btrfs: fix btrfs containers
btrfs: fix btrfs containers

Closes #2612.
Closes #2655.

Fixes: 9de31d5a1394 ("tree-wide: s/strncpy()/strlcpy()/g")
Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@ubuntu.com>

caglar10ur/lxc,ss1h2a3tw/lxc,hallyn/lxc,ss1h2a3tw/lxc,caglar10ur/lxc,ss1h2a3tw/lxc,hallyn/lxc,hallyn/lxc,caglar10ur/lxc