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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 5BD84C49ED8 for ; Tue, 10 Sep 2019 15:16:34 +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 2D1A121479 for ; Tue, 10 Sep 2019 15:16:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D1A121479 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]:41292 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i7hsf-0005qq-Ac for qemu-devel@archiver.kernel.org; Tue, 10 Sep 2019 11:16:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57713) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i7hfM-0007SM-JC for qemu-devel@nongnu.org; Tue, 10 Sep 2019 11:02:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i7hfL-0006NT-Hd for qemu-devel@nongnu.org; Tue, 10 Sep 2019 11:02:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33563) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i7hfI-0006L4-T5; Tue, 10 Sep 2019 11:02:45 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id EB6E4793C4; Tue, 10 Sep 2019 15:02:43 +0000 (UTC) Received: from localhost.localdomain (ovpn-116-217.ams2.redhat.com [10.36.116.217]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DCEB360BF3; Tue, 10 Sep 2019 15:02:42 +0000 (UTC) Date: Tue, 10 Sep 2019 17:02:41 +0200 From: Kevin Wolf To: Max Reitz Message-ID: <20190910150241.GJ4446@localhost.localdomain> References: <20190809161407.11920-1-mreitz@redhat.com> <20190809161407.11920-24-mreitz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190809161407.11920-24-mreitz@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Tue, 10 Sep 2019 15:02:43 +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 v6 23/42] blockdev: Use CAF in external_snapshot_prepare() 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: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 09.08.2019 um 18:13 hat Max Reitz geschrieben: > This allows us to differentiate between filters and nodes with COW > backing files: Filters cannot be used as overlays at all (for this > function). > > Signed-off-by: Max Reitz > Reviewed-by: Vladimir Sementsov-Ogievskiy Didn't we occasionally advertise blockdev-snapshot as the way to insert filters on top at runtime? Though it seems it has always only worked for filters that use bs->backing, among which I think there aren't any user-creatable ones. So we're probably good. Kevin > blockdev.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/blockdev.c b/blockdev.c > index 29c6c6044a..c540802127 100644 > --- a/blockdev.c > +++ b/blockdev.c > @@ -1664,7 +1664,12 @@ static void external_snapshot_prepare(BlkActionState *common, > goto out; > } > > - if (state->new_bs->backing != NULL) { > + if (state->new_bs->drv->is_filter) { > + error_setg(errp, "Filters cannot be used as overlays"); > + goto out; > + } > + > + if (bdrv_filtered_cow_child(state->new_bs)) { > error_setg(errp, "The overlay already has a backing image"); > goto out; > } > -- > 2.21.0 >