qcow2: Remove request from in-flight list after error

If we complete a request with a failure we need to remove it from the list of
requests that are in flight. If we don't do it, the next time the same AIOCB is
used for a cluster allocation it will create a loop in the list and qemu will
hang in an endless loop.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/block/qcow2.c b/block/qcow2.c
index b44a12c..4e97eb6 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -625,11 +625,15 @@
                                     qcow_aio_write_cb, acb);
     if (acb->hd_aiocb == NULL) {
         ret = -EIO;
-        goto done;
+        goto fail;
     }
 
     return;
 
+fail:
+    if (acb->l2meta.nb_clusters != 0) {
+        QLIST_REMOVE(&acb->l2meta, next_in_flight);
+    }
 done:
     if (acb->qiov->niov > 1)
         qemu_vfree(acb->orig_buf);