From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933395AbcIERNY (ORCPT ); Mon, 5 Sep 2016 13:13:24 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53131 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935721AbcIEQzY (ORCPT ); Mon, 5 Sep 2016 12:55:24 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ross Zwisler , Jeff Moyer , Dan Williams , Dave Chinner , Dave Hansen , Jan Kara , Andrew Morton , Linus Torvalds Subject: [PATCH 4.7 110/143] mm: silently skip readahead for DAX inodes Date: Mon, 5 Sep 2016 18:44:46 +0200 Message-Id: <20160905164435.277325191@linuxfoundation.org> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20160905164430.593075551@linuxfoundation.org> References: <20160905164430.593075551@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ross Zwisler commit 11bd969fdefea3ac0cb9791224f1e09784e21e58 upstream. For DAX inodes we need to be careful to never have page cache pages in the mapping->page_tree. This radix tree should be composed only of DAX exceptional entries and zero pages. ltp's readahead02 test was triggering a warning because we were trying to insert a DAX exceptional entry but found that a page cache page had already been inserted into the tree. This page was being inserted into the radix tree in response to a readahead(2) call. Readahead doesn't make sense for DAX inodes, but we don't want it to report a failure either. Instead, we just return success and don't do any work. Link: http://lkml.kernel.org/r/20160824221429.21158-1-ross.zwisler@linux.intel.com Signed-off-by: Ross Zwisler Reported-by: Jeff Moyer Cc: Dan Williams Cc: Dave Chinner Cc: Dave Hansen Cc: Jan Kara Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/readahead.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/mm/readahead.c +++ b/mm/readahead.c @@ -8,6 +8,7 @@ */ #include +#include #include #include #include @@ -545,6 +546,14 @@ do_readahead(struct address_space *mappi if (!mapping || !mapping->a_ops) return -EINVAL; + /* + * Readahead doesn't make sense for DAX inodes, but we don't want it + * to report a failure either. Instead, we just return success and + * don't do any work. + */ + if (dax_mapping(mapping)) + return 0; + return force_page_cache_readahead(mapping, filp, index, nr); }