From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50135) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eMfCq-00019U-EK for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:18:11 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eMfCn-00019z-37 for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:18:08 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:48448) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eMfCm-00018o-Qf for qemu-devel@nongnu.org; Wed, 06 Dec 2017 14:18:05 -0500 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vB6JE3I5043514 for ; Wed, 6 Dec 2017 14:18:04 -0500 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0a-001b2d01.pphosted.com with ESMTP id 2epmpw5esk-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 06 Dec 2017 14:18:03 -0500 Received: from localhost by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Dec 2017 12:18:03 -0700 From: Michael Roth Date: Wed, 6 Dec 2017 13:16:46 -0600 In-Reply-To: <20171206191648.18208-1-mdroth@linux.vnet.ibm.com> References: <20171206191648.18208-1-mdroth@linux.vnet.ibm.com> Message-Id: <20171206191648.18208-54-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 53/55] nbd/client: Don't hard-disconnect on ESHUTDOWN from server List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Eric Blake From: Eric Blake 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-stable@nongnu.org Signed-off-by: Eric Blake Message-Id: <20171113194857.13933-1-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy (cherry picked from commit 01b05c66a3616d5a4adc39fc90962e9efaf791d1) Conflicts: nbd/client.c *drop dep on d2febedb Signed-off-by: Michael Roth --- nbd/client.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/nbd/client.c b/nbd/client.c index 4caff77119..f04e95542f 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -945,12 +945,6 @@ ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp) reply->handle = ldq_be_p(buf + 8); reply->error = nbd_errno_to_system_errno(reply->error); - - if (reply->error == ESHUTDOWN) { - /* This works even on mingw which lacks a native ESHUTDOWN */ - error_setg(errp, "server shutting down"); - return -EINVAL; - } trace_nbd_receive_reply(magic, reply->error, reply->handle); if (magic != NBD_REPLY_MAGIC) { -- 2.11.0