Attached is the 2.4 patch need to support the  zeroing of RPC stats.
The 2.6 patch is  on people.redhat.com/steved/NFS/nfszerostats

I basically reused  tux's hex_write_proc() routine to
read a bit field from user land. Parts or all of the
rpc_stat or svc_stat structures will be zero depending
on which bit is set.

Also the permission modes on /proc/net/rpc/nfs[d] are
changed from 0444 to 0644 which signals to nfsstat
that zeroing is supported.

SteveD.