tmpfs unsupported mount options tmpcopyup, rprivate

[r10r]

crio-o seems adds the mount options rprivate and tmpcopyup to tmpfs container mounts. See drachenfels-de/lxcri-defork#13

As far as I can see these options are added to all tmpfs mounts but /dev This includes:

/run
/run/lock
/tmp
/var/log/journal

The kernel log (dmesg) then shows the following errors:

[721537.855698] tmpfs: Unknown parameter 'rprivate'
[721602.257009] tmpfs: Unknown parameter 'tmpcopyup'

The mount options rprivate and tmpcopyup are not support for tmpfs. See man 5 tmpfs

Platform

Linux k8s-cluster2-controller 5.10.11-arch1-1 drachenfels-de/lxcri#7 SMP PREEMPT Wed, 27 Jan 2021 13:53:16 +0000 x86_64 GNU/Linux

[r10r]

https://github.com/opencontainers/runc/releases/tag/v1.0.0-rc3

Add a tmpcopyup mount extension for tmpfs mounts that are mounted over
already existing directories, allowing for the contents of a volume to
be copied up transparently. #845

[r10r]

Can be easily reproduced with a plain lxc container created with lxc cmdline tools:

lxc-create -n test-mount --template download -- --dist ubuntu --release xenial --arch amd64
#
cat  >> /usr/local/var/lib/lxc/test-mount/config  <<EOF
lxc.mount.entry = tmpfs foobar tmpfs rw,rprivate,noexec,nosuid,nodev,tmpcopyup,create=dir
lxc.log.file = /dev/stderr
lxc.log.level = DEBUG
EOF
#
lxc-start -n  test-mount

lxc-start test-systemd 20210211111711.916 ERROR    utils - utils.c:safe_mount:1204 - Invalid argument - Failed to mount "tmpfs" onto "/usr/local/lib/lxc/rootfs/foobar"
lxc-start test-systemd 20210211111711.916 ERROR    conf - conf.c:mount_entry:1966 - Invalid argument - Failed to mount "tmpfs" on "/usr/local/lib/lxc/rootfs/foobar"
lxc-start test-systemd 20210211111711.916 ERROR    conf - conf.c:lxc_setup:3442 - Failed to setup mount entries
lxc-start test-systemd 20210211111711.916 ERROR    start - start.c:do_start:1264 - Failed to setup container "test-systemd"

[r10r]

This is related to #31