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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 0493BC433FF for ; Fri, 9 Aug 2019 16:18:45 +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 A7D3F2086A for ; Fri, 9 Aug 2019 16:18:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7D3F2086A 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]:60870 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hw7bH-0002Oo-Ue for qemu-devel@archiver.kernel.org; Fri, 09 Aug 2019 12:18:43 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57133) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hw7XU-0001Wn-EZ for qemu-devel@nongnu.org; Fri, 09 Aug 2019 12:14:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hw7XT-0004Bg-7m for qemu-devel@nongnu.org; Fri, 09 Aug 2019 12:14:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50334) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hw7XQ-00049E-Hj; Fri, 09 Aug 2019 12:14:44 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CF9906869A; Fri, 9 Aug 2019 16:14:43 +0000 (UTC) Received: from localhost (unknown [10.40.205.179]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6948119C70; Fri, 9 Aug 2019 16:14:43 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Fri, 9 Aug 2019 18:13:40 +0200 Message-Id: <20190809161407.11920-16-mreitz@redhat.com> In-Reply-To: <20190809161407.11920-1-mreitz@redhat.com> References: <20190809161407.11920-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 09 Aug 2019 16:14:43 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v6 15/42] block: Re-evaluate backing file handling in reopen 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: Kevin Wolf , Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Reopening a node's backing child needs a bit of special handling because the "backing" child has different defaults than all other children (among other things). Adding filter support here is a bit more difficult than just using the child access functions. In fact, we often have to directly use bs->backing because these functions are about the "backing" child (which may or may not be the COW backing file). Signed-off-by: Max Reitz --- block.c | 45 ++++++++++++++++++++++++++++++++++++++------- 1 file changed, 38 insertions(+), 7 deletions(-) diff --git a/block.c b/block.c index 42abbaf0ba..064cc99857 100644 --- a/block.c +++ b/block.c @@ -3660,25 +3660,56 @@ static int bdrv_reopen_parse_backing(BDRVReopenSt= ate *reopen_state, } } =20 + /* + * Ensure that @bs can really handle backing files, because we are + * about to give it one (or swap the existing one) + */ + if (bs->drv->is_filter) { + /* Filters always have a file or a backing child */ + if (!bs->backing) { + error_setg(errp, "'%s' is a %s filter node that does not sup= port a " + "backing child", bs->node_name, bs->drv->format_n= ame); + return -EINVAL; + } + } else if (!bs->drv->supports_backing) { + error_setg(errp, "Driver '%s' of node '%s' does not support back= ing " + "files", bs->drv->format_name, bs->node_name); + return -EINVAL; + } + /* * Find the "actual" backing file by skipping all links that point * to an implicit node, if any (e.g. a commit filter node). + * We cannot use any of the bdrv_skip_*() functions here because + * those return the first explicit node, while we are looking for + * its overlay here. */ overlay_bs =3D bs; - while (backing_bs(overlay_bs) && backing_bs(overlay_bs)->implicit) { - overlay_bs =3D backing_bs(overlay_bs); + while (bdrv_filtered_bs(overlay_bs) && + bdrv_filtered_bs(overlay_bs)->implicit) + { + overlay_bs =3D bdrv_filtered_bs(overlay_bs); } =20 /* If we want to replace the backing file we need some extra checks = */ - if (new_backing_bs !=3D backing_bs(overlay_bs)) { + if (new_backing_bs !=3D bdrv_filtered_bs(overlay_bs)) { /* Check for implicit nodes between bs and its backing file */ if (bs !=3D overlay_bs) { error_setg(errp, "Cannot change backing link if '%s' has " "an implicit backing file", bs->node_name); return -EPERM; } - /* Check if the backing link that we want to replace is frozen *= / - if (bdrv_is_chain_frozen(overlay_bs, backing_bs(overlay_bs), err= p)) { + /* + * Check if the backing link that we want to replace is frozen. + * Note that + * bdrv_filtered_child(overlay_bs) =3D=3D overlay_bs->backing, + * because we know that overlay_bs =3D=3D bs, and that @bs + * either is an R/W filter that uses ->backing or a COW format + * with bs->drv->supports_backing =3D=3D true. + */ + if (bdrv_is_chain_frozen(overlay_bs, child_bs(overlay_bs->backin= g), + errp)) + { return -EPERM; } reopen_state->replace_backing_bs =3D true; @@ -3829,7 +3860,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_sta= te, BlockReopenQueue *queue, * its metadata. Otherwise the 'backing' option can be omitted. */ if (drv->supports_backing && reopen_state->backing_missing && - (backing_bs(reopen_state->bs) || reopen_state->bs->backing_file[= 0])) { + (reopen_state->bs->backing || reopen_state->bs->backing_file[0])= ) { error_setg(errp, "backing is missing for '%s'", reopen_state->bs->node_name); ret =3D -EINVAL; @@ -3974,7 +4005,7 @@ void bdrv_reopen_commit(BDRVReopenState *reopen_sta= te) * from bdrv_set_backing_hd()) has the new values. */ if (reopen_state->replace_backing_bs) { - BlockDriverState *old_backing_bs =3D backing_bs(bs); + BlockDriverState *old_backing_bs =3D child_bs(bs->backing); assert(!old_backing_bs || !old_backing_bs->implicit); /* Abort the permission update on the backing bs we're detaching= */ if (old_backing_bs) { --=20 2.21.0