Using file discovery on a system with BTRFS, multiple mount points can belong to different subvolumes of the same BTRFS.

All mounts are discovered separately which is expected. However, since they are sub volumes of the same filesystem they share the same storage space, as a result, Zabbix reports the same data for each of them.

Filtering is possible but is not a generic solutions. It would be useful if vfs.fs.get provided enough information to identify if mount points belongs to BTRFS and which one.