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=-5.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,URIBL_DBL_ABUSE_MALW,USER_AGENT_SANE_1 autolearn=unavailable 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 ABCDBC33CB3 for ; Wed, 29 Jan 2020 00:46:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7E5D72073A for ; Wed, 29 Jan 2020 00:46:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726742AbgA2AqN (ORCPT ); Tue, 28 Jan 2020 19:46:13 -0500 Received: from mail105.syd.optusnet.com.au ([211.29.132.249]:57488 "EHLO mail105.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726583AbgA2AqN (ORCPT ); Tue, 28 Jan 2020 19:46:13 -0500 Received: from dread.disaster.area (pa49-195-111-217.pa.nsw.optusnet.com.au [49.195.111.217]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 7DEE13A22C7; Wed, 29 Jan 2020 11:46:10 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1iwbUf-0005pB-EV; Wed, 29 Jan 2020 11:46:09 +1100 Date: Wed, 29 Jan 2020 11:46:09 +1100 From: Dave Chinner To: Matthew Wilcox Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH 06/12] btrfs: Convert from readpages to readahead Message-ID: <20200129004609.GI18610@dread.disaster.area> References: <20200125013553.24899-1-willy@infradead.org> <20200125013553.24899-7-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200125013553.24899-7-willy@infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=LYdCFQXi c=1 sm=1 tr=0 a=0OveGI8p3fsTA6FL6ss4ZQ==:117 a=0OveGI8p3fsTA6FL6ss4ZQ==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=Jdjhy38mL1oA:10 a=JfrnYn6hAAAA:8 a=VwQbUJbxAAAA:8 a=7-415B0cAAAA:8 a=UZ-t7uxK7-gaYzqRExwA:9 a=IundfOnBDp5_hQnb:21 a=yYqAdPtR5S2h3kNd:21 a=CjuIK1q_8ugA:10 a=1CNFftbPRP8L7MoqJWF3:22 a=AjGcO6oz07-iQ99wixmX:22 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Jan 24, 2020 at 05:35:47PM -0800, Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" > > Use the new readahead operation in btrfs > > Signed-off-by: Matthew Wilcox (Oracle) > Cc: linux-btrfs@vger.kernel.org > --- > fs/btrfs/extent_io.c | 15 ++++----------- > fs/btrfs/extent_io.h | 2 +- > fs/btrfs/inode.c | 18 +++++++++--------- > 3 files changed, 14 insertions(+), 21 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 2f4802f405a2..b1e2acbec165 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -4283,7 +4283,7 @@ int extent_writepages(struct address_space *mapping, > return ret; > } > > -int extent_readpages(struct address_space *mapping, struct list_head *pages, > +unsigned extent_readahead(struct address_space *mapping, pgoff_t start, > unsigned nr_pages) > { > struct bio *bio = NULL; > @@ -4294,20 +4294,13 @@ int extent_readpages(struct address_space *mapping, struct list_head *pages, > int nr = 0; > u64 prev_em_start = (u64)-1; > > - while (!list_empty(pages)) { > + while (nr_pages) { > u64 contig_end = 0; > > - for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) { > - struct page *page = lru_to_page(pages); > + for (nr = 0; nr < ARRAY_SIZE(pagepool) && nr_pages--;) { What is stopping nr_pages from going negative here, and then looping forever on the outer nr_pages loop? Perhaps "while(nr_pages > 0) {" would be better there? -Dave. -- Dave Chinner david@fromorbit.com