librbd: get image name on open if it is opened by id

Signed-off-by: Mykola Golub <mgolub@mirantis.com>

src/librbd/image/RefreshRequest.cc

@@ -244,6 +244,51 @@ Context *RefreshRequest<I>::handle_v2_get_mutable_metadata(int *result) {
     return m_on_finish;
   }
 
+  if (m_image_ctx.name.empty()) {
+    send_v2_get_name();
+  } else {
+    send_v2_get_flags();
+  }
+  return nullptr;
+}
+
+template <typename I>
+void RefreshRequest<I>::send_v2_get_name() {
+  CephContext *cct = m_image_ctx.cct;
+  ldout(cct, 10) << this << " " << __func__ << dendl;
+
+  librados::ObjectReadOperation op;
+  cls_client::dir_get_name_start(&op, m_image_ctx.id);
+
+  using klass = RefreshRequest<I>;
+  librados::AioCompletion *comp = create_rados_ack_callback<
+    klass, &klass::handle_v2_get_name>(this);
+  m_out_bl.clear();
+  int r = m_image_ctx.md_ctx.aio_operate(RBD_DIRECTORY, comp, &op, &m_out_bl);
+  assert(r == 0);
+  comp->release();
+}
+
+template <typename I>
+Context *RefreshRequest<I>::handle_v2_get_name(int *result) {
+  CephContext *cct = m_image_ctx.cct;
+  ldout(cct, 10) << this << " " << __func__ << ": "
+                 << "r=" << *result << dendl;
+
+  if (*result == 0) {
+    bufferlist::iterator it = m_out_bl.begin();
+    cls_client::dir_get_name_finish(&it, &m_name);
+  }
+  if (*result == -ENOENT) {
+    ldout(cct, 10) << "out-of-sync snapshot state detected" << dendl;
+    send_v2_get_mutable_metadata();
+    return nullptr;
+  } else if (*result < 0) {
+    lderr(cct) << "failed to retrieve name: " << cpp_strerror(*result)
+               << dendl;
+    return m_on_finish;
+  }
+
   send_v2_get_flags();
   return nullptr;
 }
@@ -730,6 +775,9 @@ void RefreshRequest<I>::apply() {
       m_image_ctx.init_layout();
     } else {
       m_image_ctx.features = m_features;
+      if (m_image_ctx.name.empty()) {
+	m_image_ctx.name = m_name;
+      }
       m_image_ctx.flags = m_flags;
       m_image_ctx.parent_md = m_parent_md;
     }

src/librbd/image/RefreshRequest.h

@@ -49,6 +49,9 @@ class RefreshRequest {
    *    \-----> V2_GET_MUTABLE_METADATA                    <apply>
    *                |                                         |
    *                v                                         |
+   *            V2_GET_NAME (skip if known)                   |
+   *                |                                         |
+   *                v                                         |
    *            V2_GET_FLAGS                                  |
    *                |                                         |
    *                v                                         |
@@ -109,6 +112,7 @@ class RefreshRequest {
   uint64_t m_size;
   uint64_t m_features;
   uint64_t m_incompatible_features;
+  std::string m_name;
   uint64_t m_flags;
   std::string m_object_prefix;
   parent_info m_parent_md;
@@ -137,6 +141,9 @@ class RefreshRequest {
   void send_v2_get_mutable_metadata();
   Context *handle_v2_get_mutable_metadata(int *result);
 
+  void send_v2_get_name();
+  Context *handle_v2_get_name(int *result);
+
   void send_v2_get_flags();
   Context *handle_v2_get_flags(int *result);
 

src/test/librbd/test_internal.cc

@@ -6,6 +6,7 @@
 #include "librbd/AioImageRequest.h"
 #include "librbd/AioImageRequestWQ.h"
 #include "librbd/ExclusiveLock.h"
+#include "librbd/ImageState.h"
 #include "librbd/ImageWatcher.h"
 #include "librbd/internal.h"
 #include "librbd/ObjectMap.h"
@@ -71,6 +72,20 @@ class DummyContext : public Context {
   }
 };
 
+TEST_F(TestInternal, OpenByID) {
+   REQUIRE_FORMAT_V2();
+
+   librbd::ImageCtx *ictx;
+   ASSERT_EQ(0, open_image(m_image_name, &ictx));
+   std::string id = ictx->id;
+   close_image(ictx);
+
+   ictx = new librbd::ImageCtx("", id, nullptr, m_ioctx, true);
+   ASSERT_EQ(0, ictx->state->open());
+   ASSERT_EQ(ictx->name, m_image_name);
+   close_image(ictx);
+}
+
 TEST_F(TestInternal, IsExclusiveLockOwner) {
   REQUIRE_FEATURE(RBD_FEATURE_EXCLUSIVE_LOCK);