libhal_volume_get_device_file
libhal_volume_get_device_file (volume_to_unmount),
mounted_vol_device_file = libhal_volume_get_device_file (mounted_vol);
if ((device = libhal_volume_get_device_file(v)) ==
dev = libhal_volume_get_device_file(v);
const char *libhal_volume_get_device_file (LibHalVolume *volume);