On the radar: maintainers summit discussion about keeping old, unmaintained filesystems in the kernel:https://lwn.net/ml/ksummit-discuss/ZO9NK0FchtYjOuIH@infradead.org/
The kernel has a "no regressions" rule, and it's hard to argue that removing a filesystem that has users is not a regression. But there are also limits to how long some of those filesystems can be carried forward.
I looked at one aspect of this back in July (https://lwn.net/Articles/939097/
), but the discussion seems destined to continue for a while yet.
Still, should this topic show up at the actual maintainers summit, I'm guessing Linus would stop it short by saying "we don't remove code that people are using; next topic".