From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753269AbcEIHxM (ORCPT ); Mon, 9 May 2016 03:53:12 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55950 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752721AbcEIHhM (ORCPT ); Mon, 9 May 2016 03:37:12 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ming Lei , Neil Brown , Jens Axboe , Shaohua Li Subject: [PATCH 4.5 36/88] MD: make bio mergeable Date: Mon, 9 May 2016 09:21:25 +0200 Message-Id: <20160509071953.925402757@linuxfoundation.org> X-Mailer: git-send-email 2.8.2 In-Reply-To: <20160509071952.129092535@linuxfoundation.org> References: <20160509071952.129092535@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shaohua Li commit 9c573de3283af007ea11c17bde1e4568d9417328 upstream. blk_queue_split marks bio unmergeable, which makes sense for normal bio. But if dispatching the bio to underlayer disk, the blk_queue_split checks are invalid, hence it's possible the bio becomes mergeable. In the reported bug, this bug causes trim against raid0 performance slash https://bugzilla.kernel.org/show_bug.cgi?id=117051 Reported-and-tested-by: Park Ju Hyung Fixes: 6ac45aeb6bca(block: avoid to merge splitted bio) Cc: Ming Lei Cc: Neil Brown Reviewed-by: Jens Axboe Signed-off-by: Shaohua Li Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -284,6 +284,8 @@ static blk_qc_t md_make_request(struct r * go away inside make_request */ sectors = bio_sectors(bio); + /* bio could be mergeable after passing to underlayer */ + bio->bi_rw &= ~REQ_NOMERGE; mddev->pers->make_request(mddev, bio); cpu = part_stat_lock();