AUTOFS_DEV_IOCTL_IOC_FIRST
#define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||