text: /*
   * GPL HEADER START
   *
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 only,
   * as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License version 2 for more details (a copy is included
   * in the LICENSE file that accompanied this code).
   *
   * You should have received a copy of the GNU General Public License
   * version 2 along with this program; If not, see
   * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
   *
   * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
   * CA 95054 USA or visit www.sun.com if you need additional information or
   * have any questions.
   *
   * GPL HEADER END
   */
  /*
   * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
   * Use is subject to license terms.
   *
   * Copyright (c) 2011, 2012, Intel Corporation.
   */
  /*
   * This file is part of Lustre, http://www.lustre.org/
   * Lustre is a trademark of Sun Microsystems, Inc.
   *
   * lustre/obdclass/lustre_handles.c
   *
   * Author: Phil Schwan <phil@clusterfs.com>
   */
  
  #define DEBUG_SUBSYSTEM S_CLASS
  
  #include "../include/obd_support.h"
  #include "../include/lustre_handles.h"
  #include "../include/lustre_lib.h"
  
  
  static __u64 handle_base;
  #define HANDLE_INCR 7
  static spinlock_t handle_base_lock;
  
  static struct handle_bucket {
  	spinlock_t	lock;
  	struct list_head	head;
  } *handle_hash;
  
  #define HANDLE_HASH_SIZE (1 << 16)
  #define HANDLE_HASH_MASK (HANDLE_HASH_SIZE - 1)
  
  /*
   * Generate a unique 64bit cookie (hash) for a handle and insert it into
   * global (per-node) hash-table.
   */
  void class_handle_hash(struct portals_handle *h,
  		       struct portals_handle_ops *ops)
  {
  	struct handle_bucket *bucket;
  
  	LASSERT(h != NULL);
  	LASSERT(list_empty(&h->h_link));
  
  	/*
  	 * This is fast, but simplistic cookie generation algorithm, it will
  	 * need a re-do at some point in the future for security.
  	 */
  	spin_lock(&handle_base_lock);
  	handle_base += HANDLE_INCR;
  
  	if (unlikely(handle_base == 0)) {
  		/*
  		 * Cookie of zero is "dangerous", because in many places it's
  		 * assumed that 0 means "unassigned" handle, not bound to any
  		 * object.
  		 */
  		CWARN("The universe has been exhausted: cookie wrap-around.\n");
  		handle_base += HANDLE_INCR;
  	}
  	h->h_cookie = handle_base;
  	spin_unlock(&handle_base_lock);
  
  	h->h_ops = ops;
  	spin_lock_init(&h->h_lock);
  
  	bucket = &handle_hash[h->h_cookie & HANDLE_HASH_MASK];
  	spin_lock(&bucket->lock);
  	list_add_rcu(&h->h_link, &bucket->head);
  	h->h_in = 1;
  	spin_unlock(&bucket->lock);
  
  	CDEBUG(D_INFO, "added object %p with handle %#llx to hash\n",
  	       h, h->h_cookie);
  }
  EXPORT_SYMBOL(class_handle_hash);
  
  static void class_handle_unhash_nolock(struct portals_handle *h)
  {
  	if (list_empty(&h->h_link)) {
  		CERROR("removing an already-removed handle (%#llx)\n",
  		       h->h_cookie);
  		return;
  	}
  
  	CDEBUG(D_INFO, "removing object %p with handle %#llx from hash\n",
  	       h, h->h_cookie);
  
  	spin_lock(&h->h_lock);
  	if (h->h_in == 0) {
  		spin_unlock(&h->h_lock);
  		return;
  	}
  	h->h_in = 0;
  	spin_unlock(&h->h_lock);
  	list_del_rcu(&h->h_link);
  }
  
  void class_handle_unhash(struct portals_handle *h)
  {
  	struct handle_bucket *bucket;
  	bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
  
  	spin_lock(&bucket->lock);
  	class_handle_unhash_nolock(h);
  	spin_unlock(&bucket->lock);
  }
  EXPORT_SYMBOL(class_handle_unhash);
  
