X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fsrc%2Flibrbd%2FImageState.cc;fp=src%2Fceph%2Fsrc%2Flibrbd%2FImageState.cc;h=5c2d92a4eedc75b124e2f8b3e7b4df69377a2279;hb=812ff6ca9fcd3e629e49d4328905f33eee8ca3f5;hp=0000000000000000000000000000000000000000;hpb=15280273faafb77777eab341909a3f495cf248d9;p=stor4nfv.git

diff --git a/src/ceph/src/librbd/ImageState.cc b/src/ceph/src/librbd/ImageState.cc
new file mode 100644
index 0000000..5c2d92a
--- /dev/null
+++ b/src/ceph/src/librbd/ImageState.cc
@@ -0,0 +1,745 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "librbd/ImageState.h"
+#include "include/rbd/librbd.hpp"
+#include "common/dout.h"
+#include "common/errno.h"
+#include "common/Cond.h"
+#include "common/WorkQueue.h"
+#include "librbd/ImageCtx.h"
+#include "librbd/Utils.h"
+#include "librbd/image/CloseRequest.h"
+#include "librbd/image/OpenRequest.h"
+#include "librbd/image/RefreshRequest.h"
+#include "librbd/image/SetSnapRequest.h"
+
+#define dout_subsys ceph_subsys_rbd
+#undef dout_prefix
+#define dout_prefix *_dout << "librbd::ImageState: " << this << " "
+
+namespace librbd {
+
+using util::create_async_context_callback;
+using util::create_context_callback;
+
+class ImageUpdateWatchers {
+public:
+
+  ImageUpdateWatchers(CephContext *cct) : m_cct(cct),
+    m_lock(util::unique_lock_name("librbd::ImageUpdateWatchers::m_lock", this)) {
+  }
+
+  ~ImageUpdateWatchers() {
+    assert(m_watchers.empty());
+    assert(m_in_flight.empty());
+    assert(m_pending_unregister.empty());
+    assert(m_on_shut_down_finish == nullptr);
+
+    destroy_work_queue();
+  }
+
+  void flush(Context *on_finish) {
+    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__ << dendl;
+    {
+      Mutex::Locker locker(m_lock);
+      if (!m_in_flight.empty()) {
+	Context *ctx = new FunctionContext(
+	  [this, on_finish](int r) {
+	    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__
+	                     << ": completing flush" << dendl;
+	    on_finish->complete(r);
+	  });
+	m_work_queue->queue(ctx, 0);
+	return;
+      }
+    }
+    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__
+		     << ": completing flush" << dendl;
+    on_finish->complete(0);
+  }
+
+  void shut_down(Context *on_finish) {
+    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__ << dendl;
+    {
+      Mutex::Locker locker(m_lock);
+      assert(m_on_shut_down_finish == nullptr);
+      m_watchers.clear();
+      if (!m_in_flight.empty()) {
+	m_on_shut_down_finish = on_finish;
+	return;
+      }
+    }
+    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__
+		     << ": completing shut down" << dendl;
+    on_finish->complete(0);
+  }
+
+  void register_watcher(UpdateWatchCtx *watcher, uint64_t *handle) {
+    ldout(m_cct, 20) << __func__ << ": watcher=" << watcher << dendl;
+
+    Mutex::Locker locker(m_lock);
+    assert(m_on_shut_down_finish == nullptr);
+
+    create_work_queue();
+
+    *handle = m_next_handle++;
+    m_watchers.insert(std::make_pair(*handle, watcher));
+  }
+
+  void unregister_watcher(uint64_t handle, Context *on_finish) {
+    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__ << ": handle="
+		     << handle << dendl;
+    int r = 0;
+    {
+      Mutex::Locker locker(m_lock);
+      auto it = m_watchers.find(handle);
+      if (it == m_watchers.end()) {
+	r = -ENOENT;
+      } else {
+	if (m_in_flight.find(handle) != m_in_flight.end()) {
