From nobody Sun Oct 5 19:22:55 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1543615918306100.88512175447545; Fri, 30 Nov 2018 14:11:58 -0800 (PST) Received: from localhost ([::1]:34860 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gSr0r-0003Dn-62 for importer@patchew.org; Fri, 30 Nov 2018 17:11:53 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56121) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gSqtQ-0004Um-5a for qemu-devel@nongnu.org; Fri, 30 Nov 2018 17:04:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gSqtP-00053y-9N for qemu-devel@nongnu.org; Fri, 30 Nov 2018 17:04:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58950) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gSqtJ-0004SK-Sk; Fri, 30 Nov 2018 17:04:06 -0500 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 mx1.redhat.com (Postfix) with ESMTPS id 16C5699D2D; Fri, 30 Nov 2018 22:04:05 +0000 (UTC) Received: from red.redhat.com (ovpn-117-105.phx2.redhat.com [10.3.117.105]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7D34C105B1FA; Fri, 30 Nov 2018 22:04:04 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Date: Fri, 30 Nov 2018 16:03:41 -0600 Message-Id: <20181130220344.3350618-13-eblake@redhat.com> In-Reply-To: <20181130220344.3350618-1-eblake@redhat.com> References: <20181130220344.3350618-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 30 Nov 2018 22:04:05 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 12/14] nbd/client: Work around 3.0 bug for listing meta contexts X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: nsoffer@redhat.com, vsementsov@virtuozzo.com, jsnow@redhat.com, rjones@redhat.com, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Commit 3d068aff forgot to advertise available qemu: contexts when the client requests a list with 0 queries. Furthermore, 3.0 shipped with a qemu-img hack of x-dirty-bitmap (commit 216ee365) that _silently_ acts as though the entire image is clean if a requested bitmap is not present. Both bugs have been recently fixed to give full output from the start, and to refuse a connection if a requested x-dirty-bitmap was not found. Still, it is likely that there will be users that have to work with a mix of old and new qemu versions, depending on which features get backported where, at which point being able to rely on 'qemu-img --list' output to know for sure whether a given NBD export has the desired dirty bitmap is much nicer than blindly connecting and risking that the entire image may appear clean. We can make our --list code smart enough to work around buggy servers by tracking whether we've seen any qemu: replies in the original 0-query list; if not, recurse to a single query on "qemu:" (which may still have no replies, but then we know for sure we didn't trip up on the server bug). Signed-off-by: Eric Blake --- Done as a separate patch to make it easier to revert when we no longer care about 3.0 servers --- nbd/client.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/nbd/client.c b/nbd/client.c index 6292de560ee..928ecabd420 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -21,6 +21,7 @@ #include "qapi/error.h" #include "trace.h" #include "nbd-internal.h" +#include "qemu/cutils.h" /* Definitions for opaque data types */ @@ -736,12 +737,13 @@ static int nbd_negotiate_simple_meta_context(QIOChann= el *ioc, return -1; } g_free(name); + received =3D true; } else { info->contexts =3D g_renew(char *, info->contexts, ++info->n_contexts); info->contexts[info->n_contexts - 1] =3D name; + received |=3D strstart(name, "qemu:", NULL); } - received =3D true; /* receive NBD_REP_ACK */ if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) { @@ -771,6 +773,13 @@ static int nbd_negotiate_simple_meta_context(QIOChanne= l *ioc, info->meta_base_allocation_id =3D received_id; } + /* Recurse to work around qemu 3.0 bug - the server forgot to send + * "qemu:" replies to 0 queries. */ + if (!context && !received) { + return nbd_negotiate_simple_meta_context(ioc, opt, "qemu:", info, + errp); + } + return received || opt =3D=3D NBD_OPT_LIST_META_CONTEXT; } --=20 2.17.2