Comment # 4 on bug 931571 from ill lume

$ btrfs filesystem df /
Data, single: total=20.01GiB, used=8.48GiB
System, single: total=4.00MiB, used=16.00KiB
Metadata, single: total=1.01GiB, used=320.94MiB
GlobalReserve, single: total=112.00MiB, used=0.00B

the df information seems wrong as well. It says the total for data single is
20GB, when root partition is 30GB.