X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fsrc%2Flibrbd%2FImageWatcher.cc;fp=src%2Fceph%2Fsrc%2Flibrbd%2FImageWatcher.cc;h=487eabaa69c18f5c7b374362982ce071b40de1b2;hb=812ff6ca9fcd3e629e49d4328905f33eee8ca3f5;hp=0000000000000000000000000000000000000000;hpb=15280273faafb77777eab341909a3f495cf248d9;p=stor4nfv.git

diff --git a/src/ceph/src/librbd/ImageWatcher.cc b/src/ceph/src/librbd/ImageWatcher.cc
new file mode 100644
index 0000000..487eaba
--- /dev/null
+++ b/src/ceph/src/librbd/ImageWatcher.cc
@@ -0,0 +1,1013 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "librbd/ImageWatcher.h"
+#include "librbd/ExclusiveLock.h"
+#include "librbd/ImageCtx.h"
+#include "librbd/ImageState.h"
+#include "librbd/internal.h"
+#include "librbd/Operations.h"
+#include "librbd/TaskFinisher.h"
+#include "librbd/Utils.h"
+#include "librbd/exclusive_lock/Policy.h"
+#include "librbd/image_watcher/NotifyLockOwner.h"
+#include "librbd/io/AioCompletion.h"
+#include "librbd/watcher/Utils.h"
+#include "include/encoding.h"
+#include "common/errno.h"
+#include "common/WorkQueue.h"
+#include <boost/bind.hpp>
+
+#define dout_subsys ceph_subsys_rbd
+#undef dout_prefix
+#define dout_prefix *_dout << "librbd::ImageWatcher: "
+
+namespace librbd {
+
+using namespace image_watcher;
+using namespace watch_notify;
+using util::create_async_context_callback;
+using util::create_context_callback;
+using util::create_rados_callback;
+using librbd::watcher::util::HandlePayloadVisitor;
+
+static const double	RETRY_DELAY_SECONDS = 1.0;
+
+template <typename I>
+struct ImageWatcher<I>::C_ProcessPayload : public Context {
+  ImageWatcher *image_watcher;
+  uint64_t notify_id;
+  uint64_t handle;
+  watch_notify::Payload payload;
+
+  C_ProcessPayload(ImageWatcher *image_watcher_, uint64_t notify_id_,
+                   uint64_t handle_, const watch_notify::Payload &payload)
+    : image_watcher(image_watcher_), notify_id(notify_id_), handle(handle_),
+      payload(payload) {
+  }
+
+  void finish(int r) override {
+    image_watcher->m_async_op_tracker.start_op();
+    if (image_watcher->notifications_blocked()) {
+      // requests are blocked -- just ack the notification
+      bufferlist bl;
+      image_watcher->acknowledge_notify(notify_id, handle, bl);
+    } else {
+      image_watcher->process_payload(notify_id, handle, payload);
+    }
+    image_watcher->m_async_op_tracker.finish_op();
+  }
+};
+
+template <typename I>
+ImageWatcher<I>::ImageWatcher(I &image_ctx)
+  : Watcher(image_ctx.md_ctx, image_ctx.op_work_queue, image_ctx.header_oid),
+    m_image_ctx(image_ctx),
+    m_task_finisher(new TaskFinisher<Task>(*m_image_ctx.cct)),
+    m_async_request_lock(util::unique_lock_name("librbd::ImageWatcher::m_async_request_lock", this)),
+    m_owner_client_id_lock(util::unique_lock_name("librbd::ImageWatcher::m_owner_client_id_lock", this))
+{
+}
+
+template <typename I>
+ImageWatcher<I>::~ImageWatcher()
+{
+  delete m_task_finisher;
+}
+
+template <typename I>
+void ImageWatcher<I>::unregister_watch(Context *on_finish) {
+  CephContext *cct = m_image_ctx.cct;
+  ldout(cct, 10) << this << " unregistering image watcher" << dendl;
+
+  cancel_async_requests();
+
+  FunctionContext *ctx = new FunctionContext([this, on_finish](int r) {
+    m_task_finisher->cancel_all(on_finish);
+  });
+  Watcher::unregister_watch(ctx);
+}
+
+template <typename I>
+void ImageWatcher<I>::block_notifies(Context *on_finish) {
+  CephContext *cct = m_image_ctx.cct;
+  ldout(cct, 10) << this << " "  << __func__ << dendl;
+
+  on_finish = new FunctionContext([this, on_finish](int r) {
+      cancel_async_requests();
+      on_finish->complete(r);
+    });
+  Watcher::block_notifies(on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::schedule_async_progress(const AsyncRequestId &request,
+					      uint64_t offset, uint64_t total) {
+  FunctionContext *ctx = new FunctionContext(
+    boost::bind(&ImageWatcher<I>::notify_async_progress, this, request, offset,
+                total));
+  m_task_finisher->queue(Task(TASK_CODE_ASYNC_PROGRESS, request), ctx);
+}
+
+template <typename I>
