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Date: Fri, 10 Jul 2026 17:11:23 -0600
From: Keith Busch <kbusch@kernel.org>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>,
	Keith Busch <kbusch@meta.com>, linux-block@vger.kernel.org,
	linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	axboe@kernel.dk, brauner@kernel.org, cem@kernel.org,
	jaegeuk@kernel.org, aalbersh@kernel.org, tytso@mit.edu
Subject: Re: [PATCH] fs: report direct io constraints through file_getattr
Message-ID: <alF8G6Fw2aFh-2_o@kbusch-mbp>
References: <20260708011843.1036846-1-kbusch@meta.com>
 <20260709071352.GA20180@lst.de>
 <neamg3phll7hjwd765ddtqebtxasdvkoskff75dqzmgzv2xy5i@mf4agr6yoizn>
 <20260710212058.GA1911@quark>
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In-Reply-To: <20260710212058.GA1911@quark>

On Fri, Jul 10, 2026 at 05:20:58PM -0400, Eric Biggers wrote:
> So far I haven't seen the point.  Yes, applications can benefit from the
> lower alignment in theory.  But especially with encryption/decryption,
> it isn't at all easy to support.  This has apparently been getting
> learned the hard way, as (for example) alignment was initially relaxed
> for dm-crypt without testing it, and it had to be reverted
> (https://lore.kernel.org/dm-devel/20221103152559.1909328-1-kbusch@meta.com/).

To be fair, that was most certainly tested in production, and it was
reverted for a bug not related to alignment. It was just a mishandled
early exit corner case accessing uninitialized fields; a trivial fixup.