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Re: Discussion: what would not blocking on btrfs look like?



On Mon, Aug 26, 2019 at 11:16 AM Laura Abbott <labbott redhat com> wrote:
>
> On 8/23/19 9:00 PM, Chris Murphy wrote:
> > On Fri, Aug 23, 2019 at 1:17 PM Adam Williamson
> > <adamwill fedoraproject org> wrote:
> >
> >> So, there was recently a Thing where btrfs installs were broken, and
> >> this got accepted as a release blocker:
> >>
> >> https://bugzilla.redhat.com/show_bug.cgi?id=1733388
> >
> > Summary: This bug was introduced and discovered in linux-next, it
> > started to affect Fedora 5.3.0-rc0 kernels in openqa tests, patch
> > appeared during rc1, and the patch was merged into 5.3.0-rc2. The bug
> > resulted in a somewhat transient deadlock which caused installs to
> > hang, but no corruption. The fix, 2 files changed, 12 insertions, 8
> > deletions (1/2 the insertions are comments).
> >
> > How remarkable or interesting is this bug? And in particular, exactly
> > how much faster should it have been fixed in order to avoid worrying
> > about it being a blocker bug?
> >
> > 7/25 14:27 utc bug patch was submitted to linux-btrfs@
> > 7/25 22:33 utc bug was first reported in Fedora bugzilla
> > 7/26 19:20 utc I confirmed upstream's patch related to this bug with
> > upstream and updated the Fedora bug
> > 7/26 22:50 utc I confirmed it was merged into rc2, and updated the Fedora bug
> >
> > So in the context of status quo, where Btrfs is presented as an option
> > in the installer and if there are bugs they Beta blocking, how could
> > or should this have been fixed sooner? What about the handling should
> > have been different?
> >
>
> That's a fair question. This bug actually represents how this _should_
> work. The concern is that in the past we haven't seen a lot engagement
> in the past. Maybe today that has changed as demonstrated by this thread.
> I'm still concerned about having this be a blocker vs. just keeping it
> as an option, simply because a blocker stops the entire release and it
> can be a last minute scramble to get things fixed. This was the ideal
> case for a blocker bugs and I'm skeptical about all bugs going this well.
> If we had a few more people who were willing to be on the btrfs alias and
> do the work for blocker bugs it would be a much stronger case.
>

Out of curiosity, how many such issues have we had in the past 2
years? I personally can't recall any monumental occasions where people
were scrambling over *Btrfs* in Fedora. If anything, we continue to
inherit the work that SUSE and Facebook are doing upstream as part of
us continually updating our kernels, which I'm grateful for.

And in the instances where we've had such issues, has anyone reached
out to btrfs folks in Fedora? Chris and myself are the current ones,
but there have been others in the past. Both of us are subscribed to
the linux-btrfs mailing list, and Chris has a decent rapport with most
of the btrfs developers.

What more do you want? Actual btrfs developers in Fedora? We don't
have any for the majority of filesystems Fedora supports, only XFS. Is
there some kind of problem with communicating with the upstream kernel
developers about Fedora bugs that I'm not aware of?

> > I note here that ext2 and ext3 are offered as file systems in
> > Custom/Advanced partitioning and in this sense have parity with Btrfs.
> > If this same bug occurred in ext2 or ext3 would or should that cause
> > discussion to drop them from the installer, even if the bug were fixed
> > within 24 hours of discovery and patch? What about vfat? That's
> > literally the only truly required filesystem that must work, for the
> > most commonly supported hardware so it can't be dropped, we'd just be
> > stuck until it got fixed. That work would have to be done upstream,
> > yes?
> >
>
> I don't think that's really a fair comparison. Just because options
> are presented doesn't mean all of them are equal. ext2/ext3 and vfat
> have been in development for much longer than btrfs and length of development
> is something that's particularly important for file system stability
> from talking with file system developers. It's not impossible for there
> to be bugs in ext4 for example (we've certainly seen them before) but
> btrfs is only now gaining overall stability and we're still more likely to see
> bugs, especially with custom setups where people are likely to find
> edge cases.
>

Nope. We can totally use this because LVM has not existed as long (we
use LVM + filesystem by default, not plain partitions), and we still
encounter quirks with things like thinp LVM combined with these
filesystems. OverlayFS is mostly hot garbage (kernel people know it,
container people know it, filesystem people know it, etc.), and yet we
continue to try to use it in more places. Stratis is in an odd state
of limbo now, since its main developer and advocate left Red Hat.

There are plenty of examples of Red Hat doing crazy/experimental
things... I'd like to think Red Hat isn't supposed to be special here,
but in this realm, it seems like it is...


-- 
真実はいつも一つ!/ Always, there's only one truth!


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