[PATCH v4 26/32] nbd/client-connection: return only one io channel

[Vladimir Sementsov-Ogievskiy]

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>
---
 include/block/nbd.h     |  4 ++--
 block/nbd.c             | 13 ++-----------
 nbd/client-connection.c | 33 +++++++++++++++++++++++++--------
 3 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 5bb54d831c..10c8a0bcca 100644
--- a/include/block/nbd.h
+++ b/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);
 
diff --git a/block/nbd.c b/block/nbd.c
index 9f193d130b..411435c155 100644
--- a/block/nbd.c
+++ b/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);
 
diff --git a/nbd/client-connection.c b/nbd/client-connection.c
index 80c19f4eff..500b8591e8 100644
--- a/nbd/client-connection.c
+++ b/nbd/client-connection.c
@@ -271,15 +271,15 @@ 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)
 {
+    QIOChannel *ioc;
     QemuThread thread;
 
     if (conn->do_negotiation) {
         assert(info);
-        assert(ioc);
     }
 
     WITH_QEMU_LOCK_GUARD(&conn->mutex) {
@@ -293,10 +293,17 @@ 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);
+                    ioc = g_steal_pointer(&conn->ioc);
                     memcpy(info, &conn->updated_info, sizeof(*info));
                 }
-                return g_steal_pointer(&conn->sioc);
+                if (ioc) {
+                    /* TLS channel now has own reference to parent */
+                    object_unref(OBJECT(conn->sioc));
+                } else {
+                    ioc = QIO_CHANNEL(conn->sioc);
+                }
+                conn->sioc = NULL;
+                return ioc;
             }
 
             conn->running = true;
@@ -328,11 +335,21 @@ 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) {
+                ioc = g_steal_pointer(&conn->ioc);
                 memcpy(info, &conn->updated_info, sizeof(*info));
             }
-            return g_steal_pointer(&conn->sioc);
+            if (ioc) {
+                /* TLS channel now has own reference to parent */
+                object_unref(OBJECT(conn->sioc));
+            } else {
+                ioc = QIO_CHANNEL(conn->sioc);
+            }
+            conn->sioc = NULL;
+            return ioc;
         }
     }
 
-- 
2.29.2