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 464BBC47080 for ; Mon, 31 May 2021 16:38:59 +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 B0AE0610A6 for ; Mon, 31 May 2021 16:38:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B0AE0610A6 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]:42588 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lnkwL-00020C-Li for qemu-devel@archiver.kernel.org; Mon, 31 May 2021 12:38:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48376) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lnksx-00008A-V5 for qemu-devel@nongnu.org; Mon, 31 May 2021 12:35:35 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:34502) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lnkst-0007Yx-Vb for qemu-devel@nongnu.org; Mon, 31 May 2021 12:35:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1622478920; 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=f+MRli41onuOJizNix7KDCP1Qz08oLePlDqHO4UaKTA=; b=XbOx/BW/8LTFdJe1rBhjaZqeHlPzsRc2IlScsoPqemKgznvluSOgoihljBEQRgpeip+DWk dEOTXX+PUs43bMAJMTZocvVJ73JLdElqIAixQMzmAViAs1ZaWhJCRdIX4zXod0tmQduuUR fz29jra0qC6KgHd99QPuTrkuCncd5mA= 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-450-ssypu8gnO8WTC-4dos4zGQ-1; Mon, 31 May 2021 12:35:19 -0400 X-MC-Unique: ssypu8gnO8WTC-4dos4zGQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D63DA1007467; Mon, 31 May 2021 16:35:17 +0000 (UTC) Received: from merkur.fritz.box (ovpn-114-215.ams2.redhat.com [10.36.114.215]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 60DC05C1B4; Mon, 31 May 2021 16:35:16 +0000 (UTC) Date: Mon, 31 May 2021 18:35:14 +0200 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v2 5/5] block: improve permission conflict error message Message-ID: References: <20210504094510.25032-1-vsementsov@virtuozzo.com> <20210504094510.25032-6-vsementsov@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.372, 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_H4=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: berto@igalia.com, qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 31.05.2021 um 18:18 hat Vladimir Sementsov-Ogievskiy geschrieben: > 31.05.2021 19:07, Kevin Wolf wrote: > > Am 04.05.2021 um 11:45 hat Vladimir Sementsov-Ogievskiy geschrieben: > > > Now permissions are updated as follows: > > > 1. do graph modifications ignoring permissions > > > 2. do permission update > > > > > > (of course, we rollback [1] if [2] fails) > > > > > > So, on stage [2] we can't say which users are "old" and which are > > > "new" and exist only since [1]. And current error message is a bit > > > outdated. Let's improve it, to make everything clean. > > > > > > While being here, add also a comment and some good assertions. > > > > > > iotests 283, 307, qsd-jobs outputs are updated. > > > > > > Signed-off-by: Vladimir Sementsov-Ogievskiy > > > --- > > > block.c | 29 ++++++++++++++++++++------- > > > tests/qemu-iotests/283.out | 2 +- > > > tests/qemu-iotests/307.out | 2 +- > > > tests/qemu-iotests/tests/qsd-jobs.out | 2 +- > > > 4 files changed, 25 insertions(+), 10 deletions(-) > > > > > > diff --git a/block.c b/block.c > > > index 2f73523285..354438d918 100644 > > > --- a/block.c > > > +++ b/block.c > > > @@ -2032,20 +2032,35 @@ static char *bdrv_child_user_desc(BdrvChild *c) > > > return c->klass->get_parent_desc(c); > > > } > > > +/* > > > + * Check that @a allows everything that @b needs. @a and @b must reference same > > > + * child node. > > > + */ > > > static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp) > > > { > > > - g_autofree char *user = NULL; > > > - g_autofree char *perm_names = NULL; > > > + g_autofree char *a_user = NULL; > > > + g_autofree char *a_against = NULL; > > > + g_autofree char *b_user = NULL; > > > + g_autofree char *b_perm = NULL; > > > + > > > + assert(a->bs); > > > + assert(a->bs == b->bs); > > > if ((b->perm & a->shared_perm) == b->perm) { > > > return true; > > > } > > > - perm_names = bdrv_perm_names(b->perm & ~a->shared_perm); > > > - user = bdrv_child_user_desc(a); > > > - error_setg(errp, "Conflicts with use by %s as '%s', which does not " > > > - "allow '%s' on %s", > > > - user, a->name, perm_names, bdrv_get_node_name(b->bs)); > > > + a_user = bdrv_child_user_desc(a); > > > + a_against = bdrv_perm_names(b->perm & ~a->shared_perm); > > > + > > > + b_user = bdrv_child_user_desc(b); > > > + b_perm = bdrv_perm_names(b->perm); > > > + error_setg(errp, "Permission conflict on node '%s': %s wants to use it as " > > > + "'%s', which requires these permissions: %s. On the other hand %s " > > > + "wants to use it as '%s', which doesn't share: %s", > > > + bdrv_get_node_name(b->bs), > > > + b_user, b->name, b_perm, a_user, a->name, a_against); > > > > I think the combination of a_against and b_perm is confusing to report > > because one is the intersection of permissions (i.e. only the > > permissions that actually conflict) and the other the full