CtxFreeResource( streamContext->Resource );
        }
        
        //
        //  Free the file name
        //
        
        if (streamContext->FileName.Buffer != NULL) {
        
            CtxFreeUnicodeString(&streamContext->FileName);
        }

        DebugTrace( DEBUG_TRACE_STREAM_CONTEXT_OPERATIONS,
                    ("[Ctx]: Stream context cleanup complete.\n") );

        break;

    case FLT_STREAMHANDLE_CONTEXT:

        streamHandleContext = (PCTX_STREAMHANDLE_CONTEXT) Context;

        DebugTrace( DEBUG_TRACE_STREAMHANDLE_CONTEXT_OPERATIONS,
                    ("[Ctx]: Cleaning up stream handle context for file %wZ (StreamContext = %p)\n",
                     &streamHandleContext->FileName,
                     streamHandleContext) );        
            
        //
        //  Delete the resource and memory the memory allocated for the resource
        //
        
        if (streamHandleContext->Resource != NULL) {
        
            ExDeleteResourceLite( streamHandleContext->Resource );
            CtxFreeResource( streamHandleContext->Resource );
        }
        
        //
        //  Free the file name
        //
        
        if (streamHandleContext->FileName.Buffer != NULL) {
        
            CtxFreeUnicodeString(&streamHandleContext->FileName);
        }

        DebugTrace( DEBUG_TRACE_STREAMHANDLE_CONTEXT_OPERATIONS,
                    ("[Ctx]: Stream handle context cleanup complete.\n") );

        break;
        
    }
    
}

//
//  Instance setup/teardown routines.
//

NTSTATUS
CtxInstanceSetup (
    IN PCFLT_RELATED_OBJECTS FltObjects,
    IN FLT_INSTANCE_SETUP_FLAGS Flags,
    IN DEVICE_TYPE VolumeDeviceType,
    IN FLT_FILESYSTEM_TYPE VolumeFilesystemType
    )
/*++

Routine Description:

    This routine is called whenever a new instance is created on a volume. This
    gives us a chance to decide if we need to attach to this volume or not.

Arguments:

    FltObjects - Pointer to the FLT_RELATED_OBJECTS data structure containing
        opaque handles to this filter, instance and its associated volume.

    Flags - Flags describing the reason for this attach request.

Return Value:

    STATUS_SUCCESS - attach
    STATUS_FLT_DO_NOT_ATTACH - do not attach

--*/
{
    PCTX_INSTANCE_CONTEXT instanceContext = NULL;
    NTSTATUS status = STATUS_SUCCESS;
    ULONG volumeNameLength;

    UNREFERENCED_PARAMETER( Flags );
    UNREFERENCED_PARAMETER( VolumeDeviceType );
    UNREFERENCED_PARAMETER( VolumeFilesystemType );

    DebugTrace( DEBUG_TRACE_INSTANCES, 
                ("[Ctx]: Instance setup started (Volume = %p, Instance = %p)\n",
                 FltObjects->Volume, 
                 FltObjects->Instance) );



    //
    //  Allocate and initialize the context for this volume
    //


    //
    //  Allocate the instance context
    //

    DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS,
                ("[Ctx]: Allocating instance context (Volume = %p, Instance = %p)\n",
                 FltObjects->Volume, 
                 FltObjects->Instance) );

    status = FltAllocateContext( FltObjects->Filter,
                                 FLT_INSTANCE_CONTEXT,
                                 CTX_INSTANCE_CONTEXT_SIZE,
                                 NonPagedPool,
                                 &instanceContext );

    if( !NT_SUCCESS( status )) {

        DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS | DEBUG_TRACE_ERROR,
                    ("[Ctx]: Failed to allocate instance context (Volume = %p, Instance = %p, Status = 0x%x)\n",
                     FltObjects->Volume, 
                     FltObjects->Instance,
                     status) );

        goto CtxInstanceSetupCleanup;
    }

    //
    //  Get the NT volume name length
    //

    status = FltGetVolumeName( FltObjects->Volume, NULL, &volumeNameLength );

    if( !NT_SUCCESS( status ) && 
        (status != STATUS_BUFFER_TOO_SMALL) ) {

        DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS | DEBUG_TRACE_ERROR,
                    ("[Ctx]: Unexpected failure in FltGetVolumeName. (Volume = %p, Instance = %p, Status = 0x%x)\n",
                     FltObjects->Volume, 
                     FltObjects->Instance,
                     status) );

