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, Whamcloud, Inc.
  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 #ifndef __KERNEL__
  43 # include <liblustre.h>
  44 #endif
  45
  46 #include <obd_support.h>
  47 #include <lustre_handles.h>
  48 #include <lustre_lib.h>
  49
  50 #ifndef __KERNEL__
  51 # define list_add_rcu            cfs_list_add
  52 # define list_del_rcu            cfs_list_del
  53 # define list_for_each_rcu       cfs_list_for_each
  54 # define list_for_each_safe_rcu  cfs_list_for_each_safe
  55 # define list_for_each_entry_rcu cfs_list_for_each_entry
  56 # define rcu_read_lock()         cfs_spin_lock(&bucket->lock)
  57 # define rcu_read_unlock()       cfs_spin_unlock(&bucket->lock)
  58 #endif /* !__KERNEL__ */
  59
  60 static __u64 handle_base;
  61 #define HANDLE_INCR 7
  62 static cfs_spinlock_t handle_base_lock;
  63
  64 static struct handle_bucket {
  65         cfs_spinlock_t  lock;
  66         cfs_list_t      head;
  67 } *handle_hash;
  68
  69 #ifdef __arch_um__
  70 /* For unknown reason, UML uses kmalloc rather than vmalloc to allocate
  71  * memory(OBD_VMALLOC). Therefore, we have to redefine the
  72  * HANDLE_HASH_SIZE to make the hash heads don't exceed 128K.
  73  */
  74 #define HANDLE_HASH_SIZE 4096
  75 #else
  76 #define HANDLE_HASH_SIZE (1 << 16)
  77 #endif /* ifdef __arch_um__ */
  78
  79 #define HANDLE_HASH_MASK (HANDLE_HASH_SIZE - 1)
  80
  81 /*
  82  * Generate a unique 64bit cookie (hash) for a handle and insert it into
  83  * global (per-node) hash-table.
  84  */
  85 void class_handle_hash(struct portals_handle *h,
  86                        struct portals_handle_ops *ops)
  87 {
  88         struct handle_bucket *bucket;
  89         ENTRY;
  90
  91         LASSERT(h != NULL);
  92         LASSERT(cfs_list_empty(&h->h_link));
  93
  94         /*
  95          * This is fast, but simplistic cookie generation algorithm, it will
  96          * need a re-do at some point in the future for security.
  97          */
  98         cfs_spin_lock(&handle_base_lock);
  99         handle_base += HANDLE_INCR;
 100
 101         h->h_cookie = handle_base;
 102         if (unlikely(handle_base == 0)) {
 103                 /*
 104                  * Cookie of zero is "dangerous", because in many places it's
 105                  * assumed that 0 means "unassigned" handle, not bound to any
 106                  * object.
 107                  */
 108                 CWARN("The universe has been exhausted: cookie wrap-around.\n");
 109                 handle_base += HANDLE_INCR;
 110         }
 111         cfs_spin_unlock(&handle_base_lock);
 112
 113         h->h_ops = ops;
 114         cfs_spin_lock_init(&h->h_lock);
 115
 116         bucket = &handle_hash[h->h_cookie & HANDLE_HASH_MASK];
 117         cfs_spin_lock(&bucket->lock);
 118         list_add_rcu(&h->h_link, &bucket->head);
 119         h->h_in = 1;
 120         cfs_spin_unlock(&bucket->lock);
 121
 122         CDEBUG(D_INFO, "added object %p with handle "LPX64" to hash\n",
 123                h, h->h_cookie);
 124         EXIT;
 125 }
 126 EXPORT_SYMBOL(class_handle_hash);
 127
 128 static void class_handle_unhash_nolock(struct portals_handle *h)
 129 {
 130         if (cfs_list_empty(&h->h_link)) {
 131                 CERROR("removing an already-removed handle ("LPX64")\n",
 132                        h->h_cookie);
 133                 return;
 134         }
 135
 136         CDEBUG(D_INFO, "removing object %p with handle "LPX64" from hash\n",
 137                h, h->h_cookie);
 138
 139         cfs_spin_lock(&h->h_lock);
 140         if (h->h_in == 0) {
 141                 cfs_spin_unlock(&h->h_lock);
 142                 return;
 143         }
 144         h->h_in = 0;
 145         cfs_spin_unlock(&h->h_lock);
 146         list_del_rcu(&h->h_link);
 147 }
 148
 149 void class_handle_unhash(struct portals_handle *h)
 150 {
 151         struct handle_bucket *bucket;
 152         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 153
 154         cfs_spin_lock(&bucket->lock);
 155         class_handle_unhash_nolock(h);
 156         cfs_spin_unlock(&bucket->lock);
