FLT_PREOP_SUCCESS_NO_CALLBACK
The minifilter driver is returning the I/O operation to the filter manager for further processing. In this case, the filter manager does not call the minifilter driver's post-operation callback, if one exists, during I/O completion.
FLT_PREOP_SUCCESS_WITH_CALLBACK
The minifilter driver is returning the I/O operation to the filter manager for further processing. In this case, the filter manager calls the minifilter driver's post-operation callback during I/O completion.