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