X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fsrc%2Ftools%2Frbd_mirror%2FInstanceWatcher.cc;fp=src%2Fceph%2Fsrc%2Ftools%2Frbd_mirror%2FInstanceWatcher.cc;h=7f94976ea1c60d8ce7cad511505ab95a316f25af;hb=812ff6ca9fcd3e629e49d4328905f33eee8ca3f5;hp=0000000000000000000000000000000000000000;hpb=15280273faafb77777eab341909a3f495cf248d9;p=stor4nfv.git

diff --git a/src/ceph/src/tools/rbd_mirror/InstanceWatcher.cc b/src/ceph/src/tools/rbd_mirror/InstanceWatcher.cc
new file mode 100644
index 0000000..7f94976
--- /dev/null
+++ b/src/ceph/src/tools/rbd_mirror/InstanceWatcher.cc
@@ -0,0 +1,1308 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "InstanceWatcher.h"
+#include "include/stringify.h"
+#include "common/debug.h"
+#include "common/errno.h"
+#include "cls/rbd/cls_rbd_client.h"
+#include "librbd/ManagedLock.h"
+#include "librbd/Utils.h"
+#include "InstanceReplayer.h"
+#include "ImageSyncThrottler.h"
+
+#define dout_context g_ceph_context
+#define dout_subsys ceph_subsys_rbd_mirror
+#undef dout_prefix
+#define dout_prefix *_dout << "rbd::mirror::InstanceWatcher: "
+
+namespace rbd {
+namespace mirror {
+
+using namespace instance_watcher;
+
+using librbd::util::create_async_context_callback;
+using librbd::util::create_context_callback;
+using librbd::util::create_rados_callback;
+using librbd::util::unique_lock_name;
+
+namespace {
+
+struct C_GetInstances : public Context {
+  std::vector<std::string> *instance_ids;
+  Context *on_finish;
+  bufferlist out_bl;
+
+  C_GetInstances(std::vector<std::string> *instance_ids, Context *on_finish)
+    : instance_ids(instance_ids), on_finish(on_finish) {
+  }
+
+  void finish(int r) override {
+    dout(20) << "C_GetInstances: " << this << " " <<  __func__ << ": r=" << r
+             << dendl;
+
+    if (r == 0) {
+      bufferlist::iterator it = out_bl.begin();
+      r = librbd::cls_client::mirror_instances_list_finish(&it, instance_ids);
+    } else if (r == -ENOENT) {
+      r = 0;
+    }
+    on_finish->complete(r);
+  }
+};
+
+template <typename I>
+struct C_RemoveInstanceRequest : public Context {
+  InstanceWatcher<I> instance_watcher;
+  Context *on_finish;
+
+  C_RemoveInstanceRequest(librados::IoCtx &io_ctx, ContextWQ *work_queue,
+                          const std::string &instance_id, Context *on_finish)
+    : instance_watcher(io_ctx, work_queue, nullptr, instance_id),
+      on_finish(on_finish) {
+  }
+
+  void send() {
+    dout(20) << "C_RemoveInstanceRequest: " << this << " " << __func__ << dendl;
+
+    instance_watcher.remove(this);
+  }
+
+  void finish(int r) override {
+    dout(20) << "C_RemoveInstanceRequest: " << this << " " << __func__ << ": r="
+             << r << dendl;
+    assert(r == 0);
+
+    on_finish->complete(r);
+  }
+};
+
+} // anonymous namespace
+
+template <typename I>
+struct InstanceWatcher<I>::C_NotifyInstanceRequest : public Context {
+  InstanceWatcher<I> *instance_watcher;
+  std::string instance_id;
+  uint64_t request_id;
+  bufferlist bl;
+  Context *on_finish;
+  bool send_to_leader;
+  std::unique_ptr<librbd::watcher::Notifier> notifier;
+  librbd::watcher::NotifyResponse response;
+  bool canceling = false;
+
+  C_NotifyInstanceRequest(InstanceWatcher<I> *instance_watcher,
+                          const std::string &instance_id, uint64_t request_id,
+                          bufferlist &&bl, Context *on_finish)
+    : instance_watcher(instance_watcher), instance_id(instance_id),
+      request_id(request_id), bl(bl), on_finish(on_finish),
+      send_to_leader(instance_id.empty()) {
+    dout(20) << "C_NotifyInstanceRequest: " << this << " " << __func__
+             << ": instance_watcher=" << instance_watcher << ", instance_id="
+             << instance_id << ", request_id=" << request_id << dendl;
+
+    assert(instance_watcher->m_lock.is_locked());
+
+    if (!send_to_leader) {
+      assert((!instance_id.empty()));
+      notifier.reset(new librbd::watcher::Notifier(
+                         instance_watcher->m_work_queue,
+                         instance_watcher->m_ioctx,
+                         RBD_MIRROR_INSTANCE_PREFIX + instance_id));
+    }
+
+    instance_watcher->m_notify_op_tracker.start_op();
+    auto result = instance_watcher->m_notify_ops.insert(
+        std::make_pair(instance_id, this)).second;
+    assert(result);
+  }
+
+  void send() {
+    dout(20) << "C_NotifyInstanceRequest: " << this << " " << __func__ << dendl;
+
+    assert(instance_watcher->m_lock.is_locked());
+
+    if (canceling) {
+      dout(20) << "C_NotifyInstanceRequest: " << this << " " << __func__
+               << ": canceling" << dendl;
+      instance_watcher->m_work_queue->queue(this, -ECANCELED);
+      return;
+    }
+
+    if (send_to_leader) {
+      if (instance_watcher->m_leader_instance_id.empty()) {
+        dout(20) << "C_NotifyInstanceRequest: " << this << " " << __func__
+                 << ": suspending" << dendl;
