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            list_add
  52 # define list_del_rcu            list_del
  53 # define list_for_each_rcu       list_for_each
  54 # define list_for_each_safe_rcu  list_for_each_safe
  55 # define rcu_read_lock()         spin_lock(&bucket->lock)
  56 # define rcu_read_unlock()       spin_unlock(&bucket->lock)
  57 #endif /* ifndef HAVE_RCU */
  58
  59 static __u64 handle_base;
  60 #define HANDLE_INCR 7
  61 static spinlock_t handle_base_lock;
  62
  63 static struct handle_bucket {
  64         spinlock_t lock;
  65         struct list_head head;
  66 } *handle_hash;
  67
  68 static atomic_t handle_count = ATOMIC_INIT(0);
  69
  70 #ifdef __arch_um__
  71 /* For unknown reason, UML uses kmalloc rather than vmalloc to allocate
  72  * memory(OBD_VMALLOC). Therefore, we have to redefine the
  73  * HANDLE_HASH_SIZE to make the hash heads don't exceed 128K.
  74  */
  75 #define HANDLE_HASH_SIZE 4096
  76 #else
  77 #define HANDLE_HASH_SIZE (1 << 14)
  78 #endif /* ifdef __arch_um__ */
  79
  80 #define HANDLE_HASH_MASK (HANDLE_HASH_SIZE - 1)
  81
  82 /*
  83  * Generate a unique 64bit cookie (hash) for a handle and insert it into
  84  * global (per-node) hash-table.
  85  */
  86 void class_handle_hash(struct portals_handle *h, portals_handle_addref_cb cb)
  87 {
  88         struct handle_bucket *bucket;
  89         ENTRY;
  90
  91         LASSERT(h != NULL);
  92         LASSERT(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         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         spin_unlock(&handle_base_lock);
 112
 113         atomic_inc(&handle_count);
 114         h->h_addref = cb;
 115         spin_lock_init(&h->h_lock);
 116
 117         bucket = &handle_hash[h->h_cookie & HANDLE_HASH_MASK];
 118         spin_lock(&bucket->lock);
 119         list_add_rcu(&h->h_link, &bucket->head);
 120         h->h_in = 1;
 121         spin_unlock(&bucket->lock);
 122
 123         CDEBUG(D_INFO, "added object %p with handle "LPX64" to hash\n",
 124                h, h->h_cookie);
 125         EXIT;
 126 }
 127
 128 static void class_handle_unhash_nolock(struct portals_handle *h)
 129 {
 130         if (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         spin_lock(&h->h_lock);
 140         if (h->h_in == 0) {
 141                 spin_unlock(&h->h_lock);
 142                 return;
 143         }
 144         h->h_in = 0;
 145         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         spin_lock(&bucket->lock);
 155         class_handle_unhash_nolock(h);
 156         spin_unlock(&bucket->lock);
 157
 158         atomic_dec(&handle_count);
 159 }
 160
 161 void class_handle_hash_back(struct portals_handle *h)
 162 {
 163         struct handle_bucket *bucket;
 164         ENTRY;
 165
 166         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 167
 168         atomic_inc(&handle_count);
 169         spin_lock(&bucket->lock);
 170         list_add_rcu(&h->h_link, &bucket->head);
 171         h->h_in = 1;
 172         spin_unlock(&bucket->lock);
 173
 174         EXIT;
 175 }
 176
 177 void *class_handle2object(__u64 cookie)
 178 {
 179         struct handle_bucket *bucket;
 180         struct list_head *tmp;
 181         void *retval = NULL;
 182         ENTRY;
 183
 184         LASSERT(handle_hash != NULL);
 185
 186         /* Be careful when you want to change this code. See the
 187          * rcu_read_lock() definition on top this file. - jxiong */
 188         bucket = handle_hash + (cookie & HANDLE_HASH_MASK);
 189
 190         rcu_read_lock();
 191         list_for_each_rcu(tmp, &bucket->head) {
 192                 struct portals_handle *h;
 193                 h = list_entry(tmp, struct portals_handle, h_link);
 194                 if (h->h_cookie != cookie)
 195                         continue;
 196
 197                 spin_lock(&h->h_lock);
 198                 if (likely(h->h_in != 0)) {
 199                         h->h_addref(h);
 200                         retval = h;
 201                 }
 202                 spin_unlock(&h->h_lock);
 203                 break;
 204         }
 205         rcu_read_unlock();
 206
 207         RETURN(retval);
 208 }
 209
 210 void class_handle_free_cb(struct rcu_head *rcu)
 211 {
 212         struct portals_handle *h = RCU2HANDLE(rcu);
 213         if (h->h_free_cb) {
 214                 h->h_free_cb(h->h_ptr, h->h_size);
 215         } else {
 216                 void *ptr = h->h_ptr;
 217                 unsigned int size = h->h_size;
 218                 OBD_FREE(ptr, size);
 219         }
 220 }
 221
 222 int class_handle_init(void)
 223 {
 224         struct handle_bucket *bucket;
 225
 226         LASSERT(handle_hash == NULL);
 227
 228         OBD_VMALLOC(handle_hash, sizeof(*bucket) * HANDLE_HASH_SIZE);
 229         if (handle_hash == NULL)
 230                 return -ENOMEM;
 231
 232         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                 spin_lock_init(&bucket->lock);
 237         }
 238         ll_get_random_bytes(&handle_base, sizeof(handle_base));
 239         LASSERT(handle_base != 0ULL);
 240
 241         return 0;
 242 }
 243
 244 static void cleanup_all_handles(void)
 245 {
 246         int i;
 247
 248         for (i = 0; i < HANDLE_HASH_SIZE; i++) {
 249                 struct list_head *pos, *n;
 250                 n = NULL;
 251                 spin_lock(&handle_hash[i].lock);
 252                 list_for_each_safe_rcu(pos, n, &(handle_hash[i].head)) {
 253                         struct portals_handle *h;
 254                         h = list_entry(pos, struct portals_handle, h_link);
 255
 256                         CERROR("force clean handle "LPX64" addr %p addref %p\n",
 257                                h->h_cookie, h, h->h_addref);
 258
 259                         class_handle_unhash_nolock(h);
 260                 }
 261                 spin_unlock(&handle_hash[i].lock);
 262         }
 263 }
 264
 265 void class_handle_cleanup(void)
 266 {
 267         int count;
 268         LASSERT(handle_hash != NULL);
 269
 270         count = atomic_read(&handle_count);
 271         if (count != 0) {
 272                 CERROR("handle_count at cleanup: %d\n", count);
 273                 cleanup_all_handles();
 274         }
 275
 276         OBD_VFREE(handle_hash, sizeof(*handle_hash) * HANDLE_HASH_SIZE);
 277         handle_hash = NULL;
 278
 279         if (atomic_read(&handle_count))
 280                 CERROR("leaked %d handles\n", atomic_read(&handle_count));
 281 }