  void class_handle_hash_back(struct portals_handle *h)
  {
  	struct handle_bucket *bucket;
  
  	bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
  
  	spin_lock(&bucket->lock);
  	list_add_rcu(&h->h_link, &bucket->head);
  	h->h_in = 1;
  	spin_unlock(&bucket->lock);
  }
  EXPORT_SYMBOL(class_handle_hash_back);
  
  void *class_handle2object(__u64 cookie)
  {
  	struct handle_bucket *bucket;
  	struct portals_handle *h;
  	void *retval = NULL;
  
  	LASSERT(handle_hash != NULL);
  
  	/* Be careful when you want to change this code. See the
  	 * rcu_read_lock() definition on top this file. - jxiong */
  	bucket = handle_hash + (cookie & HANDLE_HASH_MASK);
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(h, &bucket->head, h_link) {
  		if (h->h_cookie != cookie)
  			continue;
  
  		spin_lock(&h->h_lock);
  		if (likely(h->h_in != 0)) {
  			h->h_ops->hop_addref(h);
  			retval = h;
  		}
  		spin_unlock(&h->h_lock);
  		break;
  	}
  	rcu_read_unlock();
  
  	return retval;
  }
  EXPORT_SYMBOL(class_handle2object);
  
  void class_handle_free_cb(struct rcu_head *rcu)
  {
  	struct portals_handle *h = RCU2HANDLE(rcu);
  	void *ptr = (void *)(unsigned long)h->h_cookie;
  
  	if (h->h_ops->hop_free != NULL)
  		h->h_ops->hop_free(ptr, h->h_size);
  	else
  		kfree(ptr);
  }
  EXPORT_SYMBOL(class_handle_free_cb);
  
  int class_handle_init(void)
  {
  	struct handle_bucket *bucket;
  	struct timeval tv;
  	int seed[2];
  
  	LASSERT(handle_hash == NULL);
  
  	handle_hash = libcfs_kvzalloc(sizeof(*bucket) * HANDLE_HASH_SIZE,
  				      GFP_NOFS);
  	if (handle_hash == NULL)
  		return -ENOMEM;
  
  	spin_lock_init(&handle_base_lock);
  	for (bucket = handle_hash + HANDLE_HASH_SIZE - 1; bucket >= handle_hash;
  	     bucket--) {
  		INIT_LIST_HEAD(&bucket->head);
  		spin_lock_init(&bucket->lock);
  	}
  
  	/** bug 21430: add randomness to the initial base */
  	cfs_get_random_bytes(seed, sizeof(seed));
  	do_gettimeofday(&tv);
  	cfs_srand(tv.tv_sec ^ seed[0], tv.tv_usec ^ seed[1]);
  
  	cfs_get_random_bytes(&handle_base, sizeof(handle_base));
  	LASSERT(handle_base != 0ULL);
  
  	return 0;
  }
  
  static int cleanup_all_handles(void)
  {
  	int rc;
  	int i;
  
  	for (rc = i = 0; i < HANDLE_HASH_SIZE; i++) {
  		struct portals_handle *h;
  
  		spin_lock(&handle_hash[i].lock);
  		list_for_each_entry_rcu(h, &(handle_hash[i].head), h_link) {
  			CERROR("force clean handle %#llx addr %p ops %p\n",
  			       h->h_cookie, h, h->h_ops);
  
  			class_handle_unhash_nolock(h);
  			rc++;
  		}
  		spin_unlock(&handle_hash[i].lock);
  	}
  
  	return rc;
  }
  
  void class_handle_cleanup(void)
  {
  	int count;
  	LASSERT(handle_hash != NULL);
  
  	count = cleanup_all_handles();
  
  	kvfree(handle_hash);
  	handle_hash = NULL;
  
  	if (count != 0)
  		CERROR("handle_count at cleanup: %d\n", count);
  }
  