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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 2017, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * lustre/obdclass/lustre_handles.c
  33  *
  34  * Author: Phil Schwan <phil@clusterfs.com>
  35  */
  36
  37 #define DEBUG_SUBSYSTEM S_CLASS
  38
  39 #include <obd_support.h>
  40 #include <lustre_handles.h>
  41 #include <lustre_lib.h>
  42
  43
  44 static __u64 handle_base;
  45 #define HANDLE_INCR 7
  46 static DEFINE_SPINLOCK(handle_base_lock);
  47
  48 static struct handle_bucket {
  49         spinlock_t lock;
  50         struct list_head head;
  51 } *handle_hash;
  52
  53 #define HANDLE_HASH_SIZE (1 << 16)
  54 #define HANDLE_HASH_MASK (HANDLE_HASH_SIZE - 1)
  55
  56 /*
  57  * Generate a unique 64bit cookie (hash) for a handle and insert it into
  58  * global (per-node) hash-table.
  59  */
  60 void class_handle_hash(struct portals_handle *h,
  61                        struct portals_handle_ops *ops)
  62 {
  63         struct handle_bucket *bucket;
  64
  65         ENTRY;
  66
  67         LASSERT(h != NULL);
  68         LASSERT(list_empty(&h->h_link));
  69
  70         /*
  71          * This is fast, but simplistic cookie generation algorithm, it will
  72          * need a re-do at some point in the future for security.
  73          */
  74         spin_lock(&handle_base_lock);
  75         handle_base += HANDLE_INCR;
  76
  77         if (unlikely(handle_base == 0)) {
  78                 /*
  79                  * Cookie of zero is "dangerous", because in many places it's
  80                  * assumed that 0 means "unassigned" handle, not bound to any
  81                  * object.
  82                  */
  83                 CWARN("The universe has been exhausted: cookie wrap-around.\n");
  84                 handle_base += HANDLE_INCR;
  85         }
  86         h->h_cookie = handle_base;
  87         spin_unlock(&handle_base_lock);
  88
  89         h->h_ops = ops;
  90         spin_lock_init(&h->h_lock);
  91
  92         bucket = &handle_hash[h->h_cookie & HANDLE_HASH_MASK];
  93         spin_lock(&bucket->lock);
  94         list_add_rcu(&h->h_link, &bucket->head);
  95         h->h_in = 1;
  96         spin_unlock(&bucket->lock);
  97
  98         CDEBUG(D_INFO, "added object %p with handle %#llx to hash\n",
  99                h, h->h_cookie);
 100         EXIT;
 101 }
 102 EXPORT_SYMBOL(class_handle_hash);
 103
 104 static void class_handle_unhash_nolock(struct portals_handle *h)
 105 {
 106         if (list_empty(&h->h_link)) {
 107                 CERROR("removing an already-removed handle (%#llx)\n",
 108                        h->h_cookie);
 109                 return;
 110         }
 111
 112         CDEBUG(D_INFO, "removing object %p with handle %#llx from hash\n",
 113                h, h->h_cookie);
 114
 115         spin_lock(&h->h_lock);
 116         if (h->h_in == 0) {
 117                 spin_unlock(&h->h_lock);
 118                 return;
 119         }
 120         h->h_in = 0;
 121         spin_unlock(&h->h_lock);
 122         list_del_rcu(&h->h_link);
 123 }
 124
 125 void class_handle_unhash(struct portals_handle *h)
 126 {
 127         struct handle_bucket *bucket;
 128         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 129
 130         spin_lock(&bucket->lock);
 131         class_handle_unhash_nolock(h);
 132         spin_unlock(&bucket->lock);
 133 }
 134 EXPORT_SYMBOL(class_handle_unhash);
 135
 136 void class_handle_hash_back(struct portals_handle *h)
 137 {
 138         struct handle_bucket *bucket;
 139         ENTRY;
 140
 141         bucket = handle_hash + (h->h_cookie & HANDLE_HASH_MASK);
 142
 143         spin_lock(&bucket->lock);
 144         list_add_rcu(&h->h_link, &bucket->head);
 145         h->h_in = 1;
 146         spin_unlock(&bucket->lock);
 147
 148         EXIT;
 149 }
 150 EXPORT_SYMBOL(class_handle_hash_back);
 151
 152 void *class_handle2object(__u64 cookie, const void *owner)
 153 {
 154         struct handle_bucket *bucket;
 155         struct portals_handle *h;
 156         void *retval = NULL;
 157
 158         ENTRY;
 159
 160         LASSERT(handle_hash != NULL);
 161
 162         /*
 163          * Be careful when you want to change this code. See the
 164          * rcu_read_lock() definition on top this file. - jxiong
 165          */
 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 || h->h_owner != owner)
 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(struct rcu_head *rcu)
 188 {
 189         struct portals_handle *h;
 190         void *ptr;
 191
 192         h = container_of(rcu, struct portals_handle, h_rcu);
 193         ptr = (void *)(unsigned long)h->h_cookie;
 194
 195         if (h->h_ops->hop_free != NULL)
 196                 h->h_ops->hop_free(ptr, h->h_size);
 197         else
 198                 OBD_FREE(ptr, h->h_size);
 199 }
 200 EXPORT_SYMBOL(class_handle_free_cb);
 201
 202 int class_handle_init(void)
 203 {
 204         struct handle_bucket *bucket;
 205
 206         LASSERT(handle_hash == NULL);
 207
 208         OBD_ALLOC_LARGE(handle_hash, sizeof(*bucket) * HANDLE_HASH_SIZE);
 209         if (handle_hash == NULL)
 210                 return -ENOMEM;
 211
 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         cfs_get_random_bytes(&handle_base, sizeof(handle_base));
 219         LASSERT(handle_base != 0ULL);
 220
 221         return 0;
 222 }
 223
 224 static int cleanup_all_handles(void)
 225 {
 226         int rc;
 227         int i;
 228
 229         for (rc = i = 0; i < HANDLE_HASH_SIZE; i++) {
 230                 struct portals_handle *h;
 231
 232                 spin_lock(&handle_hash[i].lock);
 233                 list_for_each_entry_rcu(h, &(handle_hash[i].head), h_link) {
 234                         CERROR("force clean handle %#llx addr %p ops %p\n",
 235                                h->h_cookie, h, h->h_ops);
 236
 237                         class_handle_unhash_nolock(h);
 238                         rc++;
 239                 }
 240                 spin_unlock(&handle_hash[i].lock);
 241         }
 242
 243         return rc;
 244 }
 245
 246 void class_handle_cleanup(void)
 247 {
 248         int count;
 249
 250         LASSERT(handle_hash != NULL);
 251
 252         count = cleanup_all_handles();
 253
 254         OBD_FREE_LARGE(handle_hash, sizeof(*handle_hash) * HANDLE_HASH_SIZE);
 255         handle_hash = NULL;
 256
 257         if (count != 0)
 258                 CERROR("handle_count at cleanup: %d\n", count);
 259 }