+        instance_watcher->suspend_notify_request(this);
+        return;
+      }
+
+      if (instance_watcher->m_leader_instance_id != instance_id) {
+        auto count = instance_watcher->m_notify_ops.erase(
+            std::make_pair(instance_id, this));
+        assert(count > 0);
+
+        instance_id = instance_watcher->m_leader_instance_id;
+
+        auto result = instance_watcher->m_notify_ops.insert(
+            std::make_pair(instance_id, this)).second;
+        assert(result);
+
+        notifier.reset(new librbd::watcher::Notifier(
+                           instance_watcher->m_work_queue,
+                           instance_watcher->m_ioctx,
+                           RBD_MIRROR_INSTANCE_PREFIX + instance_id));
+      }
+    }
+
+    dout(20) << "C_NotifyInstanceRequest: " << this << " " << __func__
+             << ": sending to " << instance_id << dendl;
+    notifier->notify(bl, &response, this);
+  }
+
+  void cancel() {
+    dout(20) << "C_NotifyInstanceRequest: " << this << " " << __func__ << dendl;
+
+    assert(instance_watcher->m_lock.is_locked());
+
+    canceling = true;
+    instance_watcher->unsuspend_notify_request(this);
+  }
+
+  void finish(int r) override {
+    dout(20) << "C_NotifyInstanceRequest: " << this << " " << __func__ << ": r="
+             << r << dendl;
+
+    if (r == 0 || r == -ETIMEDOUT) {
+      bool found = false;
+      for (auto &it : response.acks) {
+        auto &bl = it.second;
+        if (it.second.length() == 0) {
+          dout(20) << "C_NotifyInstanceRequest: " << this << " " << __func__
+                   << ": no payload in ack, ignoring" << dendl;
+          continue;
+        }
+        try {
+          auto iter = bl.begin();
+          NotifyAckPayload ack;
+          ::decode(ack, iter);
+          if (ack.instance_id != instance_watcher->get_instance_id()) {
+            derr << "C_NotifyInstanceRequest: " << this << " " << __func__
+                 << ": ack instance_id (" << ack.instance_id << ") "
+                 << "does not match, ignoring" << dendl;
+            continue;
+          }
+          if (ack.request_id != request_id) {
+            derr << "C_NotifyInstanceRequest: " << this << " " << __func__
+                 << ": ack request_id (" << ack.request_id << ") "
+                 << "does not match, ignoring" << dendl;
+            continue;
+          }
+          r = ack.ret_val;
+          found = true;
+          break;
+        } catch (const buffer::error &err) {
+          derr << "C_NotifyInstanceRequest: " << this << " " << __func__
+               << ": failed to decode ack: " << err.what() << dendl;
+          continue;
+        }
+      }
+
+      if (!found) {
+        if (r == -ETIMEDOUT) {
+          derr << "C_NotifyInstanceRequest: " << this << " " << __func__
+               << ": resending after timeout" << dendl;
+          Mutex::Locker locker(instance_watcher->m_lock);
+          send();
+          return;
+        } else {
+          r = -EINVAL;
+        }
+      } else {
+        if (r == -ESTALE && send_to_leader) {
+          derr << "C_NotifyInstanceRequest: " << this << " " << __func__
+               << ": resending due to leader change" << dendl;
+          Mutex::Locker locker(instance_watcher->m_lock);
+          send();
+          return;
+        }
+      }
+    }
+
+    on_finish->complete(r);
+
+    {
+      Mutex::Locker locker(instance_watcher->m_lock);
+      auto result = instance_watcher->m_notify_ops.erase(
+        std::make_pair(instance_id, this));
+      assert(result > 0);
+      instance_watcher->m_notify_op_tracker.finish_op();
+    }
+
+    delete this;
+  }
+
+  void complete(int r) override {
+    finish(r);
+  }
+};
+
+template <typename I>
+struct InstanceWatcher<I>::C_SyncRequest : public Context {
+  InstanceWatcher<I> *instance_watcher;
+  std::string sync_id;
+  Context *on_start;
+  Context *on_complete = nullptr;
+  C_NotifyInstanceRequest *req = nullptr;
+
+  C_SyncRequest(InstanceWatcher<I> *instance_watcher,
+                const std::string &sync_id, Context *on_start)
+    : instance_watcher(instance_watcher), sync_id(sync_id),
+      on_start(on_start) {
+    dout(20) << "C_SyncRequest: " << this << " " << __func__ << ": sync_id="
+             << sync_id << dendl;
+  }
+
+  void finish(int r) override {
+    dout(20) << "C_SyncRequest: " << this << " " << __func__ << ": r="
+             << r << dendl;
+
+    if (on_start != nullptr) {
+      instance_watcher->handle_notify_sync_request(this, r);
+    } else {
+      instance_watcher->handle_notify_sync_complete(this, r);
+      delete this;
+    }
+  }
+
+  // called twice
+  void complete(int r) override {
+    finish(r);
+  }
+};
+
+#undef dout_prefix
+#define dout_prefix *_dout << "rbd::mirror::InstanceWatcher: " \
+                           << this << " " << __func__ << ": "
+template <typename I>
