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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 0A102C7618F for ; Tue, 16 Jul 2019 17:02:15 +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 D23A5205ED for ; Tue, 16 Jul 2019 17:02:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D23A5205ED 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]:51332 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hnQqD-0006mX-Kr for qemu-devel@archiver.kernel.org; Tue, 16 Jul 2019 13:02:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34010) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hnQq2-0006JZ-E2 for qemu-devel@nongnu.org; Tue, 16 Jul 2019 13:02:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hnQq1-0007M1-EG for qemu-devel@nongnu.org; Tue, 16 Jul 2019 13:02:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53622) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hnQpz-0007Iz-4P; Tue, 16 Jul 2019 13:01:59 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7663DC034DF3; Tue, 16 Jul 2019 17:01:58 +0000 (UTC) Received: from linux.fritz.box (ovpn-117-24.ams2.redhat.com [10.36.117.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 947201001B04; Tue, 16 Jul 2019 17:01:57 +0000 (UTC) Date: Tue, 16 Jul 2019 19:01:56 +0200 From: Kevin Wolf To: Max Reitz Message-ID: <20190716170156.GJ7297@linux.fritz.box> References: <20190703172813.6868-1-mreitz@redhat.com> <20190703172813.6868-7-mreitz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190703172813.6868-7-mreitz@redhat.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Tue, 16 Jul 2019 17:01:58 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v2 06/12] block: Deep-clear inherits_from 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: qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 03.07.2019 um 19:28 hat Max Reitz geschrieben: > BDS.inherits_from does not always point to an immediate parent node. > When launching a block job with a filter node, for example, the node > directly below the filter will not point to the filter, but keep its old > pointee (above the filter). > > If that pointee goes away while the job is still running, the node's > inherits_from will not be updated and thus point to garbage. To fix > this, bdrv_unref_child() has to check not only the parent node's > immediate children for nodes whose inherits_from needs to be cleared, > but its whole subtree. > > Signed-off-by: Max Reitz Isn't the real bug that we keep pointing to a node that isn't a parent of the node any more? I think this will effectively disable option inheritance in bdrv_reopen() as long as the filter node is present, which is certainly not what we intended. The intuitive thing would be that after inserting a filter, the image now inherits from the filter node, and when the filter is removed, it inherits from the filter's bs->inherit_from if that becomes a parent of the node. (Though I'm not necessarily saying that my intuition is to be trusted here.) Kevin