@somenxavier
AFAIU #ZFS is #FreeSoftware.
The #FSF critizes its #CDDL license for another concern:
> This is a free software license. It has a weak per-file copyleft (like version 1 of the #MozillaPublicLicense) which makes it incompatible with the #GNU #GPL. This means a module covered by the GPL and a module covered by the CDDL cannot legally be linked together.
> We urge you not to use the #CDDL for this reason.
https://www.gnu.org/licenses/license-list.html#CDDL