Snapper support

[daftaupe]

Hello, I did a little hack in order to make grub-btrfs not reference the Snapper pre/post snapshots (as asked in issue #23) with the addition of 2 variables that one can use in /etc/default/grub.

I don't have the time to, so I didn't do any extensive testing though.

[Antynea]

Hello,

Great job,
I do not use snapper
If someone can confirm that it works

[daftaupe]

Let's wait for comments, but actually I don't think it's so important, pre/post snapshot could be included in the grub menu.
If I follow what's written in #2, I notice that you're making rw snapshots manually (or not explicitly saying that you set them in ro mode), the thing is, if you boot on them you're actually modifying them isn't it ?

[Antynea]

If I follow what's written in #2, I notice that you're making rw snapshots manually (or not explicitly saying that you set them in ro mode), the thing is, if you boot on them you're actually modifying them isn't it ?

exactly,
I create rw snapshot before an update.
If the update breaks the system, I go back on the previously created snapshot, set it by default, and finally delete the old one.
If the / boot isn't separated, don't forget to reinstall grub in the snapshot, otherwise a small suprise will be present at the next reboot :)

[daftaupe]

You should close this PR. It's not a good feature after all.
What do you mean with grub ? I have a non-separated /boot but I didn't notice anything. Are you talking about a UEFI system ?

[Antynea]

During my tests, 3 years ago,
with a non-separated /boot, Grub didn't find his cubs.
I was forced to relaunch grub-install

Not having had the opportunity to reiterate the thing at the moment (arch never broke),
It may just be my tests that went wrong.

I tested with this Btrfstree:

@root
@snaps

Where @root contains the entire system as well as /boot
Where @snaps contains snapshots rw and mounted in /snaps

If I started in /snaps/test1, then set as default and delete @root
Generates grub.cfg
To the next reboot /snaps/test1 was started by default, but grub could not find these own files.

This is certainly no longer true, today.

[daftaupe]

Thanks for the info, yes it works now (at least in my case). But 3 years is a lot compared to btrfs lifespan, you should rerun some tests in a vm maybe :)