From patchwork Thu Jan 30 17:12:33 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13954751 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 60C3AC02190 for ; Thu, 30 Jan 2025 17:13:33 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tdY6B-0000YQ-8i; Thu, 30 Jan 2025 12:13:03 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tdY68-0000Wf-7V for qemu-devel@nongnu.org; Thu, 30 Jan 2025 12:13:00 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tdY66-00039j-6E for qemu-devel@nongnu.org; Thu, 30 Jan 2025 12:12:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738257177; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=O9R1bvCZlCby3nJpaX4lx6Gi7/oQpcND1WUKEvZhskk=; b=WEOJ48rgKP5Vu07Hnrnist9gQTJA/c62jff4p+6hPHrtAeLl/yyP1ASwbCb1yNyoZtPFH9 nRlcspyl9Hc6Qcx28nBfrvaEjF2Tbzv9oIvHaRn0T24HJc567+wSUuw9XDhDmVPrrfRLW+ fJxTjQZKT1KJiLCJ/kaTEmQiP3S3KxQ= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-481-0UBNsMEPNjG7tnJvPJ-h4g-1; Thu, 30 Jan 2025 12:12:56 -0500 X-MC-Unique: 0UBNsMEPNjG7tnJvPJ-h4g-1 X-Mimecast-MFC-AGG-ID: 0UBNsMEPNjG7tnJvPJ-h4g Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D0E6919560B0; Thu, 30 Jan 2025 17:12:54 +0000 (UTC) Received: from merkur.redhat.com (unknown [10.39.193.13]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6DD643003FD2; Thu, 30 Jan 2025 17:12:52 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, hreitz@redhat.com, stefanha@redhat.com, pkrempa@redhat.com, peterx@redhat.com, farosas@suse.de, qemu-devel@nongnu.org Subject: [PATCH v2 02/15] block: Inactivate external snapshot overlays when necessary Date: Thu, 30 Jan 2025 18:12:33 +0100 Message-ID: <20250130171240.286878-3-kwolf@redhat.com> In-Reply-To: <20250130171240.286878-1-kwolf@redhat.com> References: <20250130171240.286878-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -33 X-Spam_score: -3.4 X-Spam_bar: --- X-Spam_report: (-3.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.3, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Putting an active block node on top of an inactive one is strictly speaking an invalid configuration and the next patch will turn it into a hard error. However, taking a snapshot while disk images are inactive after completing migration has an important use case: After migrating to a file, taking an external snapshot is what is needed to take a full VM snapshot. In order for this to keep working after the later patches, change creating a snapshot such that it automatically inactivates an overlay that is added on top of an already inactive node. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- blockdev.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/blockdev.c b/blockdev.c index 218024497b..eb2517f1dd 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1497,6 +1497,22 @@ static void external_snapshot_action(TransactionAction *action, return; } + /* + * Older QEMU versions have allowed adding an active parent node to an + * inactive child node. This is unsafe in the general case, but there is an + * important use case, which is taking a VM snapshot with migration to file + * and then adding an external snapshot while the VM is still stopped and + * images are inactive. Requiring the user to explicitly create the overlay + * as inactive would break compatibility, so just do it automatically here + * to keep this working. + */ + if (bdrv_is_inactive(state->old_bs) && !bdrv_is_inactive(state->new_bs)) { + ret = bdrv_inactivate(state->new_bs, errp); + if (ret < 0) { + return; + } + } + ret = bdrv_append(state->new_bs, state->old_bs, errp); if (ret < 0) { return;