Reiser4 and NFS

[Oliver Korpilla <okorpil@fh-landshut.de>]

Hello!

I've recently upgraded my Debian Sarge to use a Reiser4 as a root filesystem out 
of curiosity.

I've been doing development on this box, involving serving a root filesystem to 
an embedded target via NFS.

My box (the host) is a vanilla kernel.org Linux 2.6.8.1-mm1 with 
reiser-all.diff.gz patchset. It's configured to serve NFSv3.

The target has a TimeSys 2.4.21 (realtime) Linux kernel with NFSv3 client support.

Before that, I've used 2.4.26 with an ext3 filesystem, and everything went fine. 
Then I've upgraded kernel and my root filesystem (to Reiser4, I surely consider 
that an upgrade! ;) ), and I get NFS error -45 (Operation not supported), when 
target wants to do the LOOKUP operation (I can see that on Ethereal).

I've found a similar error occuring when serving VFAT partitions over NFS:
http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-02/7848.html

I've switched the particular subtree of my root FS that I want to serve via NFS 
back to ext3, and the problem is gone, so this problem is clearly rooted in the 
interaction between NFS and Reiser4.

If I were to do a wild guess, I'd say: Since both VFAT and Reiser4 directory 
semantics differ from "standard Unix" (or at least ext*) conventions, this is 
interferring with the NFS LOOKUP operation, don't you think?

I'll be glad to provide any additional information if required.

Thanks and with kind regards,
Oliver Korpilla