Re: Unionmount status?

[Michal Suchanek <hramrach@centrum.cz>]

On 14 April 2011 06:50, Ian Kent <ikent@redhat.com> wrote:
> On Wed, 2011-04-13 at 21:47 +0200, Michal Suchanek wrote:
>> On 13 April 2011 21:11, Ric Wheeler <ricwheeler@gmail.com> wrote:
>> > On 04/13/2011 02:58 PM, Michal Suchanek wrote:
>> >>
>> >> On 13 April 2011 19:26, Ric Wheeler<ricwheeler@gmail.com>  wrote:
>> >>>
>> >>> On 04/12/2011 05:36 PM, Michal Suchanek wrote:
>> >>>>
>> >>>> On 12 April 2011 22:31, Ric Wheeler<ricwheeler@gmail.com>    wrote:
>> >>>>>
>> >>>>> On 04/12/2011 11:00 AM, Michal Suchanek wrote:
>> >>>>>>
>> >>>>>> Hello,
>> >>>>>>
>> >>>>>> as some already know the Unionmount VFS union which has been in
>> >>>>>> development for some years now is the only True Union (TM) that can be
>> >>>>>> accepted into the kernel mainline by the VFS maintainers (for reasons
>> >>>>>> of their own which you can surely find if you search the web or ask
>> >>>>>> them directly).
>> >>>>>>
>> >>>>>> The current UnionMount version that can be found here:
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>> http://git.kernel.org/?p=linux/kernel/git/val/linux-2.6.git;a=shortlog;h=refs/heads/ext2_works
>> >>>>>>
>> >>>>>> works for me as good as aufs does. That is I can build a live CD using
>> >>>>>> this unioning solution and it boots and runs without any apparent
>> >>>>>> issues.
>> >>>>>>
>> >>>>>> There are probably many possible uses of the union which I did not
>> >>>>>> test nor did I test long term stability of using the unioned
>> >>>>>> filesystem. As far as ephemeral live systems go it works fine for me,
>> >>>>>> though.
>> >>>>>>
>> >>>>>> The issue is that while the code is (nearly) finished it is not yet
>> >>>>>> merged into mainline and as I am not familiar with the details of
>> >>>>>> ever-changing Linux VFS layer forward-porting this code to current
>> >>>>>> kernels is somewhat challenging.
>> >>>>>>
>> >>>>>> What is the plan with unionmount now?
>> >>>>>>
>> >>>>>> What is required  for it to be merged into mainline?
>> >>>>>>
>> >>>>>> Thanks
>> >>>>>>
>> >>>>>> Michal
>> >>>>>
>> >>>>> Hi Michal,
>> >>>>>
>> >>>>> People are actively looking to see what union mount (or overlayfs)
>> >>>>> solution
>> >>>>> to pursue. Val has shifted her focus away from kernel hacking these
>> >>>>> days,
>> >>>>> but did refresh her patch set in the last month or so.
>> >>>>
>> >>>> I am not aware of such refreshed patch set, at least it is not
>> >>>> published in her repo.
>> >>>>
>> >>> Val posted the refreshed patches with the title on March 22nd:
>> >>>
>> >>> http://lwn.net/Articles/435019/
>> >>>
>> >> That article references the same four months old repo which I
>> >> mentioned at the start of the thread, only a slightly different
>> >> branch.
>> >>
>> >> While it maybe useful for testing unionmount (which I already tried)
>> >> it is not a patch against current kernel which could be used to build
>> >> current live images.
>> >>
>> >> Thanks
>> >>
>> >> Michal
>> >
>> > She did post the patch series that same date in March - you can probably
>> > grab the series from linux-fsdevel, look for this series:
>> >
>> > "[PATCH 00/74] Union mounts version something or other"
>> >
>> > Al Viro was planning on looking at her refreshed patches (he had reviewed
>> > them with her in person), but that is not going to happen any time soon so
>> > getting more eyes and testing would be great!
>> >
>>
>> Even gmame can't collect the patches back from the ML, I don't want to try.
>>
>> However, the discussion suggests that these are exactly the 4 months
>> old branch ending in a commit with the summary "Temporary commit"
>> which did not inspire confidence in me so I used the previous (also 4
>> moths old) branch.
>
> Yes, that's the impression I have too.
>
> I believe David was working to update the patches and his silence
> indicates he is probably bogged down with other priority work. If that's
> the case, and your still interested, I might be able to help updating
> the series some time soon. I haven't reviewed any of Val's series posts
> for a while now so I'd need to catch up with the current state of the
> project first.

I guess overlayfs includes the better part of unionmount and achieves
similar level of functionality in much smaller code size and is
actively developed.

This might make it the best candidate for inclusion so far.

It does not (yet?) support NFS which is one of the options commonly
used with union solutions, though.

I personally don;t use NFS and have not tested overlayfs so far so I can't tell.

Thanks

Michal