+void InstanceWatcher<I>::get_instances(librados::IoCtx &io_ctx,
+                                       std::vector<std::string> *instance_ids,
+                                       Context *on_finish) {
+  librados::ObjectReadOperation op;
+  librbd::cls_client::mirror_instances_list_start(&op);
+  C_GetInstances *ctx = new C_GetInstances(instance_ids, on_finish);
+  librados::AioCompletion *aio_comp = create_rados_callback(ctx);
+
+  int r = io_ctx.aio_operate(RBD_MIRROR_LEADER, aio_comp, &op, &ctx->out_bl);
+  assert(r == 0);
+  aio_comp->release();
+}
+
+template <typename I>
+void InstanceWatcher<I>::remove_instance(librados::IoCtx &io_ctx,
+                                         ContextWQ *work_queue,
+                                         const std::string &instance_id,
+                                         Context *on_finish) {
+  auto req = new C_RemoveInstanceRequest<I>(io_ctx, work_queue, instance_id,
+                                            on_finish);
+  req->send();
+}
+
+template <typename I>
+InstanceWatcher<I> *InstanceWatcher<I>::create(
+    librados::IoCtx &io_ctx, ContextWQ *work_queue,
+    InstanceReplayer<I> *instance_replayer) {
+  return new InstanceWatcher<I>(io_ctx, work_queue, instance_replayer,
+                                stringify(io_ctx.get_instance_id()));
+}
+
+template <typename I>
+InstanceWatcher<I>::InstanceWatcher(librados::IoCtx &io_ctx,
+                                    ContextWQ *work_queue,
+                                    InstanceReplayer<I> *instance_replayer,
+                                    const std::string &instance_id)
+  : Watcher(io_ctx, work_queue, RBD_MIRROR_INSTANCE_PREFIX + instance_id),
+    m_instance_replayer(instance_replayer), m_instance_id(instance_id),
+    m_lock(unique_lock_name("rbd::mirror::InstanceWatcher::m_lock", this)),
+    m_instance_lock(librbd::ManagedLock<I>::create(
+      m_ioctx, m_work_queue, m_oid, this, librbd::managed_lock::EXCLUSIVE, true,
+      m_cct->_conf->get_val<int64_t>("rbd_blacklist_expire_seconds"))) {
+}
+
+template <typename I>
+InstanceWatcher<I>::~InstanceWatcher() {
+  assert(m_notify_ops.empty());
+  assert(m_notify_op_tracker.empty());
+  assert(m_suspended_ops.empty());
+  assert(m_inflight_sync_reqs.empty());
+  assert(m_image_sync_throttler == nullptr);
+  m_instance_lock->destroy();
+}
+
+template <typename I>
+int InstanceWatcher<I>::init() {
+  C_SaferCond init_ctx;
+  init(&init_ctx);
+  return init_ctx.wait();
+}
+
+template <typename I>
+void InstanceWatcher<I>::init(Context *on_finish) {
+  dout(20) << "instance_id=" << m_instance_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  assert(m_on_finish == nullptr);
+  m_on_finish = on_finish;
+  m_ret_val = 0;
+
+  register_instance();
+}
+
+template <typename I>
+void InstanceWatcher<I>::shut_down() {
+  C_SaferCond shut_down_ctx;
+  shut_down(&shut_down_ctx);
+  int r = shut_down_ctx.wait();
+  assert(r == 0);
+}
+
+template <typename I>
+void InstanceWatcher<I>::shut_down(Context *on_finish) {
+  dout(20) << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  assert(m_on_finish == nullptr);
+  m_on_finish = on_finish;
+  m_ret_val = 0;
+
+  release_lock();
+}
+
+template <typename I>
+void InstanceWatcher<I>::remove(Context *on_finish) {
+  dout(20) << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  assert(m_on_finish == nullptr);
+  m_on_finish = on_finish;
+  m_ret_val = 0;
+  m_removing = true;
+
+  get_instance_locker();
+}
+
+template <typename I>
+void InstanceWatcher<I>::notify_image_acquire(
+    const std::string &instance_id, const std::string &global_image_id,
+    Context *on_notify_ack) {
+  dout(20) << "instance_id=" << instance_id << ", global_image_id="
+           << global_image_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  assert(m_on_finish == nullptr);
+
+  if (instance_id == m_instance_id) {
+    handle_image_acquire(global_image_id, on_notify_ack);
+  } else {
+    uint64_t request_id = ++m_request_seq;
+    bufferlist bl;
+    ::encode(NotifyMessage{ImageAcquirePayload{request_id, global_image_id}},
+             bl);
+    auto req = new C_NotifyInstanceRequest(this, instance_id, request_id,
+                                           std::move(bl), on_notify_ack);
+    req->send();
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::notify_image_release(
+    const std::string &instance_id, const std::string &global_image_id,
+    Context *on_notify_ack) {
+  dout(20) << "instance_id=" << instance_id << ", global_image_id="
+           << global_image_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  assert(m_on_finish == nullptr);
+
+  if (instance_id == m_instance_id) {
+    handle_image_release(global_image_id, on_notify_ack);
+  } else {
+    uint64_t request_id = ++m_request_seq;
+    bufferlist bl;
+    ::encode(NotifyMessage{ImageReleasePayload{request_id, global_image_id}},
+             bl);
