Duperemove

Duperemove is a btrfs tool for finding duplicated extents and submitting them to the kernel for deduplication.

Usage
Detailed information can be seen by running.

Reading a file list created with fdupes
By passing the  option,  can work in conjunction with  in order to deduplicate a pre-calculated list of files. When in this mode, input will be accepted on stdin:

This is handy when a list of duplicates has already been created so that disk-intensive deduplication job can be ran at a time when the system is not under heavy load.

It is also possible to deduplicate directly from fdupes (without creating a file list):