Blame SOURCES/kvm-nbd-Permit-simple-error-to-NBD_CMD_BLOCK_STATUS.patch

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From b9bef7082ee3ffe7f7f66b719e07a8ad37e3eaff Mon Sep 17 00:00:00 2001
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From: John Snow <jsnow@redhat.com>
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Date: Mon, 6 May 2019 17:56:14 +0200
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Subject: [PATCH 04/53] nbd: Permit simple error to NBD_CMD_BLOCK_STATUS
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RH-Author: John Snow <jsnow@redhat.com>
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Message-id: <20190506175629.11079-5-jsnow@redhat.com>
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Patchwork-id: 87186
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O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 04/19] nbd: Permit simple error to NBD_CMD_BLOCK_STATUS
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Bugzilla: 1692018
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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From: Eric Blake <eblake@redhat.com>
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The NBD spec is clear that when structured replies are active, a
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simple error reply is acceptable to any command except for
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NBD_CMD_READ.  However, we were mistakenly requiring structured errors
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for NBD_CMD_BLOCK_STATUS, and hanging up on a server that gave a
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simple error (since qemu does not behave as such a server, we didn't
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notice the problem until now).  Broken since its introduction in
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commit 78a33ab5 (v2.12).
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Noticed while debugging a separate failure reported by nbdkit while
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working out its initial implementation of BLOCK_STATUS, although it
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turns out that nbdkit also chose to send structured error replies for
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BLOCK_STATUS, so I had to manually provoke the situation by hacking
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qemu's server to send a simple error reply:
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| diff --git i/nbd/server.c w/nbd/server.c
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| index fd013a2817a..833288d7c45 100644
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| 00--- i/nbd/server.c
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| +++ w/nbd/server.c
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| @@ -2269,6 +2269,8 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
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|                                        "discard failed", errp);
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|
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|      case NBD_CMD_BLOCK_STATUS:
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| +        return nbd_co_send_simple_reply(client, request->handle, ENOMEM,
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| +                                        NULL, 0, errp);
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|          if (!request->len) {
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|              return nbd_send_generic_reply(client, request->handle, -EINVAL,
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|                                            "need non-zero length", errp);
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|
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Signed-off-by: Eric Blake <eblake@redhat.com>
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Acked-by: Richard W.M. Jones <rjones@redhat.com>
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Message-Id: <20190325190104.30213-3-eblake@redhat.com>
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Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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(cherry picked from commit ebd82cd872726549d0a55d329d22c731e2e660ff)
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Signed-off-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/nbd-client.c | 4 +---
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 1 file changed, 1 insertion(+), 3 deletions(-)
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diff --git a/block/nbd-client.c b/block/nbd-client.c
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index 532f90c..eee909f 100644
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--- a/block/nbd-client.c
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+++ b/block/nbd-client.c
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@@ -716,9 +716,7 @@ static int nbd_co_receive_blockstatus_reply(NBDClientSession *s,
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     bool received = false;
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     assert(!extent->length);
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-    NBD_FOREACH_REPLY_CHUNK(s, iter, handle, s->info.structured_reply,
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-                            NULL, &reply, &payload)
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-    {
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+    NBD_FOREACH_REPLY_CHUNK(s, iter, handle, false, NULL, &reply, &payload) {
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         int ret;
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         NBDStructuredReplyChunk *chunk = &reply.structured;
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-- 
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1.8.3.1
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