DUF use percentage completely wrong for BTRFS RAID

[petaramesh]

Hi,

When using DUF on BTRFS RAID filesystem, it does, as plain df does, display as “total size” the sum of all the RAID components (and not the resulting usable space on the RAID filesystem).

It displays the “used” and “available” fields right, but the calculated percentage is plain wrong, as it is calculated against the “total size” which is the sum ot the RAID components, and not against the actually usable space.

By some magic, plain df has it right, but duf has it wrong, and the difference makes the “USE %” value and graph both useless, and worse, misleading.

Please see attached screenshots that better show the discrepancy.