Re: [PATCH 0/4] btrfs: sysfs and unsupported temp-fsid features for clones

[David Sterba <dsterba@suse.cz>]

On Wed, Oct 18, 2023 at 03:37:54PM +0200, Guilherme G. Piccoli wrote:
> On 10/10/2023 01:59, David Sterba wrote:
> > On Mon, Oct 09, 2023 at 01:37:22PM +0530, Anand Jain wrote:
> >>>> Can Guilherme send an RFC patch for feedback from others and
> >>>> copy suggested-by. Because, I haven't found a compelling reason
> >>>> for the restriction, except to improve the user experience.
> >>
> >> My comments about the superblock flag are above.
> >>
> >> User experiences are subjective, so we need others to comment;
> >> an RFC will help.
> > 
> > A few things changed, the incompat bit was supposed to prevent
> > accidentally duplicated fsids but with your recent changes this is safe.
> > This would need to let Guilherme check if the A/B use case still works
> > but this seems to be so as I'm reading the changelog.
> > 
> > In a controlled environment the incompat bit will not bring much value
> > other than yet another sanity check preventing some user error, but
> > related only to the multiple devices.
> 
> Hi David and Anand, I've manage to test misc-next of today, that
> includes both this patchset as well as the "support cloned-device mount
> capability​" one.
> 
> It seems to be working fine for our use case, though I'll test a bit
> more on Deck. I was able to mount the same filesystem (spread in 2 nvme
> devices) at the same time, in any order...the second one always get the
> temp-fsid. Tested also re-mounting the devices on other locations, and
> it seems all consistent, with no error observed.

Great, thanks.

> I also question the value of the incompat flag, not seeing much use for
> that..looping Qu Wenruo as they first suggested this flag-based
> approach, in case there is some more feedback...

Yeah at this point I don't see the need for the incompat bit, which is
the better outcome.

> Anyway, thanks for your improved approach Anand and to David: is it
> expected to land on 6.7?

Yes, what's in misc-next is queued for 6.7, also we have the whole
development cycle to fix remaining bugs.