vnode interface structure. the VOCALL,
VCALL, VDESC, and VOFFSET macros.
The vop_t table pointed to by a vnode is just a virtual
function table (vtable) used in programming languages with class inheritance.
The vnode_if.src and vnode_if.pl files.
generating interfaces from declarative descriptions. relationship
with remote procedure calls (RPCs) and RPC stub generators.
NFS:
Statelessness.
NFS uses RPCs.
The coherence/consistency issues -- very similar to those faced
in shared memory multiprocessors. Cache coherence protocols for
processor caches.