$ sudo btrfs fi show
Label: none  uuid: 6be69c75-8ef8-4e55-88d7-b9aeab0b79ec
	Total devices 1 FS bytes used 61.89GiB
	devid    1 size 117.99GiB used 117.99GiB path /dev/mapper/vg0-lvm_root

Btrfs v3.12

$ sudo btrfs fi df /
Data, single: total=113.96GiB, used=60.64GiB
System, DUP: total=8.00MiB, used=16.00KiB
System, single: total=4.00MiB, used=0.00
Metadata, DUP: total=2.00GiB, used=1.25GiB
Metadata, single: total=8.00MiB, used=0.00

$ sudo btrfs fi balance /
Done, had to relocate 120 out of 120 chunks

$ sudo btrfs fi show
Label: none  uuid: 6be69c75-8ef8-4e55-88d7-b9aeab0b79ec
	Total devices 1 FS bytes used 61.93GiB
	devid    1 size 117.99GiB used 65.06GiB path /dev/mapper/vg0-lvm_root

Btrfs v3.12

$ sudo btrfs fi df /
Data, single: total=61.00GiB, used=60.69GiB
System, DUP: total=32.00MiB, used=16.00KiB
Metadata, DUP: total=2.00GiB, used=1.24GiB