Media_changed (dev dev)

This function is very similar to the original function in structI>file_operations. It returns 1 if the medium of the device dev has changed since the last call, and 0 otherwise. Note that by `re-routing' this function through cdrom_media_changed (), we can implement separate queues for the VFS and a new ioctl () function that can report device changes to software (e.g., an auto-mounting daemon).