+int ImageWatcher<I>::notify_async_progress(const AsyncRequestId &request,
+				           uint64_t offset, uint64_t total) {
+  ldout(m_image_ctx.cct, 20) << this << " remote async request progress: "
+			     << request << " @ " << offset
+			     << "/" << total << dendl;
+
+  send_notify(AsyncProgressPayload(request, offset, total));
+  return 0;
+}
+
+template <typename I>
+void ImageWatcher<I>::schedule_async_complete(const AsyncRequestId &request,
+                                              int r) {
+  FunctionContext *ctx = new FunctionContext(
+    boost::bind(&ImageWatcher<I>::notify_async_complete, this, request, r));
+  m_task_finisher->queue(ctx);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_async_complete(const AsyncRequestId &request,
+                                            int r) {
+  ldout(m_image_ctx.cct, 20) << this << " remote async request finished: "
+			     << request << " = " << r << dendl;
+
+  send_notify(AsyncCompletePayload(request, r),
+    new FunctionContext(boost::bind(&ImageWatcher<I>::handle_async_complete,
+                        this, request, r, _1)));
+}
+
+template <typename I>
+void ImageWatcher<I>::handle_async_complete(const AsyncRequestId &request,
+                                            int r, int ret_val) {
+  ldout(m_image_ctx.cct, 20) << this << " " << __func__ << ": "
+                             << "request=" << request << ", r=" << ret_val
+                             << dendl;
+  if (ret_val < 0) {
+    lderr(m_image_ctx.cct) << this << " failed to notify async complete: "
+			   << cpp_strerror(ret_val) << dendl;
+    if (ret_val == -ETIMEDOUT) {
+      schedule_async_complete(request, r);
+    }
+  } else {
+    RWLock::WLocker async_request_locker(m_async_request_lock);
+    m_async_pending.erase(request);
+  }
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_flatten(uint64_t request_id,
+                                     ProgressContext &prog_ctx,
+                                     Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  AsyncRequestId async_request_id(get_client_id(), request_id);
+
+  notify_async_request(async_request_id, FlattenPayload(async_request_id),
+                       prog_ctx, on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_resize(uint64_t request_id, uint64_t size,
+			            bool allow_shrink,
+                                    ProgressContext &prog_ctx,
+                                    Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  AsyncRequestId async_request_id(get_client_id(), request_id);
+
+  notify_async_request(async_request_id,
+                       ResizePayload(size, allow_shrink, async_request_id),
+                       prog_ctx, on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_snap_create(const cls::rbd::SnapshotNamespace &snap_namespace,
+					 const std::string &snap_name,
+                                         Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  notify_lock_owner(SnapCreatePayload(snap_namespace, snap_name), on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_snap_rename(const snapid_t &src_snap_id,
+				         const std::string &dst_snap_name,
+					 Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  notify_lock_owner(SnapRenamePayload(src_snap_id, dst_snap_name), on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_snap_remove(const cls::rbd::SnapshotNamespace &snap_namespace,
+					 const std::string &snap_name,
+                                         Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  notify_lock_owner(SnapRemovePayload(snap_namespace, snap_name), on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_snap_protect(const cls::rbd::SnapshotNamespace &snap_namespace,
+					  const std::string &snap_name,
+                                          Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  notify_lock_owner(SnapProtectPayload(snap_namespace, snap_name), on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_snap_unprotect(const cls::rbd::SnapshotNamespace &snap_namespace,
+					    const std::string &snap_name,
