From: Keith Busch <kbusch@kernel.org>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Keith Busch <kbusch@meta.com>,
dm-devel@lists.linux.dev, linux-block@vger.kernel.org,
snitzer@kernel.org
Subject: Re: [RESEND PATCHv3 2/2] dm-crypt: dynamic scatterlist for many segments
Date: Wed, 18 Mar 2026 11:53:26 -0600 [thread overview]
Message-ID: <abrmlumkhOQEBk-Z@kbusch-mbp> (raw)
In-Reply-To: <7cdd50b4-afcf-aa5a-af0b-a00a35b88bdf@redhat.com>
On Wed, Mar 18, 2026 at 06:40:52PM +0100, Mikulas Patocka wrote:
> On Wed, 18 Mar 2026, Keith Busch wrote:
>
> > But even then, the only thing I know of that really wants this has an
> > offset that straddles two pages per block, so I never need more than 2
> > segments, and the inline scatterlist has four. There's just currently no
> > way for the block layer to report a max-segments-per-block limit, so I'm
> > including this patch to be consistent with the reportable limits.
>
> Can userspace use preadv/pwritev with many small iovecs on a file opened
> for direct I/O?
Yes, I have several patches that were accepted last year to block and
iomap that align direct-io memory requirements to the backing device's
dma constraints. You can do dword aligned and sized vectored IO to a
block device today if the block limits say its okay.
next prev parent reply other threads:[~2026-03-18 17:53 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 15:02 [RESEND PATCHv3 1/2] dm-crypt: allow unaligned bio_vecs for direct io Keith Busch
2026-03-16 15:09 ` [RESEND PATCHv3 2/2] dm-crypt: dynamic scatterlist for many segments Keith Busch
2026-03-18 16:34 ` Mikulas Patocka
2026-03-18 17:01 ` Keith Busch
2026-03-18 17:40 ` Mikulas Patocka
2026-03-18 17:53 ` Keith Busch [this message]
2026-03-18 18:16 ` Mikulas Patocka
2026-03-18 18:32 ` Keith Busch
2026-03-18 18:41 ` Mikulas Patocka
2026-03-16 15:09 ` [RESEND PATCHv3 0/2] dm-crypt: support relaxed memory alignment Keith Busch
2026-03-18 16:19 ` [RESEND PATCHv3 1/2] dm-crypt: allow unaligned bio_vecs for direct io Mikulas Patocka
2026-03-18 17:40 ` Keith Busch
2026-03-18 18:06 ` Mikulas Patocka
2026-03-18 18:35 ` Keith Busch
2026-03-25 18:34 ` Keith Busch
-- strict thread matches above, loose matches on Subject: below --
2026-01-14 15:49 [RESEND PATCHv3 0/2] dm-crypt: support relaxed memory alignment Keith Busch
2026-01-14 15:49 ` [RESEND PATCHv3 2/2] dm-crypt: dynamic scatterlist for many segments Keith Busch
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