From nobody Sun Oct 5 15:34:44 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 Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1510602627519810.5613665920856; Mon, 13 Nov 2017 11:50:27 -0800 (PST) Received: from localhost ([::1]:56128 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eEKkP-0005i1-MA for importer@patchew.org; Mon, 13 Nov 2017 14:50:21 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53196) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eEKjF-00050w-16 for qemu-devel@nongnu.org; Mon, 13 Nov 2017 14:49:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eEKjE-0004gK-5Y for qemu-devel@nongnu.org; Mon, 13 Nov 2017 14:49:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53956) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eEKj8-0004a4-M4; Mon, 13 Nov 2017 14:49:02 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 80DD8C047B91; Mon, 13 Nov 2017 19:49:01 +0000 (UTC) Received: from red.redhat.com (ovpn-123-105.rdu2.redhat.com [10.10.123.105]) by smtp.corp.redhat.com (Postfix) with ESMTP id 47867993DD; Mon, 13 Nov 2017 19:49:00 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Date: Mon, 13 Nov 2017 13:48:57 -0600 Message-Id: <20171113194857.13933-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 13 Nov 2017 19:49:01 +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 for-2.11] nbd/client: Don't hard-disconnect on ESHUTDOWN from server 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: qemu-trivial@nongnu.org, Paolo Bonzini , vsementsov@virtuozzo.com, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The NBD spec says that a server may fail any transmission request with ESHUTDOWN when it is apparent that no further request from the client can be successfully honored. The client is supposed to then initiate a soft shutdown (wait for all remaining in-flight requests to be answered, then send NBD_CMD_DISC). However, since qemu's server never uses ESHUTDOWN errors, this code was mostly untested since its introduction in commit b6f5d3b5. More recently, I learned that nbdkit as the NBD server is able to send ESHUTDOWN errors, so I finally tested this code, and noticed that our client was special-casing ESHUTDOWN to cause a hard shutdown (immediate disconnect, with no NBD_CMD_DISC), but only if the server sends this error as a simple reply. Further investigation found that commit d2febedb introduced a regression where structured replies behave differently than simple replies - but that the structured reply behavior is more in line with the spec (even if we still lack code in nbd-client.c to properly quit sending further requests). So this patch reverts the portion of b6f5d3b5 that introduced an improper hard-disconnect special-case at the lower level, and leaves the future enhancement of a nicer soft-disconnect at the higher level for another day. CC: qemu-trivial@nongnu.org Signed-off-by: Eric Blake Reviewed-by: Vladimir Sementsov-Ogievskiy --- nbd/client.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/nbd/client.c b/nbd/client.c index 4e15fc484d..eea236ca06 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -996,15 +996,9 @@ int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply= , Error **errp) if (ret < 0) { break; } - trace_nbd_receive_simple_reply(reply->simple.error, nbd_err_lookup(reply->simple.error), reply->handle); - if (reply->simple.error =3D=3D NBD_ESHUTDOWN) { - /* This works even on mingw which lacks a native ESHUTDOWN */ - error_setg(errp, "server shutting down"); - return -EINVAL; - } break; case NBD_STRUCTURED_REPLY_MAGIC: ret =3D nbd_receive_structured_reply_chunk(ioc, &reply->structured= , errp); --=20 2.13.6