Chris Ball wrote:
Hi,
> Is it possible, with current btrfs:
Yes, I think so.
> - to take a rootfs snapshot (i.e. prior to a major update),
btrfsctl -s newsnap /
> - do changes in the root filesystem (i.e. install major update),
>
> - if we don't like what the major update did to the system
> (rootfs), "rollback" the snapshot and make it the "original"
> rootfs again (perhaps, with a reboot in between).
Before rebooting, edit whatever mounts your root partition (initrd,
fstab, kernel argument) to add a "subvol=newsnap" mount argument.
So, if I understand it correctly, it's not really "rolling back".
Rather, with a "failed upgrade", we would mount a "newsnap" snapshot to
use the old rootfs again.
What's still left here would be:
- remove the "failed upgrade" "(sub)volume" (which is "/" now?)
- turn everything to such a state, so that you can mount the
old/original rootfs without adding any "subvol=newsnap" mount arguments
Correct me if I'm wrong.
--
Tomasz Chmielewski
http://wpkg.org
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