/*
* File handle to vnode
*
* Have to be really careful about stale file handles:
* - check that the inode number is valid
* - call ffs_vget() to get the locked inode
* - check for an unallocated inode (i_mode == 0)
* - check that the given client host has export rights and return
* those rights via. exflagsp and credanonp
*/