PIOCPARM_MASK
inp->coda_ioctl.cmd = (cmd & ~(PIOCPARM_MASK << 16));
iocsize = ((cmd >> 16) & PIOCPARM_MASK) - sizeof(char *) - sizeof(int);
inp->coda_ioctl.cmd |= (iocsize & PIOCPARM_MASK) << 16;