Agreed, ZFS has its caveats, but feature-wise and stability-wise ZFS is to -- a large degree -- what BTRFS should have been.
The licensing is incredibly unfortunate, though. (I don't care about the reasoning for the license, it's just bad that it isn't GPL-compatible so that it could be compatible with the most prolific kernel in the world.)
Anyway, back to BTRFS-vs-ZFS. It seems abundantly clear that a filesystem is (no longer) a thing where you can just "throw an early idea out there" and hope that others will pick up the slack and fix all the bugs. There's just too much design (not code) that goes into these things that it's not just about code any more.
My (small) bet right now as to the "next gen" FS on Linux is on bcachefs[1, 2]. It sounds much sounder from a design perspective than BFS, plus it's built on the already-proven bcache, etc. etc. (Read the page for details.)
According to Canonical, it _is_ GPL compatible. Either way, that shouldn't get in the way of the best file system in existence being used with the kernel of last resort.
Canonical ships ZoL binaries as of April 2016. They claim doing so doesn't violate the GPL since they are shipping it as a module rather than built into the kernel.
No, they're supplied as kernel modules, packaged separately from the kernel. Before Ubuntu 15.10 you could still install it as a DKMS module (such that it compiled on the system it's being installed on). Now they just ship the pre-built .ko's, saving the user compilation time. There are still userland tools to interact with it zpool, zfs etc.
The licensing is incredibly unfortunate, though. (I don't care about the reasoning for the license, it's just bad that it isn't GPL-compatible so that it could be compatible with the most prolific kernel in the world.)
Anyway, back to BTRFS-vs-ZFS. It seems abundantly clear that a filesystem is (no longer) a thing where you can just "throw an early idea out there" and hope that others will pick up the slack and fix all the bugs. There's just too much design (not code) that goes into these things that it's not just about code any more.
My (small) bet right now as to the "next gen" FS on Linux is on bcachefs[1, 2]. It sounds much sounder from a design perspective than BFS, plus it's built on the already-proven bcache, etc. etc. (Read the page for details.)
[1] https://www.patreon.com/bcachefs [1] https://bcache.evilpiepirate.org/Bcachefs/