From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3954C433F5 for ; Mon, 13 Dec 2021 08:03:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231484AbhLMID4 (ORCPT ); Mon, 13 Dec 2021 03:03:56 -0500 Received: from verein.lst.de ([213.95.11.211]:46547 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229547AbhLMIDz (ORCPT ); Mon, 13 Dec 2021 03:03:55 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 2F0D268BFE; Mon, 13 Dec 2021 09:03:53 +0100 (CET) Date: Mon, 13 Dec 2021 09:03:53 +0100 From: Christoph Hellwig To: Matthew Wilcox Cc: Alexander Viro , Christoph Hellwig , linux-fsdevel@vger.kernel.org Subject: Re: [RFC] iov_iter support for a single kernel address Message-ID: <20211213080353.GA21192@lst.de> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Dec 13, 2021 at 03:30:41AM +0000, Matthew Wilcox wrote: > > When working on the vmcore conversion to iov_iter, I noticed we had a > lot of places that construct a single kvec on the stack, and it seems a > little wasteful. Adding an ITER_KADDR type makes the iov_iter a little > easier to use. > > I included conversion of 9p to use ITER_KADDR so you can see whether you > think it's worth doing. While it does look sensible on its own, I'm rather worried about bloating the iov_iter interface with ever more types.