btrfs balance on single device

[Leonidas Spyropoulos <artafinde@gmail.com>]

Hey all,

Just did a btrfs balance on a single device. Before the balance
operation here is the df result:

inglor@tiamat ~$ btrfs fi df /home
Data: total=19.19GB, used=9.34GB
System, DUP: total=32.00MB, used=4.00KB
Metadata, DUP: total=896.00MB, used=227.98MB

Then I issues a balance operation relocating the chunks across a single device:
inglor@tiamat ~$ sudo btrfs fi balance /home
[sudo] password for inglor:
Done, had to relocate 28 out of 28 chunks

After I did another df:
inglor@tiamat ~$ btrfs fi df /home
Data: total=10.00GB, used=9.34GB
System, DUP: total=32.00MB, used=4.00KB
Metadata, DUP: total=384.00MB, used=226.80MB

Anyone can explain me the Data row of the above output ? It used to be
19.19GB and now it's 10.00GB. It's like the partition shrunk!? The
balance operation finished without issues.

Here's some other information:

inglor@tiamat ~$ sudo btrfs filesystem show
Label: 'home'  uuid: 458c70e2-7037-4c4d-bba2-3d5288f04510
    Total devices 1 FS bytes used 9.56GB
    devid    1 size 21.00GB used 10.81GB path /dev/sda3

Label: none  uuid: 699d671b-7064-441d-95ec-c616049fe287
    Total devices 1 FS bytes used 13.94GB
    devid    1 size 20.00GB used 20.00GB path /dev/sda2

Btrfs v0.20-rc1-358-g194aa4a-dirty
inglor@tiamat ~$ df
Filesystem     1K-blocks      Used Available Use% Mounted on
/dev/sda2       20971520  15362816   3960288  80% /
/dev/sda3       22020096  10256168  11375416  48% /home

Thanks,
Leonidas


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