ref: 2f4c39ec2bf7a5eb84ed1a7c810a0a85b2e47cd0
dir: /sys/src/cmd/ext4srv/NOTES/
Based on https://github.com/gkostka/lwext4 None of the sources are GPL-licensed: * xattr handling removed altogether * extents logic replaced with a BSD-3 licensed one found in https://github.com/ngkaho1234/lwext