From nobody Tue Nov 11 20:53:33 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1565367529; cv=none; d=zoho.com; s=zohoarc; b=SLGCJk4tlHyNIvTA4r/L+TXcA0oWUwEx/bdxFT0Q4eL6c7pfeP3L3FXhkl85D8hXDfhv5p5XYZc3l+fZgMpTxjjgGA/o4FQtSikTFzR7vCJu75olxifG5FO+58UaX01a8XW1FuGpvZPCe1gyDkLqu2jRBLriwmkGoH5/yflkTTU= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1565367529; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=UJW7XZpmULGZPmXtB9lL7nlMB0l4wdwOQpnSN56MFlE=; b=JHE9cl5/sTF42GznNton6CgnQPHR6sLIq7EHAsREWGcoaosJUn7qvAcYF6PqIpA/C5Q9eH/TZYlxJnZ7tWAylE0DzN6zgKzIBenHeL4KKPKK/SOYWJ9f602kJrkroDmG73n8oZ7Lb35RWF6IHdmMd8upaeiVqi1TuHE15WZ0bNo= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1565367529942650.0900478203217; Fri, 9 Aug 2019 09:18:49 -0700 (PDT) Received: from localhost ([::1]:60870 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hw7bK-0002Oo-JD for importer@patchew.org; Fri, 09 Aug 2019 12:18:46 -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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Vladimir Sementsov-Ogievskiy --- 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(BDRVReopenStat= e *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 suppo= rt a " + "backing child", bs->node_name, bs->drv->format_nam= e); + return -EINVAL; + } + } else if (!bs->drv->supports_backing) { + error_setg(errp, "Driver '%s' of node '%s' does not support backin= g " + "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), errp)= ) { + /* + * 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->backing), + errp)) + { return -EPERM; } reopen_state->replace_backing_bs =3D true; @@ -3829,7 +3860,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state= , 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_state) * 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