Article: Filesystem UID mapping for User namespaces: yet another shiftfs

There is an article on LWN about filesystem UID shifting for user namespaces,

(source:, it is their subscriber link)

The article talks about the three ways of shifting UIDs,

  1. using the shiftfs filesystem
  2. shifting is done in the bind-mount
  3. [shifting is now a property of the user namespace] (the new proposed way, authored by @brauner ).