+	  assert(m_pending_unregister.find(handle) == m_pending_unregister.end());
+	  m_pending_unregister[handle] = on_finish;
+	  on_finish = nullptr;
+	}
+	m_watchers.erase(it);
+      }
+    }
+
+    if (on_finish) {
+      ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__
+		       << ": completing unregister" << dendl;
+      on_finish->complete(r);
+    }
+  }
+
+  void notify() {
+    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__ << dendl;
+
+    Mutex::Locker locker(m_lock);
+    for (auto it : m_watchers) {
+      send_notify(it.first, it.second);
+    }
+  }
+
+  void send_notify(uint64_t handle, UpdateWatchCtx *watcher) {
+    assert(m_lock.is_locked());
+
+    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__ << ": handle="
+		     << handle << ", watcher=" << watcher << dendl;
+
+    m_in_flight.insert(handle);
+
+    Context *ctx = new FunctionContext(
+      [this, handle, watcher](int r) {
+	handle_notify(handle, watcher);
+      });
+
+    m_work_queue->queue(ctx, 0);
+  }
+
+  void handle_notify(uint64_t handle, UpdateWatchCtx *watcher) {
+
+    ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__ << ": handle="
+		     << handle << ", watcher=" << watcher << dendl;
+
+    watcher->handle_notify();
+
+    Context *on_unregister_finish = nullptr;
+    Context *on_shut_down_finish = nullptr;
+
+    {
+      Mutex::Locker locker(m_lock);
+
+      auto in_flight_it = m_in_flight.find(handle);
+      assert(in_flight_it != m_in_flight.end());
+      m_in_flight.erase(in_flight_it);
+
+      // If there is no more in flight notifications for this watcher
+      // and it is pending unregister, complete it now.
+      if (m_in_flight.find(handle) == m_in_flight.end()) {
+	auto it = m_pending_unregister.find(handle);
+	if (it != m_pending_unregister.end()) {
+	  on_unregister_finish = it->second;
+	  m_pending_unregister.erase(it);
+	}
+      }
+
+      if (m_in_flight.empty()) {
+	assert(m_pending_unregister.empty());
+	if (m_on_shut_down_finish != nullptr) {
+	  std::swap(m_on_shut_down_finish, on_shut_down_finish);
+	}
+      }
+    }
+
+    if (on_unregister_finish != nullptr) {
+      ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__
+		       << ": completing unregister" << dendl;
+      on_unregister_finish->complete(0);
+    }
+
+    if (on_shut_down_finish != nullptr) {
+      ldout(m_cct, 20) << "ImageUpdateWatchers::" << __func__
+		       << ": completing shut down" << dendl;
+      on_shut_down_finish->complete(0);
+    }
+  }
+
+private:
+  class ThreadPoolSingleton : public ThreadPool {
+  public:
+    explicit ThreadPoolSingleton(CephContext *cct)
+      : ThreadPool(cct, "librbd::ImageUpdateWatchers::thread_pool", "tp_librbd",
+		   1) {
+      start();
+    }
+    ~ThreadPoolSingleton() override {
+      stop();
+    }
+  };
+
+  CephContext *m_cct;
+  Mutex m_lock;
+  ContextWQ *m_work_queue = nullptr;
+  std::map<uint64_t, UpdateWatchCtx*> m_watchers;
+  uint64_t m_next_handle = 0;
+  std::multiset<uint64_t> m_in_flight;
+  std::map<uint64_t, Context*> m_pending_unregister;
+  Context *m_on_shut_down_finish = nullptr;
+
+  void create_work_queue() {
+    if (m_work_queue != nullptr) {
+      return;
+    }
+    ThreadPoolSingleton *thread_pool_singleton;
+    m_cct->lookup_or_create_singleton_object<ThreadPoolSingleton>(
+      thread_pool_singleton, "librbd::ImageUpdateWatchers::thread_pool");
+    m_work_queue = new ContextWQ("librbd::ImageUpdateWatchers::op_work_queue",
