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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 3C240C433E0 for ; Wed, 3 Feb 2021 21:35:15 +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 A131964F5F for ; Wed, 3 Feb 2021 21:35:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A131964F5F 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]:43396 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l7Pnt-00041V-GK for qemu-devel@archiver.kernel.org; Wed, 03 Feb 2021 16:35:13 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:46642) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l7Pmg-0003PL-6v for qemu-devel@nongnu.org; Wed, 03 Feb 2021 16:33:58 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:36703) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l7Pmd-0007ZV-4G for qemu-devel@nongnu.org; Wed, 03 Feb 2021 16:33:57 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612388032; 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: in-reply-to:in-reply-to:references:references; bh=y6JhyDcRTrcMeHILFbUDFzatac77S4PVESNexOfahXA=; b=cVUlbn8RraDwGhvVUYG1VKad95OFZsih3ZCZrEM++TzJAZmSVI6fblNc2x+bPQv9Chl4IA cZ5uK6/w96TuUSYdqSrYL5jqP5EVLG+nHtQ9/I8m2VBp2HvUFYyimMTvQxnheFXvfY25yR ahtkT27lxfHI/bajXNFj7m+2jgvj6b8= 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-553-l2azhLdWPMCT5NhJ2NUfGg-1; Wed, 03 Feb 2021 16:33:50 -0500 X-MC-Unique: l2azhLdWPMCT5NhJ2NUfGg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8E517801961; Wed, 3 Feb 2021 21:33:49 +0000 (UTC) Received: from merkur.fritz.box (ovpn-115-32.ams2.redhat.com [10.36.115.32]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F192B4D; Wed, 3 Feb 2021 21:33:47 +0000 (UTC) Date: Wed, 3 Feb 2021 22:33:46 +0100 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v2 23/36] block: adapt bdrv_append() for inserting filters Message-ID: <20210203213346.GJ5507@merkur.fritz.box> References: <20201127144522.29991-1-vsementsov@virtuozzo.com> <20201127144522.29991-24-vsementsov@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20201127144522.29991-24-vsementsov@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.539, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=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: qemu-block@nongnu.org, armbru@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, den@openvz.org, jsnow@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 27.11.2020 um 15:45 hat Vladimir Sementsov-Ogievskiy geschrieben: > bdrv_append is not very good for inserting filters: it does extra > permission update as part of bdrv_set_backing_hd(). During this update > filter may conflict with other parents of top_bs. > > Instead, let's first do all graph modifications and after it update > permissions. This sounds like it fixes a bug. If so, should we have a test like for the other cases fixed by this series? > Note: bdrv_append() is still only works for backing-child based > filters. It's something to improve later. > > It simplifies the fact that bdrv_append() used to append new nodes, > without backing child. Let's add an assertion. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > block.c | 28 +++++++++++++++++----------- > 1 file changed, 17 insertions(+), 11 deletions(-) > > diff --git a/block.c b/block.c > index 02da1a90bc..7094922509 100644 > --- a/block.c > +++ b/block.c > @@ -4998,22 +4998,28 @@ int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, > int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, > Error **errp) > { > - Error *local_err = NULL; > + int ret; > + GSList *tran = NULL; > > - bdrv_set_backing_hd(bs_new, bs_top, &local_err); > - if (local_err) { > - error_propagate(errp, local_err); > - return -EPERM; > + assert(!bs_new->backing); > + > + ret = bdrv_attach_child_noperm(bs_new, bs_top, "backing", > + &child_of_bds, bdrv_backing_role(bs_new), > + &bs_new->backing, &tran, errp); > + if (ret < 0) { > + goto out; > } I don't think changing bs->backing without bdrv_set_backing_hd() is correct at the moment. We lose a few things: 1. The bdrv_is_backing_chain_frozen() check 2. Updating backing_hd->inherits_from if necessary 3. bdrv_refresh_limits() If I'm not missing anything, all of these are needed in the context of bdrv_append(). > - bdrv_replace_node(bs_top, bs_new, &local_err); > - if (local_err) { > - error_propagate(errp, local_err); > - bdrv_set_backing_hd(bs_new, NULL, &error_abort); > - return -EPERM; > + ret = bdrv_replace_node_noperm(bs_top, bs_new, true, &tran, errp); > + if (ret < 0) { > + goto out; > } > > - return 0; > + ret = bdrv_refresh_perms(bs_new, errp); > +out: > + tran_finalize(tran, ret); > + > + return ret; > } Kevin