root # btrfs filesystem du -s /home COPY TO CLIPBOARD
Total Exclusive Set shared Filename
8.11TiB 6.23GiB 215.76GiB /home
Total
The sum of all files, as "du" would display them in a conventional file system. This is how much space a conventional file system would use to store these files (and all the necessary copies).
Exclusive
The sum of the files that "only" occur in one of the subvolumes and are not shared with other subvolumes
Set shared
The sum of files shared with other subvolumes
Exclusive + Set shared
This is the actual space used in the file system