Re: Question about btrfs as root filesystem

Goffredo Baroncelli
Fri, 08 Nov 2013 17:59:25 -0000

On 2013-11-08 18:44, Chris Murphy wrote:
>
> On Nov 8, 2013, at 5:55 AM, Goffredo Baroncelli <kreijack@libero.it>
> <kreijack@libero.it> wrote:
>>
>> Instead of using set-default, I am used to rename the subvolume.
>> I.E. I assume that the root filesystem is a subvolume always called
>>  "__active". When I want to rollback, I rename
"__active" in
>> "__broken" (or remove it), then I rename (or re-snapshot)
>> "snapshot-yyyymmdd" in "__active".
>>
>>>> That way, we ensure the best compatibility and lowest
>>>> maintenance,
>>> as we don''t overwrite default init functions.
>>>
>>> I''m sympathetic to the alternative problem, which is that
you
>>> need to alter grub.cfg to use the proper rootflags=subvol= to
>>> explicitly use the proper snapshot, and also it would mean
>>> altering the /etc/fstab within that snapshot.
>>
>> With rename you can address both the issues
>
> Now I don''t know what snapshot that is, since it''s just
renamed to
> some non-descriptive name like "root" which happens to, by
> convention, always be the active root. This is the problem with using
> user domain to store contextual metadata. We need another way to do
> this, rather than inject these changes into filename/foldername which
> are primarily user domain. And we need agreement on a right way to do
> this rather than distribution convention.

Put all the required information in an xattr...

>
> We need some distribution collaboration in this area, or this is
> going to turn into an end-user pain point, with multiboot users top
> on the list of the injured.

I fully agree: whatever solution we found, it has to be shared across
all distributions.
>
>
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