From patchwork Tue Feb 8 15:36:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 1590021 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=IGxeC9XL; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) 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 bilbo.ozlabs.org (Postfix) with ESMTPS id 4JtWZX59lrz9s0B for ; Wed, 9 Feb 2022 05:22:28 +1100 (AEDT) Received: from localhost ([::1]:59740 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nHV8E-0003xH-0w for incoming@patchwork.ozlabs.org; Tue, 08 Feb 2022 13:22:26 -0500 Received: from eggs.gnu.org ([209.51.188.92]:47266) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nHSYe-0000Tx-Vd for qemu-devel@nongnu.org; Tue, 08 Feb 2022 10:37:33 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:35270) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nHSYE-0002eN-Py for qemu-devel@nongnu.org; Tue, 08 Feb 2022 10:37:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1644334626; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=I3/bM+4lQ/kO8LqzI5XVk+qD+YU+/kn83G35vECh8vc=; b=IGxeC9XLLIGscyPH0WKYCMfasnYj9UWe02I6S0sR+vpADm3tHFnOTG+gYQxufHw7R8ENmZ vUFD0Aws81tsGg7orAPteapZwhA1dvjvWZP1yWoe3U+etotBvKecoLXKdIF8MnMEEODMgk Hqn9RPCeMTLKWlF7X2q0UyDfDNjNLm0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-253-ppz_WKFLNY2TlK3DmFm3Tg-1; Tue, 08 Feb 2022 10:37:03 -0500 X-MC-Unique: ppz_WKFLNY2TlK3DmFm3Tg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 66956363A6; Tue, 8 Feb 2022 15:37:01 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id A2DF07D473; Tue, 8 Feb 2022 15:37:00 +0000 (UTC) From: Emanuele Giuseppe Esposito To: qemu-block@nongnu.org Subject: [PATCH 3/6] block.c: bdrv_replace_child_noperm: first call ->attach(), and then add child Date: Tue, 8 Feb 2022 10:36:52 -0500 Message-Id: <20220208153655.1251658-4-eesposit@redhat.com> In-Reply-To: <20220208153655.1251658-1-eesposit@redhat.com> References: <20220208153655.1251658-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eesposit@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.129.124; envelope-from=eesposit@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, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Cc: Kevin Wolf , Fam Zheng , Vladimir Sementsov-Ogievskiy , Emanuele Giuseppe Esposito , qemu-devel@nongnu.org, Hanna Reitz , Stefan Hajnoczi , Paolo Bonzini , John Snow Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Doing the opposite can make adding the child node to a non-drained node, as apply_subtree_drain is only done in ->attach() and thus make assert_bdrv_graph_writable fail. This can happen for example during a transaction rollback (test 245, test_io_with_graph_changes): 1. a node is removed from the graph, thus it is undrained 2. then something happens, and we need to roll back the transactions through tran_abort() 3. at this point, the current code would first attach the undrained node to the graph via QLIST_INSERT_HEAD, and then call ->attach() that will take care of restoring the drain with apply_subtree_drain(), leaving the node undrained between the two operations. Signed-off-by: Emanuele Giuseppe Esposito Reviewed-by: Stefan Hajnoczi --- block.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index ec346a7e2e..08a6e3a4ef 100644 --- a/block.c +++ b/block.c @@ -2872,8 +2872,6 @@ static void bdrv_replace_child_noperm(BdrvChild **childp, } if (new_bs) { - assert_bdrv_graph_writable(new_bs); - QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); /* * Detaching the old node may have led to the new node's @@ -2890,6 +2888,10 @@ static void bdrv_replace_child_noperm(BdrvChild **childp, if (child->klass->attach) { child->klass->attach(child); } + + assert_bdrv_graph_writable(new_bs); + QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); + } /*