partly revoking NFS export

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

Is there a way to partly revoke NFS export, temporarily?

Say I export /export/foo and /export/bar and I want to fsck /export/foo while 
continuing to export /export/bar.

What would happen if I remove /export/foo from /etc/exports (and HUP mountd) 
and then unmount it? Would NFS clients get ESTALE for any files they happen 
to have open? Is there a way to make them just hang on those files until I 
re-mount and re-export the file system?