NbtDispatchCleanup(
  IN  PDEVICE_OBJECT   Device,
  IN  PIRP             irp
  );

Routine Description:

    This is the NBT driver's dispatch function for IRP_MJ_CLEANUP
    requests.

    This function is called when the last reference to the handle is closed.
    Hence, an NtClose() results in an IRP_MJ_CLEANUP first, and then an
    IRP_MJ_CLOSE.  This function runs down all activity on the object, and
    when the close comes in the object is actually deleted.

Arguments:

    device    - ptr to device object for target device
    irp       - ptr to I/O request packet

Return Value:

    STATUS_SUCCESS