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 B8BBAC6FD19 for ; Fri, 10 Mar 2023 22:17:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pal3M-0001th-GF; Fri, 10 Mar 2023 17:17:32 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pal3G-0001p7-RT for qemu-devel@nongnu.org; Fri, 10 Mar 2023 17:17:27 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pal3E-00052V-D2 for qemu-devel@nongnu.org; Fri, 10 Mar 2023 17:17:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1678486643; 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=VoGATSYAmYDYHgE0LEJldi2s67n6gZJ7XV9ethas4So=; b=RVZp3nYCLcAWNGh5W5Th4cMoGcjBz6Eu8BieHeKt/K12NIW7NyAMW3UjBjeIT+8tMO4q8i M36V15mWPh4hTMofKi4vZ+WjoN5csLOMoqvgXhbFx12IseuzzKgJkY4ponDVI4LsBcxloh iRd4EMPMPJLnw0cZ0DMuCchPrim/3/0= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-204-Xp4jxYw_OdmI6YYNt0g32A-1; Fri, 10 Mar 2023 17:17:20 -0500 X-MC-Unique: Xp4jxYw_OdmI6YYNt0g32A-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 A14E13C0253D; Fri, 10 Mar 2023 22:17:19 +0000 (UTC) Received: from redhat.com (unknown [10.2.16.147]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E8E542026D4B; Fri, 10 Mar 2023 22:17:18 +0000 (UTC) Date: Fri, 10 Mar 2023 16:17:17 -0600 From: Eric Blake To: "Richard W.M. Jones" Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, vsementsov@yandex-team.ru, hreitz@redhat.com, kwolf@redhat.com Subject: Re: [PATCH nbd 1/4] nbd: Add multi-conn option Message-ID: <20230310221717.vb2b72e3tkjkpyqi@redhat.com> References: <20230309113946.1528247-1-rjones@redhat.com> <20230309113946.1528247-2-rjones@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230309113946.1528247-2-rjones@redhat.com> User-Agent: NeoMutt/20220429 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Mar 09, 2023 at 11:39:43AM +0000, Richard W.M. Jones wrote: > Add multi-conn option to the NBD client. This commit just adds the > option, it is not functional. Maybe add the phrase "until later in this patch series" ? > > Setting this to a value > 1 permits multiple connections to the NBD > server; a typical value might be 4. The default is 1, meaning only a > single connection is made. If the NBD server does not advertise that > it is safe for multi-conn then this setting is forced to 1. > > Signed-off-by: Richard W.M. Jones > --- > block/nbd.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/block/nbd.c b/block/nbd.c > index bf2894ad5c..5ffae0b798 100644 > --- a/block/nbd.c > +++ b/block/nbd.c > @@ -49,6 +49,7 @@ > > #define EN_OPTSTR ":exportname=" > #define MAX_NBD_REQUESTS 16 > +#define MAX_MULTI_CONN 16 > > #define HANDLE_TO_INDEX(bs, handle) ((handle) ^ (uint64_t)(intptr_t)(bs)) > #define INDEX_TO_HANDLE(bs, index) ((index) ^ (uint64_t)(intptr_t)(bs)) > @@ -98,6 +99,7 @@ typedef struct BDRVNBDState { > /* Connection parameters */ > uint32_t reconnect_delay; > uint32_t open_timeout; > + uint32_t multi_conn; > SocketAddress *saddr; > char *export; > char *tlscredsid; > @@ -1803,6 +1805,15 @@ static QemuOptsList nbd_runtime_opts = { > "attempts until successful or until @open-timeout seconds " > "have elapsed. Default 0", > }, > + { > + .name = "multi-conn", > + .type = QEMU_OPT_NUMBER, > + .help = "If > 1 permit up to this number of connections to the " > + "server. The server must also advertise multi-conn " > + "support. If <= 1, only a single connection is made " > + "to the server even if the server advertises multi-conn. " > + "Default 1", > + }, > { /* end of list */ } > }, > }; > @@ -1858,6 +1869,10 @@ static int nbd_process_options(BlockDriverState *bs, QDict *options, > > s->reconnect_delay = qemu_opt_get_number(opts, "reconnect-delay", 0); > s->open_timeout = qemu_opt_get_number(opts, "open-timeout", 0); > + s->multi_conn = qemu_opt_get_number(opts, "multi-conn", 1); > + if (s->multi_conn > MAX_MULTI_CONN) { > + s->multi_conn = MAX_MULTI_CONN; > + } This silently ignores out-of-range values (negative, greater than 16) and treats 0 as a synonym for 1. The latter I'm okay with, the former I wonder if we should instead raise an error that the user is requesting something we can't honor, instead of silently bounding it. > > ret = 0; > > @@ -1912,6 +1927,15 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags, > > nbd_client_connection_enable_retry(s->conn); > > + /* > + * We set s->multi_conn in nbd_process_options above, but now that > + * we have connected if the server doesn't advertise that it is s/connected/connected,/ > + * safe for multi-conn, force it to 1. > + */ > + if (!(s->info.flags & NBD_FLAG_CAN_MULTI_CONN)) { > + s->multi_conn = 1; > + } > + > return 0; Is there an intended QAPI counterpart for this command? We'll need that if it is to be set during the command line of qemu-storage-daemon. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org