From: Mike Snitzer <snitzer@kernel.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>,
Johannes Weiner <hannes@cmpxchg.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
dm-devel@lists.linux.dev
Subject: Re: [GIT PULL] Block updates for 6.9-rc1
Date: Tue, 12 Mar 2024 18:22:21 -0400 [thread overview]
Message-ID: <ZfDVnVuDYwzDVnDx@redhat.com> (raw)
In-Reply-To: <ZfDEtchBNeFLG-GV@infradead.org>
On Tue, Mar 12 2024 at 5:10P -0400,
Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Mar 12, 2024 at 11:22:53AM -0400, Mike Snitzer wrote:
> > blk_validate_limits() is currently very pedantic. I discussed with Jens
> > briefly and we're thinking it might make sense for blk_validate_limits()
> > to be more forgiving by _not_ imposing hard -EINVAL failure. That in
> > the interim, during this transition to more curated and atomic limits, a
> > WARN_ON_ONCE() splat should serve as enough notice to developers (be it
> > lower level nvme or higher-level virtual devices like DM).
>
> I guess. And it more closely matches the status quo. That being said
> I want to move to hard rejection eventually to catch all the issues.
>
> > BUT for this specific max_segment_size case, the constraints of dm-crypt
> > are actually more conservative due to crypto requirements.
>
> Honestly, to me the dm-crypt requirement actually doesn't make much
> sense: max_segment_size is for hardware drivers that have requirements
> for SGLs or equivalent hardware interfaces. If dm-crypt never wants to
> see more than a single page per bio_vec it should just always iterate
> them using bio_for_each_segment.
>
> > Yet nvme's
> > more general "don't care, but will care if non-nvme driver does" for
> > this particular max_segment_size limit is being imposed when validating
> > the combined limits that dm-crypt will impose at the top-level.
>
> The real problem is that we combine the limits while we shouldn't.
> Every since we've supported immutable biovecs and do the splitting
> down in blk-mq there is no point to even inherit such limits in the
> upper drivers.
immutable biovecs, late splitting and blk-mq aren't a factor.
dm-crypt has to contend with the crypto subsystem and HW crypto
engines that have their own constraints.
next prev parent reply other threads:[~2024-03-12 22:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <eaeec3b6-75c2-4b65-8c50-2d37450ccdd9@kernel.dk>
[not found] ` <20240311235023.GA1205@cmpxchg.org>
[not found] ` <CAHk-=wgOfw8NBQ2Qyh8QUjhp5z4v--PuciLE7drn5LJkTtgPVw@mail.gmail.com>
[not found] ` <e3fea6c3-7704-46cd-b078-0c6e8d966474@kernel.dk>
[not found] ` <CAHk-=wgXZ6dE1yHK_jQmnSjbEbndyzZHC5dJNsmQYTD2K-m61w@mail.gmail.com>
[not found] ` <Ze-hwnd3ocfJc9xU@redhat.com>
[not found] ` <Ze-rRvKpux44ueao@infradead.org>
2024-03-12 15:22 ` [GIT PULL] Block updates for 6.9-rc1 Mike Snitzer
2024-03-12 16:28 ` Keith Busch
2024-03-12 21:10 ` Christoph Hellwig
2024-03-12 22:22 ` Mike Snitzer [this message]
2024-03-12 22:30 ` Christoph Hellwig
2024-03-12 22:50 ` Mike Snitzer
2024-03-12 22:58 ` Christoph Hellwig
2024-04-11 20:15 ` [PATCH for-6.10 0/2] dm: use late bio-splitting and queue_limits_set Mike Snitzer
2024-04-11 20:15 ` [PATCH for-6.10 1/2] dm-crypt: stop constraining max_segment_size to PAGE_SIZE Mike Snitzer
2024-04-12 6:11 ` Christoph Hellwig
2024-04-15 14:08 ` Mikulas Patocka
2024-04-23 7:32 ` Ming Lei
2024-04-11 20:15 ` [PATCH for-6.10 2/2] dm: use queue_limits_set Mike Snitzer
2024-04-23 7:33 ` Ming Lei
2024-03-13 13:11 ` [GIT PULL] Block updates for 6.9-rc1 Ming Lei
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