I'm surprised rename() wasn't mentioned in the article, it's a well known technique to atomically update a file, which is very practical for small-ish files.

Note that in the general case, you should fsync() the temporary file before you rename() it over the original - but ext3 and ext4 in writeback mode added a heuristic to do that automatically, because ext3 in the default ordered mode would effectively do that and many applications came to assume it.