Created attachment 777693 [details]
disk_map_dev_sda2
Disk map for current system. So, while /dev/sda2 the root partition is, it
cannot be unmounted to do 'btrfsck' command. And it's needed some another ways
to check the filesystem state.
One more thing to say here: disk looks full, because it contained 2,5Gb
test.txt file, which was created with 'truncate -s' command. And, after this
file was deleted (rm test.txt), free space didn't gain back.