librbd/image: fix immutable object cache read failed bug when daemon down

Fix bug: read child image failed when enabling immutable object cache and daemon down

Signed-off-by: Yin Congmin <congmin.yin@intel.com>

qa/suites/rbd/immutable-object-cache/pool/ceph_and_immutable_object_cache.yaml

@@ -4,8 +4,9 @@ tasks:
 - ceph:
     conf:
       client:
-        rbd_parent_cache_enabled: true
-        immutable object cache path: /tmp/ceph-immutable-object-cache
-        immutable object cache max size: 10G
+        rbd parent cache enabled: true
+        rbd plugins: parent_cache
+        immutable_object_cache_path: /tmp/ceph-immutable-object-cache
+        immutable_object_cache_max_size: 10G
 - immutable_object_cache:
     client.0:

qa/suites/rbd/immutable-object-cache/workloads/qemu_on_immutable_object_cache_and_thrash.yaml

@@ -1,11 +1,11 @@
+tasks:
 - qemu:
     client.0:
       clone: true
       test: qa/run_xfstests_qemu.sh
-      image_url: http://cloud-images.ubuntu.com/releases/bionic/release/ubuntu-18.04-server-cloudimg-amd64.img
+      type: block
       cpus: 4
       memory: 4096
       disks: 3
-tasks:
 - immutable_object_cache_thrash:
     client.0:

qa/tasks/immutable_object_cache.py

@@ -1,19 +1,12 @@
 """
 immutable object cache task
 """
-from io import StringIO
-
 import contextlib
 import logging
-import os
-import yaml
-import time
 
 from teuthology import misc as teuthology
 from teuthology import contextutil
-from tasks import rbd
 from teuthology.orchestra import run
-from teuthology.config import config as teuth_config
 
 log = logging.getLogger(__name__)
 

qa/tasks/immutable_object_cache_thrash.py

@@ -1,19 +1,12 @@
 """
 immutable object cache thrash task
 """
-from io import StringIO
-
 import contextlib
 import logging
-import os
-import yaml
-import time
 
 from teuthology import misc as teuthology
 from teuthology import contextutil
-from tasks import rbd
 from teuthology.orchestra import run
-from teuthology.config import config as teuth_config
 
 DEFAULT_KILL_DAEMON_TIME = 2
 DEFAULT_DEAD_TIME = 30

src/librbd/image/OpenRequest.cc

@@ -544,8 +544,6 @@ Context* OpenRequest<I>::handle_init_plugin_registry(int *result) {
   if (*result < 0) {
     lderr(cct) << "failed to initialize plugin registry: "
                << cpp_strerror(*result) << dendl;
-    send_close_image(*result);
-    return nullptr;
   }
 
   return send_init_cache(result);