+                                            Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  notify_lock_owner(SnapUnprotectPayload(snap_namespace, snap_name), on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_rebuild_object_map(uint64_t request_id,
+                                                ProgressContext &prog_ctx,
+                                                Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  AsyncRequestId async_request_id(get_client_id(), request_id);
+
+  notify_async_request(async_request_id,
+                       RebuildObjectMapPayload(async_request_id),
+                       prog_ctx, on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_rename(const std::string &image_name,
+                                    Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  notify_lock_owner(RenamePayload(image_name), on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_update_features(uint64_t features, bool enabled,
+                                             Context *on_finish) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  notify_lock_owner(UpdateFeaturesPayload(features, enabled), on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_header_update(Context *on_finish) {
+  ldout(m_image_ctx.cct, 10) << this << ": " << __func__ << dendl;
+
+  // supports legacy (empty buffer) clients
+  send_notify(HeaderUpdatePayload(), on_finish);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_header_update(librados::IoCtx &io_ctx,
+				           const std::string &oid) {
+  // supports legacy (empty buffer) clients
+  bufferlist bl;
+  ::encode(NotifyMessage(HeaderUpdatePayload()), bl);
+  io_ctx.notify2(oid, bl, watcher::Notifier::NOTIFY_TIMEOUT, nullptr);
+}
+
+template <typename I>
+void ImageWatcher<I>::schedule_cancel_async_requests() {
+  FunctionContext *ctx = new FunctionContext(
+    boost::bind(&ImageWatcher<I>::cancel_async_requests, this));
+  m_task_finisher->queue(TASK_CODE_CANCEL_ASYNC_REQUESTS, ctx);
+}
+
+template <typename I>
+void ImageWatcher<I>::cancel_async_requests() {
+  RWLock::WLocker l(m_async_request_lock);
+  for (std::map<AsyncRequestId, AsyncRequest>::iterator iter =
+	 m_async_requests.begin();
+       iter != m_async_requests.end(); ++iter) {
+    iter->second.first->complete(-ERESTART);
+  }
+  m_async_requests.clear();
+}
+
+template <typename I>
+void ImageWatcher<I>::set_owner_client_id(const ClientId& client_id) {
+  assert(m_owner_client_id_lock.is_locked());
+  m_owner_client_id = client_id;
+  ldout(m_image_ctx.cct, 10) << this << " current lock owner: "
+                             << m_owner_client_id << dendl;
+}
+
+template <typename I>
+ClientId ImageWatcher<I>::get_client_id() {
+  RWLock::RLocker l(this->m_watch_lock);
+  return ClientId(m_image_ctx.md_ctx.get_instance_id(), this->m_watch_handle);
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_acquired_lock() {
+  ldout(m_image_ctx.cct, 10) << this << " notify acquired lock" << dendl;
+
+  ClientId client_id = get_client_id();
+  {
+    Mutex::Locker owner_client_id_locker(m_owner_client_id_lock);
+    set_owner_client_id(client_id);
+  }
+
+  send_notify(AcquiredLockPayload(client_id));
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_released_lock() {
+  ldout(m_image_ctx.cct, 10) << this << " notify released lock" << dendl;
+
+  {
+    Mutex::Locker owner_client_id_locker(m_owner_client_id_lock);
+    set_owner_client_id(ClientId());
+  }
+
+  send_notify(ReleasedLockPayload(get_client_id()));
+}
+
+template <typename I>
+void ImageWatcher<I>::schedule_request_lock(bool use_timer, int timer_delay) {
+  assert(m_image_ctx.owner_lock.is_locked());
+
+  if (m_image_ctx.exclusive_lock == nullptr) {
+    // exclusive lock dynamically disabled via image refresh
+    return;
+  }
+  assert(m_image_ctx.exclusive_lock &&
+         !m_image_ctx.exclusive_lock->is_lock_owner());
+
+  RWLock::RLocker watch_locker(this->m_watch_lock);
+  if (this->m_watch_state == Watcher::WATCH_STATE_REGISTERED) {
+    ldout(m_image_ctx.cct, 15) << this << " requesting exclusive lock" << dendl;
