Re: [XFS SUMMIT] Ugh, Rebasing Sucks!

[Dave Chinner <david@fromorbit.com>]

On Wed, May 27, 2020 at 07:44:10PM -0700, Darrick J. Wong wrote:
> On Thu, May 28, 2020 at 10:03:51AM +1000, Dave Chinner wrote:
> > From my perspective, an update from for-next after the -rc6 update
> > gets me all the stuff that will be in the next release. That's the
> > major rebase for my work, and everything pulled in from for-next
> > starts getting test coverage a couple of weeks out from the merge
> > window.  Once the merge window closes, another local update to the
> > -rc1 kernel (which should be a no-op for all XFS work) then gets
> > test coverage for the next release. -rc1 to -rc4 is when
> > review/rework for whatever I want merged in -rc4/-rc6 would get
> > posted to the list....
> 
> <nod>
> 
> My workflow is rather different -- I rebase my dev tree off the latest
> rc every week, and when a series is ready I port it to a branch off of
> for-next.

I do actually update the base kernel quite frequently - usually
every monday after a -rc is released. This is easy, and rarely
causes rebase issues because all the XFS changes in the base tree
have already been in the for-next tree. i.e. my typical weekly
"rebase" is:

git remote update
for each git branch:
	guilt pop -a
	git reset --hard origin/master # latest Linus tree
	git merge linux-xfs/for-next
	<merge any dependencies>
	loop {
		guilt push -a
		<fix patch that doesn't apply>
	} until all patches applied

If there's no significant change in for-next, then this is all easy
and is done in a few minutes. But if there's substantial change to
for-next, then the problems occur when pushing the patches back
onto the stack...

I've always based my dev work on the for-next branch (or equivalent
dev tree tip) because that way I'm always testing the latest dev
code from everyone else and I know my code works with it.

> Occasionally I'll port a refactoring from for-next into my
> dev tree to keep the code bases similar. 

Yup, that's the "<merge any dependencies>" in the process above.
i.e. someone has posted a cleanup patchset that's going to be merged
into for-next before the work I'm doing. That's where all the recent
problems have been coming from - the pain either occurs at the next
for-next update, or I take it when it's clear it's going to be
merged soon...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com