 157 }
 158 EXPORT_SYMBOL(class_handle_unhash);
 159
 160 void class_handle_hash_back(struct portals_handle *h)
 161 {
 162         struct handle_bucket *bucket;
 163         ENTRY;
 164
 165         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 166
 167         cfs_spin_lock(&bucket->lock);
 168         list_add_rcu(&h->h_link, &bucket->head);
 169         h->h_in = 1;
 170         cfs_spin_unlock(&bucket->lock);
 171
 172         EXIT;
 173 }
 174 EXPORT_SYMBOL(class_handle_hash_back);
 175
 176 void *class_handle2object(__u64 cookie)
 177 {
 178         struct handle_bucket *bucket;
 179         struct portals_handle *h;
 180         void *retval = NULL;
 181         ENTRY;
 182
 183         LASSERT(handle_hash != NULL);
 184
 185         /* Be careful when you want to change this code. See the
 186          * rcu_read_lock() definition on top this file. - jxiong */
 187         bucket = handle_hash + (cookie & HANDLE_HASH_MASK);
 188
 189         rcu_read_lock();
 190         list_for_each_entry_rcu(h, &bucket->head, h_link) {
 191                 if (h->h_cookie != cookie)
 192                         continue;
 193
 194                 cfs_spin_lock(&h->h_lock);
 195                 if (likely(h->h_in != 0)) {
 196                         h->h_ops->hop_addref(h);
 197                         retval = h;
 198                 }
 199                 cfs_spin_unlock(&h->h_lock);
 200                 break;
 201         }
 202         rcu_read_unlock();
 203
 204         RETURN(retval);
 205 }
 206 EXPORT_SYMBOL(class_handle2object);
 207
 208 void class_handle_free_cb(cfs_rcu_head_t *rcu)
 209 {
 210         struct portals_handle *h = RCU2HANDLE(rcu);
 211         void *ptr = (void *)(unsigned long)h->h_cookie;
 212
 213         if (h->h_ops->hop_free != NULL)
 214                 h->h_ops->hop_free(ptr, h->h_size);
 215         else
 216                 OBD_FREE(ptr, h->h_size);
 217 }
 218 EXPORT_SYMBOL(class_handle_free_cb);
 219
 220 int class_handle_init(void)
 221 {
 222         struct handle_bucket *bucket;
 223         struct timeval tv;
 224         int seed[2];
 225
 226         LASSERT(handle_hash == NULL);
 227
 228         OBD_ALLOC_LARGE(handle_hash, sizeof(*bucket) * HANDLE_HASH_SIZE);
 229         if (handle_hash == NULL)
 230                 return -ENOMEM;
 231
 232         cfs_spin_lock_init(&handle_base_lock);
 233         for (bucket = handle_hash + HANDLE_HASH_SIZE - 1; bucket >= handle_hash;
 234              bucket--) {
 235                 CFS_INIT_LIST_HEAD(&bucket->head);
 236                 cfs_spin_lock_init(&bucket->lock);
 237         }
 238
 239         /** bug 21430: add randomness to the initial base */
 240         cfs_get_random_bytes(seed, sizeof(seed));
 241         cfs_gettimeofday(&tv);
 242         cfs_srand(tv.tv_sec ^ seed[0], tv.tv_usec ^ seed[1]);
 243
 244         cfs_get_random_bytes(&handle_base, sizeof(handle_base));
 245         LASSERT(handle_base != 0ULL);
 246
 247         return 0;
 248 }
 249
 250 static int cleanup_all_handles(void)
 251 {
 252         int rc;
 253         int i;
 254
 255         for (rc = i = 0; i < HANDLE_HASH_SIZE; i++) {
 256                 struct portals_handle *h;
 257
 258                 cfs_spin_lock(&handle_hash[i].lock);
 259                 list_for_each_entry_rcu(h, &(handle_hash[i].head), h_link) {
 260                         CERROR("force clean handle "LPX64" addr %p ops %p\n",
 261                                h->h_cookie, h, h->h_ops);
 262
 263                         class_handle_unhash_nolock(h);
 264                         rc++;
 265                 }
 266                 cfs_spin_unlock(&handle_hash[i].lock);
 267         }
 268
 269         return rc;
 270 }
 271
 272 void class_handle_cleanup(void)
 273 {
 274         int count;
 275         LASSERT(handle_hash != NULL);
 276
 277         count = cleanup_all_handles();
 278
 279         OBD_FREE_LARGE(handle_hash, sizeof(*handle_hash) * HANDLE_HASH_SIZE);
 280         handle_hash = NULL;
 281
 282         if (count != 0)
 283                 CERROR("handle_count at cleanup: %d\n", count);
 284 }