FSCTL_QUERY_REFS_SMR_VOLUME_INFO control code

The FSCTL_QUERY_REFS_SMR_VOLUME_INFO control code queries the Shingled Magnetic Recording (SMR) volume for its current state on space and garbage collection activities.

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

BOOL
DeviceIoControl( (HANDLE)       hDevice,         // handle to device
                    (DWORD)        FSCTL_QUERY_REFS_SMR_VOLUME_INFO, // dwIoControlCode
                    (LPDWORD)      lpInBuffer,      // input buffer
                    (DWORD)        nInBufferSize,   // size of input buffer
                    (LPDWORD)      lpOutBuffer,     // output buffer
                    (DWORD)        nOutBufferSize,  // size of output buffer
                    (LPDWORD)      lpBytesReturned, // number of bytes returned
                    (LPOVERLAPPED) lpOverlapped );  // OVERLAPPED structure

Parameters

• hDevice [in]: A handle to the device. To obtain a device handle, call the CreateFile function.

• dwIoControlCode [in]: The control code for the operation. Use FSCTL_QUERY_REFS_SMR_VOLUME_INFO for this operation.

• lpInBuffer [in]: Not used with this operation; set to NULL.

• nInBufferSize [in]: Not used with this operation; set to zero.

• lpOutBuffer [out]: A pointer to a buffer that receives a REFS_SMR_VOLUME_INFO_OUTPUT structure which specifies a volume's current state on space and garbage collection activities.

• nOutBufferSize [in]: The size of the output buffer, in bytes.

• lpBytesReturned [out]: A pointer to a variable that receives the size of the data stored in the output buffer, in bytes.

  If the output buffer is too small, the call fails, GetLastError returns ERROR_INSUFFICIENT_BUFFER, and lpBytesReturned is zero.

  If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl makes use of lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless.

  If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If the hDevice parameter is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.

• lpOverlapped [in]: A pointer to an OVERLAPPED structure.

  If hDevice was opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored.

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

  For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed. Otherwise, the function does not return until the operation has been completed or an error occurs.

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.

Requirements

See also

DeviceIoControl

REFS_SMR_VOLUME_INFO_OUTPUT

REFS_SMR_VOLUME_GC_STATE