+    auto req = new C_NotifyInstanceRequest(this, instance_id, request_id,
+                                           std::move(bl), on_notify_ack);
+    req->send();
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::notify_peer_image_removed(
+    const std::string &instance_id, const std::string &global_image_id,
+    const std::string &peer_mirror_uuid, Context *on_notify_ack) {
+  dout(20) << "instance_id=" << instance_id << ", "
+           << "global_image_id=" << global_image_id << ", "
+           << "peer_mirror_uuid=" << peer_mirror_uuid << dendl;
+
+  Mutex::Locker locker(m_lock);
+  assert(m_on_finish == nullptr);
+
+  if (instance_id == m_instance_id) {
+    handle_peer_image_removed(global_image_id, peer_mirror_uuid, on_notify_ack);
+  } else {
+    uint64_t request_id = ++m_request_seq;
+    bufferlist bl;
+    ::encode(NotifyMessage{PeerImageRemovedPayload{request_id, global_image_id,
+                                                   peer_mirror_uuid}}, bl);
+    auto req = new C_NotifyInstanceRequest(this, instance_id, request_id,
+                                           std::move(bl), on_notify_ack);
+    req->send();
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::notify_sync_request(const std::string &sync_id,
+                                             Context *on_sync_start) {
+  dout(20) << "sync_id=" << sync_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  assert(m_inflight_sync_reqs.count(sync_id) == 0);
+
+  uint64_t request_id = ++m_request_seq;
+
+  bufferlist bl;
+  ::encode(NotifyMessage{SyncRequestPayload{request_id, sync_id}}, bl);
+
+  auto sync_ctx = new C_SyncRequest(this, sync_id, on_sync_start);
+  sync_ctx->req = new C_NotifyInstanceRequest(this, "", request_id,
+                                              std::move(bl), sync_ctx);
+
+  m_inflight_sync_reqs[sync_id] = sync_ctx;
+  sync_ctx->req->send();
+}
+
+template <typename I>
+bool InstanceWatcher<I>::cancel_sync_request(const std::string &sync_id) {
+  dout(20) << "sync_id=" << sync_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  auto it = m_inflight_sync_reqs.find(sync_id);
+  if (it == m_inflight_sync_reqs.end()) {
+    return false;
+  }
+
+  auto sync_ctx = it->second;
+
+  if (sync_ctx->on_start == nullptr) {
+    return false;
+  }
+
+  assert(sync_ctx->req != nullptr);
+  sync_ctx->req->cancel();
+  return true;
+}
+
+template <typename I>
+void InstanceWatcher<I>::notify_sync_start(const std::string &instance_id,
+                                           const std::string &sync_id) {
+  dout(20) << "sync_id=" << sync_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  uint64_t request_id = ++m_request_seq;
+
+  bufferlist bl;
+  ::encode(NotifyMessage{SyncStartPayload{request_id, sync_id}}, bl);
+
+  auto ctx = new FunctionContext(
+    [this, sync_id] (int r) {
+      dout(20) << "finish: sync_id=" << sync_id << ", r=" << r << dendl;
+      Mutex::Locker locker(m_lock);
+      if (r != -ESTALE && m_image_sync_throttler != nullptr) {
+        m_image_sync_throttler->finish_op(sync_id);
+      }
+    });
+  auto req = new C_NotifyInstanceRequest(this, instance_id, request_id,
+                                         std::move(bl), ctx);
+  req->send();
+}
+
+template <typename I>
+void InstanceWatcher<I>::notify_sync_complete(const std::string &sync_id) {
+  dout(20) << "sync_id=" << sync_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  auto it = m_inflight_sync_reqs.find(sync_id);
+  assert(it != m_inflight_sync_reqs.end());
+
+  auto sync_ctx = it->second;
+  assert(sync_ctx->req == nullptr);
+
+  m_inflight_sync_reqs.erase(it);
+  m_work_queue->queue(sync_ctx, 0);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_notify_sync_request(C_SyncRequest *sync_ctx,
+                                                    int r) {
+  dout(20) << "sync_id=" << sync_ctx->sync_id << ", r=" << r << dendl;
+
+  Context *on_start = nullptr;
+  {
+    Mutex::Locker locker(m_lock);
+
+    assert(sync_ctx->req != nullptr);
+    assert(sync_ctx->on_start != nullptr);
+
+    if (sync_ctx->req->canceling) {
+      r = -ECANCELED;
+    }
+
+    std::swap(sync_ctx->on_start, on_start);
+    sync_ctx->req = nullptr;
+  }
+
+  on_start->complete(r == -ECANCELED ? r : 0);
+
+  if (r == -ECANCELED) {
+    notify_sync_complete(sync_ctx->sync_id);
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_notify_sync_complete(C_SyncRequest *sync_ctx,
+                                                     int r) {
+  dout(20) << "sync_id=" << sync_ctx->sync_id << ", r=" << r << dendl;
+
+  if (sync_ctx->on_complete != nullptr) {
+    sync_ctx->on_complete->complete(r);
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::print_sync_status(Formatter *f, stringstream *ss) {
+  dout(20) << dendl;
+
+  Mutex::Locker locker(m_lock);
+  if (m_image_sync_throttler != nullptr) {
+    m_image_sync_throttler->print_status(f, ss);
