svn commit: r344316 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

Enji Cooper yaneurabeya at
Wed Feb 20 18:32:49 UTC 2019

On Feb 20, 2019, at 09:11, Rodney W. Grimes <freebsd at> wrote:

> One can personally link ZoL into your own kernel, and a company/corporate
> can even do this and run it on 1000's of servers, you just can not
> distribute it to anyone else, which in the end is not really a big
> deal, unless your in the Linux distribution business.

Very little organizations roll their own Linux kernels in the grand scheme of things (run of the mill sysadmins aren’t hackers), and making Linux VFS work with ZFS is a nontrivial job (ZoL might work with a kernel version, but it won’t work with all target kernel versions). Groups like Facebook, Google, Oracle, etc, do it because they have the developer manpower and it’s in their vested interest to run a custom kernel config/kernel with backports/enhancements. Plus, they don’t need to release their changes, as their server platforms won’t be productized (thus skating around the GPLv2).

I couldn’t find gregkh@‘s diatribe about Linux kernel compatibility, but it was basically (put nicely), “put your code in the kernel tree, cause we won’t necessarily provide backwards compatibility, as we need to break interfaces from time to time.”

Given that zfs is licensed under the CDDL (a viral license to Linux), that code will never, ever, hit the mainline tree.

This is one of the code reasons why, over time, btrfs has evolved into the file system that it is: it fills a niche that ext4 couldn’t and zfs did, while being licensed under an acceptable kernel license (GPLv2).


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