drivers/staging/lustre/lustre/obdclass/lustre_handles.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * lustre/obdclass/lustre_handles.c
  37  *
  38  * Author: Phil Schwan <phil@clusterfs.com>
  39  */
  40
  41 #define DEBUG_SUBSYSTEM S_CLASS
  42
  43 #include <obd_support.h>
  44 #include <lustre_handles.h>
  45 #include <lustre_lib.h>
  46
  47
  48 static __u64 handle_base;
  49 #define HANDLE_INCR 7
  50 static spinlock_t handle_base_lock;
  51
  52 static struct handle_bucket {
  53         spinlock_t      lock;
  54         struct list_head        head;
  55 } *handle_hash;
  56
  57 #define HANDLE_HASH_SIZE (1 << 16)
  58 #define HANDLE_HASH_MASK (HANDLE_HASH_SIZE - 1)
  59
  60 /*
  61  * Generate a unique 64bit cookie (hash) for a handle and insert it into
  62  * global (per-node) hash-table.
  63  */
  64 void class_handle_hash(struct portals_handle *h,
  65                        struct portals_handle_ops *ops)
  66 {
  67         struct handle_bucket *bucket;
  68         ENTRY;
  69
  70         LASSERT(h != NULL);
  71         LASSERT(list_empty(&h->h_link));
  72
  73         /*
  74          * This is fast, but simplistic cookie generation algorithm, it will
  75          * need a re-do at some point in the future for security.
  76          */
  77         spin_lock(&handle_base_lock);
  78         handle_base += HANDLE_INCR;
  79
  80         if (unlikely(handle_base == 0)) {
  81                 /*
  82                  * Cookie of zero is "dangerous", because in many places it's
  83                  * assumed that 0 means "unassigned" handle, not bound to any
  84                  * object.
  85                  */
  86                 CWARN("The universe has been exhausted: cookie wrap-around.\n");
  87                 handle_base += HANDLE_INCR;
  88         }
  89         h->h_cookie = handle_base;
  90         spin_unlock(&handle_base_lock);
  91
  92         h->h_ops = ops;
  93         spin_lock_init(&h->h_lock);
  94
  95         bucket = &handle_hash[h->h_cookie & HANDLE_HASH_MASK];
  96         spin_lock(&bucket->lock);
  97         list_add_rcu(&h->h_link, &bucket->head);
  98         h->h_in = 1;
  99         spin_unlock(&bucket->lock);
 100
 101         CDEBUG(D_INFO, "added object %p with handle "LPX64" to hash\n",
 102                h, h->h_cookie);
 103         EXIT;
 104 }
 105 EXPORT_SYMBOL(class_handle_hash);
 106
 107 static void class_handle_unhash_nolock(struct portals_handle *h)
 108 {
 109         if (list_empty(&h->h_link)) {
 110                 CERROR("removing an already-removed handle ("LPX64")\n",
 111                        h->h_cookie);
 112                 return;
 113         }
 114
 115         CDEBUG(D_INFO, "removing object %p with handle "LPX64" from hash\n",
 116                h, h->h_cookie);
 117
 118         spin_lock(&h->h_lock);
 119         if (h->h_in == 0) {
 120                 spin_unlock(&h->h_lock);
 121                 return;
 122         }
 123         h->h_in = 0;
 124         spin_unlock(&h->h_lock);
 125         list_del_rcu(&h->h_link);
 126 }
 127
 128 void class_handle_unhash(struct portals_handle *h)
 129 {
 130         struct handle_bucket *bucket;
 131         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 132
 133         spin_lock(&bucket->lock);
 134         class_handle_unhash_nolock(h);
 135         spin_unlock(&bucket->lock);
 136 }
 137 EXPORT_SYMBOL(class_handle_unhash);
 138
 139 void class_handle_hash_back(struct portals_handle *h)
 140 {
 141         struct handle_bucket *bucket;
 142         ENTRY;
 143
 144         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 145
 146         spin_lock(&bucket->lock);
 147         list_add_rcu(&h->h_link, &bucket->head);
