Linus Torvalds has warned developers not to use the module for the ZFS file system designed by Sun Microsystems – and now owned by Oracle – due to licensing issues.
As it became known, Torvalds warned kernel developers against using ZFS on Linux, an implementation of OpenZFS, and refuses to merge any ZFS code until Oracle changes the open source license it uses.
ZFS is licensed under the Sun Common Development and Distribution License (CDDL), unlike the Linux kernel, which is licensed under the GNU General Public License (GPL).
Torvalds expressed his opinion on the matter in response to a developer who claimed that a recent kernel change “broke an important module: ZFS.”.
The Linux kernel creator refuses to merge the ZFS drive into the kernel because he can't risk a lawsuit from Oracle — which is still trying to sue Google for copyright infringement over its use of Java APIs in Android — and Torvalds won't take any action until Oracle founder Larry Ellison signs off on its use in the Linux kernel.
“If someone adds a kernel module like ZFS, it works entirely on their own initiative, I can't maintain it, and I can't commit to other people's changes to the kernel,” Torvalds explained.
“And frankly, there's no way I'm going to be able to merge any of the ZFS releases until I get an official letter from Oracle signed by their chief legal counsel or preferably Larry Ellison himself saying it's legal to do so and treat the end result as a GPL product,” Torvalds continued.
"Others think it might be right to merge the ZFS code into the Kernel, and that's their decision. But given Oracle's controversial nature and licensing questions, there's no way I feel safe with that.".
The licensing problem is explained by the developers of ZFS on Linux.
“While both are free open source licenses, they are restrictive licenses. Combining them causes problems because it prevents the use of parts of code exclusively available under one license with parts of code exclusively available under another license for the same system,” the ZFS developers write.
“In the case of the kernel, this prevents us from distributing ZFS on Linux as part of the kernel. However, there is nothing in any license that prevents its distribution in module or source code form.”
Torvalds also addressed this issue in his response and dismissed the idea of a proposed layer separating ZFS to address issues with combining two projects with different licenses, particularly due to Oracle's Java API copyright lawsuit.
“And I’m not interested in separating ZFS at all,” Torvalds replied, as some seem to be thinking about isolating the two projects. “That doesn’t add any value to us, and considering Oracle’s intellectual property rights, I don’t think it’s a real win for licensing,” he explained.
His final words on the matter are: “Don’t use ZFS. It’s that simple. It’s always been a hassle and a hassle, and the licensing issues just make it useless to me.”.
