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 496BBC46467 for ; Wed, 4 Jan 2023 17:40:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235327AbjADRkW (ORCPT ); Wed, 4 Jan 2023 12:40:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbjADRkV (ORCPT ); Wed, 4 Jan 2023 12:40:21 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C80D39FB9; Wed, 4 Jan 2023 09:40:20 -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 dfw.source.kernel.org (Postfix) with ESMTPS id CA997617AE; Wed, 4 Jan 2023 17:40:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 367CCC433EF; Wed, 4 Jan 2023 17:40:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672854019; bh=oxp/Cr7eBnm/fkJ0XG8CB8iaZWIlZwSJNK6IkH9kUkg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZAb/EZs3k+G6JEZUw2utoeQZ7xzLKwNtvwMhM960foUvai+Oib6hQAF/JtITbGBSL wntXJjRrumQrw2sp2ssNCs5e17N4JrwYtfO+HDttGMMYPWn6rMbVt50PLuQWumoGon jGdEpBiYOoHQvExCwqjmgdbVPWy8ySlB3Tuv7CiyIO04ucgVNzROEXrLlA7ytmwO2b v8V7UtrWwZdIAXQogTDGTqQBZiK8gQBCetseQIIPUBPzI/82/0hkWG1FTKKiKmtgEK hMTvX4mc2LgJH7hSghx9JEESpdshfwSpK/5F0ViD60JxwP/md7ScOMsxiE04X59ieK +5JKnlENkf2DQ== Date: Wed, 4 Jan 2023 09:40:18 -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 2/9] iomap/gfs2: Unlock and put folio in page_done handler Message-ID: References: <20221231150919.659533-1-agruenba@redhat.com> <20221231150919.659533-3-agruenba@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221231150919.659533-3-agruenba@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sat, Dec 31, 2022 at 04:09:12PM +0100, Andreas Gruenbacher wrote: > When an iomap defines a ->page_done() handler in its page_ops, delegate > unlocking the folio and putting the folio reference to that handler. > > This allows to fix a race between journaled data writes and folio > writeback in gfs2: before this change, gfs2_iomap_page_done() was called > after unlocking the folio, so writeback could start writing back the > folio's buffers before they could be marked for writing to the journal. > Also, try_to_free_buffers() could free the buffers before > gfs2_iomap_page_done() was done adding the buffers to the current > current transaction. With this change, gfs2_iomap_page_done() adds the > buffers to the current transaction while the folio is still locked, so > the problems described above can no longer occur. > > The only current user of ->page_done() is gfs2, so other filesystems are > not affected. To catch out any out-of-tree users, switch from a page to > a folio in ->page_done(). I really hope there aren't any out of tree users... > Signed-off-by: Andreas Gruenbacher Reviewed-by: Darrick J. Wong --D > --- > fs/gfs2/bmap.c | 15 ++++++++++++--- > fs/iomap/buffered-io.c | 8 ++++---- > include/linux/iomap.h | 7 ++++--- > 3 files changed, 20 insertions(+), 10 deletions(-) > > diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c > index e7537fd305dd..46206286ad42 100644 > --- a/fs/gfs2/bmap.c > +++ b/fs/gfs2/bmap.c > @@ -968,14 +968,23 @@ static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos, > } > > static void gfs2_iomap_page_done(struct inode *inode, loff_t pos, > - unsigned copied, struct page *page) > + unsigned copied, struct folio *folio) > { > struct gfs2_trans *tr = current->journal_info; > struct gfs2_inode *ip = GFS2_I(inode); > struct gfs2_sbd *sdp = GFS2_SB(inode); > > - if (page && !gfs2_is_stuffed(ip)) > - gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied); > + if (!folio) { > + gfs2_trans_end(sdp); > + return; > + } > + > + if (!gfs2_is_stuffed(ip)) > + gfs2_page_add_databufs(ip, &folio->page, offset_in_page(pos), > + copied); > + > + folio_unlock(folio); > + folio_put(folio); > > if (tr->tr_num_buf_new) > __mark_inode_dirty(inode, I_DIRTY_DATASYNC); > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index c30d150a9303..e13d5694e299 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -580,12 +580,12 @@ static void iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret, > { > const struct iomap_page_ops *page_ops = iter->iomap.page_ops; > > - if (folio) > + if (page_ops && page_ops->page_done) { > + page_ops->page_done(iter->inode, pos, ret, folio); > + } else if (folio) { > folio_unlock(folio); > - if (page_ops && page_ops->page_done) > - page_ops->page_done(iter->inode, pos, ret, &folio->page); > - if (folio) > folio_put(folio); > + } > } > > static int iomap_write_begin_inline(const struct iomap_iter *iter, > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 0983dfc9a203..743e2a909162 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -131,13 +131,14 @@ static inline bool iomap_inline_data_valid(const struct iomap *iomap) > * associated with them. > * > * When page_prepare succeeds, page_done will always be called to do any > - * cleanup work necessary. In that page_done call, @page will be NULL if the > - * associated page could not be obtained. > + * cleanup work necessary. In that page_done call, @folio will be NULL if the > + * associated folio could not be obtained. When folio is not NULL, page_done > + * is responsible for unlocking and putting the folio. > */ > struct iomap_page_ops { > int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len); > void (*page_done)(struct inode *inode, loff_t pos, unsigned copied, > - struct page *page); > + struct folio *folio); > > /* > * Check that the cached iomap still maps correctly to the filesystem's > -- > 2.38.1 >