So far I have had little problems with Tumbleweed and btrfs. The free space on my hdd has been fluctuating but it has never been as low as it is now. And it seems that after each update to Tumbleweed it is shrinking. Isn’t there some sort of btrfs related background task supposed to clean up every once in a while? Can I start in manually?
I would use Kdirstat to see what’s using all but 1,87 GB of my 40 GB root partition; however, it seems to have KDE3.5 dependencies. Isn’t there a more up-to-date tool available?
After you edit the defaults to a bit more sane settings, the daily cleanup should take care of it all and leave you with ample disk space in addition to some peace of mind.