ref: 47a1f5464ee6213bee7eac6d868b7a0f2cc3ef06
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