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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id DE91DC43334 for ; Fri, 17 Jun 2022 14:31:09 +0000 (UTC) Received: from localhost ([::1]:51330 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o2D08-0002xo-QZ for qemu-devel@archiver.kernel.org; Fri, 17 Jun 2022 10:31:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59410) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o2Cyh-00021t-1p for qemu-devel@nongnu.org; Fri, 17 Jun 2022 10:29:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:50019) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o2Cyb-0006UA-60 for qemu-devel@nongnu.org; Fri, 17 Jun 2022 10:29:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655476171; h=from:from:reply-to: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=IFdLwGPEi7ZtbLcu3BqPIzHDuzd24sde/HrkOJZnY+4=; b=PpK8uzkRvwapaRS9cDeZX/mYhStInBRgfdHd+gVT7pwssieXlemcvnmA21Cjsrj4HJdzt5 F6OoS9coiFMP7b0aEEhrAK+B9JsWlCjP6KrFOc2IAkiwIKub0sncoBh4PKZqDACBw/VKJu 6KUOcxwB8qWhnv2bh0K1/G+pw5+Bs7U= 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-663-f4DkFNV5PW2SG4O1ryYtgg-1; Fri, 17 Jun 2022 10:29:28 -0400 X-MC-Unique: f4DkFNV5PW2SG4O1ryYtgg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C1DC2802D1F; Fri, 17 Jun 2022 14:29:27 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.139]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 91FC520296A2; Fri, 17 Jun 2022 14:29:25 +0000 (UTC) Date: Fri, 17 Jun 2022 15:29:22 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: John Snow Cc: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , QEMU , Beraldo Leal , "open list:Block layer core" , Hanna Reitz , Wainer dos Santos Moschetta , Alex =?utf-8?Q?Benn=C3=A9e?= , Kevin Wolf , Michael Roth , Thomas Huth , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PATCH v2 03/10] qga: treat get-guest-fsinfo as "best effort" Message-ID: References: <20220616142659.3184115-1-jsnow@redhat.com> <20220616142659.3184115-4-jsnow@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.1 (2022-02-19) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Jun 17, 2022 at 10:04:14AM -0400, John Snow wrote: > On Fri, Jun 17, 2022, 5:49 AM Daniel P. Berrangé > wrote: > > > On Thu, Jun 16, 2022 at 06:35:44PM +0400, Marc-André Lureau wrote: > > > Hi > > > > > > On Thu, Jun 16, 2022 at 6:27 PM John Snow wrote: > > > > > > > In some container environments, there may be references to block > > devices > > > > witnessable from a container through /proc/self/mountinfo that > > reference > > > > devices we simply don't have access to in the container, and could not > > > > provide information about. > > > > > > > > Instead of failing the entire fsinfo command, return stub information > > > > for these failed lookups. > > > > > > > > This allows test-qga to pass under docker tests, which are in turn used > > > > by the CentOS VM tests. > > > > > > > > Signed-off-by: John Snow > > > > --- > > > > qga/commands-posix.c | 8 +++++++- > > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/qga/commands-posix.c b/qga/commands-posix.c > > > > index 0469dc409d4..5989d4dca9d 100644 > > > > --- a/qga/commands-posix.c > > > > +++ b/qga/commands-posix.c > > > > @@ -1207,7 +1207,13 @@ static void build_guest_fsinfo_for_device(char > > > > const *devpath, > > > > > > > > syspath = realpath(devpath, NULL); > > > > if (!syspath) { > > > > - error_setg_errno(errp, errno, "realpath(\"%s\")", devpath); > > > > + if (errno == ENOENT) { > > > > + /* This devpath may not exist because of container config, > > > > etc. */ > > > > + fprintf(stderr, "realpath(%s) returned NULL/ENOENT\n", > > > > devpath); > > > > > > > > > > qga uses g_critical() (except for some win32 code paths atm) > > > > > > > > > > + fs->name = y > > > > > > > > > > Hmm, maybe we should make the field optional instead. > > > > In my own testing, this method is called in various scenarios. > > Some example: > > > > devpath==/sys/dev/block/253:0 > > syspath==/sys/devices/virtual/block/dm-0 > > > > => fs->name == dm-0 > > > > devpath==/sys/devices/virtual/block/dm-0/slaves/nvme0n1p4 > > > > syspath==/sys/devices/pci0000:00/0000:00:1d.0/0000:02:00.0/nvme/nvme0/nvme0n1/nvme0n1p4 > > > > => fs->name == nvme0n1p4 > > > > devpath==/sys/dev/block/259:2 > > > > syspath==/sys/devices/pci0000:00/0000:00:1d.0/0000:02:00.0/nvme/nvme0/nvme0n1/nvme0n1p2 > > > > => fs->name == nvme0n1p2 > > > > We set fs->name from basename(syspath) > > > > If the realpath call fails, we could use basename(devpath). That > > would sometimes give the correct answer, and in other types it > > would at least give the major:minor number, which an admin can > > manually correlate if desired via /proc/partitions. > > > > If we want to be really advanced, we could just open /proc/partitions > > and resolve the proper name ourselves, but that's probably overkill > > > > basename(sysfspath) > > > > is better than g_strdup("??\?-ENOENT") IMHO > > > > Sure! I had something like that initially, but chickened out specifically > because I thought major:minor was a nonsense kind of reply, so I opted for > more egregiously obvious nonsense. I figured I'd find strong opinions that > way ;) It is a different format but it is semantically giving similar info. If we want to just leave it empty though that's fine too. > > I'm just not sure how this data is used in practice so I had no insight as > to what would be best. I can use the basename, sure. > > (Should I also add an optional flag field that indicates the path was not > resolvable, do you think? I guess we can always add it later if needed, but > not sure if i need to head that one off at the pass.) > > As for Thomas' comment: I wasn't entirely clear on precisely when we'd run > into this scenario and I didn't know if it was a good idea to skip the > entries entirely. Maybe getting platform mount information even if we can't > access it is still important when working with containers? I don't know one > way or the other TBQH. I'm not very well traveled with devices, > filesystems, and permissions where containers are concerned. I view the primary purpose of this command to be offering a way to enumerate filesystems. Whether we report what block device the FS on host is a secondary purpose. So as long as we can fullfill the primary purpose, its sufficient IMHO. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|