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diff --git a/src/ceph/src/os/filestore/FDCache.h b/src/ceph/src/os/filestore/FDCache.h
new file mode 100644
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+++ b/src/ceph/src/os/filestore/FDCache.h
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+// -*- 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) 2013 Inktank Storage, Inc.
+ *
+ * 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_FDCACHE_H
+#define CEPH_FDCACHE_H
+
+#include <memory>
+#include <errno.h>
+#include <cstdio>
+#include "common/hobject.h"
+#include "common/Mutex.h"
+#include "common/Cond.h"
+#include "common/shared_cache.hpp"
+#include "include/compat.h"
+#include "include/intarith.h"
+
+/**
+ * FD Cache
+ */
+class FDCache : public md_config_obs_t {
+public:
+  /**
+   * FD
+   *
+   * Wrapper for an fd.  Destructor closes the fd.
+   */
+  class FD {
+  public:
+    const int fd;
+    explicit FD(int _fd) : fd(_fd) {
+      assert(_fd >= 0);
+    }
+    int operator*() const {
+      return fd;
+    }
+    ~FD() {
+      VOID_TEMP_FAILURE_RETRY(::close(fd));
+    }
+  };
+
+private:
+  CephContext *cct;
+  const int registry_shards;
+  SharedLRU<ghobject_t, FD> *registry;
+
+public:
+  explicit FDCache(CephContext *cct) : cct(cct),
+  registry_shards(MAX(cct->_conf->filestore_fd_cache_shards, 1)) {
+    assert(cct);
+    cct->_conf->add_observer(this);
+    registry = new SharedLRU<ghobject_t, FD>[registry_shards];
+    for (int i = 0; i < registry_shards; ++i) {
+      registry[i].set_cct(cct);
+      registry[i].set_size(
+          MAX((cct->_conf->filestore_fd_cache_size / registry_shards), 1));
+    }
+  }
+  ~FDCache() override {
+    cct->_conf->remove_observer(this);
+    delete[] registry;
+  }
+  typedef ceph::shared_ptr<FD> FDRef;
+
+  FDRef lookup(const ghobject_t &hoid) {
+    int registry_id = hoid.hobj.get_hash() % registry_shards;
+    return registry[registry_id].lookup(hoid);
+  }
+
+  FDRef add(const ghobject_t &hoid, int fd, bool *existed) {
+    int registry_id = hoid.hobj.get_hash() % registry_shards;
+    return registry[registry_id].add(hoid, new FD(fd), existed);
+  }
+
+  /// clear cached fd for hoid, subsequent lookups will get an empty FD
+  void clear(const ghobject_t &hoid) {
+    int registry_id = hoid.hobj.get_hash() % registry_shards;
+    registry[registry_id].purge(hoid);
+  }
+
+  /// md_config_obs_t
+  const char** get_tracked_conf_keys() const override {
+    static const char* KEYS[] = {
+      "filestore_fd_cache_size",
+      NULL
+    };
+    return KEYS;
+  }
+  void handle_conf_change(const md_config_t *conf,
+			  const std::set<std::string> &changed) override {
+    if (changed.count("filestore_fd_cache_size")) {
+      for (int i = 0; i < registry_shards; ++i)
+        registry[i].set_size(
+              MAX((conf->filestore_fd_cache_size / registry_shards), 1));
+    }
+  }
+
+};
+typedef FDCache::FDRef FDRef;
+
+#endif