Olor (Spanish for “smell”) comes from the similar Latin olere “to give off a smell”. Odor and Redolent (which is just a bad small, after all!) come from the same root.
The curious part is the o‑l to o‑d transition. This is merely a vestige of the influence of the long-dead Sabine dialects of late Latin. Yes, the same Sabines who were rapped. They did transition their l‑s to d‑s.