 148         h->h_in = 1;
 149         spin_unlock(&bucket->lock);
 150
 151         EXIT;
 152 }
 153 EXPORT_SYMBOL(class_handle_hash_back);
 154
 155 void *class_handle2object(__u64 cookie)
 156 {
 157         struct handle_bucket *bucket;
 158         struct portals_handle *h;
 159         void *retval = NULL;
 160         ENTRY;
 161
 162         LASSERT(handle_hash != NULL);
 163
 164         /* Be careful when you want to change this code. See the
 165          * rcu_read_lock() definition on top this file. - jxiong */
 166         bucket = handle_hash + (cookie & HANDLE_HASH_MASK);
 167
 168         rcu_read_lock();
 169         list_for_each_entry_rcu(h, &bucket->head, h_link) {
 170                 if (h->h_cookie != cookie)
 171                         continue;
 172
 173                 spin_lock(&h->h_lock);
 174                 if (likely(h->h_in != 0)) {
 175                         h->h_ops->hop_addref(h);
 176                         retval = h;
 177                 }
 178                 spin_unlock(&h->h_lock);
 179                 break;
 180         }
 181         rcu_read_unlock();
 182
 183         RETURN(retval);
 184 }
 185 EXPORT_SYMBOL(class_handle2object);
 186
 187 void class_handle_free_cb(cfs_rcu_head_t *rcu)
 188 {
 189         struct portals_handle *h = RCU2HANDLE(rcu);
 190         void *ptr = (void *)(unsigned long)h->h_cookie;
 191
 192         if (h->h_ops->hop_free != NULL)
 193                 h->h_ops->hop_free(ptr, h->h_size);
 194         else
 195                 OBD_FREE(ptr, h->h_size);
 196 }
 197 EXPORT_SYMBOL(class_handle_free_cb);
 198
 199 int class_handle_init(void)
 200 {
 201         struct handle_bucket *bucket;
 202         struct timeval tv;
 203         int seed[2];
 204
 205         LASSERT(handle_hash == NULL);
 206
 207         OBD_ALLOC_LARGE(handle_hash, sizeof(*bucket) * HANDLE_HASH_SIZE);
 208         if (handle_hash == NULL)
 209                 return -ENOMEM;
 210
 211         spin_lock_init(&handle_base_lock);
 212         for (bucket = handle_hash + HANDLE_HASH_SIZE - 1; bucket >= handle_hash;
 213              bucket--) {
 214                 INIT_LIST_HEAD(&bucket->head);
 215                 spin_lock_init(&bucket->lock);
 216         }
 217
 218         /** bug 21430: add randomness to the initial base */
 219         cfs_get_random_bytes(seed, sizeof(seed));
 220         do_gettimeofday(&tv);
 221         cfs_srand(tv.tv_sec ^ seed[0], tv.tv_usec ^ seed[1]);
 222
 223         cfs_get_random_bytes(&handle_base, sizeof(handle_base));
 224         LASSERT(handle_base != 0ULL);
 225
 226         return 0;
 227 }
 228
 229 static int cleanup_all_handles(void)
 230 {
 231         int rc;
 232         int i;
 233
 234         for (rc = i = 0; i < HANDLE_HASH_SIZE; i++) {
 235                 struct portals_handle *h;
 236
 237                 spin_lock(&handle_hash[i].lock);
 238                 list_for_each_entry_rcu(h, &(handle_hash[i].head), h_link) {
 239                         CERROR("force clean handle "LPX64" addr %p ops %p\n",
 240                                h->h_cookie, h, h->h_ops);
 241
 242                         class_handle_unhash_nolock(h);
 243                         rc++;
 244                 }
 245                 spin_unlock(&handle_hash[i].lock);
 246         }
 247
 248         return rc;
 249 }
 250
 251 void class_handle_cleanup(void)
 252 {
 253         int count;
 254         LASSERT(handle_hash != NULL);
 255
 256         count = cleanup_all_handles();
 257
 258         OBD_FREE_LARGE(handle_hash, sizeof(*handle_hash) * HANDLE_HASH_SIZE);
 259         handle_hash = NULL;
 260
 261         if (count != 0)
 262                 CERROR("handle_count at cleanup: %d\n", count);
 263 }