Note
For optimal reliability and performance, use file system minifilter drivers with Filter Manager support instead of legacy file system filter drivers. To port your legacy driver to a minifilter driver, see Guidelines for Porting Legacy Filter Drivers.
A legacy file system filter driver's completion routine normally returns one of the following two NTSTATUS values to the caller:
STATUS_SUCCESS
STATUS_MORE_PROCESSING_REQUIRED
STATUS_SUCCESS indicates that the driver is finished with the IRP and allows the I/O Manager to continue completion processing on the IRP.
STATUS_MORE_PROCESSING_REQUIRED halts the I/O Manager's completion processing on the IRP.
If any other NTSTATUS value is returned, the I/O Manager resets it to STATUS_SUCCESS.
For more information about returning STATUS_MORE_PROCESSING_REQUIRED, see Constraints on Completion Routines.