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Date: Mon, 13 Jul 2026 09:39:01 -0600
From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: axboe@kernel.dk, z1281552865@gmail.com, linux-block@vger.kernel.org
Subject: Re: [PATCH] block: fix aligning of bounced dio read bios
Message-ID: <alUGlVDWkZNyUE4N@kbusch-mbp>
References: <20260713152912.2333321-1-hch@lst.de>
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In-Reply-To: <20260713152912.2333321-1-hch@lst.de>

On Mon, Jul 13, 2026 at 05:29:11PM +0200, Christoph Hellwig wrote:
> bio_iov_iter_align_down expects the "normal" biovec layout from vector 0,
> while bio_iov_iter_bounce_read abuses vector 0 for a bounce buffer
> allocation.  Pass an explicit bvec to bio_iov_iter_align_down to deal
> with this case to avoid a double unpin.

Can you instead just have bio_iov_iter_bounce_read() align down the size
it extracts rather than letting it over-extract and reverting the excess?