RFC: Btrfs snapshots feature for F13

[David Zeuthen]

On Tue, 2009-11-17 at 23:34 -0500, Chris Ball wrote:
> Given the above, do you think you'd be okay with having:
> 
>    Filesystem snapshot that will be active on next boot:  <drop-down>

Shouldn't it say "next time volume is mounted" instead of "next boot"?
We can always special case rootfs to say "next boot" of course (since
rootfs can't be unmounted until next boot).

Also, what is the mechanism to configure this? Just a simple command
from btrfs-progs (best)? Or does it require surgery to /etc/fstab and/or
the initramfs (bad)?

>    Create new whole-filesystem snapshot now:  <label>  <apply>
> 
> in a Btrfs-specific section in Palimpsest?  That's all that's needed
> for the UI component of this feature.

>From a 50,000 feet view all this sounds good to me.

>    > (Oh, and if it turns out that creating/destroying btrfs snaphots
>    > isn't a privileged operation (I can't remember at this point) it
>    > would probably make sense for Nautilus to just use the btrfs
>    > tools directly instead of going through a system daemon. There's
>    > just no need to overcomplicate things.)
> 
> Creating a new snapshot is unprivileged, but mounting an old one
> (which nautilus would need to do in order to show you the contents
> of a previous snapshot, so that you can decide which files you want
> to restore from it) requires a mount(8) call for each snapshot.

OK. We need to decide how all this is going to work - maybe some of it
will go into GIO and be part of an abstraction that also works for other
filesystems, maybe it will be a Nautilus-only feature. I don't know yet,
leaning towards the latter right now, but I guess we'll find out.

Thanks,
David