From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 64F1242FCA9; Mon, 5 Oct 2026 09:10:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791191415; cv=none; b=jUYEifFURLb6EyduCGNf3D0Aj09kWhO1+2Y/FjAXXNGUSkxo807WiAySvy2WXe5OklIMhNYvNES80zN2vVBZ3TmUvufN2Sm6++NtyHsCyobY7xlklo6IeMSeq8Z1LHoq8o9WQxOJAxU9x5ZZygBJoplHuw3d1CF2126bAcV/EQk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791191415; c=relaxed/simple; bh=hNmAJf53nuCegwa5Bo6KwYtz5NCdOGq2JIipG/i7568=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nqzPJtmTUdwG1Lrov6+b4kC3Wg6D4Q3nAAZcAtJg0cyLZ1iLfQOn6OujskawFnd+1rkxrkMXlSbO0xUInjWRl1LRDTihG5u6Q/45X+9fFZgZQqdbzD34sh397OvFvvt5v67lWxl3WjpPovblREdVxiyC6FmbK1c0Eh0kv/ajN2k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id 8EEDC68BFE; Mon, 5 Oct 2026 11:10:08 +0200 (CEST) Date: Mon, 5 Oct 2026 11:10:08 +0200 From: Christoph Hellwig To: Pavel Begunkov Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, Christoph Hellwig , Sumit Semwal , Christian =?iso-8859-1?Q?K=F6nig?= , Keith Busch , Sagi Grimberg , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Jens Axboe , Nitesh Shetty , Kanchan Joshi , Anuj Gupta , Tushar Gohad , William Power , Phil Cayton , Matthew Brost , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , dm-devel@lists.linux.dev Subject: Re: [PATCH v7 02/13] iov_iter: add iterator type for dmabuf maps Message-ID: <20261005091008.GA10727@lst.de> References: <74a9d65f5c4f9acce5f57ad5921a9fadc6eda712.1790602223.git.asml.silence@gmail.com> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <74a9d65f5c4f9acce5f57ad5921a9fadc6eda712.1790602223.git.asml.silence@gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) On Mon, Sep 28, 2026 at 02:32:18PM +0100, Pavel Begunkov wrote: > Introduce a new iterator type for dmabuf maps. The map in an opaque > object with internals and format specific to the subsystem / driver, and > only it can use that subsystem / driver for issuing IO. The task of the > middle layers is to pass the map / iterator further down, maybe doing > basic splitting and length checking. The iterator can only be used by > operations of the file the associated map was created for. > > Suggested-by: Keith Busch > Reviewed-by: Christoph Hellwig > Signed-off-by: Pavel Begunkov FYI, I think the Sashiko complaint about iterate_and_advance2 is correct here. We don't really hit that in the series, but leaving iov_iter methods partially implemented and fall through to others seems dangerous. At minimum that needs a WARN_ON to catch that case.