On 4/29/18 6:23 AM, Peter Robinson wrote:
>>> On 28/04/18 14:55, Peter Robinson wrote:
>>>> On Sat, Apr 28, 2018 at 11:09 AM, Daniel Walsh <dwalsh(a)redhat.com>
>>>> wrote:
>>>>> We are adding some features to container projects for User Namespace
>>>>> support
>>>>> that can take advantage of XFS Reflink. I have talked to some of
the
>>>>> XFS
>>>>> Reflink kernel engineers in Red Hat and they have informed me that
>>>>> they
>>>>> believe it is ready to be turned on by default.
>>>>>
>>>>> I am not sure who in Red Hat I should talk to about this? Whether we
>>>>> should
>>>>> turn it on in the installer or in the mkfs.xfs command?
>>>>>
>>>>> Who should I be talking to? To make this happen.
>>>> I would speak to Eric Sandeen I believe he's the Red Hat maintainer
>>>> (or one of them) of XFS.
>>>>
>>>> Peter
>>> Indeed, and also we should look at this in the context of what is done
>>> for upstream. Ideally Fedora would just inherit the changes there, and there
>>> should not be anything special required for Fedora,
>>>
>>> Steve.
>>
>> So, for context, I am the upstream maintainer of xfsprogs as well as for
>> Fedora xfsprogs.
>>
>> Historically, new features in XFS have gone from "Experimental" (i.e.
>> under
>> development), then dropped Experimental (development is ~done) but still
>> optional,
>> and eventually default. We do this very conservatively, to give bugs a
>> chance
>> to shake out, which is one of the reasons XFS has a good reputation for
>> /not/
>> eating your data.
>>
>> Reflink on XFS only recently dropped "Experimental" and is not yet
default
>> upstream;
>> it won't be default upstream for some time to come - think on the order of
>> months.
>>
>> However, we do want to give reflink more exposure, and so jumping the gun
>> a bit and
>> turning it on for rawhide / Fedora 29 is probably a good idea.
>>
>> I'm mostly ok with patching it on by default in mkfs.xfs; it does confuse
>> things a bit
>> when "our" version behaves fundamentally differently from upstream,
but
>> it's probably
>> the right thing to do here. I'll make sure that none of the other xfs
>> developers have
>> strong objections, and if not, I'll patch it in for fedora 29.
>>
>> Unless this should be a full blown Feature? If so, I'm ok with following
>> that path
>> as well.
>
>
>
> XFS is the default filesystem on Fedora Server Edition, so yes: I think we
> should really have a System-Wide Change Proposal submitted for this,
> primarily to ensure that the information is spread widely (Change Proposals
> like this are picked up by Fedora Marketing and tech news, so it’ll be more
> widely dispersed than just on the fedora-devel list).
Assuming that the plan is to leave it enabled in F-29 on branching and
have it ship enabled in F-29 I agree, if the intention is to leave it
enabled in rawhide and disable it on branching then the Change
Proposal mechanism isn't the way to ensure wider knowledge.
I'd be happy to have it left on for F29, it /might/ even be default upstream
by the time F29 ships. I'll need to re-familiarize myself w/ the
"System-Wide Change Proposal" process, I guess.
FWIW, turning it on has very little effect until it's actually used, so it
really should not be destabilizing for most, even if bugs lurk. ;)
-Eric