+				 m_cct->_conf->get_val<int64_t>("rbd_op_thread_timeout"),
+				 thread_pool_singleton);
+  }
+
+  void destroy_work_queue() {
+    if (m_work_queue == nullptr) {
+      return;
+    }
+    m_work_queue->drain();
+    delete m_work_queue;
+  }
+};
+
+template <typename I>
+ImageState<I>::ImageState(I *image_ctx)
+  : m_image_ctx(image_ctx), m_state(STATE_UNINITIALIZED),
+    m_lock(util::unique_lock_name("librbd::ImageState::m_lock", this)),
+    m_last_refresh(0), m_refresh_seq(0),
+    m_update_watchers(new ImageUpdateWatchers(image_ctx->cct)),
+    m_skip_open_parent_image(false) {
+}
+
+template <typename I>
+ImageState<I>::~ImageState() {
+  assert(m_state == STATE_UNINITIALIZED || m_state == STATE_CLOSED);
+  delete m_update_watchers;
+}
+
+template <typename I>
+int ImageState<I>::open(bool skip_open_parent) {
+  C_SaferCond ctx;
+  open(skip_open_parent, &ctx);
+
+  int r = ctx.wait();
+  if (r < 0) {
+    delete m_image_ctx;
+  }
+  return r;
+}
+
+template <typename I>
+void ImageState<I>::open(bool skip_open_parent, Context *on_finish) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << dendl;
+
+  m_lock.Lock();
+  assert(m_state == STATE_UNINITIALIZED);
+  m_skip_open_parent_image = skip_open_parent;
+
+  Action action(ACTION_TYPE_OPEN);
+  action.refresh_seq = m_refresh_seq;
+
+  execute_action_unlock(action, on_finish);
+}
+
+template <typename I>
+int ImageState<I>::close() {
+  C_SaferCond ctx;
+  close(&ctx);
+
+  int r = ctx.wait();
+  delete m_image_ctx;
+  return r;
+}
+
+template <typename I>
+void ImageState<I>::close(Context *on_finish) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << dendl;
+
+  m_lock.Lock();
+  assert(!is_closed());
+
+  Action action(ACTION_TYPE_CLOSE);
+  action.refresh_seq = m_refresh_seq;
+  execute_action_unlock(action, on_finish);
+}
+
+template <typename I>
+void ImageState<I>::handle_update_notification() {
+  Mutex::Locker locker(m_lock);
+  ++m_refresh_seq;
+
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << ": refresh_seq = " << m_refresh_seq << ", "
+		 << "last_refresh = " << m_last_refresh << dendl;
+
+  if (m_state == STATE_OPEN) {
+    m_update_watchers->notify();
+  }
+}
+
+template <typename I>
+bool ImageState<I>::is_refresh_required() const {
+  Mutex::Locker locker(m_lock);
+  return (m_last_refresh != m_refresh_seq || find_pending_refresh() != nullptr);
+}
+
+template <typename I>
+int ImageState<I>::refresh() {
+  C_SaferCond refresh_ctx;
+  refresh(&refresh_ctx);
+  return refresh_ctx.wait();
+}
+
+template <typename I>
+void ImageState<I>::refresh(Context *on_finish) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << dendl;
+
+  m_lock.Lock();
+  if (is_closed()) {
+    m_lock.Unlock();
+    on_finish->complete(-ESHUTDOWN);
+    return;
+  }
+
+  Action action(ACTION_TYPE_REFRESH);
+  action.refresh_seq = m_refresh_seq;
+  execute_action_unlock(action, on_finish);
+}
+
+template <typename I>
+int ImageState<I>::refresh_if_required() {
+  C_SaferCond ctx;
+  {
+    m_lock.Lock();
+    Action action(ACTION_TYPE_REFRESH);
+    action.refresh_seq = m_refresh_seq;
+
+    auto refresh_action = find_pending_refresh();
+    if (refresh_action != nullptr) {
+      // if a refresh is in-flight, delay until it is finished
+      action = *refresh_action;
+    } else if (m_last_refresh == m_refresh_seq) {
+      m_lock.Unlock();
+      return 0;
+    } else if (is_closed()) {
