Re: [PATCH 8/8] dm-verity: Convert from tasklet to BH workqueue

From: Mike Snitzer <snitzer@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Mikulas Patocka <mpatocka@redhat.com>,
	linux-kernel@vger.kernel.org, dm-devel@lists.linux.dev,
	msnitzer@redhat.com, ignat@cloudflare.com, damien.lemoal@wdc.com,
	bob.liu@oracle.com, houtao1@huawei.com, peterz@infradead.org,
	mingo@kernel.org, netdev@vger.kernel.org, allen.lkml@gmail.com,
	kernel-team@meta.com, Alasdair Kergon <agk@redhat.com>
Subject: Re: [PATCH 8/8] dm-verity: Convert from tasklet to BH workqueue
Date: Thu, 22 Feb 2024 16:24:45 -0500	[thread overview]
Message-ID: <Zde7nXVx8oFepINV@redhat.com> (raw)
In-Reply-To: <ZdUGFqLCpWez42Js@slm.duckdns.org>

On Tue, Feb 20 2024 at  3:05P -0500,
Tejun Heo <tj@kernel.org> wrote:

> Hello, Mike.
> 
> On Tue, Feb 20, 2024 at 02:44:29PM -0500, Mike Snitzer wrote:
> > I'm not sure where things stand with the 6.9 workqueue changes to add
> > BH workqueue.  I had a look at your various branches and I'm not
> > seeing where you might have staged any conversion patches (like this
> > dm-verity one).
> 
> Yeah, the branch is for-6.9-bh-conversions in the wq tree but I haven't
> queued the DM patches yet. Wanted to make sure the perf signal from TCP
> conversion is okay first. FWIW, while Eric still has concerns, the initial
> test didn't show any appreciable regression with production memcache
> workload on our side.
> 
> > I just staged various unrelated dm-verity and dm-crypt 6.8 fixes from
> > Mikulas that I'll be sending to Linus later this week (for v6.8-rc6).
> > Those changes required rebasing 'dm-6.9' because of conflicts, here is
> > the dm-6.9 branch:
> > https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-6.9
> > 
> > So we'll definitely need to rebase your changes on dm-6.9 to convert
> > dm-crypt and dm-verity over to your BH workqueue.  Are you OK with
> > doing that or would you prefer I merge some 6.9 workqueue branch that
> > you have into dm-6.9? And then Mikulas and I work to make the required
> > DM target conversion changes?
> 
> Oh, if you don't mind, it'd be best if you could pull wq/for-6.9 into dm-6.9
> and do the conversions there.
> 
> Thank you.

I've rebased and made the changes available in this dm-6.9-bh-wq branch:
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-6.9-bh-wq

I left them both DM conversion commits attributed to use despite the
rebase (and churn of renames I did in the dm-verity commit); hopefully
you're fine with that but if not I can split the renames out.

I successfully tested using the cryptsetup testsuite ('make check').
And I've also added these changes to linux-next, via linux-dm.git's
'for-next':
https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/log/?h=for-next

Mikulas, feel free to review/test and possibly add another patch for
dm-verity that only uses a single work_struct in struct dm_verity_io

Thanks,
Mike