From patchwork Thu Jan 30 21:44:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 1231656 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: 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: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=MTarBBpW; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 487vG94YChz9sNx for ; Fri, 31 Jan 2020 08:52:17 +1100 (AEDT) Received: from localhost ([::1]:39792 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ixHjT-0006at-Ht for incoming@patchwork.ozlabs.org; Thu, 30 Jan 2020 16:52:15 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:33283) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ixHcP-0004ke-Na for qemu-devel@nongnu.org; Thu, 30 Jan 2020 16:44:59 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ixHcO-0003uQ-Bw for qemu-devel@nongnu.org; Thu, 30 Jan 2020 16:44:57 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:27870 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ixHcO-0003tN-7l for qemu-devel@nongnu.org; Thu, 30 Jan 2020 16:44:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580420695; 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=iCAmo/jwaRQqIDZ5IhRZyCsBgUlZuKmTMDrYNtPvXbM=; b=MTarBBpWuKgX0m1LilcDfB97mhYuJEsNnd0t0b8JiQBlQRQzRd1h49mLgmfNSZPj81z4Aq OKpxVN/VamK/A7M9+Dwe6rSuRvdG+UOWbjqZr9sGRymKtzHEIMOAeVzDf0sBovckad/KST EH2JolHvSZBN6UgX3YKnXuGqCo6bt/k= 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-155-hBNhTg2APdCRHWtIvgbDtQ-1; Thu, 30 Jan 2020 16:44:48 -0500 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 C2F9E801A08; Thu, 30 Jan 2020 21:44:47 +0000 (UTC) Received: from localhost (ovpn-204-145.brq.redhat.com [10.40.204.145]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5B92577949; Thu, 30 Jan 2020 21:44:47 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v3 06/21] block: Add bdrv_recurse_can_replace() Date: Thu, 30 Jan 2020 22:44:16 +0100 Message-Id: <20200130214431.333510-7-mreitz@redhat.com> In-Reply-To: <20200130214431.333510-1-mreitz@redhat.com> References: <20200130214431.333510-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: hBNhTg2APdCRHWtIvgbDtQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" After a couple of follow-up patches, this function will replace bdrv_recurse_is_first_non_filter() in check_to_replace_node(). bdrv_recurse_is_first_non_filter() is both not sufficiently specific for check_to_replace_node() (it allows cases that should not be allowed, like replacing child nodes of quorum with dissenting data that have more parents than just quorum), and it is too restrictive (it is perfectly fine to replace filters). Signed-off-by: Max Reitz Reviewed-by: Vladimir Sementsov-Ogievskiy --- block.c | 38 ++++++++++++++++++++++++++++++++++++++ include/block/block_int.h | 10 ++++++++++ 2 files changed, 48 insertions(+) diff --git a/block.c b/block.c index 6f58a4900f..6623248443 100644 --- a/block.c +++ b/block.c @@ -6212,6 +6212,44 @@ bool bdrv_recurse_is_first_non_filter(BlockDriverState *bs, return false; } +/* + * This function checks whether the given @to_replace is allowed to be + * replaced by a node that always shows the same data as @bs. This is + * used for example to verify whether the mirror job can replace + * @to_replace by the target mirrored from @bs. + * To be replaceable, @bs and @to_replace may either be guaranteed to + * always show the same data (because they are only connected through + * filters), or some driver may allow replacing one of its children + * because it can guarantee that this child's data is not visible at + * all (for example, for dissenting quorum children that have no other + * parents). + */ +bool bdrv_recurse_can_replace(BlockDriverState *bs, + BlockDriverState *to_replace) +{ + if (!bs || !bs->drv) { + return false; + } + + if (bs == to_replace) { + return true; + } + + /* See what the driver can do */ + if (bs->drv->bdrv_recurse_can_replace) { + return bs->drv->bdrv_recurse_can_replace(bs, to_replace); + } + + /* For filters without an own implementation, we can recurse on our own */ + if (bs->drv->is_filter) { + BdrvChild *child = bs->file ?: bs->backing; + return bdrv_recurse_can_replace(child->bs, to_replace); + } + + /* Safe default */ + return false; +} + BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs, const char *node_name, Error **errp) { diff --git a/include/block/block_int.h b/include/block/block_int.h index dd033d0b37..75f03dcc38 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -102,6 +102,13 @@ struct BlockDriver { */ bool (*bdrv_recurse_is_first_non_filter)(BlockDriverState *bs, BlockDriverState *candidate); + /* + * Return true if @to_replace can be replaced by a BDS with the + * same data as @bs without it affecting @bs's behavior (that is, + * without it being visible to @bs's parents). + */ + bool (*bdrv_recurse_can_replace)(BlockDriverState *bs, + BlockDriverState *to_replace); int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename); int (*bdrv_probe_device)(const char *filename); @@ -1264,6 +1271,9 @@ void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared); +bool bdrv_recurse_can_replace(BlockDriverState *bs, + BlockDriverState *to_replace); + /* * Default implementation for drivers to pass bdrv_co_block_status() to * their file.