From patchwork Fri Apr 9 09:46:20 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 49797 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 601D4B7CF6 for ; Fri, 9 Apr 2010 19:57:00 +1000 (EST) Received: from localhost ([127.0.0.1]:42635 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O0Av7-00061I-Vv for incoming@patchwork.ozlabs.org; Fri, 09 Apr 2010 05:54:38 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O0Ao3-0004FT-LE for qemu-devel@nongnu.org; Fri, 09 Apr 2010 05:47:19 -0400 Received: from [140.186.70.92] (port=44218 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O0Ao0-0004Dd-Do for qemu-devel@nongnu.org; Fri, 09 Apr 2010 05:47:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O0Any-0005v2-QA for qemu-devel@nongnu.org; Fri, 09 Apr 2010 05:47:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:23931) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O0Any-0005uu-GS for qemu-devel@nongnu.org; Fri, 09 Apr 2010 05:47:14 -0400 Received: from int-mx05.intmail.prod.int.phx2.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.18]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o399l4Pv014957 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 9 Apr 2010 05:47:04 -0400 Received: from localhost.localdomain (vpn1-4-18.ams2.redhat.com [10.36.4.18]) by int-mx05.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o399kvEE009943; Fri, 9 Apr 2010 05:47:02 -0400 From: Kevin Wolf To: aurelien@aurel32.net Date: Fri, 9 Apr 2010 11:46:20 +0200 Message-Id: <1270806388-28138-3-git-send-email-kwolf@redhat.com> In-Reply-To: <1270806388-28138-1-git-send-email-kwolf@redhat.com> References: <1270806388-28138-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.18 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [Qemu-devel] [STABLE][PATCH 02/10] block: avoid creating too large iovecs in multiwrite_merge X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Christoph Hellwig If we go over the maximum number of iovecs support by syscall we get back EINVAL from the kernel which translate to I/O errors for the guest. Add a MAX_IOV defintion for platforms that don't have it. For now we use the same 1024 define that's used on Linux and various other platforms, but until the windows block backend implements some kind of vectored I/O it doesn't matter. Signed-off-by: Christoph Hellwig Signed-off-by: Anthony Liguori (cherry picked from commit e2a305fb13ff0f5cf6ff805555aaa90a5ed5954c) Signed-off-by: Kevin Wolf --- block.c | 4 ++++ qemu-common.h | 4 ++++ 2 files changed, 8 insertions(+), 0 deletions(-) diff --git a/block.c b/block.c index 97af3f5..9697dc9 100644 --- a/block.c +++ b/block.c @@ -1669,6 +1669,10 @@ static int multiwrite_merge(BlockDriverState *bs, BlockRequest *reqs, merge = bs->drv->bdrv_merge_requests(bs, &reqs[outidx], &reqs[i]); } + if (reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1 > IOV_MAX) { + merge = 0; + } + if (merge) { size_t size; QEMUIOVector *qiov = qemu_mallocz(sizeof(*qiov)); diff --git a/qemu-common.h b/qemu-common.h index d96060a..a23afbc 100644 --- a/qemu-common.h +++ b/qemu-common.h @@ -54,6 +54,10 @@ struct iovec { void *iov_base; size_t iov_len; }; +/* + * Use the same value as Linux for now. + */ +#define IOV_MAX 1024 #else #include #endif