From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B53DECE587 for ; Tue, 1 Oct 2019 17:50:06 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 25C2121855 for ; Tue, 1 Oct 2019 17:50:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 25C2121855 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46050 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iFMHl-0004Ug-AR for qemu-devel@archiver.kernel.org; Tue, 01 Oct 2019 13:50:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36458) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iFMGM-0002sP-9f for qemu-devel@nongnu.org; Tue, 01 Oct 2019 13:48:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iFMGL-0000dl-44 for qemu-devel@nongnu.org; Tue, 01 Oct 2019 13:48:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37406) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iFMGI-0000bg-Q6; Tue, 01 Oct 2019 13:48:34 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1326810F2E96; Tue, 1 Oct 2019 17:48:34 +0000 (UTC) Received: from localhost (unknown [10.40.205.251]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9E0B15D9C9; Tue, 1 Oct 2019 17:48:33 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH 1/2] block: Skip COR for inactive nodes Date: Tue, 1 Oct 2019 19:48:26 +0200 Message-Id: <20191001174827.11081-2-mreitz@redhat.com> In-Reply-To: <20191001174827.11081-1-mreitz@redhat.com> References: <20191001174827.11081-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.66]); Tue, 01 Oct 2019 17:48:34 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-devel@nongnu.org, Stefan Hajnoczi , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" We must not write data to inactive nodes, and a COR is certainly something we can simply not do without upsetting anyone. So skip COR operations on inactive nodes. Signed-off-by: Max Reitz --- block/io.c | 41 +++++++++++++++++++++++++++-------------- 1 file changed, 27 insertions(+), 14 deletions(-) diff --git a/block/io.c b/block/io.c index f8c3596131..4f9ee97c2b 100644 --- a/block/io.c +++ b/block/io.c @@ -1246,11 +1246,18 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(= BdrvChild *child, int max_transfer =3D MIN_NON_ZERO(bs->bl.max_transfer, BDRV_REQUEST_MAX_BYTES); unsigned int progress =3D 0; + bool skip_write; =20 if (!drv) { return -ENOMEDIUM; } =20 + /* + * Do not write anything when the BDS is inactive. That is not + * allowed, and it would not help. + */ + skip_write =3D (bs->open_flags & BDRV_O_INACTIVE); + /* FIXME We cannot require callers to have write permissions when al= l they * are doing is a read request. If we did things right, write permis= sions * would be obtained anyway, but internally by the copy-on-read code= . As @@ -1274,23 +1281,29 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(= BdrvChild *child, while (cluster_bytes) { int64_t pnum; =20 - ret =3D bdrv_is_allocated(bs, cluster_offset, - MIN(cluster_bytes, max_transfer), &pnum)= ; - if (ret < 0) { - /* Safe to treat errors in querying allocation as if - * unallocated; we'll probably fail again soon on the - * read, but at least that will set a decent errno. - */ + if (skip_write) { + ret =3D 1; /* "already allocated", so nothing will be copied= */ pnum =3D MIN(cluster_bytes, max_transfer); - } + } else { + ret =3D bdrv_is_allocated(bs, cluster_offset, + MIN(cluster_bytes, max_transfer), &p= num); + if (ret < 0) { + /* + * Safe to treat errors in querying allocation as if + * unallocated; we'll probably fail again soon on the + * read, but at least that will set a decent errno. + */ + pnum =3D MIN(cluster_bytes, max_transfer); + } =20 - /* Stop at EOF if the image ends in the middle of the cluster */ - if (ret =3D=3D 0 && pnum =3D=3D 0) { - assert(progress >=3D bytes); - break; - } + /* Stop at EOF if the image ends in the middle of the cluste= r */ + if (ret =3D=3D 0 && pnum =3D=3D 0) { + assert(progress >=3D bytes); + break; + } =20 - assert(skip_bytes < pnum); + assert(skip_bytes < pnum); + } =20 if (ret <=3D 0) { QEMUIOVector local_qiov; --=20 2.21.0