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Date: Mon, 24 Feb 2025 17:02:24 -0700
From: Keith Busch <kbusch@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: Keith Busch <kbusch@meta.com>, ming.lei@redhat.com,
	asml.silence@gmail.com, linux-block@vger.kernel.org,
	io-uring@vger.kernel.org, bernd@bsbernd.com,
	csander@purestorage.com
Subject: Re: [PATCHv5 02/11] io_uring/nop: reuse req->buf_index
Message-ID: <Z70IkEtkNUkdDDg4@kbusch-mbp>
References: <20250224213116.3509093-1-kbusch@meta.com>
 <20250224213116.3509093-3-kbusch@meta.com>
 <54284f45-b597-415a-a954-5ab282747704@kernel.dk>
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In-Reply-To: <54284f45-b597-415a-a954-5ab282747704@kernel.dk>

On Mon, Feb 24, 2025 at 04:30:48PM -0700, Jens Axboe wrote:
> On 2/24/25 2:31 PM, Keith Busch wrote:
> > From: Keith Busch <kbusch@kernel.org>
> > 
> > There is already a field in io_kiocb that can store a registered buffer
> > index, use that instead of stashing the value into struct io_nop.
> 
> Only reason it was done this way is that ->buf_index is initially the
> buffer group ID, and then the buffer ID when a buffer is selected. But I
> _think_ we always restore that and hence we don't need to do this
> anymore, should be checked. Maybe you already did?

The IORING_OP_NOP opdef doesn't set the buffer_select flag, so the req
buf_index couldn't be used for a buffer select id.