Description

FS_FILTER_CALLBACK_DATA is the callback data structure for a FS_FILTER_CALLBACKS's FS_FILTER_CALLBACK or FS_FILTER_COMPLETION_CALLBACK operation.

Members

SizeOfFsFilterCallbackData

Size of this structure, in bytes. Set to sizeof(FS_FILTER_CALLBACK_DATA).

Operation

File system operation for which the callback routine is to be invoked. This operation can be one of:

• FS_FILTER_ACQUIRE_FOR_SECTION_SYNCHRONIZATION
• FS_FILTER_RELEASE_FOR_SECTION_SYNCHRONIZATION
• FS_FILTER_ACQUIRE_FOR_MOD_WRITE
• FS_FILTER_RELEASE_FOR_MOD_WRITE
• FS_FILTER_ACQUIRE_FOR_CC_FLUSH
• FS_FILTER_RELEASE_FOR_CC_FLUSH FS_FILTER_QUERY_OPEN

Reserved

Reserved for system use.

DeviceObject

Device object for this operation.

FileObject

File object for this operation.

Parameters

Union containing any operation-specific parameters. See Remarks.

Remarks

is a member of the FS_FILTER_CALLBACKS structure, which is passed to FsRtlRegisterFileSystemFilterCallbacks in a file system or filter driver's DriverEntry routine.

The Parameters union is defined as follows:

typedef union _FS_FILTER_PARAMETERS {
    //
    //  AcquireForModifiedPageWriter
    //
    struct {
        PLARGE_INTEGER EndingOffset;
        PERESOURCE *ResourceToRelease;
    } AcquireForModifiedPageWriter;

    //
    //  ReleaseForModifiedPageWriter
    //
    struct {
        PERESOURCE ResourceToRelease;
    } ReleaseForModifiedPageWriter;

    //
    //  AcquireForSectionSynchronization
    //
    struct {
        FS_FILTER_SECTION_SYNC_TYPE SyncType;
        ULONG PageProtection;
        PFS_FILTER_SECTION_SYNC_OUTPUT OutputInformation;
        ULONG Flags;
    } AcquireForSectionSynchronization;

    //
    // QueryOpen
    //
    struct {
        PIRP Irp;
        PVOID FileInformation;
        PULONG Length;
        FILE_INFORMATION_CLASS FileInformationClass;
        NTSTATUS CompletionStatus;
    } QueryOpen;

    //
    //  Other
    //
    struct {
        PVOID Argument1;
        PVOID Argument2;
        PVOID Argument3;
        PVOID Argument4;
        PVOID Argument5;
    } Others;
} FS_FILTER_PARAMETERS, *PFS_FILTER_PARAMETERS;

Structure members of the FS_FILTER_PARAMETERS union are described as follows.

• AcquireForModifiedPageWriter

  • EndingOffset: Offset of the last byte being written plus one.
  • ResourceToRelease: Resource to be released. This parameter must not have a NULL value.

• ReleaseForModifiedPageWriter

  • ResourceToRelease: Resource to be released. This parameter must not have a NULL value.

• AcquireForSectionSynchronization

  • SyncType: Type of synchronization requested for the section. Set to SyncTypeCreateSection if a section is being created; SyncTypeOther otherwise.

  • PageProtection: Type of page protection requested for the section. Must be zero if SyncType is SyncTypeOther. Otherwise, one of the following flags, possibly ORed with PAGE_NOCACHE:

    • PAGE_NOACCESS
    • PAGE_READONLY
    • PAGE_READWRITE
    • PAGE_WRITECOPY
    • PAGE_EXECUTE
    • PAGE_EXECUTE_READ
    • PAGE_EXECUTE_READWRITE
    • PAGE_EXECUTE_WRITECOPY
    • PAGE_GUARD
    • PAGE_NOCACHE
    • PAGE_WRITECOMBINE

  • OutputInformation: An FS_FILTER_SECTION_SYNC_OUTPUT structure that contains the extended output information for the section.

  • Flags: When SyncType is SyncTypeCreateSection, Flags can be one of the following values:

    • FS_FILTER_SECTION_SYNC_IN_FLAG_DONT_UPDATE_LAST_ACCESS (0x00000001): The file system should not update the last access time for access to the file through the section that's being created.
    • FS_FILTER_SECTION_SYNC_IN_FLAG_DONT_UPDATE_LAST_WRITE (0x00000002): The file system should not update the last write time for modifications to the file through the section that is being created.

• QueryOpen

  • Irp: Pointer to the IRP associated with this operation.
  • FileInformation: Pointer to a caller-allocated buffer into which the routine writes the requested information about the file object. The FileInformationClass member specifies the type of information that the caller requests.
  • Length: The size, in bytes, of the buffer pointed to by FileInformation.

  • CompletionStatus: An NTSTATUS value that receives the final completion status and information about the operation. CompletionStatus can be set by the PostQueryOpen callback to fail the operation, since post callbacks have no return value. This is primarily used so the PostQueryOpen callback can return STATUS_FLT_DISALLOW_FSFILTER_IO to request fallback to the slow path. Doing so causes the I/O manager to service the request by performing an open/query/close of the file. Similarly, the PreQueryOpen callback can return STATUS_FLT_DISALLOW_FSFILTER_IO to request fallback to the slow path.

  • FileInformationClass: Type of information to be returned about the file, in the buffer that FileInformation points to. Device and intermediate drivers can specify any of the following FILE_INFORMATION_CLASS values. Other values cause the call to fail and should not be passed to PreQueryOpen/PostQueryOpen calls.

    FILE_INFORMATION_CLASS value	Type of information returned
    FileStatInformation	A FILE_STAT_INFORMATION structure. This structure contains an access mask. For more information about access masks, see ACCESS_MASK.
    FileStatLxInformation	A FILE_STAT_LX_INFORMATION structure. This structure contains an access mask. For more information about access masks, see ACCESS_MASK.
    FileCaseSensitiveInformation	A FILE_CASE_SENSITIVE_INFORMATION structure.

• Others

  • Argument1: Reserved for future use.
  • Argument2: Reserved for future use.
  • Argument3: Reserved for future use.
  • Argument4: Reserved for future use.
  • Argument5: Reserved for future use.

See also

FS_FILTER_CALLBACKS

FsRtlRegisterFileSystemFilterCallbacks