NFSv4 defines a number of state errors which the client does not currently
handle. Among those we should worry about are:
NFS4ERR_ADMIN_REVOKED - the server's administrator revoked our locks
and/or delegations.
NFS4ERR_BAD_STATEID - the client and server are out of sync, possibly
due to a delegation return racing with an OPEN
request.
NFS4ERR_OPENMODE - the client attempted to do something not sanctioned
by the open mode of the stateid. Should normally just
occur as a result of a delegation return race.