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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 664BDC34051 for ; Wed, 19 Feb 2020 01:02:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3050D2465D for ; Wed, 19 Feb 2020 01:02:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="eAZdgCeC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726749AbgBSBCK (ORCPT ); Tue, 18 Feb 2020 20:02:10 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:39080 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726422AbgBSBCK (ORCPT ); Tue, 18 Feb 2020 20:02:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=dmgQq76s5htd6QK1djoTrZsBDESqx9Po29KnZ84sMso=; b=eAZdgCeC8YnlA9szfqlWljjWDh UQdArvzLM0oiT5XqIC/Q7h5+HeHL9h7cGk8uQK7lBmcw6zYNiJPBANRy3Kwp44uDdtkV2GwprxPbm 2qK75Ii01IRiWR/ENG9UpNAtQ6GGFmxoDicA6zhQykS1pxRxOwf5Iqo0m6NjHXkdBzku6LESIgg13 MNO5VqW3ruk/ciL+0+OSHHUM0uvKmDauMYS1h6HQC5+eUgS66IZUqnL5ZBn4iPhOROjAMtOQnLmUp r0l8D5tGUQYLIWt9/cYhYmOOb/1dYr6JEJYp93FoEhbgXTOlcGKNkDzg1ltXOO9ME1PREkt7eWceP c68pLuUA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4Dkf-0005UF-KW; Wed, 19 Feb 2020 01:02:09 +0000 Date: Tue, 18 Feb 2020 17:02:09 -0800 From: Matthew Wilcox To: John Hubbard Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org Subject: Re: [PATCH v6 07/19] mm: Put readahead pages in cache earlier Message-ID: <20200219010209.GI24185@bombadil.infradead.org> References: <20200217184613.19668-1-willy@infradead.org> <20200217184613.19668-12-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Feb 18, 2020 at 04:01:43PM -0800, John Hubbard wrote: > How about this instead? It uses the "for" loop fully and more naturally, > and is easier to read. And it does the same thing: > > static inline struct page *readahead_page(struct readahead_control *rac) > { > struct page *page; > > if (!rac->_nr_pages) > return NULL; > > page = xa_load(&rac->mapping->i_pages, rac->_start); > VM_BUG_ON_PAGE(!PageLocked(page), page); > rac->_batch_count = hpage_nr_pages(page); > > return page; > } > > static inline struct page *readahead_next(struct readahead_control *rac) > { > rac->_nr_pages -= rac->_batch_count; > rac->_start += rac->_batch_count; > > return readahead_page(rac); > } > > #define readahead_for_each(rac, page) \ > for (page = readahead_page(rac); page != NULL; \ > page = readahead_page(rac)) I'm assuming you mean 'page = readahead_next(rac)' on that second line. If you keep reading all the way to the penultimate patch, it won't work for iomap ... at least not in the same way.