This is built on a misunderstanding of what the ZFS licensing issue is.

ZFS is licensed under the CDDL [0], which is a copyleft license that grants you full rights to use the ZFS source code for basically anything, providing that any derivative works incorporating its source code are also are under the CDDL. There is no "licensing fee" that you can pay Oracle related to this.

Linux is licensed under the GPL, which just like the CDDL, is a copyleft license which requires derivative works to be distributed under the GPL.

The conflict here is that both require the entire derived work to be distributed under CDDL/GPL, but obviously only one license can be picked.... even though realistically, GPL and CDDL are quite similar licenses.

The additional fact that is useful to know is that zfs.ko, the zfs kernel module, is distributed under the CDDL by ubuntu, and any other distro distributing it that I know of.

So, with that knowledge, who can sue who and why?

1. The people that can be sued are people distributing compiled zfs binaries (the 'zfs.ko' kernel binary). In practice, this means canonical, and anyone else who distributes disk images using ZFS (such as snapshotted EC2 AMIs)

2. The people who can sue are the holders of the Linux GPL license, and they can do so by claiming zfs.ko violates their copyright by being a derived work of the linux kernel, but being distributed under the CDDL rather than the GPL.

So, first of all, the vast majority of companies using ZFS aren't also distributing binary distributions containing zfs.ko and the linux kernel together, therefore this whole thing is moot. Realistically, most companies using ZFS only have the risk of _canonical_ being sued, and that breaking their filesystem, not them running into legal issues themselves.

And second, it would require a holder of Linux copyright to file suit, and realistically, no court could find significant damages here.

Canonical also has lawyers that claim 2 wouldn't legally follow, that 'zfs.ko' is not in fact a derived work of the linux kernel. There's differing opinions there, but pretty much everyone agrees that the people who could sue if this interpretation is wrong is the holders of Linux copyright, not oracle.

[0]: https://en.wikipedia.org/wiki/Common_Development_and_Distrib...

On what grounds? ZFS has an open-source license. The only semi-open question related to the topic is packaging it together with another, different open-source license that is viral and mandates more things (GPL). That part is not being “violated” by an enduser, but the distro maintainer.