FltOplockFsctrl function

The FltOplockFsctrl routine performs various opportunistic lock (oplock) operations on behalf of a minifilter driver.

Syntax

FLT_PREOP_CALLBACK_STATUS FltOplockFsctrl(
  _In_ POPLOCK            Oplock,
  _In_ PFLT_CALLBACK_DATA CallbackData,
  _In_ ULONG              OpenCount
);

Parameters

Oplock

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

CallbackData

Pointer to the callback data structure for the I/O operation (FLT_CALLBACK_DATA). This parameter is required and cannot be NULL.

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 Semantics Overview.

Return Value

FltOplockFsctrl returns FLT_PREOP_PENDING for some FSCTL operations. For more information, see the reference pages for the FSCTL codes listed in the following Remarks section. Otherwise, FltOplockFsctrl returns FLT_PREOP_COMPLETE.

Remarks

A minifilter driver calls FltOplockFsctrl to perform various opportunistic lock operations for a create or file system control I/O operation. The FLT_CALLBACK_DATA structure pointed to by the CallbackData parameter must represent an IRP-based IRP_MJ_FILE_SYSTEM_CONTROL or IRP_MJ_CREATE operation.

If the operation is an IRP_MJ_FILE_SYSTEM_CONTROL operation, FltOplockFsctrl can be used with the following FSCTL codes:

FSCTL_OPBATCH_ACK_CLOSE_PENDING

FSCTL_OPLOCK_BREAK_ACK_NO_2

FSCTL_OPLOCK_BREAK_ACKNOWLEDGE

FSCTL_OPLOCK_BREAK_NOTIFY

FSCTL_REQUEST_BATCH_OPLOCK

FSCTL_REQUEST_FILTER_OPLOCK

FSCTL_REQUEST_OPLOCK_LEVEL_1

FSCTL_REQUEST_OPLOCK_LEVEL_2

The FSCTL code is set in the FsControlCode member of the FLT_PARAMETERS structure for the operation. For more information about FsControlCode and other IRP_MJ_FILE_SYSTEM_CONTROL parameters, see FLT_PARAMETERS for IRP_MJ_FILE_SYSTEM_CONTROL.

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

If the operation is an IRP_MJ_CREATE request, FltOplockFsctrl can be used to request a pending filter opportunistic lock if all of the following conditions are true:

  • The value of the OpenCount parameter is 1.
  • The value of the DesiredAccess parameter for the IRP_MJ_CREATE request is FILE_READ_ATTRIBUTES. This parameter is set in the SecurityContext member of the FLT_PARAMETERS structure for the operation. For more information, see FLT_PARAMETERS for IRP_MJ_CREATE.
  • The value of the ShareAccess parameter for the IRP_MJ_CREATE operation is FILE_SHARE_READ, FILE_SHARE_WRITE, or FILE_SHARE_DELETE. This parameter is set in the ShareAccess member of the FLT_PARAMETERS structure for the operation. For more information, see FLT_PARAMETERS for IRP_MJ_CREATE.

Requirements

   
Target Platform Universal
Header fltkernel.h (include Fltkernel.h)
Library FltMgr.lib
DLL Fltmgr.sys
IRQL "<= APC_LEVEL"

See Also

FSCTL_REQUEST_OPLOCK_LEVEL_2

FSCTL_REQUEST_BATCH_OPLOCK

FSCTL_OPLOCK_BREAK_ACKNOWLEDGE

IRP_MJ_CREATE

FltCurrentBatchOplock

FLT_CALLBACK_DATA

FltInitializeOplock

FLT_PARAMETERS for IRP_MJ_CREATE

FSCTL_REQUEST_FILTER_OPLOCK

FsRtlOplockFsctrl

FSCTL_REQUEST_OPLOCK_LEVEL_1

FltUninitializeOplock

FSCTL_OPLOCK_BREAK_ACK_NO_2

FltCheckOplock

FSCTL_OPBATCH_ACK_CLOSE_PENDING

FLT_PARAMETERS for IRP_MJ_FILE_SYSTEM_CONTROL

FltOplockIsFastIoPossible

IRP_MJ_FILE_SYSTEM_CONTROL

FSCTL_OPLOCK_BREAK_NOTIFY

Send comments about this topic to Microsoft