Re: Recursive subvolume snapshots and deletion?

[Lennart Poettering <lennart@poettering.net>]

On Mon, 23.03.15 08:36, Chris Mason (clm@fb.com) wrote:

> On Mon, Mar 23, 2015 at 12:57 AM, Lennart Poettering <mzerqung@0pointer.de>
> wrote:
> >Heya!
> >
> >So what's the story on recursive btrfs snapshotting and snapshot
> >removal? Since a while systemd has now by default creating btrfs
> >subvolumes for /var/lib/machines for example. Now, if that code is run
> >inside a container, and the container itself already is stored in a
> >subvolume we end up with a subvolume inside a subvolume, which
> >currently breaks snapshotting and deletion of the outer container
> >subvolume.
> >
> >What's the plan regarding recursive versions of the operations? Any
> >plan to add this? We could work around this in userspace, of course,
> >but it would not be atomic, and I'd much prefer if the kernel could do
> >this on its own!
> 
> Hi Lennart,
> 
> I've got a patch to btrfs-progs that can do the recursive snapshotting, let
> me clean it up and submit to Dave.  For recursive deletion I think the same
> method can be used.

OK, so this means you want this to be solved in userspace, hence in a
non-atomic fashion?

What precisely will your code do? Enumerate the subvolumes and simply
snapshot all subvolumes below the desired path? Or anything smarter?

Lennart

-- 
Lennart Poettering, Red Hat