I can’t seem to find anything like it, neither as a Fuse fs. Is there really no file system, that just evicts the oldest entries once it’s full? I mean, it could be a simple stack.
This would have been the ideal tool for cache; no bothering with size limits and background daemons.
Not 100% on what ‘stack-based’ means here, but if ‘stacking’ = ‘tiering’, you could use a normal filesystem like bcachefs that have tiered storage ?
You can declare different tier devices for speed, availability or what you prefer, and have different compression, managed cache, auto-move hot data from cold storage, cold data to cold storage, and what not…
However, I’ve never actually tried it, so I’m likely exaggerating the possibilities. I think ZFS have tiering too, but maybe a filesystem specialist can chime in with some advice.
Alternatively, if it doesn’t bother you, it could be a great task for a sota ai, to help/create/setup a simple fuse fs for your needs.