From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757136AbZGPGqN (ORCPT ); Thu, 16 Jul 2009 02:46:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756438AbZGPGqN (ORCPT ); Thu, 16 Jul 2009 02:46:13 -0400 Received: from hera.kernel.org ([140.211.167.34]:45991 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752418AbZGPGqM (ORCPT ); Thu, 16 Jul 2009 02:46:12 -0400 Message-ID: <4A5ECC62.7050607@kernel.org> Date: Thu, 16 Jul 2009 15:44:50 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Linux Kernel , Jens Axboe , Boaz Harrosh , FUJITA Tomonori , Jeff Garzik Subject: [PATCH #tj-block-for-linus] block: fix failfast merge testing in elv_rq_merge_ok() X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Thu, 16 Jul 2009 06:45:06 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit ab0fd1debe730ec9998678a0c53caefbd121ed10 tries to prevent merge of requests with different failfast settings. In elv_rq_merge_ok(), it compares new bio's failfast flags against the merge target request's. However, the flag testing accessors for bio and blk don't return boolean but the tested bit value directly and FAILFAST on bio and blk don't match, so directly comparing them with == results in false negative unnecessary preventing merge of readahead requests. This patch convert the results to boolean by negating them before comparison. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Boaz Harrosh Cc: FUJITA Tomonori Cc: James Bottomley Cc: Jeff Garzik --- Eh... talk about being obscure. :-( I've put this onto the following temp block tree I'm running and will push toward Linus in a few days. git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git tj-block-for-linus Thanks. block/elevator.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/block/elevator.c b/block/elevator.c index 6f23753..977aa7c 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -103,9 +103,9 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio) /* * Don't merge if failfast settings don't match */ - if (bio_failfast_dev(bio) != blk_failfast_dev(rq) || - bio_failfast_transport(bio) != blk_failfast_transport(rq) || - bio_failfast_driver(bio) != blk_failfast_driver(rq)) + if (!bio_failfast_dev(bio) != !blk_failfast_dev(rq) || + !bio_failfast_transport(bio) != !blk_failfast_transport(rq) || + !bio_failfast_driver(bio) != !blk_failfast_driver(rq)) return 0; if (!elv_iosched_allow_merge(rq, bio)) -- 1.6.0.2