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diff --git a/src/common/mutex_debug.h b/src/common/mutex_debug.h
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@@ -0,0 +1,209 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#ifndef CEPH_COMMON_MUTEX_DEBUG_H
+#define CEPH_COMMON_MUTEX_DEBUG_H
+
+#include <atomic>
+#include <system_error>
+#include <thread>
+
+#include <pthread.h>
+
+#include "include/ceph_assert.h"
+#include "include/common_fwd.h"
+
+#include "ceph_time.h"
+#include "likely.h"
+#include "lockdep.h"
+
+namespace ceph {
+namespace mutex_debug_detail {
+
+class mutex_debugging_base
+{
+protected:
+  std::string group;
+  int id = -1;
+  bool lockdep;   // track this mutex using lockdep_*
+  bool backtrace; // gather backtrace on lock acquisition
+
+  std::atomic<int> nlock = 0;
+  std::thread::id locked_by = {};
+
+  bool _enable_lockdep() const {
+    return lockdep && g_lockdep;
+  }
+  void _register();
+  void _will_lock(bool recursive=false); // about to lock
+  void _locked(); // just locked
+  void _will_unlock(); // about to unlock
+
+  mutex_debugging_base(std::string group, bool ld = true, bool bt = false);
+  ~mutex_debugging_base();
+
+public:
+  bool is_locked() const {
+    return (nlock > 0);
+  }
+  bool is_locked_by_me() const {
+    return nlock.load(std::memory_order_acquire) > 0 && locked_by == std::this_thread::get_id();
+  }
+  operator bool() const {
+    return is_locked_by_me();
+  }
+};
+
+// Since this is a /debugging/ mutex just define it in terms of the
+// pthread error check mutex.
+template<bool Recursive>
+class mutex_debug_impl : public mutex_debugging_base
+{
+private:
+  pthread_mutex_t m;
+
+  void _init() {
+    pthread_mutexattr_t a;
+    pthread_mutexattr_init(&a);
+    int r;
+    if (recursive)
+      r = pthread_mutexattr_settype(&a, PTHREAD_MUTEX_RECURSIVE);
+    else
+      r = pthread_mutexattr_settype(&a, PTHREAD_MUTEX_ERRORCHECK);
+    ceph_assert(r == 0);
+    r = pthread_mutex_init(&m, &a);
+    ceph_assert(r == 0);
+  }
+
+  bool enable_lockdep(bool no_lockdep) const {
+    if (recursive) {
+      return false;
+    } else if (no_lockdep) {
+      return false;
+    } else {
+      return _enable_lockdep();
+    }
+  }
+
+public:
+  static constexpr bool recursive = Recursive;
+
+  mutex_debug_impl(std::string group, bool ld = true, bool bt = false)
+    : mutex_debugging_base(group, ld, bt) {
+    _init();
+  }
+
+  // Mutex is Destructible
+  ~mutex_debug_impl() {
+    int r = pthread_mutex_destroy(&m);
+    ceph_assert(r == 0);
+  }
+
+  // Mutex concept is non-Copyable
+  mutex_debug_impl(const mutex_debug_impl&) = delete;
+  mutex_debug_impl& operator =(const mutex_debug_impl&) = delete;
+
+  // Mutex concept is non-Movable
+  mutex_debug_impl(mutex_debug_impl&&) = delete;
+  mutex_debug_impl& operator =(mutex_debug_impl&&) = delete;
+
+  void lock_impl() {
+    int r = pthread_mutex_lock(&m);
+    // Allowed error codes for Mutex concept
+    if (unlikely(r == EPERM ||
+		 r == EDEADLK ||
+		 r == EBUSY)) {
+      throw std::system_error(r, std::generic_category());
+    }
+    ceph_assert(r == 0);
+  }
+
+  void unlock_impl() noexcept {
+    int r = pthread_mutex_unlock(&m);
+    ceph_assert(r == 0);
+  }
+
+  bool try_lock_impl() {
+    int r = pthread_mutex_trylock(&m);
+    switch (r) {
+    case 0:
+      return true;
+    case EBUSY:
+      return false;
+    default:
+      throw std::system_error(r, std::generic_category());
+    }
+  }
+  pthread_mutex_t* native_handle() {
+    return &m;
+  }
+
+  void _post_lock() {
+    if (!recursive)
+      ceph_assert(nlock == 0);
+    locked_by = std::this_thread::get_id();
+    nlock.fetch_add(1, std::memory_order_release);
+  }
+
+  void _pre_unlock() {
+    if (recursive) {
+      ceph_assert(nlock > 0);
+    } else {
+      ceph_assert(nlock == 1);
+    }
+    ceph_assert(locked_by == std::this_thread::get_id());
+    if (nlock == 1)
+      locked_by = std::thread::id();
+    nlock.fetch_sub(1, std::memory_order_release);
+  }
+
+  bool try_lock(bool no_lockdep = false) {
+    bool locked = try_lock_impl();
+    if (locked) {
+      if (enable_lockdep(no_lockdep))
+	_locked();
+      _post_lock();
+    }
+    return locked;
+  }
+
+  void lock(bool no_lockdep = false) {
+    if (enable_lockdep(no_lockdep))
+      _will_lock(recursive);
+
+    if (try_lock(no_lockdep))
+      return;
+
+    lock_impl();
+    if (enable_lockdep(no_lockdep))
+      _locked();
+    _post_lock();
+  }
+
+  void unlock(bool no_lockdep = false) {
+    _pre_unlock();
+    if (enable_lockdep(no_lockdep))
+      _will_unlock();
+    unlock_impl();
+  }
+
+};
+
+
+} // namespace mutex_debug_detail
+typedef mutex_debug_detail::mutex_debug_impl<false> mutex_debug;
+typedef mutex_debug_detail::mutex_debug_impl<true> mutex_recursive_debug;
+} // namespace ceph
+
+#endif