FltCbdqInsertIo callback function

FltCbdqInsertIo inserts the callback data structure for an I/O operation into a minifilter driver's callback data queue.


NTSTATUS FltCbdqInsertIo(
  _Inout_  PFLT_CALLBACK_DATA_QUEUE            Cbdq,
  _In_     PFLT_CALLBACK_DATA                  Cbd,
  _In_opt_ PVOID                               InsertContext


Cbdq [in, out]

Pointer to the caller's cancel-safe callback data queue. This queue must have been initialized by calling FltCbdqInitialize.

Cbd [in]

Pointer to the callback data (FLT_CALLBACK_DATA) structure for the I/O operation to be queued. The operation must be an IRP-based I/O operation.

Context [in, optional]

Caller-supplied variable that receives an opaque context pointer for the I/O request. Minifilter drivers can use this pointer to identify a specific item in the queue so that it can be removed by calling FltCbdqRemoveIo. If the minifilter driver is not required to remove particular I/O requests from the queue, this parameter can be NULL.

InsertContext [in, optional]

Context pointer to be passed to the minifilter driver's CbdqInsertIo callback routine.

Return value

FltCbdqInsertIo returns STATUS_SUCCESS or an appropriate NTSTATUS value such as one of the following:

Return codeDescription

The callback data structure was inserted into the callback data queue.


The callback data structure was not inserted into the callback data queue because the queue is currently disabled. To reenable the queue, call FltCbdqEnable. This is an error code.



FltCbdqInsertIo inserts the specified callback data (FLT_CALLBACK_DATA) structure into a minifilter driver's callback data queue.

Minifilter drivers can use the FltCbdqXxx routines to implement a callback data queue for IRP-based I/O operations. By using these routines, minifilter drivers can make their queues cancel-safe; the system transparently handles I/O cancellation for the minifilter drivers.

The FltCbdqXxx routines can only be used for IRP-based I/O operations. To determine whether a given callback data structure represents an IRP-based I/O operation, use the FLT_IS_IRP_OPERATION macro.

A callback data queue is initialized by calling FltCbdqInitialize. FltCbdqInsertIo uses the functions provided in the queue's dispatch table to lock the queue and insert the callback data structure into the queue. The insert operation itself is performed by the queue's CbdqInsertIo routine.

See FltCbdqInitialize for details on how to create a callback data queue. Use FltCbdqRemoveIo to remove a particular I/O request from the queue, or FltCbdqRemoveNextIo to remove the next available I/O request.

If the queue is protected by a spin lock rather than a mutex object or resource variable, the caller of FltCbdqInsertIo can be running at IRQL <= DISPATCH_LEVEL. If a mutex or resource is used, the caller must be running at IRQL <= APC_LEVEL.


Target platform



Fltkernel.h (include Fltkernel.h)


See Remarks section.

See also




Send comments about this topic to Microsoft