[systemd-devel] [PATCH] tmpfiles: don't create subvolumes in chroot

[Lennart Poettering]

On Thu, 02.04.15 12:31, Jóhann B. Guðmundsson (johannbg at gmail.com) wrote:

> >>On 04/01/2015 02:37 PM, Lennart Poettering wrote:
> >>>Note that I intend to add more subvolume lines to tmpfiles even. For
> >>>example, I am pretty sure /home should be created as subvolume if it
> >>>doesn't exist already, and similar.
> >>I'm afraid that will still only work on a single host setup ( laptop/desktop
> >>) and I'm pretty sure if the intent from you is to default to more subvolume
> >>creation i'm afraid you will start conflicting with installers on top of
> >>everything else as well.
> > Why would this conflict with installers?
>
> Beside the obvious point that you on your own accord have started to decide
> *for* the end user what his intend are based on your own assumption ( which
> is something the end user decided at install time or later on if he
> administrates said host ) after install time, last time I checked installers
> ( as many other tools ) had a hard time themselves dealing properly with
> subvolumes and support btrfs properly.

Well, first of all, we make decisions for the users all the times. I
mean, we declared that "/usr" is where the OS is located, and not
"/foobar" or any other user-chosen name. 

And this case isn't even one where we make such a decision, since the
user can easily opt-out of the logic, by simple making the dir a dir,
so that tmpfiles won't do anything anymore.

> You thought that /var/lib/machines being a subvolume was the right thing to
> do and you were wrong, it only works for you on your own host but never in
> practice for administrators whom are the target audience for that
> feature.

Well, I disagree. And yeah, I still think that /var/lib/machines
should be a subvolume, if it is not created manually as something else
before. I hear no convincing case why it shouldn't be one.

> You think that /home should be created as subvolume by default, again wrong
> not only for the end user who will be scratching their heads wondering where
> their space went but also for administrators whom have this stored on
> NAS/SAN with their own specific btrfs policy build on top of storage pools (
> if they are using btrfs )

Hmm? "where their space went"? I am not sure I follow. Multiple
subvolumes on the same btrfs volume are all fed from the same big
pool. 

Please read up on btrfs subvolumes, I don't think they work the way
you think they do. They aren't fixed size partitions, but simply
directories with special semantics.

Lennart

-- 
Lennart Poettering, Red Hat