librbd: retrieve image name when opening by id

src/cls/rbd/cls_rbd_client.cc

@@ -758,25 +758,37 @@ namespace librbd {
       return 0;
     }
 
-    int dir_get_name(librados::IoCtx *ioctx, const std::string &oid,
-		     const std::string &id, std::string *name)
-    {
-      bufferlist in, out;
-      ::encode(id, in);
-      int r = ioctx->exec(oid, "rbd", "dir_get_name", in, out);
-      if (r < 0)
-	return r;
+    void dir_get_name_start(librados::ObjectReadOperation *op,
+			    const std::string &id) {
+      bufferlist in_bl;
+      ::encode(id, in_bl);
+      op->exec("rbd", "dir_get_name", in_bl);
+    }
 
-      bufferlist::iterator iter = out.begin();
+    int dir_get_name_finish(bufferlist::iterator *it, std::string *name) {
       try {
-	::decode(*name, iter);
+	::decode(*name, *it);
       } catch (const buffer::error &err) {
 	return -EBADMSG;
       }
-
       return 0;
     }
 
+    int dir_get_name(librados::IoCtx *ioctx, const std::string &oid,
+		     const std::string &id, std::string *name) {
+      librados::ObjectReadOperation op;
+      dir_get_name_start(&op, id);
+
+      bufferlist out_bl;
+      int r = ioctx->operate(oid, &op, &out_bl);
+      if (r < 0) {
+        return r;
+      }
+
+      bufferlist::iterator it = out_bl.begin();
+      return dir_get_name_finish(&it, name);
+    }
+
     int dir_list(librados::IoCtx *ioctx, const std::string &oid,
 		 const std::string &start, uint64_t max_return,
 		 map<string, string> *images)

src/cls/rbd/cls_rbd_client.h

@@ -152,6 +152,9 @@ namespace librbd {
     // operations on rbd_directory objects
     int dir_get_id(librados::IoCtx *ioctx, const std::string &oid,
 		   const std::string &name, std::string *id);
+    void dir_get_name_start(librados::ObjectReadOperation *op,
+			    const std::string &id);
+    int dir_get_name_finish(bufferlist::iterator *it, std::string *name);
     int dir_get_name(librados::IoCtx *ioctx, const std::string &oid,
 		     const std::string &id, std::string *name);
     int dir_list(librados::IoCtx *ioctx, const std::string &oid,

src/librbd/ImageCtx.cc

@@ -175,8 +175,6 @@ struct C_InvalidateCache : public Context {
     if (snap)
       snap_name = snap;
 
-    asok_hook = new LibrbdAdminSocketHook(this);
-
     memset(&header, 0, sizeof(header));
     memset(&layout, 0, sizeof(layout));
 
@@ -196,6 +194,7 @@ struct C_InvalidateCache : public Context {
     assert(exclusive_lock == NULL);
     assert(object_map == NULL);
     assert(journal == NULL);
+    assert(asok_hook == NULL);
 
     if (perfcounter) {
       perf_stop();
@@ -221,7 +220,6 @@ struct C_InvalidateCache : public Context {
 
     delete op_work_queue;
     delete aio_work_queue;
-    delete asok_hook;
     delete operations;
     delete state;
   }
@@ -234,6 +232,8 @@ struct C_InvalidateCache : public Context {
     }
     apply_metadata_confs();
 
+    asok_hook = new LibrbdAdminSocketHook(this);
+
     string pname = string("librbd-") + id + string("-") +
       data_ctx.get_pool_name() + string("-") + name;
     if (!snap_name.empty()) {
@@ -286,6 +286,15 @@ struct C_InvalidateCache : public Context {
     readahead.set_max_readahead_size(readahead_max_bytes);
   }
 
+  void ImageCtx::shutdown() {
+    if (image_watcher != nullptr) {
+      unregister_watch();
+    }
+
+    delete asok_hook;
+    asok_hook = nullptr;
+  }
+
   void ImageCtx::init_layout()
   {
     if (stripe_unit == 0 || stripe_count == 0) {

src/librbd/ImageCtx.h

@@ -197,6 +197,7 @@ namespace librbd {
 	     const char *snap, IoCtx& p, bool read_only);
     ~ImageCtx();
     void init();
+    void shutdown();
     void init_layout();
     void perf_start(std::string name);
     void perf_stop();

src/librbd/image/CloseRequest.cc

@@ -248,10 +248,7 @@ void CloseRequest<I>::handle_flush_image_watcher(int r) {
 
 template <typename I>
 void CloseRequest<I>::finish() {
-  if (m_image_ctx->image_watcher != nullptr) {
-    m_image_ctx->unregister_watch();
-  }
-
+  m_image_ctx->shutdown();
   m_on_finish->complete(m_error_result);
   delete this;
 }

src/librbd/image/OpenRequest.cc

@@ -102,7 +102,7 @@ void OpenRequest<I>::send_v2_detect_header() {
                                    comp, &op, &m_out_bl);
     comp->release();
   } else {
-    send_v2_get_immutable_metadata();
+    send_v2_get_name();
   }
 }
 
@@ -141,7 +141,7 @@ void OpenRequest<I>::send_v2_get_id() {
                                     comp, &op, &m_out_bl);
     comp->release();
   } else {
-    send_v2_get_immutable_metadata();
+    send_v2_get_name();
   }
 }
 
@@ -164,6 +164,42 @@ Context *OpenRequest<I>::handle_v2_get_id(int *result) {
   return nullptr;
 }
 
+template <typename I>
+void OpenRequest<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 = OpenRequest<I>;
+  librados::AioCompletion *comp = create_rados_ack_callback<
+    klass, &klass::handle_v2_get_name>(this);
+  m_out_bl.clear();
+  m_image_ctx->md_ctx.aio_operate(RBD_DIRECTORY, comp, &op, &m_out_bl);
+  comp->release();
+}
+
+template <typename I>
+Context *OpenRequest<I>::handle_v2_get_name(int *result) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << __func__ << ": r=" << *result << dendl;
+
+  if (*result == 0) {
+    bufferlist::iterator it = m_out_bl.begin();
+    *result = cls_client::dir_get_name_finish(&it, &m_image_ctx->name);
+  }
+  if (*result < 0) {
+    lderr(cct) << "failed to retreive name: "
+               << cpp_strerror(*result) << dendl;
+    send_close_image(*result);
+  } else {
+    send_v2_get_immutable_metadata();
+  }
+
+  return nullptr;
+}
+
 template <typename I>
 void OpenRequest<I>::send_v2_get_immutable_metadata() {
   CephContext *cct = m_image_ctx->cct;

src/librbd/image/OpenRequest.h

@@ -38,7 +38,7 @@ class OpenRequest {
    *    \-----> V2_DETECT_HEADER                    |             .
    *                |                               |             .
    *                v                               |             .
-   *            V2_GET_ID                           |             .
+   *            V2_GET_ID|NAME                      |             .
    *                |                               |             .
    *                v                               |             .
    *            V2_GET_IMMUTABLE_METADATA           |             .
@@ -78,6 +78,9 @@ class OpenRequest {
   void send_v2_get_id();
   Context *handle_v2_get_id(int *result);
 
+  void send_v2_get_name();
+  Context *handle_v2_get_name(int *result);
+
   void send_v2_get_immutable_metadata();
   Context *handle_v2_get_immutable_metadata(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);