/root on a separate dataset breaks FreeBSD-base installation

[Rodney W. Grimes]

> 
> > Here we disagree, I consider /root very much a part of the base
> > system and it should be pretty much unused.  And I am a person
> > that logs in as root and su -'s out to user accounts, but I
> > still do not use /root as a normal home directory, everything
> > else is done and stored some other place.
> 
> 
> Do you see /root as part of the base here 
> https://svnweb.freebsd.org/base/head/ ? ;-)

Yes, at a few places, that pkg base has majorly moved stuff around
and I am not going to hunt for it but etc/Makefile and etc/mtree/BSD.root.dist.
${DESTDIR}/root is created and populated during a make distribution.

> 
> Also look here https://www.freebsd.org/doc/handbook/jails-application.html
> 
> /root is treated as editable part of the read-only base system, the same 
> way as /home
editable != seperate vfs or zfs dataset.  Try it, I suspect the jail
create fails with the same error that it can not cross link the files.

> > The fact that it is shipped with the base system, created by the
> > base system installer, and is pretty much a mandatory required directoy,
> > however does make it very much part of the base system.
> 
> 
> We actually don't argue here if /root is part of a base system but if 
> it's reasonable for the installer to assume that /root is on the same 
> dataset as /.

It is totally reasonable for it to assume that since the contents
of / and /root are shipped in one tar ball, base.txz.

> Based on the links I mentioned above, and on your comment, my 
> understanding is that /root is not part of the base system but it's 
> created and populated by the installer when installing the base.

Yo have miss undertood my comments then.  It is populated by the
installer when it extracts base.txz.

> Is the 
> requirement that the /root dataset should be on the same dataset as / 
> mentioned anywhere in the official documentation? I couldn't find it 
> here 
> <https://www.freebsd.org/doc/handbook/bsdinstall-partitioning.html#bsdinstall-part-shell> 
> but it's also hard to search for due to root being a very common word in 
> various contexts. Certainly bsdinstall doesn't require /root to be on 
> the same dataset as /.

Loack of documentation does not change the assumptions made by the
base system.

> 
> If indeed there is no such existing requirement, then it would be 

As it exists today "there is a requirement that /root and / be
in the same filesystem."  That requirement is why your getting
an error.  That requirement goes back to BSD 4.3 or earlier.

> something new that pkgbase is introducing. Which might be fine, but is 
> it reasonable?

This is not something new that pkg base has introduced, this requirement
has existed for > 2 decades.

> I don't think so. Regardless if /root should be 
> considered part of the base system or not, I don't see any reason for 
> pkgbase or the FreeBSD's base system to require /root to be on the same 
> dataset as / apart from those two hardlinks discussed earlier.

Yep, it is those 2 hard links that create the requirement,
and the reasons behind them being hard linked are rather
practical, it is so that when/if the system fails to single
user and HOME becomes / the user has the same environment
that they would had root loged in, sans having to manual
pick a shell.

> 
> 
> >> It's home directory for the /root user,
> >> where I often have larger files that I either copy to install or just as
> >> a backup of some parts of the system.
> > I would never store backup's in /root!
> 
> 
> Backup may mean different things. I don't mean backups of the system. 
> Consider a tarball of the kernel copied from another system that needs 
> to be unpacked to / or temporary copies of some configs that are being 
> edited, e.g. pf.conf or rc.conf. Where would you store those?

Probably in /tmp, maybe in ~rgrimes, but defanitly not in /root.

> >> Versioning it per boot environment
> >> wouldn't make sense.
> > Double edge sword.  The set of tweaks needed in .cshrc or .profile may
> > vary by version of FreeBSD installed.
> >
> 
> Well, I would assume that an administrator is free to edit .cshrc and 
> .profile for their own needs, e.g. add aliases or env variables. Once 
> changed they would no longer be updated with the system but skipped. 

Actually I believe the update process, especially pkg base knows how to
do 3 way merges of files marked as conf.

> There are always reference versions in / which the administrator should 
> consult and copy over any required changes after the system has been 
> updated.

The files in / are NOT seperate versions, they are a second pointer
to the same file contents.  Editing /.cshrc also changes /root/.cshrc.

> GrzegorzJ
-- 
Rod Grimes                                                 rgrimes at freebsd.org