FsRtlCheckOplock macro (rxprocs.h)

Article
02/22/2024

The FsRtlCheckOplock routine synchronizes the IRP for a file I/O operation with the file's current opportunistic lock (oplock) state.

Syntax

void FsRtlCheckOplock(
   A1,
   A2,
   A3,
   A4,
   A5
);

Parameters

A1

An opaque opportunistic lock pointer for the file. This pointer must have been initialized by a previous call to FsRtlInitializeOplock.

A2

A pointer to the IRP for the I/O operation.

A3

A pointer to caller-defined context information to be passed to the callback routines that the CompletionRoutine and PostIrpRoutine parameters point to.

A4

A pointer to a caller-supplied callback routine. If an opportunistic lock break is in progress, this routine is called when the break is completed. This parameter is optional and can be NULL. If it is NULL, the caller is put into a wait state until the opportunistic lock break is completed.

This routine is declared as follows:


typedef VOID (*POPLOCK_WAIT_COMPLETE_ROUTINE) ( IN PVOID Context, IN PIRP Irp );

This routine has the following parameters:

Context
Irp

A5

A pointer to a caller-supplied callback routine to be called if the I/O operation is posted to a work queue. This parameter is optional and can be NULL.

This routine is declared as follows:


typedef VOID (*POPLOCK_FS_PREPOST_IRP) ( IN PVOID Context, IN PIRP Irp );

Context
Irp

Return value

None

Remarks

FsRtlCheckOplock synchronizes the IRP for an I/O operation with the current opportunistic lock state of a file according to the following conditions:

If the I/O operation will cause the opportunistic lock to break, the opportunistic lock break is initiated.
If the I/O operation cannot continue until the opportunistic lock break is complete, FsRtlCheckOplock returns STATUS_PENDING and calls the callback routine that the PostIrpRoutine parameter points to.

If a file system or filter driver uses opportunistic locks, it must call FsRtlCheckOplock from any dispatch routines for I/O operations that can cause opportunistic lock breaks. This rule applies to the following types of I/O operations, because these operations can cause opportunistic lock breaks:

IRP_MJ_CLEANUP

IRP_MJ_CREATE

IRP_MJ_FILE_SYSTEM_CONTROL

IRP_MJ_FLUSH_BUFFERS

IRP_MJ_LOCK_CONTROL

IRP_MJ_READ

IRP_MJ_SET_INFORMATION

IRP_MJ_WRITE

For detailed information about opportunistic locks, see the Microsoft Windows SDK documentation.

Minifilters should call FltCheckOplock instead of FsRtlCheckOplock.

Requirements

Requirement	Value
Minimum supported client	This routine is available in Microsoft Windows 2000 and later versions of Windows operating systems.
Target Platform	Universal
Header	rxprocs.h (include FltKernel.h, Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	<= APC_LEVEL