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_acquire_leader() {
+  dout(20) << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  assert(m_image_sync_throttler == nullptr);
+  m_image_sync_throttler = ImageSyncThrottler<I>::create();
+
+  m_leader_instance_id = m_instance_id;
+  unsuspend_notify_requests();
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_release_leader() {
+  dout(20) << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  assert(m_image_sync_throttler != nullptr);
+
+  m_leader_instance_id.clear();
+
+  m_image_sync_throttler->drain(-ESTALE);
+  m_image_sync_throttler->destroy();
+  m_image_sync_throttler = nullptr;
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_update_leader(
+  const std::string &leader_instance_id) {
+  dout(20) << "leader_instance_id=" << leader_instance_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  m_leader_instance_id = leader_instance_id;
+
+  if (!m_leader_instance_id.empty()) {
+    unsuspend_notify_requests();
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::cancel_notify_requests(
+    const std::string &instance_id) {
+  dout(20) << "instance_id=" << instance_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  for (auto op : m_notify_ops) {
+    if (op.first == instance_id && !op.second->send_to_leader) {
+      op.second->cancel();
+    }
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::register_instance() {
+  assert(m_lock.is_locked());
+
+  dout(20) << dendl;
+
+  librados::ObjectWriteOperation op;
+  librbd::cls_client::mirror_instances_add(&op, m_instance_id);
+  librados::AioCompletion *aio_comp = create_rados_callback<
+    InstanceWatcher<I>, &InstanceWatcher<I>::handle_register_instance>(this);
+
+  int r = m_ioctx.aio_operate(RBD_MIRROR_LEADER, aio_comp, &op);
+  assert(r == 0);
+  aio_comp->release();
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_register_instance(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  Context *on_finish = nullptr;
+  {
+    Mutex::Locker locker(m_lock);
+
+    if (r == 0) {
+      create_instance_object();
+      return;
+    }
+
+    derr << "error registering instance: " << cpp_strerror(r) << dendl;
+
+    std::swap(on_finish, m_on_finish);
+  }
+  on_finish->complete(r);
+}
+
+
+template <typename I>
+void InstanceWatcher<I>::create_instance_object() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  librados::ObjectWriteOperation op;
+  op.create(true);
+
+  librados::AioCompletion *aio_comp = create_rados_callback<
+    InstanceWatcher<I>,
+    &InstanceWatcher<I>::handle_create_instance_object>(this);
+  int r = m_ioctx.aio_operate(m_oid, aio_comp, &op);
+  assert(r == 0);
+  aio_comp->release();
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_create_instance_object(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  if (r < 0) {
+    derr << "error creating " << m_oid << " object: " << cpp_strerror(r)
+         << dendl;
+
+    m_ret_val = r;
+    unregister_instance();
+    return;
+  }
+
+  register_watch();
+}
+
+template <typename I>
+void InstanceWatcher<I>::register_watch() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  Context *ctx = create_async_context_callback(
+    m_work_queue, create_context_callback<
+    InstanceWatcher<I>, &InstanceWatcher<I>::handle_register_watch>(this));
+
+  librbd::Watcher::register_watch(ctx);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_register_watch(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  if (r < 0) {
+    derr << "error registering instance watcher for " << m_oid << " object: "
+         << cpp_strerror(r) << dendl;
+
+    m_ret_val = r;
+    remove_instance_object();
+    return;
+  }
+
+  acquire_lock();
+}
+
+template <typename I>
+void InstanceWatcher<I>::acquire_lock() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  Context *ctx = create_async_context_callback(
+    m_work_queue, create_context_callback<
+    InstanceWatcher<I>, &InstanceWatcher<I>::handle_acquire_lock>(this));
+
+  m_instance_lock->acquire_lock(ctx);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_acquire_lock(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  Context *on_finish = nullptr;
+  {
+    Mutex::Locker locker(m_lock);
+
+    if (r < 0) {
+
+      derr << "error acquiring instance lock: " << cpp_strerror(r) << dendl;
+
+      m_ret_val = r;
+      unregister_watch();
+      return;
+    }
+
+    std::swap(on_finish, m_on_finish);
+  }
+
+  on_finish->complete(r);
+}
+
+template <typename I>
+void InstanceWatcher<I>::release_lock() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  Context *ctx = create_async_context_callback(
+    m_work_queue, create_context_callback<
+    InstanceWatcher<I>, &InstanceWatcher<I>::handle_release_lock>(this));
+
+  m_instance_lock->shut_down(ctx);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_release_lock(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  if (r < 0) {
