rfs4_check_clientid
rfs4_check_clientid(&ap->lock_owner.clientid, 0);
rfs4_check_clientid(&args->clientid, 0);
rfs4_check_clientid(&owner->clientid, 0);
rfs4_check_clientid(&args->clientid, 1);
rfs4_check_clientid(&args->owner.clientid, 0);
extern nfsstat4 rfs4_check_clientid(clientid4 *, int);