IRP_MJ_SET_INFORMATION (FS and filter drivers)

Article
03/14/2023

When Sent

The I/O Manager, other operating system components, and other kernel-mode drivers send the IRP_MJ_SET_INFORMATION request. It can be sent, for example, when a user-mode application has called a Win32 function such as SetEndOfFile or when a kernel-mode component has called ZwSetInformationFile.

Operation: File System Drivers

The file system driver should extract and decode the file object to determine whether it represents a user file or directory open. If it does, the file system driver should process the request as appropriate and complete the IRP.

The following types of information can be set on files and directories:

FileBasicInformation
FileDispositionInformation
FileLinkInformation (for file systems that allow cycles to be created in the directory hierarchy)
FilePositionInformation
FileRenameInformation

The following types of information can be set only on files:

FileAllocationInformation
FileEndOfFileInformation
FileLinkInformation: for file systems (for example, NTFS) that don't allow cycles to be created in the directory hierarchy
FileValidDataLengthInformation

Operation: Legacy File System Filter Drivers

The filter driver must pass this IRP down to the next-lower driver on the stack.

Parameters

A file system or filter driver calls IoGetCurrentIrpStackLocation for the given IRP to get a pointer to its own stack location in the IRP. In the following parameters, Irp points to the IRP and IrpSp points to the IO_STACK_LOCATION. The driver can use the information that is set in the following members of the IRP and the IRP stack location to process a set file information request:

DeviceObject is a pointer to the target device object.
Irp->AssociatedIrp.SystemBuffer points to an input buffer that contains the file or directory information to be set. This information is stored in one of the following structures:
Irp->IoStatus points to an IO_STATUS_BLOCK structure that receives the final completion status and information about the requested operation. For more information, see the description of the IoStatusBlock parameter to ZwSetInformationFile.
IrpSp->FileObject points to the file object that is associated with DeviceObject. This parameter contains a pointer to the RelatedFileObject field, which is also a FILE_OBJECT structure. The RelatedFileObject field of the FILE_OBJECT structure isn't valid during the processing of IRP_MJ_SET_INFORMATION and shouldn't be used.
IrpSp->MajorFunction* is set to IRP_MJ_SET_INFORMATION.
IrpSp->MinorFunction* can be IRP_MN_KERNEL_CALL when Irp->Parameters.SetFile.FileInformationClass is FileValidDataLengthInformation. This code indicates that the source of the request is a trusted kernel component, allowing drivers to bypass security checks.
IrpSp->Parameters.SetFile.AdvanceOnly is a flag for end-of-file operations. This flag determines the use of the EndOfFile member FILE_END_OF_FILE_INFORMATION structure when FileInformationClass is FileEndOfFileInformation. If TRUE, a new valid data length for the file is set from EndOfFile only if it increases the current valid data length. If FALSE, a new file size is set from EndOfFile.
IrpSp->Parameters.SetFile.ClusterCount is reserved for system use.
IrpSp->Parameters.SetFile.DeleteHandle is reserved for system use.

IrpSp->Parameters.SetFile.FileInformationClass indicates the type of information to be set for the file, and can be one of the following values.

Value	Meaning
FileAllocationInformation	Set FILE_ALLOCATION_INFORMATION for the file.
FileBasicInformation	Set FILE_BASIC_INFORMATION for the file.
FileDispositionInformation	Set FILE_DISPOSITION_INFORMATION for the file.
FileEndOfFileInformation	Set FILE_END_OF_FILE_INFORMATION for the file.
FileLinkInformation	Set FILE_LINK_INFORMATION for the file.
FilePositionInformation	Set FILE_POSITION_INFORMATION for the file.
FileRenameInformation	Set FILE_RENAME_INFORMATION for the file.
FileValidDataLengthInformation	Set FILE_VALID_DATA_LENGTH_INFORMATION for the file. For more information, see Irp->MinorFunction.

IrpSp->Parameters.SetFile.FileObject is for rename or link operations. If Irp->AssociatedIrp.SystemBuffer->FileName contains a fully qualified file name, or if Irp->AssociatedIrp.SystemBuffer->RootDirectory is non-NULL, this member is a file object pointer for the parent directory of the file that is the target of the operation. Otherwise it's NULL.
IrpSp->Parameters.SetFile.Length is the length, in bytes, of the buffer pointed to by Irp->AssociatedIrp.SystemBuffer.
IrpSp->Parameters.SetFile.ReplaceIfExists is set to TRUE to specify that if a file with the same name already exists, it should be replaced with the given file. Set to FALSE if the rename operation should fail if a file with the given name already exists.

Remarks

The AdvanceOnly member is set to TRUE by the cache manager to notify the file system to advance the current valid data length on the disk to the new valid data length in EndOfFile. If AdvanceOnly is FALSE, a new file size, in the EndOfFile member, is being set that can be larger or smaller than the current file size.