OpenZFS branch tracking policy

[Martin Matuska]

Thank you guys for your input.

OpenZFS 2.1 has already gone -RC3, eliminating even more diffs the code 
in our tree.

I have merged OpenZFS-2.1 RC1 the old way up to the last common commit. 
I don't know who or what body is in charge to make a decision on this 
matter but I would be very happy if a decision is made. I am personally 
slightly in favor of merging directly from OpenZFS as it makes my work 
easier and less prone to mistakes but I don't object doing it the "old" 
way. But even the "old" way is going to be different, as it would mean 
doing vendor merges into stable/13 what we are not used to. On the other 
hand I do "squashed" imports anyway so I could cherry-pick from the new 
vendor branch into stable/13 as well.

One way or another, I would like to continue pushing recent OpenZFS code 
to our tree.

Martin

On 13. 4. 2021 18:39, Warner Losh wrote:
>
>
> On Tue, Apr 13, 2021 at 8:37 AM Ulrich Spörlein <uqs at freebsd.org 
> <mailto:uqs at freebsd.org>> wrote:
>
>     Hmm, I don't have an opinion on that one really. Cherry-pick of
>     course
>     only works on a single commit and will not record an additional
>     parent,
>     while a merge commit will have (at least) 2 parents.
>
>
> Correct.
>
>     Some vendor branches sometimes have several commits in between a
>     merge
>     into head, so `git merge` is the natural extension of that. So
>     only some
>     folks can use cherry-pick and, as I said, I'm not sure what the
>     recording of 2 parents gives us ...
>
>
> So for normal, low velocity updates, there's little benefit from doing 
> more than what we've done with vendor imports.
>
> But for OpenZFS I think there's three primary values from store their 
> branches in our tree and doing merge commits:
>
> (1) git blame works
> (2) it's possible to bisect down to the exact commit
> (3) Having the merge commits recorded as merge commits makes future 
> commits easier (just like vendor branches).
>
> For most things, I agree with Uli: we should have some flavor of 
> 'squash' commit that's not really a merge commit to do this.  But for 
> OpenZFS, I think there's enough synergy between the two project that 
> having their branches in our tree would be a net win for both groups.
>
> Warner
>
>     People with more vendor experience should chime in ...
>
>     Cheers
>     Uli
>
>     On Mon, 2021-04-12 at 13:08:59 +0200, Martin Matuska wrote:
>     >If we keep the "old way" than I have an additional question:
>     >
>     >Wouldn't a "git cherry-pick -Xsubtree=sys/contrib/openzfs" from the
>     >vendor branch be a better way to go than "git merge
>     >-Xsubtree=sys/contrib/openzfs"? Especially for stable/13, where I
>     have
>     >to "merge" in the whole new vendor/openzfs/zfs-2.1-release branch.
>     >
>     >mm
>     >
>     >On 12. 4. 2021 11:02, Ulrich Spörlein wrote:
>     >> On Sun, 2021-04-11 at 01:03:30 +0200, Martin Matuska wrote:
>     >>> Thank you for your comments, Warner.
>     >>>
>     >>> What I would like to know is the timing - how much time do we
>     need to
>     >>> resolve the issues. I can pull in the OpenZFS code up to commit
>     >>> 3522f57b6 the "old" way. This is the last commit common to
>     master and
>     >>> zfs-2.1-release and can be cherry-picked to stable/13 the
>     "old" way.
>     >>> This will keep our code on par with openzfs-2.1-rc1 (rc2 is
>     out now) and
>     >>> I can add a 2-week MFC for stable/13 as usual but there are no
>     >>> significant changes at all. After that we need to split main and
>     >>> stable/13 and ideally move to direct tracking of OpenZFS.
>     >>>
>     >>> I have added some comments below.
>     >>
>     >> I think we should continue with the old way of squashing vendor
>     >> changes in, for the main reason of bloat and slowdown for our
>     users.
>     >> Note that unlike SVN, a regular user who builds world will
>     clone all
>     >> of the git repo including all history. We have many more users
>     than we
>     >> have developers working on contrib software, so the slight
>     convenience
>     >> of a few FreeBSD devs comes at the cost of the majority of our
>     users. :(
>     >>
>     >> I understand the confusion of a broken `git blame` and I'm
>     wondering
>     >> if it wouldn't be enough for the folks that want this to fetch the
>     >> full OpenZFS repo into their FreeBSD repo. Then when the need
>     arises
>     >> to `git blame foo/bar.c` they see an "unhelpful" commit that says
>     >> "upstream 01234abcdef was merged" upon which you can run `git blame
>     >> 01234abcdef -- foo/bar.c` (paths will be different but it all
>     can be
>     >> hidden behind some script and git alias).
>     >>
>     >> Would that ease enough of the developers pain?
>     >>
>     >> I wish more stuff would move into ports (llvm, lldb) for reasons of
>     >> size also.
>     >>
>     >> Cheers
>     >> Uli
>