list of > > unshared permissions. > > > > We could report both the full list of required permissions (which is > > what your current error message claims to report) and of unshared > > permissions. I'm not sure if there is actually any use for this > > information. > > > > The other option that would feel consistent is to report only the > > conflicting permissions, and report them only once because they are the > > same for both sides. > > > > Agreed. > > So, what about: > > error_setg(errp, "Permission conflict on node '%s": permissions %s are both required by %s (%s) and unshared by %s (%s).", bdrv_get_node_name(b->bs), a_against, b_user, b->name, a_user, a->name); I'm not sure if I'm happy with the child names simply in parentheses, but I don't have a good alternative. I was thinking something like "(node used as %s)", but while writing down the example below, that turned out confusing because a_user and b_user can refer to nodes, too. "permissions '%s'" with single quotes might be preferable, too. So a real error message from the current version of the patch is: Permission conflict on node 'base': node 'other' wants to use it as 'image', which requires these permissions: write. On the other hand node 'source' wants to use it as 'image', which doesn't share: write It would then become: Permission conflict on node 'base': permissions 'write' are both required by node 'other' (image) and unshared by 'source' (image). Looks like an improvement to me, but if anyone has a good idea what to do about the unclear meaning of the parentheses, I would be happy to hear suggestions. Kevin > > > return false; > > > } > > > diff --git a/tests/qemu-iotests/283.out b/tests/qemu-iotests/283.out > > > index c9397bfc44..92f3cc1ed5 100644 > > > --- a/tests/qemu-iotests/283.out > > > +++ b/tests/qemu-iotests/283.out > > > @@ -5,7 +5,7 @@ > > > {"execute": "blockdev-add", "arguments": {"driver": "blkdebug", "image": "base", "node-name": "other", "take-child-perms": ["write"]}} > > > {"return": {}} > > > {"execute": "blockdev-backup", "arguments": {"device": "source", "sync": "full", "target": "target"}} > > > -{"error": {"class": "GenericError", "desc": "Cannot append backup-top filter: Conflicts with use by node 'source' as 'image', which does not allow 'write' on base"}} > > > +{"error": {"class": "GenericError", "desc": "Cannot append backup-top filter: Permission conflict on node 'base': node 'other' wants to use it as 'image', which requires these permissions: write. On the other hand node 'source' wants to use it as 'image', which doesn't share: write"}} > > > === backup-top should be gone after job-finalize === > > > diff --git a/tests/qemu-iotests/307.out b/tests/qemu-iotests/307.out > > > index 66bf2ddb74..e03932ba4f 100644 > > > --- a/tests/qemu-iotests/307.out > > > +++ b/tests/qemu-iotests/307.out > > > @@ -53,7 +53,7 @@ exports available: 1 > > > === Add a writable export === > > > {"execute": "block-export-add", "arguments": {"description": "This is the writable second export", "id": "export1", "name": "export1", "node-name": "fmt", "type": "nbd", "writable": true, "writethrough": true}} > > > -{"error": {"class": "GenericError", "desc": "Conflicts with use by block device 'sda' as 'root', which does not allow 'write' on fmt"}} > > > +{"error": {"class": "GenericError", "desc": "Permission conflict on node 'fmt': unnamed block device wants to use it as 'root', which requires these permissions: consistent read, write. On the other hand block device 'sda' wants to use it as 'root', which doesn't share: write"}} > > > {"execute": "device_del", "arguments": {"id": "sda"}} > > > {"return": {}} > > > {"data": {"device": "sda", "path": "/machine/peripheral/sda"}, "event": "DEVICE_DELETED", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}} > > > diff --git a/tests/qemu-iotests/tests/qsd-jobs.out b/tests/qemu-iotests/tests/qsd-jobs.out > > > index 9f52255da8..b0596d2c95 100644 > > > --- a/tests/qemu-iotests/tests/qsd-jobs.out > > > +++ b/tests/qemu-iotests/tests/qsd-jobs.out > > > @@ -16,7 +16,7 @@ QMP_VERSION > > > {"return": {}} > > > {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "created", "id": "job0"}} > > > {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "null", "id": "job0"}} > > > -{"error": {"class": "GenericError", "desc": "Conflicts with use by stream job 'job0' as 'intermediate node', which does not allow 'write' on fmt_base"}} > > > +{"error": {"class": "GenericError", "desc": "Permission conflict on node 'fmt_base': unnamed block device wants to use it as 'root', which requires these permissions: consistent read, write. On the other hand stream job 'job0' wants to use it as 'intermediate node', which doesn't share: write"}} > > > {"return": {}} > > > {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_EXPORT_DELETED", "data": {"id": "export1"}} > > > *** done > > > -- > > > 2.29.2 > > > > > > > > -- > Best regards, > Vladimir >