[PATCH 0/1][SRU][D] Fix regression in /proc/pid/maps

[Seth Forshee]

BugLink: https://bugs.launchpad.net/bugs/1842382

SRU Justification

Impact: A patch to enable mounting overlayfs over shiftfs introduced a
regression in /proc/pid/maps when a proc mount over an overlayfs mount
is accessed from within a chroot. All paths within the file are /
instead of paths to the files backing memory-mapped regions. This is
causing issues in several different configurations.

Fix: Revert the offending patch.

Test Case: A simple reproducer can be found attached to the bug in
lp1842382.sh.

Regression Potential: This reverts to the previous (working) behavior.
Mounting overlayfs over shiftfs will not work until a fixed patch is
applied.

A revert has already been applied to eoan, now sending for SRU to disco.

Thanks,
Seth


Seth Forshee (1):
  UBUNTU: SAUCE: Revert "UBUNTU: SAUCE: shiftfs: enable overlayfs on
    shiftfs"

 fs/open.c            | 4 +---
 fs/overlayfs/file.c  | 1 -
 fs/overlayfs/super.c | 5 ++---
 fs/shiftfs.c         | 4 +---
 include/linux/fs.h   | 3 +--
 5 files changed, 5 insertions(+), 12 deletions(-)