mountpoint remains in use after restore snapshot

[Anatoliy]

uname -a
Linux lxd2-chel1 4.4.0-72-generic #93-Ubuntu SMP Fri Mar 31 14:07:41 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

lxd: 2.12-0ubuntu3~ubuntu16.04.1~ppa1
zfsutils-linux: 0.6.5.6-0ubuntu16

# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.2 LTS
Release: 16.04
Codename: xenial

after restore container from shapshot cannot add new snapshot or restore again
until restart container

example:

# lxc image list
+---------------+--------------+--------+--------------------------------------+--------+---------+------------------------------+
| ALIAS | FINGERPRINT | PUBLIC | DESCRIPTION | ARCH | SIZE | UPLOAD DATE |
+---------------+--------------+--------+--------------------------------------+--------+---------+------------------------------+
| debian/jessie | ba43812c4cb9 | no | Debian jessie amd64 (20170423_22:42) | x86_64 | 94.14MB | Apr 24, 2017 at 9:07am (UTC) |
+---------------+--------------+--------+--------------------------------------+--------+---------+------------------------------+

# lxc launch debian/jessie
Creating popular-kitten

The container you are starting doesn't have any network attached to it.
  To create a new network, use: lxc network create
  To attach a network to a container, use: lxc network attach

Starting popular-kitten

# lxc info popular-kitten
Name: popular-kitten
Remote: unix:/var/lib/lxd/unix.socket
Architecture: x86_64
Created: 2017/04/25 07:17 UTC
Status: Running
Type: persistent
Profiles: default
Pid: 6965
Ips:
  lo: inet 127.0.0.1
  lo: inet6 ::1
Resources:
  Processes: 7
  Disk usage:
    root: 1.48MB
  CPU usage:
    CPU usage (in seconds): 25
  Memory usage:
    Memory (current): 16.22MB
    Memory (peak): 23.01MB
  Network usage:
    lo:
      Bytes received: 0B
      Bytes sent: 0B
      Packets received: 0
      Packets sent: 0

# lxc profile show default
config: {}
description: Default LXD profile
devices:
  root:
    path: /
    pool: main-pool
    type: disk
name: default
used_by:
- /1.0/containers/popular-kitten
# lxc snapshot popular-kitten

# zfs get mounted main-pool/containers/popular-kitten
NAME PROPERTY VALUE SOURCE
main-pool/containers/popular-kitten mounted yes -

# zfs get mounted main-pool/snapshots/popular-kitten
NAME PROPERTY VALUE SOURCE
main-pool/snapshots/popular-kitten mounted yes -

# lxc restore popular-kitten snap0

# zfs get mounted main-pool/snapshots/popular-kitten
NAME PROPERTY VALUE SOURCE
main-pool/snapshots/popular-kitten mounted yes -

# zfs get mounted main-pool/containers/popular-kitten
NAME PROPERTY VALUE SOURCE
main-pool/containers/popular-kitten mounted no -

# lxc snapshot popular-kitten
error: Failed to mount ZFS filesystem: filesystem 'main-pool/containers/popular-kitten' is already mounted
cannot mount 'main-pool/containers/popular-kitten': mountpoint or dataset is busy

# lxc restore popular-kitten snap0
error: Failed to mount ZFS filesystem: filesystem 'main-pool/containers/popular-kitten' is already mounted
cannot mount 'main-pool/containers/popular-kitten': mountpoint or dataset is busy

but container still work:

# lxc info popular-kitten
Name: popular-kitten
Remote: unix:/var/lib/lxd/unix.socket
Architecture: x86_64
Created: 2017/04/25 07:17 UTC
Status: Running
...

# lxc exec popular-kitten bash
root@popular-kitten:~# uptime
 07:34:06 up 8 min, 0 users, load average: 0.00, 0.02, 0.03

after restart container:

# lxc restart popular-kitten

# zfs get mounted main-pool/containers/popular-kitten
NAME PROPERTY VALUE SOURCE
main-pool/containers/popular-kitten mounted yes -

on another server this problem missmatch:

# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.10
Release: 16.10
Codename: yakkety

# lxd --version
2.4.1

zfsutils-linux: 0.6.5.8-0ubuntu4.1

[Christian Brauner (cbrauner)]

This is very likely not a LXD bug. I suspect this is https://github.com/zfsonlinux/zfs/issues/5796 again which I reported to ZFS upstream. I'll ping them about this again tomorrow and if I don't hear back will take a look at this myself.

[Christian Brauner (cbrauner)]

Reproducible. Can you please open this bug on github.

[Anatoliy (sayto)]

created on github:
https://github.com/zfsonlinux/zfs/issues/6070

[Anatoliy (sayto)]

bug on valid repo:
https://github.com/lxc/lxd/issues/3228

[Anatoliy (sayto)]

upgrade lxd to 2.13
but bug still exist =(

[Christian Brauner (cbrauner)]

LXD 2.13 doesn't include my fix https://github.com/lxc/lxd/commit/6c6af18b4ab4720c802a61fa932179562446a4df yet.

[Stéphane Graber (stgraber)]

xenial, yakkety and zesty will get the fix when we backport LXD 2.14.

Is LXD 2.0.x also affected? If so, I'm not sure we have a fix for it in 2.0.10, so we'd need a fix in stable-2.0 upstream so that 2.0.11 can have it.