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Date: Wed, 18 Mar 2026 12:35:05 -0600
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 1/2] dm-crypt: allow unaligned bio_vecs for
 direct io
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 <7cc4892a-5a2f-09b7-1f32-320acac4c797@redhat.com>
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 <fa0978af-398b-a212-73bc-80f0f2c375a4@redhat.com>
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In-Reply-To: <fa0978af-398b-a212-73bc-80f0f2c375a4@redhat.com>

On Wed, Mar 18, 2026 at 07:06:40PM +0100, Mikulas Patocka wrote:
> > It doesn't matter what the underlying block device reports because
> > dm-crypt bounces the incoming plain text buffers to something aligned to
> > the backing device for the cypher text.
> 
> dm-crypt bounces writes, but doesn't bounce reads. When doing reads, it 
> reads the data into the target buffer and decompresses them in place.

Oh, thanks. It's been a while since I developed this, so I'll need a
moment double check for any mistaken assumptions. It may be I just used
backing devices that also had similar alignment constraints and missed
something.