From patchwork Mon Feb 17 18:45:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 11387209 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 D8286109A for ; Mon, 17 Feb 2020 18:46:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B7E3A24670 for ; Mon, 17 Feb 2020 18:46:30 +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="mG3ezOVT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730007AbgBQSqa (ORCPT ); Mon, 17 Feb 2020 13:46:30 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:48328 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729977AbgBQSq2 (ORCPT ); Mon, 17 Feb 2020 13:46:28 -0500 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=GsjiaZugI72vbGelDXh1gHsSqzMvkN1OtgDj3kywYLo=; b=mG3ezOVTlUwDZANXsCHvcKdwJB z3OlpT7AjCBCJphbep/jJMnYwWkqQCv4wTdvjax0x0CW6Nvu8+8tccy4vlbefujrJjJEj82Cnsx1d 0Z0dVex246tKQbAITwLWjKWZ5u/u/QkHJfmmheFgDcrAuXqy1jKQgdOFfs9OG8e4Jv179uA6lHT0C rj7l1UtOFC7pBjOM+uPFkUB4PEe+Mm5ggHB2nPVgYYpq1iZJM1/7wiOXsE7PHbRws4qZi4knTfp9M Abo7HX1ADfB8vHy4nwtU2Q4tJcbww1fj8NQ9P/NHWgtRpkc995sdbYd50dglXP3xbP8Qt8cWX4AgS 6OQh+pkw==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j3lPL-00058r-DR; Mon, 17 Feb 2020 18:46:15 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" , 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: [PATCH v6 04/19] mm: Rearrange readahead loop Date: Mon, 17 Feb 2020 10:45:45 -0800 Message-Id: <20200217184613.19668-5-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200217184613.19668-1-willy@infradead.org> References: <20200217184613.19668-1-willy@infradead.org> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: "Matthew Wilcox (Oracle)" Move the declaration of 'page' to inside the loop and move the 'kick off a fresh batch' code to the end of the function for easier use in subsequent patches. Signed-off-by: Matthew Wilcox (Oracle) --- mm/readahead.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 15329309231f..3eca59c43a45 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -154,7 +154,6 @@ void __do_page_cache_readahead(struct address_space *mapping, unsigned long lookahead_size) { struct inode *inode = mapping->host; - struct page *page; unsigned long end_index; /* The last page we want to read */ LIST_HEAD(page_pool); int page_idx; @@ -175,6 +174,7 @@ void __do_page_cache_readahead(struct address_space *mapping, * Preallocate as many pages as we will need. */ for (page_idx = 0; page_idx < nr_to_read; page_idx++) { + struct page *page; pgoff_t page_offset = offset + page_idx; if (page_offset > end_index) @@ -183,14 +183,14 @@ void __do_page_cache_readahead(struct address_space *mapping, page = xa_load(&mapping->i_pages, page_offset); if (page && !xa_is_value(page)) { /* - * Page already present? Kick off the current batch of - * contiguous pages before continuing with the next - * batch. + * Page already present? Kick off the current batch + * of contiguous pages before continuing with the + * next batch. This page may be the one we would + * have intended to mark as Readahead, but we don't + * have a stable reference to this page, and it's + * not worth getting one just for that. */ - if (readahead_count(&rac)) - read_pages(&rac, &page_pool, gfp_mask); - rac._nr_pages = 0; - continue; + goto read; } page = __page_cache_alloc(gfp_mask); @@ -201,6 +201,11 @@ void __do_page_cache_readahead(struct address_space *mapping, if (page_idx == nr_to_read - lookahead_size) SetPageReadahead(page); rac._nr_pages++; + continue; +read: + if (readahead_count(&rac)) + read_pages(&rac, &page_pool, gfp_mask); + rac._nr_pages = 0; } /*