Btrfs scrub is a filesystem checking tool that reads all the data and metadata on the filesystem and uses checksums and the duplicate copies from RAID storage to identify and repair any corrupt data

To start a BTRFS scrub and to check the status of this process:

(1) # btrfs scrub start /

(2) # btrfs scrub status /

https://www.phoronix.com/news/Btrfs-Linux-6.4-Better-Scrub