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Tue, 15 Nov 2022 04:09:06 +0000 Date: Tue, 15 Nov 2022 04:09:06 +0000 From: Matthew Wilcox To: David Howells Cc: dwysocha@redhat.com, Rohith Surabattula , Steve French , Shyam Prasad N , Dominique Martinet , Ilya Dryomov , linux-cachefs@redhat.com, linux-cifs@vger.kernel.org, linux-afs@lists.infradead.org, v9fs-developer@lists.sourceforge.net, ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2] mm, netfs, fscache: Stop read optimisation when folio removed from pagecache Message-ID: References: <166844174069.1124521.10890506360974169994.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <166844174069.1124521.10890506360974169994.stgit@warthog.procyon.org.uk> ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=cqcPHDV+; spf=none (imf24.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; 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dmarc=none X-Stat-Signature: yhg5zdn78drah83mdrz5ucn4mrgmnxmo X-Rspamd-Queue-Id: D7B0118000C X-Rspamd-Server: rspam09 X-HE-Tag: 1668485380-383205 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 Mon, Nov 14, 2022 at 04:02:20PM +0000, David Howells wrote: > +++ b/mm/filemap.c > @@ -3941,6 +3941,10 @@ bool filemap_release_folio(struct folio *folio, gfp_t gfp) > struct address_space * const mapping = folio->mapping; > > BUG_ON(!folio_test_locked(folio)); > + if ((!mapping || !mapping_release_always(mapping)) > + && !folio_test_private(folio) && > + !folio_test_private_2(folio)) > + return true; Why do you need to test 'mapping' here? Also this is the most inconsistent style ... if ((!mapping || !mapping_release_always(mapping)) && !folio_test_private(folio) && !folio_test_private_2(folio)) works fine, but if you insist on splitting over three lines, then: if ((!mapping || !mapping_release_always(mapping)) && !folio_test_private(folio) && !folio_test_private_2(folio)) > @@ -276,7 +275,7 @@ static long mapping_evict_folio(struct address_space *mapping, > if (folio_ref_count(folio) > > folio_nr_pages(folio) + folio_has_private(folio) + 1) I think this line is incorrect, right? You don't increment the folio refcount just because the folio has private2 set, do you? > return 0; > - if (folio_has_private(folio) && !filemap_release_folio(folio, 0)) > + if (!filemap_release_folio(folio, 0)) > return 0; > > return remove_mapping(mapping, folio); Can we get rid of folio_has_private() / page_has_private() now?