Showing NFS server client mounts

[redhat buglecreek com]

Does any one know of a way to accurately show which clients are
currently mounted to a nfs server. The showmount command is always
inaccurate due to stale entries in rmtab.  

On a nfs server that definitely does not have any remote mounts using
showmount shows many clients mounted.  I have also tried looking at the
contents of /var/lib/nfs/xtab, it is sometimes correct and other times
it mirrors the output of showmount.  Using exportfs -r seems to sync the
wrong data (showmount output) to /var/lib/nfs/xtab.  According to the
man page exportfs -f only works in new mode (2.6 kernel), this server
runs a 2.4 kernel.  Is there any other way to get accurate client mount
information?

Thanks