[_8j50]

Why isn't content addressable inodes a thing? Address them by hash instead of id and avoid creating duplicate inodes. So for example, two 1TB files containing all zeroes will take up one inode worth of disk space but the fs table records 1TB worth of inodes. You tune the fs inode sllocation table disk usage a lot, what other downsides are there?

Also, how is linux support for apfs these days?

[viraptor]

That sounds like basic in-band deduplication. Apfs just doesn't support it. You can find that on zfs though.