Description of Problem:
summary covers it

How Reproducible:
100%

Steps to Reproduce:
1. make a vfat filesystem
2. add it to /etc/exports
3. exportfs -a
4. attempt to mount it from another machine

Actual Results:
client gets EPERM;
server logs permission denied

Expected Results:
it should be able to be mounted

Additional Information:
It is claimed that user-space nfsd can export vfat filesystems; if so, then
knfsd should be able to as well.