Developers who are concerned about system integrity often put a fair amount
of effort into ensuring that data stored on disk cannot be tampered with
without being detected.
Technologies like dm-verity
and fs-verity are attempts to solve this
problem, as is the recently covered integrity
policy enforcement security module. More Recently, Johannes Thumshirn
has posted a patch
series adding filesystem-level authentication to Btrfs; it promises to
provide integrity with a surprisingly small amount of code.

Source: LWN.net – [$] Authenticated Btrfs