From patchwork Tue Feb 4 21:13:54 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13959850 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 77EBBC02193 for ; Tue, 4 Feb 2025 21:18:58 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tfQFy-0005K7-M0; Tue, 04 Feb 2025 16:14:54 -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 1tfQFg-0005CS-VP for qemu-devel@nongnu.org; Tue, 04 Feb 2025 16:14:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tfQFf-0005fJ-IK for qemu-devel@nongnu.org; Tue, 04 Feb 2025 16:14:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738703675; 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=pEYb6IyR+/WWjulz36EVwQIUpHsOCFTKyj0M4JSFFpM=; b=aozIJX5SXGsJ0R0ZB5JfZLFRZG1YCqQJQYu7Ca0cC/KFeCLXEIOQN4esFIO5HPiefxBgIM gmqLZcGwpPKwMg9IgtX+89jzQs+lOeikBv2JJrIgP0m8E7AfUiElL8IM3HbbCGvZHo1fc6 Uqk/+9kv1sdq1QnQJIq//55A3k7e31s= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-608-U5bvPsBVPD2id2mRTBEreQ-1; Tue, 04 Feb 2025 16:14:31 -0500 X-MC-Unique: U5bvPsBVPD2id2mRTBEreQ-1 X-Mimecast-MFC-AGG-ID: U5bvPsBVPD2id2mRTBEreQ Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D6DD81800266; Tue, 4 Feb 2025 21:14:30 +0000 (UTC) Received: from merkur.redhat.com (unknown [10.39.194.100]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id D5A0E1800268; Tue, 4 Feb 2025 21:14:26 +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 v3 03/16] block: Inactivate external snapshot overlays when necessary Date: Tue, 4 Feb 2025 22:13:54 +0100 Message-ID: <20250204211407.381505-4-kwolf@redhat.com> In-Reply-To: <20250204211407.381505-1-kwolf@redhat.com> References: <20250204211407.381505-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H2=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=unavailable 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 Acked-by: Fabiano Rosas Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi --- 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;