+
+    FunctionContext *ctx = new FunctionContext(
+      boost::bind(&ImageWatcher<I>::notify_request_lock, this));
+    if (use_timer) {
+      if (timer_delay < 0) {
+        timer_delay = RETRY_DELAY_SECONDS;
+      }
+      m_task_finisher->add_event_after(TASK_CODE_REQUEST_LOCK,
+                                       timer_delay, ctx);
+    } else {
+      m_task_finisher->queue(TASK_CODE_REQUEST_LOCK, ctx);
+    }
+  }
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_request_lock() {
+  RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+  RWLock::RLocker snap_locker(m_image_ctx.snap_lock);
+
+  // ExclusiveLock state machine can be dynamically disabled or
+  // race with task cancel
+  if (m_image_ctx.exclusive_lock == nullptr ||
+      m_image_ctx.exclusive_lock->is_lock_owner()) {
+    return;
+  }
+
+  ldout(m_image_ctx.cct, 10) << this << " notify request lock" << dendl;
+
+  notify_lock_owner(RequestLockPayload(get_client_id(), false),
+      create_context_callback<
+        ImageWatcher, &ImageWatcher<I>::handle_request_lock>(this));
+}
+
+template <typename I>
+void ImageWatcher<I>::handle_request_lock(int r) {
+  RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+  RWLock::RLocker snap_locker(m_image_ctx.snap_lock);
+
+  // ExclusiveLock state machine cannot transition -- but can be
+  // dynamically disabled
+  if (m_image_ctx.exclusive_lock == nullptr) {
+    return;
+  }
+
+  if (r == -ETIMEDOUT) {
+    ldout(m_image_ctx.cct, 5) << this << " timed out requesting lock: retrying"
+                              << dendl;
+
+    // treat this is a dead client -- so retest acquiring the lock
+    m_image_ctx.exclusive_lock->handle_peer_notification(0);
+  } else if (r == -EROFS) {
+    ldout(m_image_ctx.cct, 5) << this << " peer will not release lock" << dendl;
+    m_image_ctx.exclusive_lock->handle_peer_notification(r);
+  } else if (r < 0) {
+    lderr(m_image_ctx.cct) << this << " error requesting lock: "
+                           << cpp_strerror(r) << dendl;
+    schedule_request_lock(true);
+  } else {
+    // lock owner acked -- but resend if we don't see them release the lock
+    int retry_timeout = m_image_ctx.cct->_conf->template get_val<int64_t>(
+      "client_notify_timeout");
+    ldout(m_image_ctx.cct, 15) << this << " will retry in " << retry_timeout
+                               << " seconds" << dendl;
+    schedule_request_lock(true, retry_timeout);
+  }
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_lock_owner(const Payload& payload,
+                                        Context *on_finish) {
+  assert(on_finish != nullptr);
+  assert(m_image_ctx.owner_lock.is_locked());
+
+  bufferlist bl;
+  ::encode(NotifyMessage(payload), bl);
+
+  NotifyLockOwner *notify_lock_owner = NotifyLockOwner::create(
+    m_image_ctx, this->m_notifier, std::move(bl), on_finish);
+  notify_lock_owner->send();
+}
+
+template <typename I>
+Context *ImageWatcher<I>::remove_async_request(const AsyncRequestId &id) {
+  RWLock::WLocker async_request_locker(m_async_request_lock);
+  auto it = m_async_requests.find(id);
+  if (it != m_async_requests.end()) {
+    Context *on_complete = it->second.first;
+    m_async_requests.erase(it);
+    return on_complete;
+  }
+  return nullptr;
+}
+
+template <typename I>
+void ImageWatcher<I>::schedule_async_request_timed_out(const AsyncRequestId &id) {
+  ldout(m_image_ctx.cct, 20) << "scheduling async request time out: " << id
+                             << dendl;
+
+  Context *ctx = new FunctionContext(boost::bind(
+    &ImageWatcher<I>::async_request_timed_out, this, id));
+
+  Task task(TASK_CODE_ASYNC_REQUEST, id);
+  m_task_finisher->cancel(task);
+
+  m_task_finisher->add_event_after(task, m_image_ctx.request_timed_out_seconds,
+                                   ctx);
+}
+
+template <typename I>
+void ImageWatcher<I>::async_request_timed_out(const AsyncRequestId &id) {
+  Context *on_complete = remove_async_request(id);
+  if (on_complete != nullptr) {
+    ldout(m_image_ctx.cct, 5) << "async request timed out: " << id << dendl;
