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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2001C433E6 for ; Sun, 30 Aug 2020 20:17:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 91067204EA for ; Sun, 30 Aug 2020 20:17:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 91067204EA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id ECCD26B0002; Sun, 30 Aug 2020 16:17:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E7FAE6B0003; Sun, 30 Aug 2020 16:17:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D6EE06B0005; Sun, 30 Aug 2020 16:17:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0116.hostedemail.com [216.40.44.116]) by kanga.kvack.org (Postfix) with ESMTP id C20286B0002 for ; Sun, 30 Aug 2020 16:17:24 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 754D7365E for ; Sun, 30 Aug 2020 20:17:24 +0000 (UTC) X-FDA: 77208344808.02.oil70_0c0680d27089 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id 4083F10097AA1 for ; Sun, 30 Aug 2020 20:17:24 +0000 (UTC) X-HE-Tag: oil70_0c0680d27089 X-Filterd-Recvd-Size: 2293 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [195.92.253.2]) by imf41.hostedemail.com (Postfix) with ESMTP for ; Sun, 30 Aug 2020 20:17:23 +0000 (UTC) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kCTlB-007hSE-66; Sun, 30 Aug 2020 20:17:05 +0000 Date: Sun, 30 Aug 2020 21:17:05 +0100 From: Al Viro To: John Hubbard Cc: Andrew Morton , Christoph Hellwig , Ilya Dryomov , Jens Axboe , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, LKML Subject: Re: [PATCH v2 2/3] iov_iter: introduce iov_iter_pin_user_pages*() routines Message-ID: <20200830201705.GV1236603@ZenIV.linux.org.uk> References: <20200829080853.20337-1-jhubbard@nvidia.com> <20200829080853.20337-3-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200829080853.20337-3-jhubbard@nvidia.com> X-Rspamd-Queue-Id: 4083F10097AA1 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Aug 29, 2020 at 01:08:52AM -0700, John Hubbard wrote: > The new routines are: > iov_iter_pin_user_pages() > iov_iter_pin_user_pages_alloc() > > and those correspond to these pre-existing routines: > iov_iter_get_pages() > iov_iter_get_pages_alloc() > > Also, pipe_get_pages() and related are changed so as to pass > down a "use_pup" (use pin_user_page() instead of get_page()) bool > argument. > > Unlike the iov_iter_get_pages*() routines, the > iov_iter_pin_user_pages*() routines assert that only ITER_IOVEC or > ITER_PIPE items are passed in. They then call pin_user_page*(), instead > of get_user_pages_fast() or get_page(). > > Why: In order to incrementally change Direct IO callers from calling > get_user_pages_fast() and put_page(), over to calling > pin_user_pages_fast() and unpin_user_page(), there need to be mid-level > routines that specifically call one or the other systems, for both page > acquisition and page release. Hmm... Do you plan to kill iov_iter_get_pages* off, eventually getting rid of that use_pup argument?