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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 EDB14C4363A for ; Tue, 13 Oct 2020 23:52:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B35D622201 for ; Tue, 13 Oct 2020 23:52:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602633145; bh=EhWnWsayRlrHqkP6dxl0ISwqXMFPoVuEHlN49BV7eZk=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=p2NsBRpy9LAy5pUBJuxhRviqOpYiiVoQdYBb5IYEUbGU0GAIuSWm3olEws7/nNNBz skcpcNceMT6EIcr5O1Bj9Xqt1cYCY+HNRIbgPfzuzy3JR/c98rgtQ/zM0bu62ii3S0 ED5FU/Ba620wbIvP7htmZIH5bITDTRrJTphiF6Tk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726648AbgJMXwX (ORCPT ); Tue, 13 Oct 2020 19:52:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:36556 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728648AbgJMXvm (ORCPT ); Tue, 13 Oct 2020 19:51:42 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E79D821D7B; Tue, 13 Oct 2020 23:51:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602633102; bh=EhWnWsayRlrHqkP6dxl0ISwqXMFPoVuEHlN49BV7eZk=; h=Date:From:To:Subject:In-Reply-To:From; b=NrGNXfYeKg7F6op77cBUaXid+TwAFqW67e7Jdth//e2SKN455rZ7NWEPP4vnKonwr euXEqvrhV/24sUAnw1mKXCDizRtnfl0gaFmBkOhSWAne5x/VOp7aYcQ2s2drjDSo6S gejstPwwiyyylabEkOkMJ34tfSlkdYZaX7EtEd+g= Date: Tue, 13 Oct 2020 16:51:41 -0700 From: Andrew Morton To: adobriyan@gmail.com, akpm@linux-foundation.org, chris@chris-wilson.co.uk, hannes@cmpxchg.org, hughd@google.com, jani.nikula@linux.intel.com, linux-mm@kvack.org, matthew.auld@intel.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, william.kucharski@oracle.com, willy@infradead.org, ying.huang@intel.com Subject: [patch 061/181] mm: add find_lock_head Message-ID: <20201013235141.5Wzerxsbz%akpm@linux-foundation.org> In-Reply-To: <20201013164658.3bfd96cc224d8923e66a9f4e@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: "Matthew Wilcox (Oracle)" Subject: mm: add find_lock_head Add a new FGP_HEAD flag which avoids calling find_subpage() and add a convenience wrapper for it. Link: https://lkml.kernel.org/r/20200910183318.20139-9-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Alexey Dobriyan Cc: Chris Wilson Cc: Huang Ying Cc: Hugh Dickins Cc: Jani Nikula Cc: Johannes Weiner Cc: Matthew Auld Cc: William Kucharski Signed-off-by: Andrew Morton --- include/linux/pagemap.h | 32 ++++++++++++++++++++++++++------ mm/filemap.c | 9 ++++++--- 2 files changed, 32 insertions(+), 9 deletions(-) --- a/include/linux/pagemap.h~mm-add-find_lock_head +++ a/include/linux/pagemap.h @@ -279,6 +279,7 @@ pgoff_t page_cache_prev_miss(struct addr #define FGP_NOFS 0x00000010 #define FGP_NOWAIT 0x00000020 #define FGP_FOR_MMAP 0x00000040 +#define FGP_HEAD 0x00000080 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset, int fgp_flags, gfp_t cache_gfp_mask); @@ -310,18 +311,37 @@ static inline struct page *find_get_page * @mapping: the address_space to search * @offset: the page index * - * Looks up the page cache slot at @mapping & @offset. If there is a + * Looks up the page cache entry at @mapping & @offset. If there is a * page cache page, it is returned locked and with an increased * refcount. * - * Otherwise, %NULL is returned. - * - * find_lock_page() may sleep. + * Context: May sleep. + * Return: A struct page or %NULL if there is no page in the cache for this + * index. */ static inline struct page *find_lock_page(struct address_space *mapping, - pgoff_t offset) + pgoff_t index) +{ + return pagecache_get_page(mapping, index, FGP_LOCK, 0); +} + +/** + * find_lock_head - Locate, pin and lock a pagecache page. + * @mapping: The address_space to search. + * @offset: The page index. + * + * Looks up the page cache entry at @mapping & @offset. If there is a + * page cache page, its head page is returned locked and with an increased + * refcount. + * + * Context: May sleep. + * Return: A struct page which is !PageTail, or %NULL if there is no page + * in the cache for this index. + */ +static inline struct page *find_lock_head(struct address_space *mapping, + pgoff_t index) { - return pagecache_get_page(mapping, offset, FGP_LOCK, 0); + return pagecache_get_page(mapping, index, FGP_LOCK | FGP_HEAD, 0); } /** --- a/mm/filemap.c~mm-add-find_lock_head +++ a/mm/filemap.c @@ -1737,6 +1737,8 @@ repeat: * * * %FGP_ACCESSED - The page will be marked accessed. * * %FGP_LOCK - The page is returned locked. + * * %FGP_HEAD - If the page is present and a THP, return the head page + * rather than the exact page specified by the index. * * %FGP_CREAT - If no page is present then a new page is allocated using * @gfp_mask and added to the page cache and the VM's LRU list. * The page is returned locked and with an increased refcount. @@ -1765,7 +1767,6 @@ repeat: page = NULL; if (!page) goto no_page; - page = find_subpage(page, index); if (fgp_flags & FGP_LOCK) { if (fgp_flags & FGP_NOWAIT) { @@ -1778,12 +1779,12 @@ repeat: } /* Has the page been truncated? */ - if (unlikely(compound_head(page)->mapping != mapping)) { + if (unlikely(page->mapping != mapping)) { unlock_page(page); put_page(page); goto repeat; } - VM_BUG_ON_PAGE(page->index != index, page); + VM_BUG_ON_PAGE(!thp_contains(page, index), page); } if (fgp_flags & FGP_ACCESSED) @@ -1793,6 +1794,8 @@ repeat: if (page_is_idle(page)) clear_page_idle(page); } + if (!(fgp_flags & FGP_HEAD)) + page = find_subpage(page, index); no_page: if (!page && (fgp_flags & FGP_CREAT)) { _