Registering Fast I/O Dispatch Routines

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.

The DriverObject parameter of the legacy filter driver's DriverEntry routine supplies a pointer to the filter driver's driver object.

To register the file system filter driver's fast I/O dispatch routines, you must allocate and initialize a fast I/O dispatch table, store the entry points of the fast I/O dispatch routines into the table, and store the address of the table in the FastIoDispatch member of the driver object.

For example, a hypothetical "MyLegacyFilter" driver can set the entry points for its fast I/O dispatch routines as follows:

RtlZeroMemory(fastIoDispatch, sizeof(FAST_IO_DISPATCH));
fastIoDispatch->SizeOfFastIoDispatch = sizeof(FAST_IO_DISPATCH);
fastIoDispatch->FastIoCheckIfPossible = MyLegacyFilterIoCheckIfPossible;
fastIoDispatch->FastIoRead = MyLegacyFilterIoRead;
fastIoDispatch->FastIoWrite = MyLegacyFilterIoWrite;
fastIoDispatch->FastIoQueryBasicInfo = MyLegacyFilterIoQueryBasicInfo;
fastIoDispatch->FastIoQueryStandardInfo = MyLegacyFilterIoQueryStandardInfo;
fastIoDispatch->FastIoLock = MyLegacyFilterIoLock;
fastIoDispatch->FastIoUnlockSingle = MyLegacyFilterIoUnlockSingle;
fastIoDispatch->FastIoUnlockAll = MyLegacyFilterIoUnlockAll;
fastIoDispatch->FastIoUnlockAllByKey = MyLegacyFilterIoUnlockAllByKey;
fastIoDispatch->FastIoDeviceControl = MyLegacyFilterIoDeviceControl;
fastIoDispatch->FastIoDetachDevice = MyLegacyFilterIoDetachDevice;
fastIoDispatch->FastIoQueryNetworkOpenInfo = MyLegacyFilterIoQueryNetworkOpenInfo;
fastIoDispatch->MdlRead = MyLegacyFilterIoMdlRead;
fastIoDispatch->MdlReadComplete = MyLegacyFilterIoMdlReadComplete;
fastIoDispatch->PrepareMdlWrite = MyLegacyFilterIoPrepareMdlWrite;
fastIoDispatch->MdlWriteComplete = MyLegacyFilterIoMdlWriteComplete;
fastIoDispatch->FastIoReadCompressed = MyLegacyFilterIoReadCompressed;
fastIoDispatch->FastIoWriteCompressed = MyLegacyFilterIoWriteCompressed;
fastIoDispatch->MdlReadCompleteCompressed = MyLegacyFilterIoMdlReadCompleteCompressed;
fastIoDispatch->MdlWriteCompleteCompressed = MyLegacyFilterIoMdlWriteCompleteCompressed;
fastIoDispatch->FastIoQueryOpen = MyLegacyFilterIoQueryOpen;

DriverObject->FastIoDispatch = fastIoDispatch;