====== overlayfs ======

===== restore changes =====

From [[https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt|overlayfs.txt]]:

  Changes to the underlying filesystems while part of a mounted overlay
  filesystem are not allowed.  If the underlying filesystem is changed,
  the behavior of the overlay is undefined, though it will not result in
  a crash or deadlock.

There are 2 hints how to restore:

[[https://stackoverflow.com/questions/57865670/overlayfs-restore-removed-or-changed-file-from-lower|Overlayfs: restore removed or changed file from "lower"]]