
> And then the client mount would be:
> a:/ on /mnt
> since "/" would be at /usr/home/yamagi. (If you do this,
> the /mnt UFS volume wouldn't be mountable via NFSv4.)

Okay, I didn't know that. What about adding a small notice to the nfsv4
(4) manpage to put users into the right direction?

A correct /etc/exports didn't solve the problem. So I took some
tcpdumps, while analyzing them I noticed that packages send by client
never arived at the server. After I changed the NIC (I was using a
rather cheap age(4) onboard NIC) everything worked okay. Apparently
NFSv4 exhibited a bug in the driver that never showed up before. I'm
sorry that i've wasted your time.

Thanks again,
Yamagi

-- 
Homepage:  www.yamagi.org
XMPP:      yamagi at yamagi.org
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