lustre/obdclass/lustre_handles.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * GPL HEADER START
   5  *
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 only,
  10  * as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License version 2 for more details (a copy is included
  16  * in the LICENSE file that accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * version 2 along with this program; If not, see
  20  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *
  26  * GPL HEADER END
  27  */
  28 /*
  29  * Copyright  2008 Sun Microsystems, Inc. All rights reserved
  30  * Use is subject to license terms.
  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 #if !defined(HAVE_RCU) || !defined(__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 /* ifndef HAVE_RCU */
  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 static cfs_atomic_t handle_count = CFS_ATOMIC_INIT(0);
  70
  71 #ifdef __arch_um__
  72 /* For unknown reason, UML uses kmalloc rather than vmalloc to allocate
  73  * memory(OBD_VMALLOC). Therefore, we have to redefine the
  74  * HANDLE_HASH_SIZE to make the hash heads don't exceed 128K.
  75  */
  76 #define HANDLE_HASH_SIZE 4096
  77 #else
  78 #define HANDLE_HASH_SIZE (1 << 14)
  79 #endif /* ifdef __arch_um__ */
  80
  81 #define HANDLE_HASH_MASK (HANDLE_HASH_SIZE - 1)
  82
  83 /*
  84  * Generate a unique 64bit cookie (hash) for a handle and insert it into
  85  * global (per-node) hash-table.
  86  */
  87 void class_handle_hash(struct portals_handle *h, portals_handle_addref_cb cb)
  88 {
  89         struct handle_bucket *bucket;
  90         ENTRY;
  91
  92         LASSERT(h != NULL);
  93         LASSERT(cfs_list_empty(&h->h_link));
  94
  95         /*
  96          * This is fast, but simplistic cookie generation algorithm, it will
  97          * need a re-do at some point in the future for security.
  98          */
  99         cfs_spin_lock(&handle_base_lock);
 100         handle_base += HANDLE_INCR;
 101
 102         h->h_cookie = handle_base;
 103         if (unlikely(handle_base == 0)) {
 104                 /*
 105                  * Cookie of zero is "dangerous", because in many places it's
 106                  * assumed that 0 means "unassigned" handle, not bound to any
 107                  * object.
 108                  */
 109                 CWARN("The universe has been exhausted: cookie wrap-around.\n");
 110                 handle_base += HANDLE_INCR;
 111         }
 112         cfs_spin_unlock(&handle_base_lock);
 113
 114         cfs_atomic_inc(&handle_count);
 115         h->h_addref = cb;
 116         cfs_spin_lock_init(&h->h_lock);
 117
 118         bucket = &handle_hash[h->h_cookie & HANDLE_HASH_MASK];
 119         cfs_spin_lock(&bucket->lock);
 120         list_add_rcu(&h->h_link, &bucket->head);
 121         h->h_in = 1;
 122         cfs_spin_unlock(&bucket->lock);
 123
 124         CDEBUG(D_INFO, "added object %p with handle "LPX64" to hash\n",
 125                h, h->h_cookie);
 126         EXIT;
 127 }
 128
 129 static void class_handle_unhash_nolock(struct portals_handle *h)
 130 {
 131         if (cfs_list_empty(&h->h_link)) {
 132                 CERROR("removing an already-removed handle ("LPX64")\n",
 133                        h->h_cookie);
 134                 return;
 135         }
 136
 137         CDEBUG(D_INFO, "removing object %p with handle "LPX64" from hash\n",
 138                h, h->h_cookie);
 139
 140         cfs_spin_lock(&h->h_lock);
 141         if (h->h_in == 0) {
 142                 cfs_spin_unlock(&h->h_lock);
 143                 return;
 144         }
 145         h->h_in = 0;
 146         cfs_spin_unlock(&h->h_lock);
 147         list_del_rcu(&h->h_link);
 148 }
 149
 150 void class_handle_unhash(struct portals_handle *h)
 151 {
 152         struct handle_bucket *bucket;
 153         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 154
 155         cfs_spin_lock(&bucket->lock);
 156         class_handle_unhash_nolock(h);
