From patchwork Tue Feb 25 21:48:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 11404841 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 99F861395 for ; Tue, 25 Feb 2020 21:51:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 773E72176D for ; Tue, 25 Feb 2020 21:51:34 +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="D9msPfR5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730233AbgBYVvI (ORCPT ); Tue, 25 Feb 2020 16:51:08 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:43490 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728756AbgBYVsl (ORCPT ); Tue, 25 Feb 2020 16:48:41 -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=w0+748cvV8fqYYK5S7voSb7ryQvDDane/jjiQr++miE=; b=D9msPfR51FpFSkZ4yp+PvhVq9v /8p2vUtvBmnkH+0U7AiCEitHwnmrbb0Cj2wMmeOctMytUSo4X8ujdyuUBoovpMt7WuBwa4WMXaCT8 lJYnZPkuWdxmkK/iIMi7H5gcLcYFemoFXyY3kyyRIM1Dn5pufEjmUJ9gQzULSpxpUh9x+yBzTL4Jf yV+nMQ8Kaq8SvlJoXbw4pKqlkmvjaLOIai5s31f+Zaep5jzhTbikbpl+vVWFQfvcBOyaX7nFC6OKq LIYbX1na3KxvUbHt1FIQ8CiO9Y5QC71++xY8kJhJLpHWtXqhLwOs7fPhZiAAHIz25pHh4LMEgvCfS jmQam+xg==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j6i4H-0007pz-AT; Tue, 25 Feb 2020 21:48:41 +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, John Hubbard Subject: [PATCH v8 12/25] mm: Move end_index check out of readahead loop Date: Tue, 25 Feb 2020 13:48:25 -0800 Message-Id: <20200225214838.30017-13-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200225214838.30017-1-willy@infradead.org> References: <20200225214838.30017-1-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)" By reducing nr_to_read, we can eliminate this check from inside the loop. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: John Hubbard --- mm/readahead.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index d01531ef9f3c..a37b68f66233 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -167,8 +167,6 @@ 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); loff_t isize = i_size_read(inode); gfp_t gfp_mask = readahead_gfp_mask(mapping); @@ -178,22 +176,29 @@ void __do_page_cache_readahead(struct address_space *mapping, ._index = index, }; unsigned long i; + pgoff_t end_index; /* The last page we want to read */ if (isize == 0) return; - end_index = ((isize - 1) >> PAGE_SHIFT); + end_index = (isize - 1) >> PAGE_SHIFT; + if (index > end_index) + return; + /* Avoid wrapping to the beginning of the file */ + if (index + nr_to_read < index) + nr_to_read = ULONG_MAX - index + 1; + /* Don't read past the page containing the last byte of the file */ + if (index + nr_to_read >= end_index) + nr_to_read = end_index - index + 1; /* * Preallocate as many pages as we will need. */ for (i = 0; i < nr_to_read; i++) { - if (index + i > end_index) - break; + struct page *page = xa_load(&mapping->i_pages, index + i); BUG_ON(index + i != rac._index + rac._nr_pages); - page = xa_load(&mapping->i_pages, index + i); if (page && !xa_is_value(page)) { /* * Page already present? Kick off the current batch of