From patchwork Tue Jul 5 15:50:13 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 644890 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3rkVK70p5Kz9sdb for ; Wed, 6 Jul 2016 02:51:39 +1000 (AEST) Received: from localhost ([::1]:56327 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKTZQ-0005PR-OV for incoming@patchwork.ozlabs.org; Tue, 05 Jul 2016 12:51:36 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42045) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKSd7-0000kY-8C for qemu-devel@nongnu.org; Tue, 05 Jul 2016 11:51:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bKSd6-0006US-8o for qemu-devel@nongnu.org; Tue, 05 Jul 2016 11:51:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53397) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKScz-0006Rd-2t; Tue, 05 Jul 2016 11:51:13 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9BC9763175; Tue, 5 Jul 2016 15:51:12 +0000 (UTC) Received: from noname.redhat.com (ovpn-116-92.ams2.redhat.com [10.36.116.92]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u65Fp6fF006758; Tue, 5 Jul 2016 11:51:11 -0400 From: Kevin Wolf To: qemu-block@nongnu.org Date: Tue, 5 Jul 2016 17:50:13 +0200 Message-Id: <1467733852-27097-5-git-send-email-kwolf@redhat.com> In-Reply-To: <1467733852-27097-1-git-send-email-kwolf@redhat.com> References: <1467733852-27097-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Tue, 05 Jul 2016 15:51:12 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 04/43] block: Fix harmless off-by-one in bdrv_aligned_preadv() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Eric Blake If the amount of data to read ends exactly on the total size of the bs, then we were wasting time creating a local qiov to read the data in preparation for what would normally be appending zeroes beyond the end, even though this corner case has nothing further to do. Signed-off-by: Eric Blake Reviewed-by: Kevin Wolf Reviewed-by: Fam Zheng Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/io.c b/block/io.c index 994d3fa..82c9ff0 100644 --- a/block/io.c +++ b/block/io.c @@ -1036,7 +1036,7 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs, } max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align); - if (bytes < max_bytes) { + if (bytes <= max_bytes) { ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0); } else if (max_bytes > 0) { QEMUIOVector local_qiov;