From patchwork Thu Oct 27 18:31:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 1695559 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=YYAaAwcn; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4MyvV31BWNz23kj for ; Fri, 28 Oct 2022 05:34:35 +1100 (AEDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oo7gL-0001qN-S2; Thu, 27 Oct 2022 14:32:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oo7gE-0001Tb-Ft for qemu-devel@nongnu.org; Thu, 27 Oct 2022 14:32:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oo7g6-0002R9-FA for qemu-devel@nongnu.org; Thu, 27 Oct 2022 14:32:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666895549; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5kOsbvaV6j0SYAFPC0Xq47Pjz2VvQMB7agejxESRzPg=; b=YYAaAwcnmAx4OXkgSBkHwFyYoUmj+UMXmy/vQy9P+Sthv47ElXb8rtDouBvRE9zAV2ynyx 4Czh8UC/giYKcZLNoIVVaCv6DaDVz8eU7kP4Zne/R7ExkHrs7kIE6NHMnPcGE4JXd9slMR 6SKxbeq/7Wdn24oRZd+nD/zfjFFWSLk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-661-B4R8g_wAMzmLSbdfA5LakA-1; Thu, 27 Oct 2022 14:32:26 -0400 X-MC-Unique: B4R8g_wAMzmLSbdfA5LakA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DB919857D0D; Thu, 27 Oct 2022 18:32:25 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.39.194.12]) by smtp.corp.redhat.com (Postfix) with ESMTP id 27C411121320; Thu, 27 Oct 2022 18:32:25 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org Subject: [PULL 15/58] block/snapshot: stress that we fallback to primary child Date: Thu, 27 Oct 2022 20:31:03 +0200 Message-Id: <20221027183146.463129-16-kwolf@redhat.com> In-Reply-To: <20221027183146.463129-1-kwolf@redhat.com> References: <20221027183146.463129-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.515, 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_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Vladimir Sementsov-Ogievskiy Actually what we chose is a primary child. Let's stress it in the code. We are going to drop indirect pointer logic here in future. Actually this commit simplifies the future work: we drop use of indirection in the assertion now. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Hanna Reitz Message-Id: <20220726201134.924743-9-vsementsov@yandex-team.ru> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- block/snapshot.c | 30 ++++++++++-------------------- 1 file changed, 10 insertions(+), 20 deletions(-) diff --git a/block/snapshot.c b/block/snapshot.c index d6f53c3065..75e8d3a937 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -161,21 +161,14 @@ bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs, static BdrvChild **bdrv_snapshot_fallback_ptr(BlockDriverState *bs) { BdrvChild **fallback; - BdrvChild *child; + BdrvChild *child = bdrv_primary_child(bs); - /* - * The only BdrvChild pointers that are safe to modify (and which - * we can thus return a reference to) are bs->file and - * bs->backing. - */ - fallback = &bs->file; - if (!*fallback && bs->drv && bs->drv->is_filter) { - fallback = &bs->backing; - } - - if (!*fallback) { + /* We allow fallback only to primary child */ + if (!child) { return NULL; } + fallback = (child == bs->file ? &bs->file : &bs->backing); + assert(*fallback == child); /* * Check that there are no other children that would need to be @@ -309,15 +302,12 @@ int bdrv_snapshot_goto(BlockDriverState *bs, } /* - * fallback_ptr is &bs->file or &bs->backing. *fallback_ptr - * was closed above and set to NULL, but the .bdrv_open() call - * has opened it again, because we set the respective option - * (with the qdict_put_str() call above). - * Assert that .bdrv_open() has attached some child on - * *fallback_ptr, and that it has attached the one we wanted - * it to (i.e., fallback_bs). + * fallback was a primary child. It was closed above and set to NULL, + * but the .bdrv_open() call has opened it again, because we set the + * respective option (with the qdict_put_str() call above). + * Assert that .bdrv_open() has attached the right BDS as primary child. */ - assert(*fallback_ptr && fallback_bs == (*fallback_ptr)->bs); + assert(bdrv_primary_bs(bs) == fallback_bs); bdrv_unref(fallback_bs); return ret; }