btrfs-compsize - 1.5-1+b1 main

Compsize takes a list of files on a btrfs filesystem (recursing directories)
and measures used compression types and the effective compression ratio.
.
Because of partially used extents on one hand, and multiple reflinks to an
extent on the other, the definition of used space can be quite unintuitive.
This program provides answers at different stages:
* blocks on the disk
* uncompressed extents
* apparent file sizes (sans holes)