+    m_image_ctx.op_work_queue->queue(on_complete, -ETIMEDOUT);
+  }
+}
+
+template <typename I>
+void ImageWatcher<I>::notify_async_request(const AsyncRequestId &async_request_id,
+                                           const Payload& payload,
+                                           ProgressContext& prog_ctx,
+                                           Context *on_finish) {
+  assert(on_finish != nullptr);
+  assert(m_image_ctx.owner_lock.is_locked());
+
+  ldout(m_image_ctx.cct, 10) << this << " async request: " << async_request_id
+                             << dendl;
+
+  Context *on_notify = new FunctionContext([this, async_request_id](int r) {
+    if (r < 0) {
+      // notification failed -- don't expect updates
+      Context *on_complete = remove_async_request(async_request_id);
+      if (on_complete != nullptr) {
+        on_complete->complete(r);
+      }
+    }
+  });
+
+  Context *on_complete = new FunctionContext(
+    [this, async_request_id, on_finish](int r) {
+      m_task_finisher->cancel(Task(TASK_CODE_ASYNC_REQUEST, async_request_id));
+      on_finish->complete(r);
+    });
+
+  {
+    RWLock::WLocker async_request_locker(m_async_request_lock);
+    m_async_requests[async_request_id] = AsyncRequest(on_complete, &prog_ctx);
+  }
+
+  schedule_async_request_timed_out(async_request_id);
+  notify_lock_owner(payload, on_notify);
+}
+
+template <typename I>
+int ImageWatcher<I>::prepare_async_request(const AsyncRequestId& async_request_id,
+                                           bool* new_request, Context** ctx,
+                                           ProgressContext** prog_ctx) {
+  if (async_request_id.client_id == get_client_id()) {
+    return -ERESTART;
+  } else {
+    RWLock::WLocker l(m_async_request_lock);
+    if (m_async_pending.count(async_request_id) == 0) {
+      m_async_pending.insert(async_request_id);
+      *new_request = true;
+      *prog_ctx = new RemoteProgressContext(*this, async_request_id);
+      *ctx = new RemoteContext(*this, async_request_id, *prog_ctx);
+    } else {
+      *new_request = false;
+    }
+  }
+  return 0;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const HeaderUpdatePayload &payload,
+			             C_NotifyAck *ack_ctx) {
+  ldout(m_image_ctx.cct, 10) << this << " image header updated" << dendl;
+
+  m_image_ctx.state->handle_update_notification();
+  m_image_ctx.perfcounter->inc(l_librbd_notify);
+  if (ack_ctx != nullptr) {
+    m_image_ctx.state->flush_update_watchers(new C_ResponseMessage(ack_ctx));
+    return false;
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const AcquiredLockPayload &payload,
+                                     C_NotifyAck *ack_ctx) {
+  ldout(m_image_ctx.cct, 10) << this << " image exclusively locked announcement"
+                             << dendl;
+
+  bool cancel_async_requests = true;
+  if (payload.client_id.is_valid()) {
+    Mutex::Locker owner_client_id_locker(m_owner_client_id_lock);
+    if (payload.client_id == m_owner_client_id) {
+      cancel_async_requests = false;
+    }
+    set_owner_client_id(payload.client_id);
+  }
+
+  RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    // potentially wake up the exclusive lock state machine now that
+    // a lock owner has advertised itself
+    m_image_ctx.exclusive_lock->handle_peer_notification(0);
+  }
+  if (cancel_async_requests &&
+      (m_image_ctx.exclusive_lock == nullptr ||
+       !m_image_ctx.exclusive_lock->is_lock_owner())) {
+    schedule_cancel_async_requests();
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const ReleasedLockPayload &payload,
+                                     C_NotifyAck *ack_ctx) {
+  ldout(m_image_ctx.cct, 10) << this << " exclusive lock released" << dendl;
+
+  bool cancel_async_requests = true;
+  if (payload.client_id.is_valid()) {
+    Mutex::Locker l(m_owner_client_id_lock);
+    if (payload.client_id != m_owner_client_id) {
+      ldout(m_image_ctx.cct, 10) << this << " unexpected owner: "
+                                 << payload.client_id << " != "
+                                 << m_owner_client_id << dendl;
