From patchwork Tue Sep 1 14:33:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 11748531 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 32062166C for ; Tue, 1 Sep 2020 14:50:51 +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 05CDB21734 for ; Tue, 1 Sep 2020 14:50:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UXUBcegz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 05CDB21734 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:59860 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kD7cY-0005Tk-5G for patchwork-qemu-devel@patchwork.kernel.org; Tue, 01 Sep 2020 10:50:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34054) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kD7NM-0008MJ-5E for qemu-devel@nongnu.org; Tue, 01 Sep 2020 10:35:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:42661) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kD7NK-00078w-5M for qemu-devel@nongnu.org; Tue, 01 Sep 2020 10:35:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598970905; 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=I6UZu6oy2R1ryVrhn3VfOXR3Jy05hV5fWO7qGTQSxwU=; b=UXUBcegzUKkTgFgutj+KxHHbcpbJ2j2TyFRJYUhZxjKiR84vyDs7IZaPaqAAnsvW9d1jsz dPsk+Lqy5BTV/ybqqna5L8kTcTIaGoXizc3dNxsibFfwA/SrLwAdx+NAiS8rEQv+pTBeZq boq7/WUSDDW++YfUaMeSR+9eNa3vWeY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-148-Ro9jbR3mNpOf9FLMJSvI4A-1; Tue, 01 Sep 2020 10:35:03 -0400 X-MC-Unique: Ro9jbR3mNpOf9FLMJSvI4A-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 381E710051D3; Tue, 1 Sep 2020 14:35:02 +0000 (UTC) Received: from localhost (ovpn-113-83.ams2.redhat.com [10.36.113.83]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CE13578B5D; Tue, 1 Sep 2020 14:35:01 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v8 15/43] block: Re-evaluate backing file handling in reopen Date: Tue, 1 Sep 2020 16:33:56 +0200 Message-Id: <20200901143424.884735-16-mreitz@redhat.com> In-Reply-To: <20200901143424.884735-1-mreitz@redhat.com> References: <20200901143424.884735-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/31 23:17:53 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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 , Andrey Shinkevich , Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.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 | 49 ++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 40 insertions(+), 9 deletions(-) diff --git a/block.c b/block.c index 96bf8672f1..660386795a 100644 --- a/block.c +++ b/block.c @@ -4004,7 +4004,7 @@ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, Error **errp) { BlockDriverState *bs = reopen_state->bs; - BlockDriverState *overlay_bs, *new_backing_bs; + BlockDriverState *overlay_bs, *below_bs, *new_backing_bs; QObject *value; const char *str; @@ -4043,26 +4043,57 @@ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, } } + /* + * 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 support a " + "backing child", bs->node_name, bs->drv->format_name); + return -EINVAL; + } + } else if (!bs->drv->supports_backing) { + error_setg(errp, "Driver '%s' of node '%s' does not support backing " + "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 = bs; - while (backing_bs(overlay_bs) && backing_bs(overlay_bs)->implicit) { - overlay_bs = backing_bs(overlay_bs); + for (below_bs = bdrv_filter_or_cow_bs(overlay_bs); + below_bs && below_bs->implicit; + below_bs = bdrv_filter_or_cow_bs(overlay_bs)) + { + overlay_bs = below_bs; } /* If we want to replace the backing file we need some extra checks */ - if (new_backing_bs != backing_bs(overlay_bs)) { + if (new_backing_bs != bdrv_filter_or_cow_bs(overlay_bs)) { /* Check for implicit nodes between bs and its backing file */ if (bs != 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_backing_chain_frozen(overlay_bs, backing_bs(overlay_bs), - errp)) { + /* + * Check if the backing link that we want to replace is frozen. + * Note that + * bdrv_filter_or_cow_child(overlay_bs) == overlay_bs->backing, + * because we know that overlay_bs == bs, and that @bs + * either is a filter that uses ->backing or a COW format BDS + * with bs->drv->supports_backing == true. + */ + if (bdrv_is_backing_chain_frozen(overlay_bs, + child_bs(overlay_bs->backing), errp)) + { return -EPERM; } reopen_state->replace_backing_bs = true; @@ -4211,7 +4242,7 @@ 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 = -EINVAL; @@ -4352,7 +4383,7 @@ 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 = backing_bs(bs); + BlockDriverState *old_backing_bs = 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) {