Restore btrfs partition
Extended partition entry was corrupted by Windows Logical Disk Manager. This entry consisted of Swap and Btrfs partitions. How one should restore correct records?
I tried Testdisk, seems that it doesn't know about btrfs. If there isn't any other way, I would be up for coding and adding btrfs support, but I have no clue how btrfs works. So I would be happy for some btrfs internals documentation too.
I imagine that it should have some special header, then superblock should follow, which should repeat after number of bytes. Finding that header would be enough to find where my partition begins.