I'm sure a handful of Oracle employees have some code in the kernel that they hold copyright on. I definitely favor Red Hat here, but I'm just saying. At the very least, think btrfs.
What is weird to me... is that btrfs is the "zfs for Linux" but it so happens that Oracle also owns zfs. They could change (or dual license) zfs for Linux if they wanted to, but no... they'd prefer to have one product that is ok with the GPL (btrfs) and one that is not (zfs).