drivers/staging/lustre/lustre/libcfs/upcall_cache.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) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 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  * libcfs/libcfs/upcall_cache.c
  37  *
  38  * Supplementary groups cache.
  39  */
  40 #define DEBUG_SUBSYSTEM S_SEC
  41
  42 #include "../../include/linux/libcfs/lucache.h"
  43
  44 static struct upcall_cache_entry *alloc_entry(struct upcall_cache *cache,
  45                                               __u64 key, void *args)
  46 {
  47         struct upcall_cache_entry *entry;
  48
  49         LIBCFS_ALLOC(entry, sizeof(*entry));
  50         if (!entry)
  51                 return NULL;
  52
  53         UC_CACHE_SET_NEW(entry);
  54         INIT_LIST_HEAD(&entry->ue_hash);
  55         entry->ue_key = key;
  56         atomic_set(&entry->ue_refcount, 0);
  57         init_waitqueue_head(&entry->ue_waitq);
  58         if (cache->uc_ops->init_entry)
  59                 cache->uc_ops->init_entry(entry, args);
  60         return entry;
  61 }
  62
  63 /* protected by cache lock */
  64 static void free_entry(struct upcall_cache *cache,
  65                        struct upcall_cache_entry *entry)
  66 {
  67         if (cache->uc_ops->free_entry)
  68                 cache->uc_ops->free_entry(cache, entry);
  69
  70         list_del(&entry->ue_hash);
  71         CDEBUG(D_OTHER, "destroy cache entry %p for key "LPU64"\n",
  72                entry, entry->ue_key);
  73         LIBCFS_FREE(entry, sizeof(*entry));
  74 }
  75
  76 static inline int upcall_compare(struct upcall_cache *cache,
  77                                  struct upcall_cache_entry *entry,
  78                                  __u64 key, void *args)
  79 {
  80         if (entry->ue_key != key)
  81                 return -1;
  82
  83         if (cache->uc_ops->upcall_compare)
  84                 return cache->uc_ops->upcall_compare(cache, entry, key, args);
  85
  86         return 0;
  87 }
  88
  89 static inline int downcall_compare(struct upcall_cache *cache,
  90                                    struct upcall_cache_entry *entry,
  91                                    __u64 key, void *args)
  92 {
  93         if (entry->ue_key != key)
  94                 return -1;
  95
  96         if (cache->uc_ops->downcall_compare)
  97                 return cache->uc_ops->downcall_compare(cache, entry, key, args);
  98
  99         return 0;
 100 }
 101
 102 static inline void get_entry(struct upcall_cache_entry *entry)
 103 {
 104         atomic_inc(&entry->ue_refcount);
 105 }
 106
 107 static inline void put_entry(struct upcall_cache *cache,
 108                              struct upcall_cache_entry *entry)
 109 {
 110         if (atomic_dec_and_test(&entry->ue_refcount) &&
 111             (UC_CACHE_IS_INVALID(entry) || UC_CACHE_IS_EXPIRED(entry))) {
 112                 free_entry(cache, entry);
 113         }
 114 }
 115
 116 static int check_unlink_entry(struct upcall_cache *cache,
 117                               struct upcall_cache_entry *entry)
 118 {
 119         if (UC_CACHE_IS_VALID(entry) &&
 120             time_before(cfs_time_current(), entry->ue_expire))
 121                 return 0;
 122
 123         if (UC_CACHE_IS_ACQUIRING(entry)) {
 124                 if (entry->ue_acquire_expire == 0 ||
 125                     time_before(cfs_time_current(), entry->ue_acquire_expire))
 126                         return 0;
 127
 128                 UC_CACHE_SET_EXPIRED(entry);
 129                 wake_up_all(&entry->ue_waitq);
 130         } else if (!UC_CACHE_IS_INVALID(entry)) {
 131                 UC_CACHE_SET_EXPIRED(entry);
 132         }
 133
 134         list_del_init(&entry->ue_hash);
 135         if (!atomic_read(&entry->ue_refcount))
 136                 free_entry(cache, entry);
 137         return 1;
 138 }
 139
 140 static inline int refresh_entry(struct upcall_cache *cache,
 141                          struct upcall_cache_entry *entry)
 142 {
 143         LASSERT(cache->uc_ops->do_upcall);
 144         return cache->uc_ops->do_upcall(cache, entry);
 145 }
 146
 147 struct upcall_cache_entry *upcall_cache_get_entry(struct upcall_cache *cache,
 148                                                   __u64 key, void *args)
 149 {
 150         struct upcall_cache_entry *entry = NULL, *new = NULL, *next;
 151         struct list_head *head;
