block/nbd: split nbd_co_do_establish_connection out of nbd_reconnect_attempt

Split out the part that we want to reuse for nbd_open().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210610100802.5888-29-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

block/nbd.c

@@ -356,11 +356,50 @@ static int nbd_handle_updated_info(BlockDriverState *bs, Error **errp)
     return 0;
 }
 
-static coroutine_fn void nbd_reconnect_attempt(BDRVNBDState *s)
+static int coroutine_fn nbd_co_do_establish_connection(BlockDriverState *bs,
+                                                       Error **errp)
 {
+    BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
     int ret;
-    AioContext *aio_context = bdrv_get_aio_context(s->bs);
 
+    assert(!s->ioc);
+
+    s->ioc = nbd_co_establish_connection(s->conn, &s->info, errp);
+    if (!s->ioc) {
+        return -ECONNREFUSED;
+    }
+
+    ret = nbd_handle_updated_info(s->bs, NULL);
+    if (ret < 0) {
+        /*
+         * We have connected, but must fail for other reasons.
+         * Send NBD_CMD_DISC as a courtesy to the server.
+         */
+        NBDRequest request = { .type = NBD_CMD_DISC };
+
+        nbd_send_request(s->ioc, &request);
+
+        object_unref(OBJECT(s->ioc));
+        s->ioc = NULL;
+
+        return ret;
+    }
+
+    qio_channel_set_blocking(s->ioc, false, NULL);
+    qio_channel_attach_aio_context(s->ioc, bdrv_get_aio_context(bs));
+
+    yank_register_function(BLOCKDEV_YANK_INSTANCE(s->bs->node_name), nbd_yank,
+                           bs);
+
+    /* successfully connected */
+    s->state = NBD_CLIENT_CONNECTED;
+    qemu_co_queue_restart_all(&s->free_sema);
+
+    return 0;
+}
+
+static coroutine_fn void nbd_reconnect_attempt(BDRVNBDState *s)
+{
     if (!nbd_client_connecting(s)) {
         return;
     }
@@ -398,42 +437,7 @@ static coroutine_fn void nbd_reconnect_attempt(BDRVNBDState *s)
         s->ioc = NULL;
     }
 
-    s->ioc = nbd_co_establish_connection(s->conn, &s->info, NULL);
-    if (!s->ioc) {
-        ret = -ECONNREFUSED;
-        goto out;
-    }
-
-    qio_channel_set_blocking(QIO_CHANNEL(s->ioc), false, NULL);
-    qio_channel_attach_aio_context(QIO_CHANNEL(s->ioc), aio_context);
-
-    yank_register_function(BLOCKDEV_YANK_INSTANCE(s->bs->node_name), nbd_yank,
-                           s->bs);
-
-    ret = nbd_handle_updated_info(s->bs, NULL);
-    if (ret < 0) {
-        /*
-         * We have connected, but must fail for other reasons.
-         * Send NBD_CMD_DISC as a courtesy to the server.
-         */
-        NBDRequest request = { .type = NBD_CMD_DISC };
-
-        nbd_send_request(s->ioc, &request);
-
-        yank_unregister_function(BLOCKDEV_YANK_INSTANCE(s->bs->node_name),
-                                 nbd_yank, s->bs);
-        object_unref(OBJECT(s->ioc));
-        s->ioc = NULL;
-
-        return;
-    }
-
-out:
-    if (ret >= 0) {
-        /* successfully connected */
-        s->state = NBD_CLIENT_CONNECTED;
-        qemu_co_queue_restart_all(&s->free_sema);
-    }
+    nbd_co_do_establish_connection(s->bs, NULL);
 }
 
 static coroutine_fn void nbd_co_reconnect_loop(BDRVNBDState *s)