There is a problem in the interaction between the Kernel
nfsd and the rpc.mountd command. The kernel provides
services for NFS version 2, but rpc.mountd registers itself
as supporting version 1,2 and 3. This causes an NFS3 client
(like SGI IRIX) to try to mount a linux filesystem using
version 3, but whenever it tries to do any actual I/O on the
filesystem, the I/O fails with a version error.
I worked around the bug by fixing the NFS startup script to
pass -V 2 -N 3 as arguments to rpc.mountd.
A better fix would of course be to add support for NFS V3.
It looks like there are bits and pieces of it in the kernel
sources, but they did not seem to make it into the build.
*** This bug has been marked as a duplicate of 2973 ***