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 57372C34054 for ; Wed, 19 Feb 2020 14:41:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D52524677 for ; Wed, 19 Feb 2020 14:41:22 +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="Eo/FW4XK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726713AbgBSOlS (ORCPT ); Wed, 19 Feb 2020 09:41:18 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:42694 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726604AbgBSOlS (ORCPT ); Wed, 19 Feb 2020 09:41:18 -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=8IjL+yb/Cvlwh+xltU0HFRJYWZSYd/0FIacDvgc30so=; b=Eo/FW4XK2MuSbkpKnJbuW9HCuj 73f56TSPDRJWs9q1g09/mEtWKWQ18dLecvixOGx9CQrSJtukF5EkaFwD5s1ht+yOHUqESKEvXDwPh 0v+9/vEPWpbgPitIQ0XolL/sviBTw/NadpXb0u4CKascGnRG+HiMvDnBy0Jkt6uvI5gFKz3giVYlB Ck/tmLQEiMP713+GIAGDUXFKV2BakBAcoFfN+jeMAlvrKRVftT0bs67UdlA5WD5YSSloWQRhWWsuF MXO0LNm1doYTcnPW+W+SjPVPp2BkpvBSZrMWKMZnHtRlYVoCghmzLJdCT71Da+z4QJbJE1SoGqiJT 7R18A8DA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4QXN-00044x-SK; Wed, 19 Feb 2020 14:41:17 +0000 Date: Wed, 19 Feb 2020 06:41:17 -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: <20200219144117.GP24185@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-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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'll go you one better ... how about we do this instead: static inline struct page *readahead_page(struct readahead_control *rac) { struct page *page; BUG_ON(rac->_batch_count > rac->_nr_pages); rac->_nr_pages -= rac->_batch_count; rac->_index += rac->_batch_count; rac->_batch_count = 0; if (!rac->_nr_pages) return NULL; page = xa_load(&rac->mapping->i_pages, rac->_index); VM_BUG_ON_PAGE(!PageLocked(page), page); rac->_batch_count = hpage_nr_pages(page); return page; } #define readahead_for_each(rac, page) \ while ((page = readahead_page(rac))) No more readahead_next() to forget to add to filesystems which don't use the readahead_for_each() iterator. Ahem.