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=-8.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, 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 AEE63C433E0 for ; Fri, 5 Feb 2021 16:28:17 +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 0B98164E12 for ; Fri, 5 Feb 2021 16:28:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0B98164E12 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]:57296 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l83xv-0002m0-Rd for qemu-devel@archiver.kernel.org; Fri, 05 Feb 2021 11:28:15 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:38090) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l83wZ-0001Lh-Nh for qemu-devel@nongnu.org; Fri, 05 Feb 2021 11:26:54 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:22542) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l83wU-0006VL-JV for qemu-devel@nongnu.org; Fri, 05 Feb 2021 11:26:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612542405; 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=TEcq0ltk07Lf0OSF/ygfFrv99IbO9E0evp/LKtf+izA=; b=XriXyBROq6wWhrUOFgy7qhwg7wgUOhEQSdFuxSPIN+coW3CGqJXEhy744uzRMTVUqK/Lzv rBdqZzVarZZyLBpeCxgO23RFJ9+TjYmtqwVNuKrSD7sEELUNpD2+xhHU7UvZieV/Eu75hF lr1oqZsEoO+bhZtk5u4Sd55OCTqegJk= 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-19-sOBoJFYiN-6vhFhksq91JA-1; Fri, 05 Feb 2021 11:26:44 -0500 X-MC-Unique: sOBoJFYiN-6vhFhksq91JA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8A613192AB7C; Fri, 5 Feb 2021 16:26:42 +0000 (UTC) Received: from merkur.fritz.box (ovpn-114-240.ams2.redhat.com [10.36.114.240]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1DEA0100164C; Fri, 5 Feb 2021 16:26:40 +0000 (UTC) Date: Fri, 5 Feb 2021 17:26:39 +0100 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v2 28/36] block: add bdrv_set_backing_noperm() transaction action Message-ID: <20210205162639.GF7072@merkur.fritz.box> References: <20201127144522.29991-1-vsementsov@virtuozzo.com> <20201127144522.29991-29-vsementsov@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20201127144522.29991-29-vsementsov@virtuozzo.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.352, 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=unavailable 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: > Split out no-perm part of bdrv_set_backing_hd() as a separate > transaction action. Note the in case of existing BdrvChild we reuse it, > not recreate, just to do less actions. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > /* > * Sets the bs->backing link of a BDS. A new reference is created; callers > * which don't need their own reference any more must call bdrv_unref(). > */ > -void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, > - Error **errp) > +static int bdrv_set_backing_noperm(BlockDriverState *bs, > + BlockDriverState *backing_bs, > + GSList **tran, Error **errp) > { > - bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) && > - bdrv_inherits_from_recursive(backing_hd, bs); > + int ret = 0; > + bool update_inherits_from = bdrv_chain_contains(bs, backing_bs) && > + bdrv_inherits_from_recursive(backing_bs, bs); > + GSList *attach_tran = NULL; > + BdrvSetBackingNoPermState *s; > > if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) { > - return; > + return -EPERM; > } > > - if (backing_hd) { > - bdrv_ref(backing_hd); > + if (bs->backing && backing_bs) { > + bdrv_replace_child_safe(bs->backing, backing_bs, tran); The old code with separate bdrv_unref_child() and then bdrv_attach_child() tried to make the AioContests of bs and backing_bs compatible by moving one of the nodes if necessary. bdrv_replace_child_safe() doesn't seem to do that, but it only asserts that both nodes are already in the same context. I see that iotest 245 doesn't crash, which I think it should if this were broken, but where does the switch happen now? Kevin