From patchwork Mon Mar 23 20:22:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 11453883 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EE7B815AB for ; Mon, 23 Mar 2020 20:24:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CEBFB2076E for ; Mon, 23 Mar 2020 20:24:25 +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="Pf6fDCqo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727681AbgCWUYZ (ORCPT ); Mon, 23 Mar 2020 16:24:25 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:36980 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727332AbgCWUXI (ORCPT ); Mon, 23 Mar 2020 16:23:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=lGGXOGXMyka6T3tpeyl3b0+hXD5oslkz5aNH49zanLk=; b=Pf6fDCqou0uVyo4WFl4VqQ3jfh OwfV7aDdHELEF0ya3H8WmQOqtYZxtlGgvCXk/oso9rELjOQtdX0l/4lJHNtY5sSAjgPtKgU/vCH93 vjbPDrAcO8jh7to++g2mgvBW3RG5Qy7bnTix0p51rEFRalw8VKlwQsU/35VG7BD9zh87kh0NoSgbw /cg6VVWGmOE9vaYsozLo1a+uRBWbWq0WnuuikJMpZV/foNlWenp4FrLUx3q+OV2oIAzsJ6SXZRxk5 6Xj4ZjrMO0ldPPJYhktUcupt7gj/j4PfvjkcUjz6VsFmVxNAscUTJ0HgKGDQBvZail6GXVph4kclo ie87fhvQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jGTbB-0003V5-MW; Mon, 23 Mar 2020 20:23:01 +0000 From: Matthew Wilcox To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , 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, Christoph Hellwig , William Kucharski Subject: [PATCH v10 10/25] mm: Put readahead pages in cache earlier Date: Mon, 23 Mar 2020 13:22:44 -0700 Message-Id: <20200323202259.13363-11-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200323202259.13363-1-willy@infradead.org> References: <20200323202259.13363-1-willy@infradead.org> MIME-Version: 1.0 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: "Matthew Wilcox (Oracle)" When populating the page cache for readahead, mappings that use ->readpages must populate the page cache themselves as the pages are passed on a linked list which would normally be used for the page cache's LRU. For mappings that use ->readpage or the upcoming ->readahead method, we can put the pages into the page cache as soon as they're allocated, which solves a race between readahead and direct IO. It also lets us remove the gfp argument from read_pages(). Use the new readahead_page() API to implement the repeated calls to ->readpage(), just like most filesystems will. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: William Kucharski --- mm/readahead.c | 46 ++++++++++++++++++++++++++++------------------ 1 file changed, 28 insertions(+), 18 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index ddc63d3b07b8..e52b3a7b9da5 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -114,14 +114,14 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages, EXPORT_SYMBOL(read_cache_pages); static void read_pages(struct readahead_control *rac, struct list_head *pages, - gfp_t gfp) + bool skip_page) { const struct address_space_operations *aops = rac->mapping->a_ops; + struct page *page; struct blk_plug plug; - unsigned page_idx; if (!readahead_count(rac)) - return; + goto out; blk_start_plug(&plug); @@ -130,23 +130,23 @@ static void read_pages(struct readahead_control *rac, struct list_head *pages, readahead_count(rac)); /* Clean up the remaining pages */ put_pages_list(pages); - goto out; - } - - for (page_idx = 0; page_idx < readahead_count(rac); page_idx++) { - struct page *page = lru_to_page(pages); - list_del(&page->lru); - if (!add_to_page_cache_lru(page, rac->mapping, page->index, - gfp)) + rac->_index += rac->_nr_pages; + rac->_nr_pages = 0; + } else { + while ((page = readahead_page(rac))) { aops->readpage(rac->file, page); - put_page(page); + put_page(page); + } } -out: blk_finish_plug(&plug); BUG_ON(!list_empty(pages)); - rac->_nr_pages = 0; + BUG_ON(readahead_count(rac)); + +out: + if (skip_page) + rac->_index++; } /* @@ -168,6 +168,7 @@ void __do_page_cache_readahead(struct address_space *mapping, struct readahead_control rac = { .mapping = mapping, .file = filp, + ._index = index, }; unsigned long i; @@ -183,6 +184,8 @@ void __do_page_cache_readahead(struct address_space *mapping, if (index + i > end_index) break; + BUG_ON(index + i != rac._index + rac._nr_pages); + page = xa_load(&mapping->i_pages, index + i); if (page && !xa_is_value(page)) { /* @@ -190,15 +193,22 @@ void __do_page_cache_readahead(struct address_space *mapping, * contiguous pages before continuing with the next * batch. */ - read_pages(&rac, &page_pool, gfp_mask); + read_pages(&rac, &page_pool, true); continue; } page = __page_cache_alloc(gfp_mask); if (!page) break; - page->index = index + i; - list_add(&page->lru, &page_pool); + if (mapping->a_ops->readpages) { + page->index = index + i; + list_add(&page->lru, &page_pool); + } else if (add_to_page_cache_lru(page, mapping, index + i, + gfp_mask) < 0) { + put_page(page); + read_pages(&rac, &page_pool, true); + continue; + } if (i == nr_to_read - lookahead_size) SetPageReadahead(page); rac._nr_pages++; @@ -209,7 +219,7 @@ void __do_page_cache_readahead(struct address_space *mapping, * uptodate then the caller will launch readpage again, and * will then handle the error. */ - read_pages(&rac, &page_pool, gfp_mask); + read_pages(&rac, &page_pool, false); } /*