FLT_PARAMETERS for IRP_MJ_FILE_SYSTEM_CONTROL union
Union component used when the MajorFunction field of the FLT_IO_PARAMETER_BLOCK structure for the operation is IRP_MJ_FILE_SYSTEM_CONTROL.
Syntax
typedef union _FLT_PARAMETERS {
... ;
union {
struct {
PVPB Vpb;
PDEVICE_OBJECT DeviceObject;
} VerifyVolume;
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT FsControlCode;
} Common;
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT FsControlCode;
PVOID InputBuffer;
PVOID OutputBuffer;
PMDL OutputMdlAddress;
} Neither;
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT FsControlCode;
PVOID SystemBuffer;
} Buffered;
struct {
ULONG OutputBufferLength;
ULONG POINTER_ALIGNMENT InputBufferLength;
ULONG POINTER_ALIGNMENT FsControlCode;
PVOID InputSystemBuffer;
PVOID OutputBuffer;
PMDL OutputMdlAddress;
} Direct;
} FileSystemControl;
... ;
} FLT_PARAMETERS, *PFLT_PARAMETERS;
Members
FileSystemControl: Structure containing the following members.
VerifyVolume: Union component used for IRP_MN_VERIFY_VOLUME operations.
Vpb: Pointer to the volume parameter block (VPB) for the volume to be verified.
DeviceObject: Pointer to the device object for the volume to be verified.
Common: Union component used for all buffering methods for IRP_MN_KERNEL_CALL and IRP_MN_USER_FS_REQUEST operations.
Common.OutputBufferLength: Length, in bytes, of the buffer that the Neither.OutputBuffer or Direct.OutputBuffer member points to.
Common.InputBufferLength: Length, in bytes, of the buffer that the Neither.InputBuffer, Buffered.SystemBuffer, or Direct.InputSystemBuffer member points to.
Common.FsControlCode: FSCTL function code to be passed to the file system, file system filter, or minifilter driver for the target device.
For detailed information about IOCTL and FSCTL requests, see Using I/O Control Codes in the Kernel Mode Architecture Guide and "Device Input and Output Control Codes" in the Microsoft Windows SDK documentation. (This resource may not be available in some languages and countries.)
Neither: Union component used for IRP_MN_KERNEL_CALL and IRP_MN_USER_FS_REQUEST operations when the buffering method is METHOD_NEITHER. For more information about buffering methods, see Defining I/O Control Codes.
Neither.InputBuffer: User-mode virtual address of the input buffer that the original requester of the operation supplied. The I/O Manager and Filter Manager do not validate these addresses. To ensure that user-space addresses are valid, the minifilter must use routines such as ProbeForRead, ProbeForWrite, and MmProbeAndLockPages, enclosing all buffer references in try/except blocks. For more information, see Using Neither Buffered Nor Direct I/O and Errors in Referencing User-Space Addresses.
Neither.OutputBuffer: User-mode virtual address of the output buffer that the original requester of the operation supplied. The I/O Manager and Filter Manager do not validate these addresses. To ensure that user-space addresses are valid, the minifilter must use routines such as ProbeForRead, ProbeForWrite, and MmProbeAndLockPages, enclosing all buffer references in try/except blocks. For more information, see Using Neither Buffered Nor Direct I/O and Errors in Referencing User-Space Addresses. Neither.OutputBuffer is optional and can be NULL if a MDL is provided in Neither.OutputMdlAddress. See Remarks.
Neither.OutputMdlAddress: Address of a memory descriptor list (MDL) that describes the buffer that the Neither.OutputBuffer member points to. This member is optional and can be NULL if a buffer is provided in Neither.OutputBuffer.
Buffered: Union component used for IRP_MN_KERNEL_CALL and IRP_MN_USER_FS_REQUEST operations when the buffering method is METHOD_BUFFERED. For more information about buffering methods, see Defining I/O Control Codes.
Buffered.SystemBuffer: Address of the system-allocated buffer for the operation. In METHOD_BUFFERED I/O, this buffer is used for both input and output. For more information, see Methods for Accessing Data Buffers.
Direct: Union component used for IRP_MN_KERNEL_CALL and IRP_MN_USER_FS_REQUEST operations when the buffering method is METHOD_IN_DIRECT or METHOD_OUT_DIRECT. For more information about buffering methods, see Defining I/O Control Codes in the Kernel Mode Architecture Guide.
Direct.InputSystemBuffer: Address of the input buffer for the operation. This buffer is locked down by the operating system so that it is safe to access from kernel mode. For more information, see Methods for Accessing Data Buffers.
Direct.OutputBuffer: User-mode virtual address of the output buffer that the original requester of the operation supplied. In direct I/O, unlike METHOD_NEITHER I/O, the operating system locks down this buffer so that it is safe to access from kernel mode, as long as the minifilter is in the same process context as the original requester of the I/O operation. (Otherwise it must call MmGetSystemAddressForMdlSafe to get the system address from the MDL that the OutputMdlAddress member points to.) For more information, see Using Direct I/O and Errors in Direct I/O.
Direct.OutputMdlAddress: Address of a memory descriptor list (MDL) that describes the buffer that the Direct.OutputBuffer member points to. This member is required and cannot be NULL.
Remarks
The FLT_PARAMETERS structure for IRP_MJ_FILE_SYSTEM_CONTROL operations contains the parameters for a file-system-control-information operation represented by a callback data (FLT_CALLBACK_DATA) structure. It is contained in an FLT_IO_PARAMETER_BLOCK structure.
If both a Neither.OutputBuffer and Neither.MdlAddress buffer are provided, it is recommended that minifilters use the MDL.
If a minifilter changes the value of Neither.MdlAddress, then after its post operation callback, Filter Manager will free the MDL currently stored in Neither.MdlAddress and restore the previous value of Neither.MdlAddress.
IRP_MJ_FILE_SYSTEM_CONTROL is an IRP-based operation.
Requirements
| Requirement type | Requirement |
|---|---|
| Header | Fltkernel.h (include Fltkernel.h) |