One of the of my 1st projects coming back to EMC a few years ago was to analyze porting ZFS onto the Linux platform. Thru this project I gained a lot of respect for the thought that the Sun folks had put into their software architecture and construction. I learned the things needed for the port were more then achievable. We faced the same kind of dilemma that now confronts the folks in this article the License Issue.
The ZFS on Linux Project was probably the first interaction I had with Mich. By the time we discussed it he had shut it down.
I was pushing the idea hard internally at the time but it was dead before I got there. The moment a legal issue appears just in range of your peripheral vision it means you're out on a limb and you'd better be sure about what side of the limb you're sawing off in relation to where on it you're sitting.
It's probably fortuitous it wasn't a runner as I'd have been looking for the company to throw who knows how many developers at getting it done only to face resistance from Oracle post Sun acquisition whom (rightfully) would be looking to get their money's worth from Solaris.
So ZFS is a Solaris thing, the BSD folks would be better off all getting behind HAMMER and even yesterday the Btrfs team were submitting new code for Linux-btrfs.
I think it's time all non-Solaris users got off the ZFS bus and supported what's working for them on their platform today.