qcow2: Don't ignore immediate read/write failures

Returning -EIO is far from optimal, but at least it's an error code.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

block/qcow2.c

@@ -468,8 +468,10 @@ static void qcow_aio_read_cb(void *opaque, int ret)
                             (acb->cluster_offset >> 9) + index_in_cluster,
                             &acb->hd_qiov, acb->cur_nr_sectors,
                             qcow_aio_read_cb, acb);
-        if (acb->hd_aiocb == NULL)
+        if (acb->hd_aiocb == NULL) {
+            ret = -EIO;
             goto done;
+        }
     }
 
     return;
@@ -621,8 +623,10 @@ static void qcow_aio_write_cb(void *opaque, int ret)
                                     (acb->cluster_offset >> 9) + index_in_cluster,
                                     &acb->hd_qiov, acb->cur_nr_sectors,
                                     qcow_aio_write_cb, acb);
-    if (acb->hd_aiocb == NULL)
+    if (acb->hd_aiocb == NULL) {
+        ret = -EIO;
         goto done;
+    }
 
     return;