        goto CtxInstanceSetupCleanup;
    }

    //
    //  Allocate a string big enough to take the volume name 
    //

    instanceContext->VolumeName.MaximumLength = (USHORT) volumeNameLength;
    status = CtxAllocateUnicodeString( &instanceContext->VolumeName );
    
    if( !NT_SUCCESS( status )) {

        DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS | DEBUG_TRACE_ERROR,
                    ("[Ctx]: Failed to allocate volume name string. (Volume = %p, Instance = %p, Status = 0x%x)\n",
                     FltObjects->Volume, 
                     FltObjects->Instance,
                     status) );

        goto CtxInstanceSetupCleanup;
    }
    
    //
    //  Get the NT volume name
    //

    status = FltGetVolumeName( FltObjects->Volume, &instanceContext->VolumeName, &volumeNameLength );

    if( !NT_SUCCESS( status ) ) {

        DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS | DEBUG_TRACE_ERROR,
                    ("[Ctx]: Unexpected failure in FltGetVolumeName. (Volume = %p, Instance = %p, Status = 0x%x)\n",
                     FltObjects->Volume, 
                     FltObjects->Instance,
                     status) );

        goto CtxInstanceSetupCleanup;
    }


    instanceContext->Instance = FltObjects->Instance;
    instanceContext->Volume = FltObjects->Volume;
   
    //
    //  Set the instance context.
    //

    DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS,
                ("[Ctx]: Setting instance context %p for volume %wZ (Volume = %p, Instance = %p)\n",
                 instanceContext,
                 &instanceContext->VolumeName,
                 FltObjects->Volume, 
                 FltObjects->Instance) );

    status = FltSetInstanceContext( FltObjects->Instance,
                                    FLT_SET_CONTEXT_KEEP_IF_EXISTS,
                                    instanceContext,
                                    NULL );

    if( !NT_SUCCESS( status )) {

        DebugTrace( DEBUG_TRACE_INSTANCES | DEBUG_TRACE_ERROR,
                    ("[Ctx]: Failed to set instance context for volume %wZ (Volume = %p, Instance = %p, Status = 0x%08X)\n",
                     &instanceContext->VolumeName,
                     FltObjects->Volume, 
                     FltObjects->Instance,
                     status) );
        goto CtxInstanceSetupCleanup;
    }

CtxInstanceSetupCleanup:

    //
    //  If FltAllocateContext suceeded then we MUST release the context, 
    //  irrespective of whether FltSetInstanceContext suceeded or not.
    //  
    //  FltAllocateContext increments the ref count by one.
    //  A successful FltSetInstanceContext increments the ref count by one 
    //  and also associates the context with the file system object
    //
    //  FltReleaseContext decrements the ref count by one.
    //
    //  When FltSetInstanceContext succeeds, calling FltReleaseContext will
    //  leave the context with a ref count of 1 corresponding to the internal 
    //  reference to the context from the file system structures
    //
    //  When FltSetInstanceContext fails, calling FltReleaseContext will
    //  leave the context with a ref count of 0 which is correct since 
    //  there is no reference to the context from the file system structures
    //

    if ( instanceContext != NULL ) {

        DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS,
                    ("[Ctx]: Releasing instance context %p (Volume = %p, Instance = %p)\n",
                     instanceContext,
                     FltObjects->Volume, 
                     FltObjects->Instance) );

        FltReleaseContext( instanceContext );
    }


    if (NT_SUCCESS( status )) {

        DebugTrace( DEBUG_TRACE_INSTANCES, 
                    ("[Ctx]: Instance setup complete (Volume = %p, Instance = %p). Filter will attach to the volume.\n",
                     FltObjects->Volume,
                     FltObjects->Instance) );    
    } else {

        DebugTrace( DEBUG_TRACE_INSTANCES, 
                    ("[Ctx]: Instance setup complete (Volume = %p, Instance = %p). Filter will not attach to the volume.\n",
                     FltObjects->Volume,
                     FltObjects->Instance) );
    }

    return status;
}


NTSTATUS
CtxInstanceQueryTeardown (
    IN PCFLT_RELATED_OBJECTS FltObjects,
    IN FLT_INSTANCE_QUERY_TEARDOWN_FLAGS Flags
    )
/*++

Routine Description:

    This is called when an instance is being manually deleted by a
    call to FltDetachVolume or FilterDetach thereby giving us a
    chance to fail that detach request.

