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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 09092C3526B for ; Wed, 16 Dec 2020 18:26:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB6DB25586 for ; Wed, 16 Dec 2020 18:26:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730482AbgLPSZK (ORCPT ); Wed, 16 Dec 2020 13:25:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730433AbgLPSY7 (ORCPT ); Wed, 16 Dec 2020 13:24:59 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA333C0611C5; Wed, 16 Dec 2020 10:23:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=+l4PSg9LRLq5JV1LxjBLu8ocwanQ7rBdRiAM4Vwc710=; b=aEZARXEJD/4PkvJxS1NfCTdcG8 7YQWHdIp9H9OCl3hS6zOu95T6qgG3M83TyJq0r+XYVdkQlMrrZwCA+ELcHanwyYGOWd6Qo410YRwG HlkPrPfX2eW1c/0nXxu1iMbALgjat9Li+0Yt9hvvYLAy5m7MYV0xrJTkwFH52pq11wsgwUlyHONq6 ylbGBPYieMT6HcMjfmjO0Xe0WgWZ2yJvVOkZAzv71NqbWmX22LEVMG69EXncLJMUI1ioKG0Ci6sBN hrwFLTRHy1LkI6TFBtZ4KH91zDorMmj8ZkK8L/q4RihpNjd7t1a7dYmbE8mkCZzsH6cmX0Fu4LimS xGUBwtrw==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kpbSa-00075x-Tr; Wed, 16 Dec 2020 18:23:36 +0000 From: "Matthew Wilcox (Oracle)" To: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" , linux-kernel@vger.kernel.org Subject: [PATCH 01/25] mm: Introduce struct folio Date: Wed, 16 Dec 2020 18:23:11 +0000 Message-Id: <20201216182335.27227-2-willy@infradead.org> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20201216182335.27227-1-willy@infradead.org> References: <20201216182335.27227-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We have trouble keeping track of whether we've already called compound_head() to ensure we're not operating on a tail page. Further, it's never clear whether we intend a struct page to refer to PAGE_SIZE bytes or page_size(compound_head(page)). Introduce a new type 'struct folio' that always refers to an entire (possibly compound) page, and points to the head page (or base page). Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/mm.h | 10 ++++++++++ include/linux/mm_types.h | 17 +++++++++++++++++ include/linux/pagemap.h | 14 ++++++++++++++ 3 files changed, 41 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 5299b90a6c40..ed20fd0c6169 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -916,6 +916,11 @@ static inline unsigned int compound_order(struct page *page) return page[1].compound_order; } +static inline unsigned int folio_order(struct folio *folio) +{ + return compound_order(&folio->page); +} + static inline bool hpage_pincount_available(struct page *page) { /* @@ -967,6 +972,11 @@ static inline unsigned int page_shift(struct page *page) void free_compound_page(struct page *page); +static inline unsigned long folio_nr_pages(struct folio *folio) +{ + return compound_nr(&folio->page); +} + #ifdef CONFIG_MMU /* * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 65df8abd90bd..d7e487d9998f 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -223,6 +223,23 @@ struct page { #endif } _struct_page_alignment; +/* + * A struct folio is either a base (order-0) page or the head page of + * a compound page. + */ +struct folio { + struct page page; +}; + +static inline struct folio *page_folio(struct page *page) +{ + unsigned long head = READ_ONCE(page->compound_head); + + if (unlikely(head & 1)) + return (struct folio *)(head - 1); + return (struct folio *)page; +} + static inline atomic_t *compound_mapcount_ptr(struct page *page) { return &page[1].compound_mapcount; diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index f18857c79478..b5af2c3719ab 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -437,6 +437,20 @@ static inline bool thp_contains(struct page *head, pgoff_t index) return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL)); } +static inline pgoff_t folio_index(struct folio *folio) +{ + if (unlikely(FolioSwapCache(folio))) + return __page_file_index(&folio->page); + return folio->page.index; +} + +static inline struct page *folio_page(struct folio *folio, pgoff_t index) +{ + index -= folio_index(folio); + VM_BUG_ON_PAGE(index >= folio_nr_pages(folio), &folio->page); + return &folio->page + index; +} + /* * Given the page we found in the page cache, return the page corresponding * to this index in the file -- 2.29.2