FltOplockFsctrl function (fltkernel.h)
FltOplockFsctrl performs various opportunistic lock (oplock) operations on behalf of a minifilter driver.
Syntax
FLT_PREOP_CALLBACK_STATUS FLTAPI FltOplockFsctrl(
[in] POPLOCK Oplock,
[in] PFLT_CALLBACK_DATA CallbackData,
[in] ULONG OpenCount
);
Parameters
[in] Oplock
Opaque oplock pointer for the file. This pointer must have been initialized by a previous call to FltInitializeOplock.
[in] CallbackData
Pointer to the FLT_CALLBACK_DATA structure 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.
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 must be 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.
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 |
|---|---|
| Target Platform | Universal |
| Header | fltkernel.h (include Fltkernel.h) |
| Library | FltMgr.lib |
| DLL | Fltmgr.sys |
| IRQL | <= APC_LEVEL |
See also
FLT_PARAMETERS for IRP_MJ_CREATE
FLT_PARAMETERS for IRP_MJ_FILE_SYSTEM_CONTROL
FSCTL_OPBATCH_ACK_CLOSE_PENDING