nbd/client-connection: return only one io channel

block/nbd doesn't need underlying sioc channel anymore. So, we can
update nbd/client-connection interface to return only one top-most io
channel, which is more straight forward.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210610100802.5888-27-vsementsov@virtuozzo.com>
[eblake: squash in Vladimir's fixes for uninit usage caught by clang]
Signed-off-by: Eric Blake <eblake@redhat.com>

block/nbd.c

@@ -360,7 +360,6 @@ static coroutine_fn void nbd_reconnect_attempt(BDRVNBDState *s)
 {
     int ret;
     AioContext *aio_context = bdrv_get_aio_context(s->bs);
-    QIOChannelSocket *sioc;
 
     if (!nbd_client_connecting(s)) {
         return;
@@ -399,20 +398,12 @@ static coroutine_fn void nbd_reconnect_attempt(BDRVNBDState *s)
         s->ioc = NULL;
     }
 
-    sioc = nbd_co_establish_connection(s->conn, &s->info, &s->ioc, NULL);
-    if (!sioc) {
+    s->ioc = nbd_co_establish_connection(s->conn, &s->info, NULL);
+    if (!s->ioc) {
         ret = -ECONNREFUSED;
         goto out;
     }
 
-    if (s->ioc) {
-        /* sioc is referenced by s->ioc */
-        object_unref(OBJECT(sioc));
-    } else {
-        s->ioc = QIO_CHANNEL(sioc);
-    }
-    sioc = NULL;
-
     qio_channel_set_blocking(QIO_CHANNEL(s->ioc), false, NULL);
     qio_channel_attach_aio_context(QIO_CHANNEL(s->ioc), aio_context);
 

include/block/nbd.h

@@ -418,9 +418,9 @@ NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr,
                                                QCryptoTLSCreds *tlscreds);
 void nbd_client_connection_release(NBDClientConnection *conn);
 
-QIOChannelSocket *coroutine_fn
+QIOChannel *coroutine_fn
 nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
-                            QIOChannel **ioc, Error **errp);
+                            Error **errp);
 
 void coroutine_fn nbd_co_establish_connection_cancel(NBDClientConnection *conn);
 

nbd/client-connection.c

@@ -272,15 +272,14 @@ void nbd_client_connection_release(NBDClientConnection *conn)
  * nbd_receive_export_list() would be zero (see description of NBDExportInfo in
  * include/block/nbd.h).
  */
-QIOChannelSocket *coroutine_fn
+QIOChannel *coroutine_fn
 nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
-                            QIOChannel **ioc, Error **errp)
+                            Error **errp)
 {
     QemuThread thread;
 
     if (conn->do_negotiation) {
         assert(info);
-        assert(ioc);
     }
 
     WITH_QEMU_LOCK_GUARD(&conn->mutex) {
@@ -294,10 +293,19 @@ nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
             if (conn->sioc) {
                 /* Previous attempt finally succeeded in background */
                 if (conn->do_negotiation) {
-                    *ioc = g_steal_pointer(&conn->ioc);
                     memcpy(info, &conn->updated_info, sizeof(*info));
+                    if (conn->ioc) {
+                        /* TLS channel now has own reference to parent */
+                        object_unref(OBJECT(conn->sioc));
+                        conn->sioc = NULL;
+
+                        return g_steal_pointer(&conn->ioc);
+                    }
                 }
-                return g_steal_pointer(&conn->sioc);
+
+                assert(!conn->ioc);
+
+                return QIO_CHANNEL(g_steal_pointer(&conn->sioc));
             }
 
             conn->running = true;
@@ -329,11 +337,23 @@ nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
         } else {
             error_propagate(errp, conn->err);
             conn->err = NULL;
-            if (conn->sioc && conn->do_negotiation) {
-                *ioc = g_steal_pointer(&conn->ioc);
+            if (!conn->sioc) {
+                return NULL;
+            }
+            if (conn->do_negotiation) {
                 memcpy(info, &conn->updated_info, sizeof(*info));
+                if (conn->ioc) {
+                    /* TLS channel now has own reference to parent */
+                    object_unref(OBJECT(conn->sioc));
+                    conn->sioc = NULL;
+
+                    return g_steal_pointer(&conn->ioc);
+                }
             }
-            return g_steal_pointer(&conn->sioc);
+
+            assert(!conn->ioc);
+
+            return QIO_CHANNEL(g_steal_pointer(&conn->sioc));
         }
     }