+      cancel_async_requests = false;
+    } else {
+      set_owner_client_id(ClientId());
+    }
+  }
+
+  RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+  if (cancel_async_requests &&
+      (m_image_ctx.exclusive_lock == nullptr ||
+       !m_image_ctx.exclusive_lock->is_lock_owner())) {
+    schedule_cancel_async_requests();
+  }
+
+  // alert the exclusive lock state machine that the lock is available
+  if (m_image_ctx.exclusive_lock != nullptr &&
+      !m_image_ctx.exclusive_lock->is_lock_owner()) {
+    m_task_finisher->cancel(TASK_CODE_REQUEST_LOCK);
+    m_image_ctx.exclusive_lock->handle_peer_notification(0);
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const RequestLockPayload &payload,
+                                     C_NotifyAck *ack_ctx) {
+  ldout(m_image_ctx.cct, 10) << this << " exclusive lock requested" << dendl;
+  if (payload.client_id == get_client_id()) {
+    return true;
+  }
+
+  RWLock::RLocker l(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr &&
+      m_image_ctx.exclusive_lock->is_lock_owner()) {
+    int r = 0;
+    bool accept_request = m_image_ctx.exclusive_lock->accept_requests(&r);
+
+    if (accept_request) {
+      assert(r == 0);
+      Mutex::Locker owner_client_id_locker(m_owner_client_id_lock);
+      if (!m_owner_client_id.is_valid()) {
+        return true;
+      }
+
+      ldout(m_image_ctx.cct, 10) << this << " queuing release of exclusive lock"
+                                 << dendl;
+      r = m_image_ctx.get_exclusive_lock_policy()->lock_requested(
+        payload.force);
+    }
+    ::encode(ResponseMessage(r), ack_ctx->out);
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const AsyncProgressPayload &payload,
+                                     C_NotifyAck *ack_ctx) {
+  RWLock::RLocker l(m_async_request_lock);
+  std::map<AsyncRequestId, AsyncRequest>::iterator req_it =
+    m_async_requests.find(payload.async_request_id);
+  if (req_it != m_async_requests.end()) {
+    ldout(m_image_ctx.cct, 20) << this << " request progress: "
+			       << payload.async_request_id << " @ "
+			       << payload.offset << "/" << payload.total
+			       << dendl;
+    schedule_async_request_timed_out(payload.async_request_id);
+    req_it->second.second->update_progress(payload.offset, payload.total);
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const AsyncCompletePayload &payload,
+                                     C_NotifyAck *ack_ctx) {
+  Context *on_complete = remove_async_request(payload.async_request_id);
+  if (on_complete != nullptr) {
+    ldout(m_image_ctx.cct, 10) << this << " request finished: "
+                               << payload.async_request_id << "="
+			       << payload.result << dendl;
+    on_complete->complete(payload.result);
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const FlattenPayload &payload,
+				     C_NotifyAck *ack_ctx) {
+
+  RWLock::RLocker l(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      bool new_request;
+      Context *ctx;
+      ProgressContext *prog_ctx;
+      r = prepare_async_request(payload.async_request_id, &new_request,
+                                &ctx, &prog_ctx);
+      if (r == 0 && new_request) {
+        ldout(m_image_ctx.cct, 10) << this << " remote flatten request: "
+				   << payload.async_request_id << dendl;
+        m_image_ctx.operations->execute_flatten(*prog_ctx, ctx);
+      }
+
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const ResizePayload &payload,
+				     C_NotifyAck *ack_ctx) {
+  RWLock::RLocker l(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      bool new_request;
+      Context *ctx;
+      ProgressContext *prog_ctx;
+      r = prepare_async_request(payload.async_request_id, &new_request,
+                                &ctx, &prog_ctx);
+      if (r == 0 && new_request) {
+        ldout(m_image_ctx.cct, 10) << this << " remote resize request: "
+				   << payload.async_request_id << " "
+				   << payload.size << " "
+				   << payload.allow_shrink << dendl;
+        m_image_ctx.operations->execute_resize(payload.size, payload.allow_shrink, *prog_ctx, ctx, 0);