+      m_lock.Unlock();
+      return -ESHUTDOWN;
+    }
+
+    execute_action_unlock(action, &ctx);
+  }
+
+  return ctx.wait();
+}
+
+template <typename I>
+const typename ImageState<I>::Action *
+ImageState<I>::find_pending_refresh() const {
+  assert(m_lock.is_locked());
+
+  auto it = std::find_if(m_actions_contexts.rbegin(),
+                         m_actions_contexts.rend(),
+                         [](const ActionContexts& action_contexts) {
+      return (action_contexts.first == ACTION_TYPE_REFRESH);
+    });
+  if (it != m_actions_contexts.rend()) {
+    return &it->first;
+  }
+  return nullptr;
+}
+
+template <typename I>
+void ImageState<I>::snap_set(const cls::rbd::SnapshotNamespace &snap_namespace,
+			     const std::string &snap_name,
+			     Context *on_finish) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << ": snap_name=" << snap_name << dendl;
+
+  Action action(ACTION_TYPE_SET_SNAP);
+  action.snap_namespace = snap_namespace;
+  action.snap_name = snap_name;
+
+  m_lock.Lock();
+  execute_action_unlock(action, on_finish);
+}
+
+template <typename I>
+void ImageState<I>::prepare_lock(Context *on_ready) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << __func__ << dendl;
+
+  m_lock.Lock();
+  if (is_closed()) {
+    m_lock.Unlock();
+    on_ready->complete(-ESHUTDOWN);
+    return;
+  }
+
+  Action action(ACTION_TYPE_LOCK);
+  action.on_ready = on_ready;
+  execute_action_unlock(action, nullptr);
+}
+
+template <typename I>
+void ImageState<I>::handle_prepare_lock_complete() {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << __func__ << dendl;
+
+  m_lock.Lock();
+  if (m_state != STATE_PREPARING_LOCK) {
+    m_lock.Unlock();
+    return;
+  }
+
+  complete_action_unlock(STATE_OPEN, 0);
+}
+
+template <typename I>
+int ImageState<I>::register_update_watcher(UpdateWatchCtx *watcher,
+					 uint64_t *handle) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << dendl;
+
+  m_update_watchers->register_watcher(watcher, handle);
+
+  ldout(cct, 20) << __func__ << ": handle=" << *handle << dendl;
+  return 0;
+}
+
+template <typename I>
+int ImageState<I>::unregister_update_watcher(uint64_t handle) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << ": handle=" << handle << dendl;
+
+  C_SaferCond ctx;
+  m_update_watchers->unregister_watcher(handle, &ctx);
+  return ctx.wait();
+}
+
+template <typename I>
+void ImageState<I>::flush_update_watchers(Context *on_finish) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << dendl;
+
+  m_update_watchers->flush(on_finish);
+}
+
+template <typename I>
+void ImageState<I>::shut_down_update_watchers(Context *on_finish) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 20) << __func__ << dendl;
+
+  m_update_watchers->shut_down(on_finish);
+}
+
+template <typename I>
+bool ImageState<I>::is_transition_state() const {
+  switch (m_state) {
+  case STATE_UNINITIALIZED:
+  case STATE_OPEN:
+  case STATE_CLOSED:
+    return false;
+  case STATE_OPENING:
+  case STATE_CLOSING:
+  case STATE_REFRESHING:
+  case STATE_SETTING_SNAP:
+  case STATE_PREPARING_LOCK:
+    break;
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageState<I>::is_closed() const {
+  assert(m_lock.is_locked());
+
+  return ((m_state == STATE_CLOSED) ||
+          (!m_actions_contexts.empty() &&
+           m_actions_contexts.back().first.action_type == ACTION_TYPE_CLOSE));
+}
+
+template <typename I>