 157         cfs_spin_unlock(&bucket->lock);
 158
 159         cfs_atomic_dec(&handle_count);
 160 }
 161
 162 void class_handle_hash_back(struct portals_handle *h)
 163 {
 164         struct handle_bucket *bucket;
 165         ENTRY;
 166
 167         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 168
 169         cfs_atomic_inc(&handle_count);
 170         cfs_spin_lock(&bucket->lock);
 171         list_add_rcu(&h->h_link, &bucket->head);
 172         h->h_in = 1;
 173         cfs_spin_unlock(&bucket->lock);
 174
 175         EXIT;
 176 }
 177
 178 void *class_handle2object(__u64 cookie)
 179 {
 180         struct handle_bucket *bucket;
 181         struct portals_handle *h;
 182         void *retval = NULL;
 183         ENTRY;
 184
 185         LASSERT(handle_hash != NULL);
 186
 187         /* Be careful when you want to change this code. See the
 188          * rcu_read_lock() definition on top this file. - jxiong */
 189         bucket = handle_hash + (cookie & HANDLE_HASH_MASK);
 190
 191         rcu_read_lock();
 192         list_for_each_entry_rcu(h, &bucket->head, h_link) {
 193                 if (h->h_cookie != cookie)
 194                         continue;
 195
 196                 cfs_spin_lock(&h->h_lock);
 197                 if (likely(h->h_in != 0)) {
 198                         h->h_addref(h);
 199                         retval = h;
 200                 }
 201                 cfs_spin_unlock(&h->h_lock);
 202                 break;
 203         }
 204         rcu_read_unlock();
 205
 206         RETURN(retval);
 207 }
 208
 209 void class_handle_free_cb(cfs_rcu_head_t *rcu)
 210 {
 211         struct portals_handle *h = RCU2HANDLE(rcu);
 212         if (h->h_free_cb) {
 213                 h->h_free_cb(h->h_ptr, h->h_size);
 214         } else {
 215                 void *ptr = h->h_ptr;
 216                 unsigned int size = h->h_size;
 217                 OBD_FREE(ptr, size);
 218         }
 219 }
 220
 221 int class_handle_init(void)
 222 {
 223         struct handle_bucket *bucket;
 224         struct timeval tv;
 225         int seed[2];
 226
 227         LASSERT(handle_hash == NULL);
 228
 229         OBD_VMALLOC(handle_hash, sizeof(*bucket) * HANDLE_HASH_SIZE);
 230         if (handle_hash == NULL)
 231                 return -ENOMEM;
 232
 233         cfs_spin_lock_init(&handle_base_lock);
 234         for (bucket = handle_hash + HANDLE_HASH_SIZE - 1; bucket >= handle_hash;
 235              bucket--) {
 236                 CFS_INIT_LIST_HEAD(&bucket->head);
 237                 cfs_spin_lock_init(&bucket->lock);
 238         }
 239
 240         /** bug 21430: add randomness to the initial base */
 241         ll_get_random_bytes(seed, sizeof(seed));
 242         cfs_gettimeofday(&tv);
 243         ll_srand(tv.tv_sec ^ seed[0], tv.tv_usec ^ seed[1]);
 244
 245         ll_get_random_bytes(&handle_base, sizeof(handle_base));
 246         LASSERT(handle_base != 0ULL);
 247
 248         return 0;
 249 }
 250
 251 static void cleanup_all_handles(void)
 252 {
 253         int i;
 254
 255         for (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 addref %p\n",
 261                                h->h_cookie, h, h->h_addref);
 262
 263                         class_handle_unhash_nolock(h);
 264                 }
 265                 cfs_spin_unlock(&handle_hash[i].lock);
 266         }
 267 }
 268
 269 void class_handle_cleanup(void)
 270 {
 271         int count;
 272         LASSERT(handle_hash != NULL);
 273
 274         count = cfs_atomic_read(&handle_count);
 275         if (count != 0) {
 276                 CERROR("handle_count at cleanup: %d\n", count);
 277                 cleanup_all_handles();
 278         }
 279
 280         OBD_VFREE(handle_hash, sizeof(*handle_hash) * HANDLE_HASH_SIZE);
 281         handle_hash = NULL;
 282
 283         if (cfs_atomic_read(&handle_count))
 284                 CERROR("leaked %d handles\n", cfs_atomic_read(&handle_count));
 285 }