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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <1b1eb3d8-c6b4-b264-1baa-1b3eb088173d@redhat.com> References: <1b1eb3d8-c6b4-b264-1baa-1b3eb088173d@redhat.com> <20230123173007.325544-1-dhowells@redhat.com> <20230123173007.325544-3-dhowells@redhat.com> To: David Hildenbrand Cc: dhowells@redhat.com, Al Viro , Christoph Hellwig , Matthew Wilcox , Jens Axboe , Jan Kara , Jeff Layton , Logan Gunthorpe , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Hellwig , John Hubbard , linux-mm@kvack.org Subject: Re: [PATCH v8 02/10] iov_iter: Add a function to extract a page list from an iterator MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <874092.1674570959.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Tue, 24 Jan 2023 14:35:59 +0000 Message-ID: <874093.1674570959@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9C788C0023 X-Stat-Signature: ad4d7mg4kox6gdgpahnzy7tprfckk93y X-HE-Tag: 1674570971-896944 X-HE-Meta: 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 NXF8hOVU qs/dgMoQX1hiFHLcSkpClp9lSO8z2Mew4mW8mcB2QccJUa+vtYBxOR7zBnJK7EYu1JcF5QR4FMK49IPxo1GCJmGpPo+Q+jZrN6RWJlZKemXd9HEwItM9TLLJrU0mIQaipLvdQ7stnErdNVs+rrT0JM65GVbsRof94xjW+VlDouK0P1h0chOQfGp0JFnK0h4Ihrz2DR2R1LlLcMHA2nTy8AFzsA6pb67jGcz14Qv/fbJxnvzPaHvZ8avkizfBcsPKAdBY9jHyAqEhrWnisTjkNSarydSe1HnQ68hQRfPdFpymykGp6iVqRBoxZeg== 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: David Hildenbrand wrote: > > +#define iov_iter_extract_mode(iter) (user_backed_iter(iter) ? FOLL_PI= N : 0) > > + > = > Does it make sense to move that to the patch where it is needed? (do we = need > it at all anymore?) Yes, we need something. Granted, there are now only two alternatives, not three: either the pages are going to be pinned or they're not going to be pinned, but I would rather have a specific function that tells you than ju= st use, say, user_backed_iter() to make it easier to adjust it later if we ne= ed to - and easier to find the places where we need to adjust. But if it's preferred we could require people to use user_backed_iter() instead. David