+void ImageState<I>::append_context(const Action &action, Context *context) {
+  assert(m_lock.is_locked());
+
+  ActionContexts *action_contexts = nullptr;
+  for (auto &action_ctxs : m_actions_contexts) {
+    if (action == action_ctxs.first) {
+      action_contexts = &action_ctxs;
+      break;
+    }
+  }
+
+  if (action_contexts == nullptr) {
+    m_actions_contexts.push_back({action, {}});
+    action_contexts = &m_actions_contexts.back();
+  }
+
+  if (context != nullptr) {
+    action_contexts->second.push_back(context);
+  }
+}
+
+template <typename I>
+void ImageState<I>::execute_next_action_unlock() {
+  assert(m_lock.is_locked());
+  assert(!m_actions_contexts.empty());
+  switch (m_actions_contexts.front().first.action_type) {
+  case ACTION_TYPE_OPEN:
+    send_open_unlock();
+    return;
+  case ACTION_TYPE_CLOSE:
+    send_close_unlock();
+    return;
+  case ACTION_TYPE_REFRESH:
+    send_refresh_unlock();
+    return;
+  case ACTION_TYPE_SET_SNAP:
+    send_set_snap_unlock();
+    return;
+  case ACTION_TYPE_LOCK:
+    send_prepare_lock_unlock();
+    return;
+  }
+  assert(false);
+}
+
+template <typename I>
+void ImageState<I>::execute_action_unlock(const Action &action,
+                                          Context *on_finish) {
+  assert(m_lock.is_locked());
+
+  append_context(action, on_finish);
+  if (!is_transition_state()) {
+    execute_next_action_unlock();
+  } else {
+    m_lock.Unlock();
+  }
+}
+
+template <typename I>
+void ImageState<I>::complete_action_unlock(State next_state, int r) {
+  assert(m_lock.is_locked());
+  assert(!m_actions_contexts.empty());
+
+  ActionContexts action_contexts(std::move(m_actions_contexts.front()));
+  m_actions_contexts.pop_front();
+
+  m_state = next_state;
+  m_lock.Unlock();
+
+  for (auto ctx : action_contexts.second) {
+    ctx->complete(r);
+  }
+
+  if (next_state != STATE_UNINITIALIZED && next_state != STATE_CLOSED) {
+    m_lock.Lock();
+    if (!is_transition_state() && !m_actions_contexts.empty()) {
+      execute_next_action_unlock();
+    } else {
+      m_lock.Unlock();
+    }
+  }
+}
+
+template <typename I>
+void ImageState<I>::send_open_unlock() {
+  assert(m_lock.is_locked());
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << dendl;
+
+  m_state = STATE_OPENING;
+
+  Context *ctx = create_async_context_callback(
+    *m_image_ctx, create_context_callback<
+      ImageState<I>, &ImageState<I>::handle_open>(this));
+  image::OpenRequest<I> *req = image::OpenRequest<I>::create(
+    m_image_ctx, m_skip_open_parent_image, ctx);
+
+  m_lock.Unlock();
+  req->send();
+}
+
+template <typename I>
+void ImageState<I>::handle_open(int r) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << ": r=" << r << dendl;
+
+  if (r < 0 && r != -ENOENT) {
+    lderr(cct) << "failed to open image: " << cpp_strerror(r) << dendl;
+  }
+
+  m_lock.Lock();
+  complete_action_unlock(r < 0 ? STATE_UNINITIALIZED : STATE_OPEN, r);
+}
+
+template <typename I>
+void ImageState<I>::send_close_unlock() {
+  assert(m_lock.is_locked());
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << dendl;
+
+  m_state = STATE_CLOSING;
+
+  Context *ctx = create_context_callback<
+    ImageState<I>, &ImageState<I>::handle_close>(this);
+  image::CloseRequest<I> *req = image::CloseRequest<I>::create(
+    m_image_ctx, ctx);
+
+  m_lock.Unlock();
+  req->send();
+}
+
+template <typename I>
+void ImageState<I>::handle_close(int r) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << ": r=" << r << dendl;
