[CRIU] [SRU][F][G][H][PATCH v2] UBUNTU: SAUCE: overlayfs: fix incorrect mnt_id of files opened from map_files

[Alexander Mihalicyn]

On Tue, Apr 27, 2021 at 10:42 PM Seth Forshee
<seth.forshee at canonical.com> wrote:
>
> On Mon, Apr 26, 2021 at 11:11:21AM +0300, alexander at mihalicyn.com wrote:
> > From: Alexander Mikhalitsyn <alexander at mihalicyn.com>
> >
> > BugLink: https://bugs.launchpad.net/bugs/1857257
> >
> > The hack was introduced in ("UBUNTU: SAUCE: overlayfs: allow with
> > shiftfs as underlay") and it broke checkpoint/restore of docker
> > contains:
> > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1857257
> >
> > The following script can be used to trigger the issue:
> >   #!/bin/bash
> >
> >   cat > test.py << EOF
> >   import sys
> >
> >   f = open("/proc/self/maps")
> >
> >   for l in f.readlines():
> >     if "python" not in l:
> >       continue
> >     print(l)
> >     s = l.split()
> >     start, end = s[0].split("-")
> >     fname = s[-1]
> >     print(start, end, fname)
> >     break
> >   else:
> >     sys.exit(1)
> >
> >   test_file1 = open(fname)
> >   test_file2 = open("/proc/self/map_files/%s-%s" % (start, end))
> >
> >   fdinfo1 = open("/proc/self/fdinfo/%d" % test_file1.fileno()).read()
> >   fdinfo2 = open("/proc/self/fdinfo/%d" % test_file2.fileno()).read()
> >
> >   if fdinfo1 != fdinfo2:
> >     print("FAIL")
> >     print(test_file1)
> >     print(fdinfo1)
> >     print(test_file2)
> >     print(fdinfo2)
> >     sys.exit(1)
> >   print("PASS")
> >   EOF
> >   sudo docker run -it --privileged --rm -v `pwd`:/mnt python python /mnt/test.py
> >
> > Thanks to Andrei Vagin for the reproducer and investigation of this problem.
> >
> > Cc: Andrei Vagin <avagin at gmail.com>
> > Cc: Adrian Reber <areber at redhat.com>
> > Cc: Christian Brauner <christian.brauner at ubuntu.com>
> > Cc: Stefan Bader <stefan.bader at canonical.com>
> > Cc: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
> > Cc: Krzysztof Kozlowski <krzysztof.kozlowski at canonical.com>
> >
> > Fixes: d24b8a5 ("UBUNTU: SAUCE: overlayfs: allow with shiftfs as underlay")
> > Signed-off-by: Alexander Mikhalitsyn <alexander at mihalicyn.com>
>
> From review I think this patch looks okay, but I'd like to put it
> through some regression testing before I ack it. I'll try to get some
> testing done this week.

Thank you!

>
> Thanks,
> Seth

Alex.