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 BCF80C46467 for ; Wed, 4 Jan 2023 17:45:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235356AbjADRpn (ORCPT ); Wed, 4 Jan 2023 12:45:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44822 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235135AbjADRpm (ORCPT ); Wed, 4 Jan 2023 12:45:42 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7AB501A3A6; Wed, 4 Jan 2023 09:45:41 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 35282B8188A; Wed, 4 Jan 2023 17:45:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3971C433EF; Wed, 4 Jan 2023 17:45:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672854339; bh=msm056/mOkbTA2byAEpjpULI3Z90pz6ivRTm/Jcj4Wg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mM9Tm7YMhSSJCWjq0WCtHKE0mrkpquzhLEMa8T8RYQmCVrErm/HRtFFhxUKl1hCEJ T6QRipu75ojlx7pi1Y6R/vsS0O3bo9dlrweLMVmPoxbW7ZxFicUG3mZ/p5tOwqSzUh LJDMMElHN+d9atSWubOP4jzPAxurd/SEpf2jS8b4VDXGXv6BT3D88WSVLF7G5r07Yv 03D2E9ky/d6mB3eTOMvtdg7ciqyixTMtIxEsE+cPECVshsVhKxxVujblEbGwU9yITS 3e/4zAZDDdv8FeIfRtu0hOriHFh/zeqjzLg/jW/g3l6v9h6GNw2i6G0CentdeNWPoU GBMqbBbrqmZMA== Date: Wed, 4 Jan 2023 09:45:38 -0800 From: "Darrick J. Wong" To: Andreas Gruenbacher Cc: Christoph Hellwig , Alexander Viro , Matthew Wilcox , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, cluster-devel@redhat.com Subject: Re: [PATCH v5 5/9] iomap/gfs2: Get page in page_prepare handler Message-ID: References: <20221231150919.659533-1-agruenba@redhat.com> <20221231150919.659533-6-agruenba@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221231150919.659533-6-agruenba@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sat, Dec 31, 2022 at 04:09:15PM +0100, Andreas Gruenbacher wrote: > Change the iomap ->page_prepare() handler to get and return a locked > folio instead of doing that in iomap_write_begin(). This allows to > recover from out-of-memory situations in ->page_prepare(), which > eliminates the corresponding error handling code in iomap_write_begin(). > The ->put_folio() handler now also isn't called with NULL as the folio > value anymore. > > Filesystems are expected to use the iomap_get_folio() helper for getting > locked folios in their ->page_prepare() handlers. > > Signed-off-by: Andreas Gruenbacher This patchset makes the page ops make a lot more sense to me now. I very much like the way that the new ->get_folio ->put_folio functions split the responsibilities for setting up the page cach write and tearing it down. Thank you for cleaning this up. :) (I would still like hch or willy to take a second look at this, however.) Reviewed-by: Darrick J. Wong --D > --- > fs/gfs2/bmap.c | 21 +++++++++++++-------- > fs/iomap/buffered-io.c | 17 ++++++----------- > include/linux/iomap.h | 9 +++++---- > 3 files changed, 24 insertions(+), 23 deletions(-) > > diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c > index 0c041459677b..41349e09558b 100644 > --- a/fs/gfs2/bmap.c > +++ b/fs/gfs2/bmap.c > @@ -956,15 +956,25 @@ static int __gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length, > goto out; > } > > -static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos, > - unsigned len) > +static struct folio * > +gfs2_iomap_page_prepare(struct iomap_iter *iter, loff_t pos, unsigned len) > { > + struct inode *inode = iter->inode; > unsigned int blockmask = i_blocksize(inode) - 1; > struct gfs2_sbd *sdp = GFS2_SB(inode); > unsigned int blocks; > + struct folio *folio; > + int status; > > blocks = ((pos & blockmask) + len + blockmask) >> inode->i_blkbits; > - return gfs2_trans_begin(sdp, RES_DINODE + blocks, 0); > + status = gfs2_trans_begin(sdp, RES_DINODE + blocks, 0); > + if (status) > + return ERR_PTR(status); > + > + folio = iomap_get_folio(iter, pos); > + if (IS_ERR(folio)) > + gfs2_trans_end(sdp); > + return folio; > } > > static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos, > @@ -974,11 +984,6 @@ static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos, > struct gfs2_inode *ip = GFS2_I(inode); > struct gfs2_sbd *sdp = GFS2_SB(inode); > > - if (!folio) { > - gfs2_trans_end(sdp); > - return; > - } > - > if (!gfs2_is_stuffed(ip)) > gfs2_page_add_databufs(ip, &folio->page, offset_in_page(pos), > copied); > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index b84838d2b5d8..7decd8cdc755 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -609,7 +609,7 @@ static void iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret, > > if (page_ops && page_ops->put_folio) { > page_ops->put_folio(iter->inode, pos, ret, folio); > - } else if (folio) { > + } else { > folio_unlock(folio); > folio_put(folio); > } > @@ -642,17 +642,12 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos, > if (!mapping_large_folio_support(iter->inode->i_mapping)) > len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos)); > > - if (page_ops && page_ops->page_prepare) { > - status = page_ops->page_prepare(iter->inode, pos, len); > - if (status) > - return status; > - } > - > - folio = iomap_get_folio(iter, pos); > - if (IS_ERR(folio)) { > - iomap_put_folio(iter, pos, 0, NULL); > + if (page_ops && page_ops->page_prepare) > + folio = page_ops->page_prepare(iter, pos, len); > + else > + folio = iomap_get_folio(iter, pos); > + if (IS_ERR(folio)) > return PTR_ERR(folio); > - } > > /* > * Now we have a locked folio, before we do anything with it we need to > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index e5732cc5716b..87b5d0f8e578 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -13,6 +13,7 @@ > struct address_space; > struct fiemap_extent_info; > struct inode; > +struct iomap_iter; > struct iomap_dio; > struct iomap_writepage_ctx; > struct iov_iter; > @@ -131,12 +132,12 @@ static inline bool iomap_inline_data_valid(const struct iomap *iomap) > * associated with them. > * > * When page_prepare succeeds, put_folio will always be called to do any > - * cleanup work necessary. In that put_folio call, @folio will be NULL if the > - * associated folio could not be obtained. When folio is not NULL, put_folio > - * is responsible for unlocking and putting the folio. > + * cleanup work necessary. put_folio is responsible for unlocking and putting > + * @folio. > */ > struct iomap_page_ops { > - int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len); > + struct folio *(*page_prepare)(struct iomap_iter *iter, loff_t pos, > + unsigned len); > void (*put_folio)(struct inode *inode, loff_t pos, unsigned copied, > struct folio *folio); > > -- > 2.38.1 >