On Thu, Jan 27, 2022 at 11:19:57AM +0100, Jan Kara wrote:

Just after writing this I have realized that the above sequence is not
actually possible due to disk->open_mutex protecting us and serializing
lo_release() with lo_open() but it needs at least a comment to explain that
we rely on disk->open_mutex to avoid races with lo_open().

The commit message already notes this.  Not sure we really need a comment
in the code itself, but if you want I can add it.