FsRtlOplockFsctrlEx function (ntifs.h)

Article
10/21/2021

The FsRtlOplockFsctrlEx routine performs various opportunistic lock (oplock) operations on behalf of a file system or filter driver.

Syntax

NTSTATUS FsRtlOplockFsctrlEx(
  [in] POPLOCK Oplock,
  [in] PIRP    Irp,
  [in] ULONG   OpenCount,
  [in] ULONG   Flags
);

Parameters

[in] Oplock

Opaque oplock pointer for the file. This pointer must have been initialized by a previous call to FsRtlInitializeOplock.

[in] Irp

Pointer to the IRP for the I/O operation. This parameter is required and cannot be NULL.

[in] OpenCount

Number of user handles for the file, if an exclusive oplock is being requested. Setting a nonzero value for a level 2, R, or RH oplock request indicates that there are byte-range locks on the file. For information about oplock types, see Oplock Overview.

[in] Flags

A bitmask for the associated oplock operations. A file system or filter driver sets bits to specify the behavior of FsRtlOplockFsctrlEx. This parameter has the following options:

Flag	Meaning
OPLOCK_FSCTRL_FLAG_ALL_KEYS_MATCH (0x00000001)	The file system verified that all oplock keys on any currently open handles match. By specifying this flag, you allow the oplock package to grant an oplock of level RW or RWH when more than one open handle to the file exists. For more information about oplock types, see Oplock Overview.

Return value

FsRtlOplockFsctrlEx returns one of the following NTSTATUS values:

Return code	Description
STATUS_SUCCESS	For an IRP_MJ_CREATE request, STATUS_SUCCESS indicates that the requested filter oplock was granted. For a FSCTL operation, the meaning of STATUS_SUCCESS depends on the FSCTL code. For more information, see the reference pages for the FSCTL codes listed in the following Remarks section.
STATUS_CANCELLED	The I/O operation was canceled. STATUS_CANCELLED is an error code.
STATUS_INVALID_PARAMETER	The FSCTL code for the I/O operation was not one of the valid values listed in the following Remarks section. STATUS_INVALID_PARAMETER is an error code.
STATUS_OPLOCK_NOT_GRANTED	The oplock could not be granted. STATUS_OPLOCK_NOT_GRANTED is an error code.
STATUS_PENDING	Used only for FSCTL operations. The meaning of STATUS_PENDING depends on the FSCTL code. For more information, see the reference pages for the FSCTL codes listed in the following Remarks section. STATUS_PENDING is a success code.
STATUS_CANNOT_BREAK_OPLOCK	A new oplock could not be granted. The IRP is an IRP_MJ_CREATE request and FILE_OPEN_REQUIRING_OPLOCK was specified in the create options parameter for the operation. STATUS_CANNOT_BREAK_OPLOCK is a success code.

Remarks

File systems and legacy filter drivers call FsRtlOplockFsctrlEx to perform various oplock operations for a create or file system control I/O operation. Minifilters should call FltOplockFsctrlEx instead of FsRtlOplockFsctrlEx.

The IRP pointed to by the Irp parameter must be a valid IRP for an IRP_MJ_FILE_SYSTEM_CONTROL or IRP_MJ_CREATE operation.

If the IRP is an IRP_MJ_FILE_SYSTEM_CONTROL request, FsRtlOplockFsctrlEx can be used with one of the following FSCTL codes, which is set in IrpSp->Parameters.FileSystemControl.FsControlCode:

For more information about these FSCTLs and about opportunistic locks in general, see the Microsoft Windows SDK documentation.

If the IRP is an IRP_MJ_CREATE request, FsRtlOplockFsctrlEx can be used to request a pending filter oplock if all of the following conditions are true:

The value of the OpenCount parameter must be 1.
The value of the DesiredAccess parameter for the IRP_MJ_CREATE request must be FILE_READ_ATTRIBUTES.
The value of the ShareAccess parameter for the IRP_MJ_CREATE request must be FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE.

If the request for a pending filter oplock is granted, FsRtlOplockFsctrlEx returns STATUS_SUCCESS. For more information about create parameters, see the reference entry for IRP_MJ_CREATE.

Filters and file systems that call this function must synchronize calls into the system-supplied oplock package. See Oplock synchronization for more information.

Requirements

Requirement	Value
Minimum supported client	The FsRtlOplockFsctrlEx routine is available starting with Windows 7.
Target Platform	Universal
Header	ntifs.h (include Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	<= APC_LEVEL