proto_cc_open
int proto_cc_open(struct puffs_usermount *, p9pfid_t, p9pfid_t, int);
error = proto_cc_open(pu, p9n->fid_base, nfid,
error = proto_cc_open(pu, p9n->fid_base, nfid,
rv = proto_cc_open(pu, p9n->fid_base, dfp->fid, P9PROTO_OMODE_READ);