+    derr << "error releasing instance lock: " << cpp_strerror(r) << dendl;
+  }
+
+  unregister_watch();
+}
+
+template <typename I>
+void InstanceWatcher<I>::unregister_watch() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  Context *ctx = create_async_context_callback(
+    m_work_queue, create_context_callback<
+      InstanceWatcher<I>, &InstanceWatcher<I>::handle_unregister_watch>(this));
+
+  librbd::Watcher::unregister_watch(ctx);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_unregister_watch(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  if (r < 0) {
+    derr << "error unregistering instance watcher for " << m_oid << " object: "
+         << cpp_strerror(r) << dendl;
+  }
+
+  Mutex::Locker locker(m_lock);
+  remove_instance_object();
+}
+
+template <typename I>
+void InstanceWatcher<I>::remove_instance_object() {
+  assert(m_lock.is_locked());
+
+  dout(20) << dendl;
+
+  librados::ObjectWriteOperation op;
+  op.remove();
+
+  librados::AioCompletion *aio_comp = create_rados_callback<
+    InstanceWatcher<I>,
+    &InstanceWatcher<I>::handle_remove_instance_object>(this);
+  int r = m_ioctx.aio_operate(m_oid, aio_comp, &op);
+  assert(r == 0);
+  aio_comp->release();
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_remove_instance_object(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  if (m_removing && r == -ENOENT) {
+    r = 0;
+  }
+
+  if (r < 0) {
+    derr << "error removing " << m_oid << " object: " << cpp_strerror(r)
+         << dendl;
+  }
+
+  Mutex::Locker locker(m_lock);
+  unregister_instance();
+}
+
+template <typename I>
+void InstanceWatcher<I>::unregister_instance() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  librados::ObjectWriteOperation op;
+  librbd::cls_client::mirror_instances_remove(&op, m_instance_id);
+  librados::AioCompletion *aio_comp = create_rados_callback<
+    InstanceWatcher<I>, &InstanceWatcher<I>::handle_unregister_instance>(this);
+
+  int r = m_ioctx.aio_operate(RBD_MIRROR_LEADER, aio_comp, &op);
+  assert(r == 0);
+  aio_comp->release();
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_unregister_instance(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  if (r < 0) {
+    derr << "error unregistering instance: " << cpp_strerror(r) << dendl;
+  }
+
+  Mutex::Locker locker(m_lock);
+  wait_for_notify_ops();
+}
+
+template <typename I>
+void InstanceWatcher<I>::wait_for_notify_ops() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  for (auto op : m_notify_ops) {
+    op.second->cancel();
+  }
+
+  Context *ctx = create_async_context_callback(
+    m_work_queue, create_context_callback<
+    InstanceWatcher<I>, &InstanceWatcher<I>::handle_wait_for_notify_ops>(this));
+
+  m_notify_op_tracker.wait_for_ops(ctx);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_wait_for_notify_ops(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  assert(r == 0);
+
+  Context *on_finish = nullptr;
+  {
+    Mutex::Locker locker(m_lock);
+
+    assert(m_notify_ops.empty());
+
+    std::swap(on_finish, m_on_finish);
+    r = m_ret_val;
+
+    if (m_removing) {
+      m_removing = false;
+    }
+  }
+  on_finish->complete(r);
+}
+
+template <typename I>
+void InstanceWatcher<I>::get_instance_locker() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  Context *ctx = create_async_context_callback(
+    m_work_queue, create_context_callback<
+    InstanceWatcher<I>, &InstanceWatcher<I>::handle_get_instance_locker>(this));
+
+  m_instance_lock->get_locker(&m_instance_locker, ctx);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_get_instance_locker(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  if (r < 0) {
+    if (r != -ENOENT) {
+      derr << "error retrieving instance locker: " << cpp_strerror(r) << dendl;
+    }
+    remove_instance_object();
+    return;
+  }
+
+  break_instance_lock();
+}
+
+template <typename I>
+void InstanceWatcher<I>::break_instance_lock() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  Context *ctx = create_async_context_callback(
+    m_work_queue, create_context_callback<
+    InstanceWatcher<I>, &InstanceWatcher<I>::handle_break_instance_lock>(this));
+
+  m_instance_lock->break_lock(m_instance_locker, true, ctx);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_break_instance_lock(int r) {
+  dout(20) << "r=" << r << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  if (r < 0) {
+    if (r != -ENOENT) {
+      derr << "error breaking instance lock: " << cpp_strerror(r) << dendl;
+    }
+    remove_instance_object();
+    return;
+  }
+
+  remove_instance_object();
+}
+
+template <typename I>
+void InstanceWatcher<I>::suspend_notify_request(C_NotifyInstanceRequest *req) {
+  dout(20) << req << dendl;
+
+  assert(m_lock.is_locked());
+
+  auto result = m_suspended_ops.insert(req).second;
+  assert(result);
+}
+
+template <typename I>
+bool InstanceWatcher<I>::unsuspend_notify_request(
