Public bug reported:

I'm having a persistent problem with a container based app breaking
after restore from snapshot, specifically several lines are truncated
from the end of a file within the container.

I can stop/start the container, copy and copy it back to the same name
and everything is fine. Taking snapshots works fine, but on restore from
a snapshot the damage has occurred in the container. Even deleting and
recreating the container leads to the same problem.

Snapshot restore was working but started breaking about 2-3 weeks ago.
Apologies for not having paid more attention when this bug started
occurring but I was dealing with bugs in the app and it wasn't
immediately clear this was a problem with lxd.

Taking a snapshot in a vbox vm with the same software installed works
perfectly, the problem seems specific to restore of an lxc container

I upgraded the host system from 16.04 to 16.10 in the (mistaken) hope it would 
fix this issue. So currently the host is/has:
Ubuntu 16.10, Linux 4.8.0-28-generic #30-Ubuntu SMP
  Installed: 2.4.1-0ubuntu1
  Candidate: 2.4.1-0ubuntu1
  Version table:
 *** 2.4.1-0ubuntu1 500
        500 yakkety/main amd64 Packages
        100 /var/lib/dpkg/status

The host is an HP N40L microserver with an AMD Turion II Neo N40L CPU.
The zpool is on a spinning HD with no hardware or software RAID.

zfs utils show no apparent problems with the zpool:
sudo zpool status -v
  pool: lxdfs
 state: ONLINE
  scan: scrub repaired 0 in 0h2m with 0 errors on Sun Oct  9 00:26:06 2016

        NAME                        STATE     READ WRITE CKSUM
        lxdfs                       ONLINE       0     0     0
          /var/lib/lxd/lxd-zfs.img  ONLINE       0     0     0

errors: No known data errors

## What I do
- lxd is setup to use bridged networking allowing containers to obtain an ip 
via dhcp on my router
- The guest container is created and the app installed with:
lxc launch ubuntu:14.04 fix -c security.privileged=true
lxc file push ~/.ssh/ ods/home/ubuntu/.ssh/authorized_keys 
--mode=0600 --uid=1000

- Then log into the container:
ssh ubuntu@ods
sudo apt-get update
sudo apt-get dist-upgrade
sudo apt-get autoremove
sudo shutdown -r now

- Take a snapshot on the host:
lxc snapshot ods upgraded

- Log into the guest and install the web app stack:
ssh ubuntu@ods
sudo -H bash --server-webserver=nginx

- Once install is complete log into the web app set admin password etc.
- Take another snapshot on the host
lxc snapshot ods devshop-installed
- Restore last snapshot:
lxc restore ods devshop-installed
- Previously working app now throws an error, on investigation it turns out one 
particular config file is now missing about 4 lines.

More details to come.

** Affects: lxd (Ubuntu)
     Importance: Undecided
         Status: New

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  File truncated after lxc snapshot restore

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