[lxc-users] overlayfs: "failed to whiteout" and "Operation not permitted"

[Ingvar Bogdahn]

Hi,

i'm running into problems with clones using overlayfs. I'm working with 
unprivileged containers only under ubuntu 14.04 trusty, with lxc version 
1.0.7.
The mother container is an ubuntu, trusty, amd64, directory-based 
container (I tried ext4 and xfs as root filesystems) and the clone was 
done with the -B overlayfs -s option.

When starting the overlayfs clone I get several "failed to whiteout" 
errors:
[949.378978] overlayfs: ERROR - failed to whiteout 'kmsg'
[949.378978] overlayfs: ERROR - failed to whiteout 'boot-log'
[949.378978] overlayfs: ERROR - failed to whiteout 'log'
[949.378978] overlayfs: ERROR - failed to whiteout 'dmesg.1.gz'
[949.378978] overlayfs: ERROR - failed to whiteout 'dmesg.0'
[949.378978] overlayfs: ERROR - failed to whiteout 'dmesg.0'

yes that last one is printed twice (numbers are not accurate).

despite these errors, the container is actually started.

However, when I want to install something nontrivial with substantial 
dependencies in the overlay container, for example wordpress or even 
something smaller like midnight commander, the installation fails due to 
"Operation not permitted":

in case of mc:
"....
Unpacking unzip ....
Processing triggers for mime-support...
dpkg: error: error removing old backup file 
'/var/lib/dpkg/available-old': Operation not permitted
E: Sub-process /user/bin/dpkg returned an error code (2)"


when I try to rerun, I'm asked to run dpkg --configure -a, which returns:
[949.378978] overlayfs: ERROR - failed to whiteout 'status-old'
dkpg: error: error removing old backup file 
'/var/lib/dpkg/available-old': Operation not permitted

Trying to manually delete that file give the same error.

If I delete the failed when logged in the mother container, then the 
overlay container works again (but fails later for similar reasons).


thanks for any hints!