[$] Yet another try for fs-verity

The fs‑verity mechanism has its origins in the Android project; its purpose
is to make individual files read-only and enable the kernel to detect
any modifications that might have been made, even if those changes happen
offline. Previous fs‑verity implementations have run into criticism in the
development community, and none have been merged. A new
version of the patch set was posted on May 23; it features a
changed user-space API and may have a better chance of getting into the
mainline.