Arguments:

    FltObjects - Pointer to the FLT_RELATED_OBJECTS data structure containing
        opaque handles to this filter, instance and its associated volume.

    Flags - Indicating where this detach request came from.

Return Value:

    Returns the status of this operation.

--*/
{
    UNREFERENCED_PARAMETER( FltObjects );
    UNREFERENCED_PARAMETER( Flags );

    DebugTrace( DEBUG_TRACE_INSTANCES,
                ("[Ctx]: Instance query teardown started (Instance = %p)\n",
                 FltObjects->Instance) );


    DebugTrace( DEBUG_TRACE_INSTANCES,
                ("[Ctx]: Instance query teadown ended (Instance = %p)\n",
                 FltObjects->Instance) );
    return STATUS_SUCCESS;
}


VOID
CtxInstanceTeardownStart (
    IN PCFLT_RELATED_OBJECTS FltObjects,
    IN FLT_INSTANCE_TEARDOWN_FLAGS Flags
    )
/*++

Routine Description:

    This routine is called at the start of instance teardown.

Arguments:

    FltObjects - Pointer to the FLT_RELATED_OBJECTS data structure containing
        opaque handles to this filter, instance and its associated volume.

    Flags - Reason why this instance is been deleted.

Return Value:

    None.

--*/
{
    UNREFERENCED_PARAMETER( FltObjects );
    UNREFERENCED_PARAMETER( Flags );

    DebugTrace( DEBUG_TRACE_INSTANCES, 
                ("[Ctx]: Instance teardown start started (Instance = %p)\n",
                 FltObjects->Instance) );


    DebugTrace( DEBUG_TRACE_INSTANCES, 
                ("[Ctx]: Instance teardown start ended (Instance = %p)\n",
                 FltObjects->Instance) );
}


VOID
CtxInstanceTeardownComplete (
    IN PCFLT_RELATED_OBJECTS FltObjects,
    IN FLT_INSTANCE_TEARDOWN_FLAGS Flags
    )
/*++

Routine Description:

    This routine is called at the end of instance teardown.

Arguments:

    FltObjects - Pointer to the FLT_RELATED_OBJECTS data structure containing
        opaque handles to this filter, instance and its associated volume.

    Flags - Reason why this instance is been deleted.

Return Value:

    None.

--*/
{
    PCTX_INSTANCE_CONTEXT instanceContext;
    NTSTATUS status;

    UNREFERENCED_PARAMETER( Flags );

    DebugTrace( DEBUG_TRACE_INSTANCES,
                ("[Ctx]: Instance teardown complete started (Instance = %p)\n",
                 FltObjects->Instance) );

    DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS,
                ("[Ctx]: Getting instance context (Volume = %p, Instance = %p)\n",
                 FltObjects->Volume, 
                 FltObjects->Instance) );

    status = FltGetInstanceContext( FltObjects->Instance,
                                    &instanceContext );

    if (NT_SUCCESS( status )) {

        DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS,
                    ("[Ctx]: Instance teardown for volume %wZ (Volume = %p, Instance = %p, InstanceContext = %p)\n",
                     &instanceContext->VolumeName,
                     FltObjects->Volume, 
                     FltObjects->Instance,
                     instanceContext) );


        //
        //  Here the filter may perform any teardown of its own structures associated
        //  with this instance.
        //
        //  The filter should not free memory or synchronization objects allocated to 
        //  objects within the instance context. That should be performed in the 
        //  cleanup callback for the instance context
        //
                    
        DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS,
                    ("[Ctx]: Releasing instance context %p for volume %wZ (Volume = %p, Instance = %p)\n",
                     instanceContext,
                     &instanceContext->VolumeName,
                     FltObjects->Volume, 
                     FltObjects->Instance) );

        FltReleaseContext( instanceContext );
    } else {

        DebugTrace( DEBUG_TRACE_INSTANCE_CONTEXT_OPERATIONS | DEBUG_TRACE_ERROR,
                    ("[Ctx]: Failed to get instance context (Volume = %p, Instance = %p Status = 0x%x)\n",
                     FltObjects->Volume, 
                     FltObjects->Instance,
                     status) );
    }

    DebugTrace( DEBUG_TRACE_INSTANCES,
                ("[Ctx]: Instance teardown complete ended (Instance = %p)\n",
                 FltObjects->Instance) );
}