AUFS permission issue

Hi, I am trying to use a separate disk to store docker images. I am using AUFS for this purpose.

The disk was mounted at /mnt and I created aufs mount point at /var/lib/docker/aufs.

mkdir /var/lib/docker/aufs
mount -t aufs -o br=/mnt=rw -o udba=reval none /var/lib/docker/aufs

Then I updated /etc/default/docker with ‘DOCKER_OPTS=“–storage-driver aufs”’ and started the docker service.

So far everything looks fine. I can pull debain:jessie

docker pull debian:jessie
jessie: Pulling from library/debian
51f5c6a04d83: Pull complete
a3ed95caeb02: Pull complete
Digest: sha256:2ca1d757fce75accad6ff84339c3327c7aa96ad6e7b7d6fdde22b2a537fac703
Status: Downloaded newer image for debian:jessie

However, I encounter issues when trying to pull the ubuntu:trusty image
docker pull ubuntu:trusty
trusty: Pulling from library/ubuntu
6c953ac5d795: Pull complete
3eed5ff20a90: Pull complete
f8419ea7c1b5: Extracting [==================================================>] 360 B/360 B
51900bc9e720: Download complete
a3ed95caeb02: Download complete
failed to register layer: Untar re-exec error: exit status 1: output: open /var/lib/apt/lists/.wh.archive.ubuntu.com_ubuntu_dists_trusty_Release: operation not permitted

Have you seen similar error before?

Here is the docker info
Containers: 0
Running: 0
Paused: 0
Stopped: 0
Images: 1
Server Version: 1.11.2
Storage Driver: aufs
Root Dir: /var/lib/docker/aufs
Backing Filesystem: extfs
Dirs: 2
Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Volume: local
Network: null host bridge
Kernel Version: 3.19.0-59-generic
Operating System: Ubuntu 14.04.3 LTS
OSType: linux
Architecture: x86_64
CPUs: 8
Total Memory: 67.01 GiB
Name: ip-10-2-87-131
Docker Root Dir: /var/lib/docker
Debug mode (client): false
Debug mode (server): false
WARNING: No swap limit support