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Date: Thu, 11 Jun 2026 15:38:33 +0200
From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Carlos Maiolino <cem@kernel.org>, Christoph Hellwig <hch@lst.de>,
	brauner@kernel.org, linux-block@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
	linux-xfs@vger.kernel.org, Hannes Reinecke <hare@suse.de>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH] iomap: enforce DIO alignment check in iomap
Message-ID: <20260611133833.GA14645@lst.de>
References: <20260610145218.141369-1-cem@kernel.org> <20260611055744.GA18538@lst.de> <aiqBvF93P4NjfaDR@nidhogg.toxiclabs.cc> <aiqwy5DfHI79KXuZ@kbusch-mbp>
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On Thu, Jun 11, 2026 at 06:57:47AM -0600, Keith Busch wrote:
> It's entirely possible a device supports byte aligned addresses. The
> block layer just doesn't let a driver report that. So either it really
> was successful because you found a bug that skips the alignment checks,
> or your device silently corrupted your payload.
> 
> Anyway, my earlier suggestion should work. Ming thinks it may go to far,
> though, in not taking the optimization when it was possible. So here's
> an alternative suggestion that should get things working as expected:

The fix below looks like it is addressing a real bug.  I'm not sure if
Carlos is hitting it, but we were missing the alignment checks for
single-bvec fast path bios so far indeed.