+      }
+
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const SnapCreatePayload &payload,
+			             C_NotifyAck *ack_ctx) {
+  RWLock::RLocker l(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      ldout(m_image_ctx.cct, 10) << this << " remote snap_create request: "
+			         << payload.snap_name << dendl;
+
+      m_image_ctx.operations->execute_snap_create(payload.snap_namespace,
+						  payload.snap_name,
+                                                  new C_ResponseMessage(ack_ctx),
+                                                  0, false);
+      return false;
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const SnapRenamePayload &payload,
+			             C_NotifyAck *ack_ctx) {
+  RWLock::RLocker l(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      ldout(m_image_ctx.cct, 10) << this << " remote snap_rename request: "
+			         << payload.snap_id << " to "
+			         << payload.snap_name << dendl;
+
+      m_image_ctx.operations->execute_snap_rename(payload.snap_id,
+                                                  payload.snap_name,
+                                                  new C_ResponseMessage(ack_ctx));
+      return false;
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const SnapRemovePayload &payload,
+			             C_NotifyAck *ack_ctx) {
+  RWLock::RLocker l(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      ldout(m_image_ctx.cct, 10) << this << " remote snap_remove request: "
+			         << payload.snap_name << dendl;
+
+      m_image_ctx.operations->execute_snap_remove(payload.snap_namespace,
+						  payload.snap_name,
+                                                  new C_ResponseMessage(ack_ctx));
+      return false;
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const SnapProtectPayload& payload,
+                                     C_NotifyAck *ack_ctx) {
+  RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      ldout(m_image_ctx.cct, 10) << this << " remote snap_protect request: "
+                                 << payload.snap_name << dendl;
+
+      m_image_ctx.operations->execute_snap_protect(payload.snap_namespace,
+						   payload.snap_name,
+                                                   new C_ResponseMessage(ack_ctx));
+      return false;
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const SnapUnprotectPayload& payload,
+                                     C_NotifyAck *ack_ctx) {
+  RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      ldout(m_image_ctx.cct, 10) << this << " remote snap_unprotect request: "
+                                 << payload.snap_name << dendl;
+
+      m_image_ctx.operations->execute_snap_unprotect(payload.snap_namespace,
+						     payload.snap_name,
+                                                     new C_ResponseMessage(ack_ctx));
+      return false;
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const RebuildObjectMapPayload& payload,
+                                     C_NotifyAck *ack_ctx) {
+  RWLock::RLocker l(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      bool new_request;
+      Context *ctx;
+      ProgressContext *prog_ctx;
+      r = prepare_async_request(payload.async_request_id, &new_request,
+                                &ctx, &prog_ctx);
+      if (r == 0 && new_request) {
+        ldout(m_image_ctx.cct, 10) << this
+                                   << " remote rebuild object map request: "
+                                   << payload.async_request_id << dendl;
+        m_image_ctx.operations->execute_rebuild_object_map(*prog_ctx, ctx);
+      }
+
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const RenamePayload& payload,
+                                     C_NotifyAck *ack_ctx) {
+  RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      ldout(m_image_ctx.cct, 10) << this << " remote rename request: "
+                                 << payload.image_name << dendl;
+
+      m_image_ctx.operations->execute_rename(payload.image_name,
+                                             new C_ResponseMessage(ack_ctx));
