[buildd-tools-devel] Bug#868883: schroot: btrfs-snapshot requires btrfs-snapshot-directory= but doesn't use it

[Roger Leigh]

On 19/07/17 13:56, Uwe Kleine-König wrote:
> I have:
> 
> 	$ cat /etc/schroot/chroot.d/unstable-amd64-default-237842
> 	[unstable-amd64-default]
> 	description=Debian unstable/amd64 chroot
> 	groups=root,sbuild
> 	root-groups=root,sbuild
> 	profile=default
> 	type=btrfs-snapshot
> 	btrfs-source-subvolume=/srv/chroot/unstable-amd64-default
> 	btrfs-snapshot-directory=/srv/chroot/unstable-amd64-default-snaps
> 
> and it works as expected. However the snapshots are created below
> /run/schroot/mount/.

Is it *created* below /run/schroot/mount or is it later *mounted* below 
this location?

Looking at the program logic, the session should be snapshotted under 
the specified snapshot directory:

   if (btrfs_snapshot && !btrfs_snapshot->get_snapshot_directory().empty())
     {
       std::string snapname(btrfs_snapshot->get_snapshot_directory());
       snapname += "/" + clone->get_name();
       btrfs_snapshot->set_snapshot_name(snapname);
     }

in sbuild/sbuild-chroot-facet-session-clonable.cc.  Would it be possible 
to double-check exactly what is where?


An unrelated FYI: On the schroot master branch, Btrfs snapshot support 
has been removed.  The repeated Btrfs filesystem unbalancing with 
intensive snapshotting made this feature unsuitable for production use. 
I will be replacing it with ZFS snapshot support.


Regards,
Roger