This content is a draft and will not be included in production builds.
https://btrfs.readthedocs.io/en/latest/dev/dev-btrfs-design.html
https://archive.kernel.org/oldwiki/btrfs.wiki.kernel.org/index.php/On-disk_Format.html
https://github.com/satoru-takeuchi/btrfs-thin-book/blob/master/usage.md
https://btrfs.readthedocs.io/en/latest/btrfs-rescue.html