+  C_NotifyInstanceRequest *req) {
+  dout(20) << req << dendl;
+
+  assert(m_lock.is_locked());
+
+  auto result = m_suspended_ops.erase(req);
+  if (result == 0) {
+    return false;
+  }
+
+  req->send();
+  return true;
+}
+
+template <typename I>
+void InstanceWatcher<I>::unsuspend_notify_requests() {
+  dout(20) << dendl;
+
+  assert(m_lock.is_locked());
+
+  std::set<C_NotifyInstanceRequest *> suspended_ops;
+  std::swap(m_suspended_ops, suspended_ops);
+
+  for (auto op : suspended_ops) {
+    op->send();
+  }
+}
+
+template <typename I>
+Context *InstanceWatcher<I>::prepare_request(const std::string &instance_id,
+                                             uint64_t request_id,
+                                             C_NotifyAck *on_notify_ack) {
+  dout(20) << "instance_id=" << instance_id << ", request_id=" << request_id
+           << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  Context *ctx = nullptr;
+  Request request(instance_id, request_id);
+  auto it = m_requests.find(request);
+
+  if (it != m_requests.end()) {
+    dout(20) << "duplicate for in-progress request" << dendl;
+    delete it->on_notify_ack;
+    m_requests.erase(it);
+  } else {
+    ctx = create_async_context_callback(
+        m_work_queue, new FunctionContext(
+            [this, instance_id, request_id] (int r) {
+              complete_request(instance_id, request_id, r);
+            }));
+  }
+
+  request.on_notify_ack = on_notify_ack;
+  m_requests.insert(request);
+  return ctx;
+}
+
+template <typename I>
+void InstanceWatcher<I>::complete_request(const std::string &instance_id,
+                                          uint64_t request_id, int r) {
+  dout(20) << "instance_id=" << instance_id << ", request_id=" << request_id
+           << dendl;
+
+  C_NotifyAck *on_notify_ack;
+  {
+    Mutex::Locker locker(m_lock);
+    Request request(instance_id, request_id);
+    auto it = m_requests.find(request);
+    assert(it != m_requests.end());
+    on_notify_ack = it->on_notify_ack;
+    m_requests.erase(it);
+  }
+
+  ::encode(NotifyAckPayload(instance_id, request_id, r), on_notify_ack->out);
+  on_notify_ack->complete(0);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_notify(uint64_t notify_id, uint64_t handle,
+                                       uint64_t notifier_id, bufferlist &bl) {
+  dout(20) << "notify_id=" << notify_id << ", handle=" << handle << ", "
+           << "notifier_id=" << notifier_id << dendl;
+
+  auto ctx = new C_NotifyAck(this, notify_id, handle);
+
+  NotifyMessage notify_message;
+  try {
+    bufferlist::iterator iter = bl.begin();
+    ::decode(notify_message, iter);
+  } catch (const buffer::error &err) {
+    derr << "error decoding image notification: " << err.what() << dendl;
+    ctx->complete(0);
+    return;
+  }
+
+  apply_visitor(HandlePayloadVisitor(this, stringify(notifier_id), ctx),
+                notify_message.payload);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_image_acquire(
+    const std::string &global_image_id, Context *on_finish) {
+  dout(20) << "global_image_id=" << global_image_id << dendl;
+
+  auto ctx = new FunctionContext(
+      [this, global_image_id, on_finish] (int r) {
+        m_instance_replayer->acquire_image(this, global_image_id, on_finish);
+        m_notify_op_tracker.finish_op();
+      });
+
+  m_notify_op_tracker.start_op();
+  m_work_queue->queue(ctx, 0);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_image_release(
+    const std::string &global_image_id, Context *on_finish) {
+  dout(20) << "global_image_id=" << global_image_id << dendl;
+
+  auto ctx = new FunctionContext(
+      [this, global_image_id, on_finish] (int r) {
+        m_instance_replayer->release_image(global_image_id, on_finish);
+        m_notify_op_tracker.finish_op();
+      });
+
+  m_notify_op_tracker.start_op();
+  m_work_queue->queue(ctx, 0);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_peer_image_removed(
+    const std::string &global_image_id, const std::string &peer_mirror_uuid,
+    Context *on_finish) {
+  dout(20) << "global_image_id=" << global_image_id << ", "
+           << "peer_mirror_uuid=" << peer_mirror_uuid << dendl;
+
+  auto ctx = new FunctionContext(
+      [this, peer_mirror_uuid, global_image_id, on_finish] (int r) {
+        m_instance_replayer->remove_peer_image(global_image_id,
+                                               peer_mirror_uuid, on_finish);
+        m_notify_op_tracker.finish_op();
+      });
+
+  m_notify_op_tracker.start_op();
+  m_work_queue->queue(ctx, 0);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_sync_request(const std::string &instance_id,
+                                             const std::string &sync_id,
+                                             Context *on_finish) {
+  dout(20) << "instance_id=" << instance_id << ", sync_id=" << sync_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  if (m_image_sync_throttler == nullptr) {
