#define CTL_CODE( DeviceType, Function, Method, Access ) (                 \
    ((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Method) \
)

#define METHOD_BUFFERED                 0
#define FILE_ANY_ACCESS                 0
#define FILE_DEVICE_FILE_SYSTEM         0x00000009

#define FSCTL_LOCK_VOLUME               CTL_CODE(FILE_DEVICE_FILE_SYSTEM,  6, METHOD_BUFFERED, FILE_ANY_ACCESS)
#define FSCTL_UNLOCK_VOLUME             CTL_CODE(FILE_DEVICE_FILE_SYSTEM,  7, METHOD_BUFFERED, FILE_ANY_ACCESS)