Merge tag 'vfs-6.11.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Merge tag 'vfs-6.11.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull pidfs updates from Christian Brauner:
 "This contains work to make it possible to derive namespace file
  descriptors from pidfd file descriptors.

  Right now it is already possible to use a pidfd with setns() to
  atomically change multiple namespaces at the same time. In other
  words, it is possible to switch to the namespace context of a process
  using a pidfd. There is no need to first open namespace file
  descriptors via procfs.

  The work included here is an extension of these abilities by allowing
  to open namespace file descriptors using a pidfd. This means it is now
  possible to interact with namespaces without ever touching procfs.

  To this end a new set of ioctls() on pidfds is introduced covering all
  supported namespace types"

* tag 'vfs-6.11.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  pidfs: allow retrieval of namespace file descriptors
  nsfs: add open_namespace()
  nsproxy: add helper to go from arbitrary namespace to ns_common
  nsproxy: add a cleanup helper for nsproxy
  file: add take_fd() cleanup helper