It's a no to ZFS in the Linux kernel from me, says Torvalds, points finger of blame at Oracle licensing

What's that coming over the hill? Is it a lawyer? It's Larry's lawyers

Linux kernel jockey, Linus Torvalds, has taken time out to remind open source loyalists that he is no fan of the ZFS file system due, in part, to the sometimes tortuous nature of open source licensing.

Torvalds was responding to a question late last week regarding a recent update to the Linux kernel breaking the third party ZFS module.

With his new non-sweary hat on, Torvalds patiently explained his position around out-of-tree components such as ZFS. In essence, they aren't his problem. We imagine ensuring nothing breaks in the user space is challenging enough.

"Note that 'we don't break users' is literally about user-space applications, and about the kernel I maintain," he explained, adding: "If somebody adds a kernel module like ZFS, they are on their own. I can't maintain it, and I can not be bound by other people's kernel changes."

So there you have it, ZFS fans. Except, of course, you don't.

The Linux supremo went on to throw a little shade at Platinum Linux Foundation member Oracle, adding, "There is no way I can merge any of the ZFS efforts until I get an official letter from Oracle that is signed by their main legal counsel or preferably by Larry Ellison himself that says that yes, it's OK to do so and treat the end result as GPL'd."

ZFS falls under the Common Development and Distribution License (CDDL), which is all well and good, but the Linux kernel uses the GNU General Public License (GPLv2), making the merging of code a tad tricky from a licensing standpoint if nothing else. "Considering Oracle's litigious nature," observed Torvalds, "and the questions over licensing, there's no way I can feel safe in ever doing so."

As for creating a shim to isolate the projects, Torvalds was similarly negative, perhaps mindful of the army of lawyers at the disposal of Big Red, and said: "That adds no value to our side, and given Oracle's interface copyright suits (see Java), I don't think it's any real licensing win either."

Before sniffing that "the benchmarks I've seen do not make ZFS look all that great," Torvalds declared: "Don't use ZFS. It's that simple."

Easier said than done.

ZFS was originally developed by Sun for use in the Solaris operating system and open-sourced under the CDDL in 2005. The acquisition of Sun by Oracle in 2010 muddied the waters somewhat (with Big Red's ZFS being trademarked.) OpenZFS has, however, continued, and the ZFS filesystem can be found as either a FUSE module or native kernel module in a variety of distributions, including the likes of Ubuntu.

However, those pesky licensing issues rumble on, despite the utility of the storage platform and those imagining a ZFS-tinged future for the Linux kernel with a Torvalds stamp of approval will have to dream for a little longer.

The Register asked Oracle to comment on Friday. ®