public IRegion writeExistingRegionAddr(long region_addr)
{
String filepath = makeFilepath(region_addr);
FileStream reader = File.Open(filepath, FileMode.Open, FileAccess.Read, FileShare.Read);
long length = reader.Length;
reader.Dispose();
return new EFRegion(region_addr, length, filepath, EFRegionMode.READ_WRITE);
}