 152         wait_queue_t wait;
 153         int rc, found;
 154
 155         LASSERT(cache);
 156
 157         head = &cache->uc_hashtable[UC_CACHE_HASH_INDEX(key)];
 158 find_again:
 159         found = 0;
 160         spin_lock(&cache->uc_lock);
 161         list_for_each_entry_safe(entry, next, head, ue_hash) {
 162                 /* check invalid & expired items */
 163                 if (check_unlink_entry(cache, entry))
 164                         continue;
 165                 if (upcall_compare(cache, entry, key, args) == 0) {
 166                         found = 1;
 167                         break;
 168                 }
 169         }
 170
 171         if (!found) {
 172                 if (!new) {
 173                         spin_unlock(&cache->uc_lock);
 174                         new = alloc_entry(cache, key, args);
 175                         if (!new) {
 176                                 CERROR("fail to alloc entry\n");
 177                                 return ERR_PTR(-ENOMEM);
 178                         }
 179                         goto find_again;
 180                 } else {
 181                         list_add(&new->ue_hash, head);
 182                         entry = new;
 183                 }
 184         } else {
 185                 if (new) {
 186                         free_entry(cache, new);
 187                         new = NULL;
 188                 }
 189                 list_move(&entry->ue_hash, head);
 190         }
 191         get_entry(entry);
 192
 193         /* acquire for new one */
 194         if (UC_CACHE_IS_NEW(entry)) {
 195                 UC_CACHE_SET_ACQUIRING(entry);
 196                 UC_CACHE_CLEAR_NEW(entry);
 197                 spin_unlock(&cache->uc_lock);
 198                 rc = refresh_entry(cache, entry);
 199                 spin_lock(&cache->uc_lock);
 200                 entry->ue_acquire_expire =
 201                         cfs_time_shift(cache->uc_acquire_expire);
 202                 if (rc < 0) {
 203                         UC_CACHE_CLEAR_ACQUIRING(entry);
 204                         UC_CACHE_SET_INVALID(entry);
 205                         wake_up_all(&entry->ue_waitq);
 206                         if (unlikely(rc == -EREMCHG)) {
 207                                 put_entry(cache, entry);
 208                                 GOTO(out, entry = ERR_PTR(rc));
 209                         }
 210                 }
 211         }
 212         /* someone (and only one) is doing upcall upon this item,
 213          * wait it to complete */
 214         if (UC_CACHE_IS_ACQUIRING(entry)) {
 215                 long expiry = (entry == new) ?
 216                               cfs_time_seconds(cache->uc_acquire_expire) :
 217                               MAX_SCHEDULE_TIMEOUT;
 218                 long left;
 219
 220                 init_waitqueue_entry(&wait, current);
 221                 add_wait_queue(&entry->ue_waitq, &wait);
 222                 set_current_state(TASK_INTERRUPTIBLE);
 223                 spin_unlock(&cache->uc_lock);
 224
 225                 left = schedule_timeout(expiry);
 226
 227                 spin_lock(&cache->uc_lock);
 228                 remove_wait_queue(&entry->ue_waitq, &wait);
 229                 if (UC_CACHE_IS_ACQUIRING(entry)) {
 230                         /* we're interrupted or upcall failed in the middle */
 231                         rc = left > 0 ? -EINTR : -ETIMEDOUT;
 232                         CERROR("acquire for key "LPU64": error %d\n",
 233                                entry->ue_key, rc);
 234                         put_entry(cache, entry);
 235                         GOTO(out, entry = ERR_PTR(rc));
 236                 }
 237         }
 238
 239         /* invalid means error, don't need to try again */
 240         if (UC_CACHE_IS_INVALID(entry)) {
 241                 put_entry(cache, entry);
 242                 GOTO(out, entry = ERR_PTR(-EIDRM));
 243         }
 244
 245         /* check expired
 246          * We can't refresh the existing one because some
 247          * memory might be shared by multiple processes.
 248          */
 249         if (check_unlink_entry(cache, entry)) {
 250                 /* if expired, try again. but if this entry is
 251                  * created by me but too quickly turn to expired
 252                  * without any error, should at least give a
 253                  * chance to use it once.