+      return false;
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const UpdateFeaturesPayload& payload,
+                                     C_NotifyAck *ack_ctx) {
+  RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r)) {
+      ldout(m_image_ctx.cct, 10) << this << " remote update_features request: "
+                                 << payload.features << " "
+                                 << (payload.enabled ? "enabled" : "disabled")
+                                 << dendl;
+
+      m_image_ctx.operations->execute_update_features(
+        payload.features, payload.enabled, new C_ResponseMessage(ack_ctx), 0);
+      return false;
+    } else if (r < 0) {
+      ::encode(ResponseMessage(r), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+bool ImageWatcher<I>::handle_payload(const UnknownPayload &payload,
+			             C_NotifyAck *ack_ctx) {
+  RWLock::RLocker l(m_image_ctx.owner_lock);
+  if (m_image_ctx.exclusive_lock != nullptr) {
+    int r;
+    if (m_image_ctx.exclusive_lock->accept_requests(&r) || r < 0) {
+      ::encode(ResponseMessage(-EOPNOTSUPP), ack_ctx->out);
+    }
+  }
+  return true;
+}
+
+template <typename I>
+void ImageWatcher<I>::process_payload(uint64_t notify_id, uint64_t handle,
+                                      const Payload &payload) {
+  apply_visitor(HandlePayloadVisitor<ImageWatcher<I>>(this, notify_id, handle),
+                payload);
+}
+
+template <typename I>
+void ImageWatcher<I>::handle_notify(uint64_t notify_id, uint64_t handle,
+			            uint64_t notifier_id, bufferlist &bl) {
+  NotifyMessage notify_message;
+  if (bl.length() == 0) {
+    // legacy notification for header updates
+    notify_message = NotifyMessage(HeaderUpdatePayload());
+  } else {
+    try {
+      bufferlist::iterator iter = bl.begin();
+      ::decode(notify_message, iter);
+    } catch (const buffer::error &err) {
+      lderr(m_image_ctx.cct) << this << " error decoding image notification: "
+			     << err.what() << dendl;
+      return;
+    }
+  }
+
+  // if an image refresh is required, refresh before processing the request
+  if (notify_message.check_for_refresh() &&
+      m_image_ctx.state->is_refresh_required()) {
+    m_image_ctx.state->refresh(new C_ProcessPayload(this, notify_id, handle,
+                                                    notify_message.payload));
+  } else {
+    process_payload(notify_id, handle, notify_message.payload);
+  }
+}
+
+template <typename I>
+void ImageWatcher<I>::handle_error(uint64_t handle, int err) {
+  lderr(m_image_ctx.cct) << this << " image watch failed: " << handle << ", "
+                         << cpp_strerror(err) << dendl;
+
+  {
+    Mutex::Locker l(m_owner_client_id_lock);
+    set_owner_client_id(ClientId());
+  }
+
+  Watcher::handle_error(handle, err);
+}
+
+template <typename I>
+void ImageWatcher<I>::handle_rewatch_complete(int r) {
+  CephContext *cct = m_image_ctx.cct;
+  ldout(cct, 10) << this << " " << __func__ << ": r=" << r << dendl;
+
+  {
+    RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
+    if (m_image_ctx.exclusive_lock != nullptr) {
+      // update the lock cookie with the new watch handle
+      m_image_ctx.exclusive_lock->reacquire_lock();
+    }
+  }
+
+  // image might have been updated while we didn't have active watch
+  handle_payload(HeaderUpdatePayload(), nullptr);
+}
+
+template <typename I>
+void ImageWatcher<I>::send_notify(const Payload &payload, Context *ctx) {
+  bufferlist bl;
+
+  ::encode(NotifyMessage(payload), bl);
+  Watcher::send_notify(bl, nullptr, ctx);
+}
+
+template <typename I>
+void ImageWatcher<I>::RemoteContext::finish(int r) {
+  m_image_watcher.schedule_async_complete(m_async_request_id, r);
+}
+
+template <typename I>
+void ImageWatcher<I>::C_ResponseMessage::finish(int r) {
+  CephContext *cct = notify_ack->cct;
+  ldout(cct, 10) << this << " C_ResponseMessage: r=" << r << dendl;
+
+  ::encode(ResponseMessage(r), notify_ack->out);
+  notify_ack->complete(0);
+}
+
+} // namespace librbd
+
+template class librbd::ImageWatcher<librbd::ImageCtx>;