In branch-0.20-security as part of
HADOOP-6566, DiskChecker#mkdirsWithExistsAndPermissionCheck will return true even if it wasn't able to create the directory, which means instead of throwing a DiskErrorException the code will proceed to getFileStatus and throw a FNF exception. Post HADOOP-7040, which modified makeInstance to catch not just DiskErrorExceptions but IOExceptions as well, this is not an issue since now the exception is caught either way. But for future modifications we should still modify this method to return false if it was unable to create the directory. This code is totally different in trunk, so not an issue there.