+
+  if (r < 0) {
+    lderr(cct) << "error occurred while closing image: " << cpp_strerror(r)
+               << dendl;
+  }
+
+  m_lock.Lock();
+  complete_action_unlock(STATE_CLOSED, r);
+}
+
+template <typename I>
+void ImageState<I>::send_refresh_unlock() {
+  assert(m_lock.is_locked());
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << dendl;
+
+  m_state = STATE_REFRESHING;
+  assert(!m_actions_contexts.empty());
+  auto &action_context = m_actions_contexts.front().first;
+  assert(action_context.action_type == ACTION_TYPE_REFRESH);
+
+  Context *ctx = create_async_context_callback(
+    *m_image_ctx, create_context_callback<
+      ImageState<I>, &ImageState<I>::handle_refresh>(this));
+  image::RefreshRequest<I> *req = image::RefreshRequest<I>::create(
+    *m_image_ctx, false, false, ctx);
+
+  m_lock.Unlock();
+  req->send();
+}
+
+template <typename I>
+void ImageState<I>::handle_refresh(int r) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << ": r=" << r << dendl;
+
+  m_lock.Lock();
+  assert(!m_actions_contexts.empty());
+
+  ActionContexts &action_contexts(m_actions_contexts.front());
+  assert(action_contexts.first.action_type == ACTION_TYPE_REFRESH);
+  assert(m_last_refresh <= action_contexts.first.refresh_seq);
+
+  if (r == -ERESTART) {
+    ldout(cct, 5) << "incomplete refresh: not updating sequence" << dendl;
+    r = 0;
+  } else {
+    m_last_refresh = action_contexts.first.refresh_seq;
+  }
+
+  complete_action_unlock(STATE_OPEN, r);
+}
+
+template <typename I>
+void ImageState<I>::send_set_snap_unlock() {
+  assert(m_lock.is_locked());
+
+  m_state = STATE_SETTING_SNAP;
+
+  assert(!m_actions_contexts.empty());
+  ActionContexts &action_contexts(m_actions_contexts.front());
+  assert(action_contexts.first.action_type == ACTION_TYPE_SET_SNAP);
+
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << ": "
+                 << "snap_name=" << action_contexts.first.snap_name << dendl;
+
+  Context *ctx = create_async_context_callback(
+    *m_image_ctx, create_context_callback<
+      ImageState<I>, &ImageState<I>::handle_set_snap>(this));
+  image::SetSnapRequest<I> *req = image::SetSnapRequest<I>::create(
+    *m_image_ctx, action_contexts.first.snap_namespace, action_contexts.first.snap_name, ctx);
+
+  m_lock.Unlock();
+  req->send();
+}
+
+template <typename I>
+void ImageState<I>::handle_set_snap(int r) {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << " r=" << r << dendl;
+
+  if (r < 0 && r != -ENOENT) {
+    lderr(cct) << "failed to set snapshot: " << cpp_strerror(r) << dendl;
+  }
+
+  m_lock.Lock();
+  complete_action_unlock(STATE_OPEN, r);
+}
+
+template <typename I>
+void ImageState<I>::send_prepare_lock_unlock() {
+  CephContext *cct = m_image_ctx->cct;
+  ldout(cct, 10) << this << " " << __func__ << dendl;
+
+  assert(m_lock.is_locked());
+  m_state = STATE_PREPARING_LOCK;
+
+  assert(!m_actions_contexts.empty());
+  ActionContexts &action_contexts(m_actions_contexts.front());
+  assert(action_contexts.first.action_type == ACTION_TYPE_LOCK);
+
+  Context *on_ready = action_contexts.first.on_ready;
+  m_lock.Unlock();
+
+  if (on_ready == nullptr) {
+    complete_action_unlock(STATE_OPEN, 0);
+    return;
+  }
+
+  // wake up the lock handler now that its safe to proceed
+  on_ready->complete(0);
+}
+
+} // namespace librbd
+
+template class librbd::ImageState<librbd::ImageCtx>;