nbd: Don't bother tracing an NBD_OPT_ABORT response failure

We really don't care if our spec-compliant reply to NBD_OPT_ABORT
was received, so shave off some lines of code by not even tracing it.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170707203049.534-3-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/nbd/server.c b/nbd/server.c
index 9b0c588..e15385b 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -376,7 +376,6 @@
 {
     uint32_t flags;
     bool fixedNewstyle = false;
-    Error *local_err = NULL;
 
     /* Client sends:
         [ 0 ..   3]   client flags
@@ -479,7 +478,9 @@
                 if (ret < 0) {
                     return ret;
                 }
-                /* Let the client keep trying, unless they asked to quit */
+                /* Let the client keep trying, unless they asked to
+                 * quit. In this mode, we've already sent an error, so
+                 * we can't ack the abort.  */
                 if (option == NBD_OPT_ABORT) {
                     return 1;
                 }
@@ -498,15 +499,7 @@
                 /* NBD spec says we must try to reply before
                  * disconnecting, but that we must also tolerate
                  * guests that don't wait for our reply. */
-                nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, option,
-                                       &local_err);
-
-                if (local_err != NULL) {
-                    const char *error = error_get_pretty(local_err);
-                    trace_nbd_opt_abort_reply_failed(error);
-                    error_free(local_err);
-                }
-
+                nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, option, NULL);
                 return 1;
 
             case NBD_OPT_EXPORT_NAME:
diff --git a/nbd/trace-events b/nbd/trace-events
index 4b233b8..c6f898e 100644
--- a/nbd/trace-events
+++ b/nbd/trace-events
@@ -40,7 +40,6 @@
 nbd_negotiate_options_no_zeroes(void) "Client supports no zeroes at handshake end"
 nbd_negotiate_options_check_magic(uint64_t magic) "Checking opts magic 0x%" PRIx64
 nbd_negotiate_options_check_option(uint32_t option) "Checking option 0x%" PRIx32
-nbd_opt_abort_reply_failed(const char *error) "Reply to NBD_OPT_ABORT request failed: %s"
 nbd_negotiate_begin(void) "Beginning negotiation"
 nbd_negotiate_old_style(uint64_t size, unsigned flags) "advertising size %" PRIu64 " and flags %x"
 nbd_negotiate_new_style_size_flags(uint64_t size, unsigned flags) "advertising size %" PRIu64 " and flags %x"