+    dout(20) << "sync request for non-leader" << dendl;
+    m_work_queue->queue(on_finish, -ESTALE);
+    return;
+  }
+
+  Context *on_start = create_async_context_callback(
+    m_work_queue, new FunctionContext(
+      [this, instance_id, sync_id, on_finish] (int r) {
+        dout(20) << "handle_sync_request: finish: instance_id=" << instance_id
+                 << ", sync_id=" << sync_id << ", r=" << r << dendl;
+        if (r == 0) {
+          notify_sync_start(instance_id, sync_id);
+        }
+        on_finish->complete(r);
+      }));
+  m_image_sync_throttler->start_op(sync_id, on_start);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_sync_start(const std::string &instance_id,
+                                           const std::string &sync_id,
+                                           Context *on_finish) {
+  dout(20) << "instance_id=" << instance_id << ", sync_id=" << sync_id << dendl;
+
+  Mutex::Locker locker(m_lock);
+
+  auto it = m_inflight_sync_reqs.find(sync_id);
+  if (it == m_inflight_sync_reqs.end()) {
+    dout(20) << "not found" << dendl;
+    m_work_queue->queue(on_finish, 0);
+    return;
+  }
+
+  auto sync_ctx = it->second;
+
+  if (sync_ctx->on_complete != nullptr) {
+    dout(20) << "duplicate request" << dendl;
+    m_work_queue->queue(sync_ctx->on_complete, -ESTALE);
+  }
+
+  sync_ctx->on_complete = on_finish;
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_payload(const std::string &instance_id,
+                                        const ImageAcquirePayload &payload,
+                                        C_NotifyAck *on_notify_ack) {
+  dout(20) << "image_acquire: instance_id=" << instance_id << ", "
+           << "request_id=" << payload.request_id << dendl;
+
+  auto on_finish = prepare_request(instance_id, payload.request_id,
+                                   on_notify_ack);
+  if (on_finish != nullptr) {
+    handle_image_acquire(payload.global_image_id, on_finish);
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_payload(const std::string &instance_id,
+                                        const ImageReleasePayload &payload,
+                                        C_NotifyAck *on_notify_ack) {
+  dout(20) << "image_release: instance_id=" << instance_id << ", "
+           << "request_id=" << payload.request_id << dendl;
+
+  auto on_finish = prepare_request(instance_id, payload.request_id,
+                                   on_notify_ack);
+  if (on_finish != nullptr) {
+    handle_image_release(payload.global_image_id, on_finish);
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_payload(const std::string &instance_id,
+                                        const PeerImageRemovedPayload &payload,
+                                        C_NotifyAck *on_notify_ack) {
+  dout(20) << "remove_peer_image: instance_id=" << instance_id << ", "
+           << "request_id=" << payload.request_id << dendl;
+
+  auto on_finish = prepare_request(instance_id, payload.request_id,
+                                   on_notify_ack);
+  if (on_finish != nullptr) {
+    handle_peer_image_removed(payload.global_image_id, payload.peer_mirror_uuid,
+                              on_finish);
+  }
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_payload(const std::string &instance_id,
+                                        const SyncRequestPayload &payload,
+                                        C_NotifyAck *on_notify_ack) {
+  dout(20) << "sync_request: instance_id=" << instance_id << ", "
+           << "request_id=" << payload.request_id << dendl;
+
+  auto on_finish = prepare_request(instance_id, payload.request_id,
+                                   on_notify_ack);
+  if (on_finish == nullptr) {
+    return;
+  }
+
+  handle_sync_request(instance_id, payload.sync_id, on_finish);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_payload(const std::string &instance_id,
+                                        const SyncStartPayload &payload,
+                                        C_NotifyAck *on_notify_ack) {
+  dout(20) << "sync_start: instance_id=" << instance_id << ", "
+           << "request_id=" << payload.request_id << dendl;
+
+  auto on_finish = prepare_request(instance_id, payload.request_id,
+                                   on_notify_ack);
+  if (on_finish == nullptr) {
+    return;
+  }
+
+  handle_sync_start(instance_id, payload.sync_id, on_finish);
+}
+
+template <typename I>
+void InstanceWatcher<I>::handle_payload(const std::string &instance_id,
+                                        const UnknownPayload &payload,
+                                        C_NotifyAck *on_notify_ack) {
+  dout(20) << "unknown: instance_id=" << instance_id << dendl;
+
+  on_notify_ack->complete(0);
+}
+
+} // namespace mirror
+} // namespace rbd
+
+template class rbd::mirror::InstanceWatcher<librbd::ImageCtx>;