IOCTL_DISK_GET_LENGTH_INFO查询硬盘物理容量居然会导致 使用驱动器X:中的光盘之前需要将其格式化

查询某个硬盘的物理容量时报错： 

使用驱动器X:中的光盘之前需要将其格式化

//获取磁盘大小,单位是MB
long CMDiskManager::GetDiskSizeMB(DWORD vDiskNo)
{
	////TRACE(" CMDiskManager::GetDiskSize 1 vDiskNo=%d \n", vDiskNo);

	HANDLE hDevice;               // handle to the drive to be examined 
	BOOL bResult;                 // results flag
	DWORD junk;                   // discard results

	wchar_t diskPath[256];				//磁盘内部路径
	//生成磁盘内部路径
	swprintf_s(diskPath, _T("\\\\.\\PhysicalDrive%d"), vDiskNo);

	try{	
	hDevice = CreateFile(diskPath,  // drive 或者 用"\\\\.\\PhysicalDrive0"  代表第一块磁盘
		GENERIC_READ,                // no access to the drive
		FILE_SHARE_READ | // share mode
		FILE_SHARE_WRITE,
		NULL,             // default security attributes
		OPEN_EXISTING,    // disposition
		0,                // file attributes
		NULL);            // do not copy file attributes
	
	}
	catch (exception e){
		//TRACE("GetDiskSize CreateFile error" ); 
		return -1; 
	}
	
	if (hDevice == INVALID_HANDLE_VALUE) // cannot open the drive
	{
		////TRACE(" CMDiskManager::GetDiskSize no disk %d \n", vDiskNo);
		return 0;
	}
	
	////TRACE(" CMDiskManager::GetDiskSize 3 \n");
	GET_LENGTH_INFORMATION pdg;
	//运行下面这段时会报错：使用驱动器X:中的光盘之前需要将其格式化，不知道什么原因,2017.2.24,wzy
	bResult = DeviceIoControl(hDevice,  // device to be queried
		IOCTL_DISK_GET_LENGTH_INFO,  // operation to perform
		NULL, 0, // no input buffer
		&pdg, sizeof(pdg),     // output buffer
		&junk,                 // # bytes returned
		(LPOVERLAPPED)NULL);  // synchronous I/O

	CloseHandle(hDevice);
	 
/*	INT64 nUseSize = disk_len.Length.QuadPart;
	INT64 sizeGB = nUseSize / 1014 / 1024 / 1024;
	CString szSize;
	szSize.Format(L"C盘大小 %I64d GB", sizeGB);
	*/
	long MB = (long)(pdg.Length.QuadPart >> 20);

	if (MB < 0){
		MB = 0;
	}
	////TRACE(" CMDiskManager::GetDiskSize %dMB \n", MB);

	//CString s; 
	//s.Format("C盘大小 %f GB", MB/1024.0);
	//AfxMessageBox(s, 0, MB_OK);  
	//float x = (float) MB ;
	
	return MB;
}