message: rafs: don't mark io-stats recoder as error with ENODATA
  It's possible that user is probing some key-value that does
  not exist. This is normal and reasonable.
  So we mark it as sucessful thus not to increase error counter
diff: @@ -621,7 +621,13 @@ impl FileSystem for Rafs {
  x if x < value.len() as u32 => Err(std::io::Error::from_raw_os_error(libc::ERANGE)),
  _ => Ok(GetxattrReply::Value(value)),
  },
  - None => Err(std::io::Error::from_raw_os_error(libc::ENODATA)),
  + None => {
  + // TODO: Hopefully, we can have a 'decorator' procedure macro in
  + // the future to wrap this method thus to handle different reasonable
  + // errors in a clean way.
  + recorder.mark_success(0);
  + Err(std::io::Error::from_raw_os_error(libc::ENODATA))
  + }
  };
  r.map(|v| {
  