FSCTL_OPLOCK_BREAK_NOTIFY control code

Enables the calling application to wait for completion of an opportunistic lock break.

This operation is not useful to application developers and is documented here only for completeness. CreateFile handles the problem that this operation was designed to handle.

To perform this operation, call the DeviceIoControl function using the following parameters.


BOOL 
WINAPI 
DeviceIoControl( (HANDLE) hDevice,              // handle to file
                 FSCTL_OPLOCK_BREAK_NOTIFY,     // dwIoControlCode
                 NULL,                          // lpInBuffer
                 0,                             // nInBufferSize
                 NULL,                          // lpOutBuffer
                 0,                             // nOutBufferSize
                 (LPDWORD) lpBytesReturned,     // number of bytes returned
                 (LPOVERLAPPED) lpOverlapped ); // OVERLAPPED structure

Parameters

hDevice

A handle to the file or alternate stream on which the operation is to be performed. To retrieve a handle, call the CreateFile function. The file or alternate stream must have been opened with the flag FILE_FLAG_OVERLAPPED. This handle must be the same one for which the opportunistic lock was originally requested.

dwIoControlCode

The control code for the operation. Use FSCTL_OPLOCK_BREAK_NOTIFY for this operation.

lpInBuffer

Not used with this operation; set to NULL.

nInBufferSize

Not used with this operation; set to zero.

lpOutBuffer

Not used with this operation; set to NULL.

nOutBufferSize

Not used with this operation; set to zero.

lpBytesReturned

A pointer to a variable that receives the size of the data stored in the output buffer, in bytes.

This parameter is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If hDevice is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.

lpOverlapped

A pointer to an OVERLAPPED structure.

Because hDevice was opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped (asynchronous) operation. Therefore, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways.

DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed.

Return value

If the operation completes successfully, DeviceIoControl returns a nonzero value.

If the operation fails or is pending, DeviceIoControl returns zero. To get extended error information, call GetLastError.

Remarks

This operation is used only by client applications that have requested an opportunistic lock from a local server. Client applications requesting opportunistic locks from remote servers must not request them directly—the network redirector transparently requests opportunistic locks for the application.

For the implications of overlapped I/O on this operation, see the Remarks section of the DeviceIoControl topic.

In Windows 8 and Windows Server 2012, this code is supported by the following technologies.

TechnologySupported

Server Message Block (SMB) 3.0 protocol

No

SMB 3.0 Transparent Failover (TFO)

No

SMB 3.0 with Scale-out File Shares (SO)

No

Cluster Shared Volume File System (CsvFS)

Yes

Resilient File System (ReFS)

Yes

 

Requirements

Minimum supported client

Windows XP [desktop apps only]

Minimum supported server

Windows Server 2003 [desktop apps only]

Header

WinIoCtl.h (include Windows.h)

See also

Oplock Semantics
CreateFile
DeviceIoControl
Opportunistic Locks
OVERLAPPED

 

 

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