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Date: Wed, 24 Jun 2026 09:39:01 +0200
From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Keith Busch <kbusch@meta.com>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	dm-devel@lists.linux.dev, axboe@kernel.dk, brauner@kernel.org,
	djwong@kernel.org, viro@zeniv.linux.org.uk, stable@vger.kernel.org
Subject: Re: [PATCHv2 6/6] block: validate user space vectors during
 extraction
Message-ID: <20260624073901.GA12649@lst.de>
References: <20260622174241.2299563-1-kbusch@meta.com> <20260622174241.2299563-7-kbusch@meta.com> <20260623151021.GA14919@lst.de> <ajqxoeZ0R_RwqEKe@kbusch-mbp>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Tue, Jun 23, 2026 at 10:17:37AM -0600, Keith Busch wrote:
> Exactly, the in-kernel users of ITER_BVEC that allocate their own
> buffers are, as far as I know, aligned already. Fabric storage targets
> like nvme allocate their own SGLs on page boundaries so the bio is
> aligned at the point it was constructed.
> 
> The ones that forward user buffers like loop and zloop are addressed in
> the previous two patches. They generally should have been fine for most
> hardware without those updates, but they're included in case a backing
> device has more restrictive constraints than 512b "sector_t" aligned.
> 
> The only other user space provided alignment that I think may trip this
> up is the io_uring registered buffer, so that's what I'm trying to call
> out here.

Sounds reasonable, but it would be really helpful to have this in
the API documentation somewhere..

Talking about documented APIs and related bits:  do you still plan
to get back to exposing our pre-vector alignment requirements and
add tests to blktests/xfstests based on that?