_DoCacheIO
error = _DoCacheIO(offset, buffer, size, bytesRead, false);
error = _DoCacheIO(offset, (uint8*)buffer, size, bytesWritten, true);
error = _DoCacheIO(0, fSmallBuffer, fSize, NULL, true);
error = _DoCacheIO(offset, buffer, length, &processed, isWrite, false);
status_t _DoCacheIO(off_t offset, uint8* buffer, ssize_t length,