Re: Unionfs patchset p19 commit?

Kurt Jaeger wrote:
> Hi!
> 
>>>> I have a big hope to get merged into FreeBSD until
>>>> 7-RELEASE. Progress is step by step slowly, but going
>>>> forward absolutely.  If you have interest in unionfs
>>>> improvements, push your passion to re_at_ and fs_at_ committers ;-)
>>> Did you have a chance to look into this ?
>>>
>>> http://lists.freebsd.org/pipermail/freebsd-stable/2007-June/035798.html
> 
>> Already we have fixed above issue.
> [...]
> 
> I'm compiling this patch on my test system right now.
> 
> Another issue is userland support for unionfs, e.g. in fstat,
> as described on this page:
> 
> http://c0mplx.org/src/fstat-unionfs-patch/
> 
> Do you plan to analyse/investigate this topic ?

It looks like interesting. But your patch has a issues.

  +		/* fprintf(stderr,"found upper vnode\n"); */
  +		res = ufs_filestat(&upper, fsp);

and

  +		/* fprintf(stderr,"found lower vnode\n"); */
  +		res = ufs_filestat(&lower, fsp);

depend on UFS. It must treat both UFS and no UFS fs.

And I am not a maintainer of fstat(1). Please contact to
maintainer. Perhaps Ed Maste(emaste) is maintainer I suppose
from commit log.

> There's another topic if one uses unionfs in jail() setups: How to
> backup the files, and only those files that a different from
> the base ?
> 
> If I traverse a mounted unionfs, how do I know where data is coming
> from, the lower mount or the higher mount ?
> 
> If I can't tell the difference, I'll backup quite a lot of stuff
> multiple times.
> 
> I've experimented a little and found no easy way to tell lower
> from upper unless I open the file (which sounds expensive). 
> Have a look at http://c0mplx.org/src/isunionfs.c -- does this
> sound like a way to go ?

The isunionfs.c looks like interesting, too :) But your
program is not complete. 'below' option gives it non-correct
work. Addition it does not consider unionfs and nullfs
combibation or something like that. To check upper/lower
completely, you need the same way of your fstat(1) patch.

But your idea looks interesting :)  Keep your concern of
unionfs. To get keep concern is very good for us!

-- 
   Daichi GOTO, http://people.freebsd.org/~daichi