From patchwork Wed Feb 15 14:58:13 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Sementsov-Ogievskiy X-Patchwork-Id: 728253 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 3vNj9S3KsFz9s2G for ; Thu, 16 Feb 2017 01:59:08 +1100 (AEDT) Received: from localhost ([::1]:41189 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ce12v-0007ZL-VS for incoming@patchwork.ozlabs.org; Wed, 15 Feb 2017 09:59:06 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39263) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ce12G-0007Eb-TY for qemu-devel@nongnu.org; Wed, 15 Feb 2017 09:58:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ce12D-0006dg-1i for qemu-devel@nongnu.org; Wed, 15 Feb 2017 09:58:25 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:21803 helo=relay.sw.ru) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ce12C-0006d7-M0 for qemu-devel@nongnu.org; Wed, 15 Feb 2017 09:58:20 -0500 Received: from kvm.sw.ru (msk-vpn.virtuozzo.com [195.214.232.6]) by relay.sw.ru (8.13.4/8.13.4) with ESMTP id v1FEwDjC026096; Wed, 15 Feb 2017 17:58:14 +0300 (MSK) From: Vladimir Sementsov-Ogievskiy To: qemu-block@nongnu.org, qemu-devel@nongnu.org Date: Wed, 15 Feb 2017 17:58:13 +0300 Message-Id: <1487170693-28224-1-git-send-email-vsementsov@virtuozzo.com> X-Mailer: git-send-email 1.8.3.1 X-detected-operating-system: by eggs.gnu.org: OpenBSD 3.x [fuzzy] X-Received-From: 195.214.232.25 Subject: [Qemu-devel] [PATCH v3] backup: allow target without .bdrv_get_info 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, vsementsov@virtuozzo.com, famz@redhat.com, jcody@redhat.com, mreitz@redhat.com, stefanha@redhat.com, den@openvz.org, jsnow@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Currently backup to nbd target is broken, as nbd doesn't have .bdrv_get_info realization. Signed-off-by: Vladimir Sementsov-Ogievskiy --- v3: fix compilation (I feel like an idiot) adjust wording (Fam) v2: add WARNING === Since commit commit 4c9bca7e39a6e07ad02c1dcde3478363344ec60b Author: John Snow Date: Thu Feb 25 15:58:30 2016 -0500 block/backup: avoid copying less than full target clusters backup to nbd target is broken, we have "Couldn't determine the cluster size of the target image". Proposed NBD protocol extension - NBD_OPT_INFO should finally solve this problem. But until it is not realized, we need allow backup to nbd target due to backward compatibility. Furthermore, is it entirely ok to disallow backup if bds lacks .bdrv_get_info? Which behavior should be default: to fail backup or to use default cluster size? block/backup.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/block/backup.c b/block/backup.c index ea38733..d800a24 100644 --- a/block/backup.c +++ b/block/backup.c @@ -638,7 +638,16 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs, * backup cluster size is smaller than the target cluster size. Even for * targets with a backing file, try to avoid COW if possible. */ ret = bdrv_get_info(target, &bdi); - if (ret < 0 && !target->backing) { + if (ret == -ENOTSUP) { + /* Cluster size is not defined */ + fprintf(stderr, + "WARNING: Target block device doesn't provide information " + "about block size and it doesn't have backing file. Default " + "block size of %u bytes is used. If actual block size of " + "target exceeds this default, backup may be unusable", + BACKUP_CLUSTER_SIZE_DEFAULT); + job->cluster_size = BACKUP_CLUSTER_SIZE_DEFAULT; + } else if (ret < 0 && !target->backing) { error_setg_errno(errp, -ret, "Couldn't determine the cluster size of the target image, " "which has no backing file");