 254                  */
 255                 if (entry != new) {
 256                         put_entry(cache, entry);
 257                         spin_unlock(&cache->uc_lock);
 258                         new = NULL;
 259                         goto find_again;
 260                 }
 261         }
 262
 263         /* Now we know it's good */
 264 out:
 265         spin_unlock(&cache->uc_lock);
 266         return entry;
 267 }
 268 EXPORT_SYMBOL(upcall_cache_get_entry);
 269
 270 void upcall_cache_put_entry(struct upcall_cache *cache,
 271                             struct upcall_cache_entry *entry)
 272 {
 273         if (!entry) {
 274                 return;
 275         }
 276
 277         LASSERT(atomic_read(&entry->ue_refcount) > 0);
 278         spin_lock(&cache->uc_lock);
 279         put_entry(cache, entry);
 280         spin_unlock(&cache->uc_lock);
 281 }
 282 EXPORT_SYMBOL(upcall_cache_put_entry);
 283
 284 int upcall_cache_downcall(struct upcall_cache *cache, __u32 err, __u64 key,
 285                           void *args)
 286 {
 287         struct upcall_cache_entry *entry = NULL;
 288         struct list_head *head;
 289         int found = 0, rc = 0;
 290
 291         LASSERT(cache);
 292
 293         head = &cache->uc_hashtable[UC_CACHE_HASH_INDEX(key)];
 294
 295         spin_lock(&cache->uc_lock);
 296         list_for_each_entry(entry, head, ue_hash) {
 297                 if (downcall_compare(cache, entry, key, args) == 0) {
 298                         found = 1;
 299                         get_entry(entry);
 300                         break;
 301                 }
 302         }
 303
 304         if (!found) {
 305                 CDEBUG(D_OTHER, "%s: upcall for key "LPU64" not expected\n",
 306                        cache->uc_name, key);
 307                 /* haven't found, it's possible */
 308                 spin_unlock(&cache->uc_lock);
 309                 return -EINVAL;
 310         }
 311
 312         if (err) {
 313                 CDEBUG(D_OTHER, "%s: upcall for key "LPU64" returned %d\n",
 314                        cache->uc_name, entry->ue_key, err);
 315                 GOTO(out, rc = -EINVAL);
 316         }
 317
 318         if (!UC_CACHE_IS_ACQUIRING(entry)) {
 319                 CDEBUG(D_RPCTRACE,"%s: found uptodate entry %p (key "LPU64")\n",
 320                        cache->uc_name, entry, entry->ue_key);
 321                 GOTO(out, rc = 0);
 322         }
 323
 324         if (UC_CACHE_IS_INVALID(entry) || UC_CACHE_IS_EXPIRED(entry)) {
 325                 CERROR("%s: found a stale entry %p (key "LPU64") in ioctl\n",
 326                        cache->uc_name, entry, entry->ue_key);
 327                 GOTO(out, rc = -EINVAL);
 328         }
 329
 330         spin_unlock(&cache->uc_lock);
 331         if (cache->uc_ops->parse_downcall)
 332                 rc = cache->uc_ops->parse_downcall(cache, entry, args);
 333         spin_lock(&cache->uc_lock);
 334         if (rc)
 335                 GOTO(out, rc);
 336
 337         entry->ue_expire = cfs_time_shift(cache->uc_entry_expire);
 338         UC_CACHE_SET_VALID(entry);
 339         CDEBUG(D_OTHER, "%s: created upcall cache entry %p for key "LPU64"\n",
 340                cache->uc_name, entry, entry->ue_key);
 341 out:
 342         if (rc) {
 343                 UC_CACHE_SET_INVALID(entry);
 344                 list_del_init(&entry->ue_hash);
 345         }
 346         UC_CACHE_CLEAR_ACQUIRING(entry);
 347         spin_unlock(&cache->uc_lock);
 348         wake_up_all(&entry->ue_waitq);
 349         put_entry(cache, entry);
 350
 351         return rc;
 352 }
 353 EXPORT_SYMBOL(upcall_cache_downcall);
 354
 355 static void cache_flush(struct upcall_cache *cache, int force)
 356 {
 357         struct upcall_cache_entry *entry, *next;
 358         int i;
 359
 360         spin_lock(&cache->uc_lock);
 361         for (i = 0; i < UC_CACHE_HASH_SIZE; i++) {
 362                 list_for_each_entry_safe(entry, next,
 363                                          &cache->uc_hashtable[i], ue_hash) {
 364                         if (!force && atomic_read(&entry->ue_refcount)) {
 365                                 UC_CACHE_SET_EXPIRED(entry);
 366                                 continue;
 367                         }
 368                         LASSERT(!atomic_read(&entry->ue_refcount));
 369                         free_entry(cache, entry);
 370                 }
 371         }
 372         spin_unlock(&cache->uc_lock);
 373 }
 374
 375 void upcall_cache_flush_idle(struct upcall_cache *cache)
 376 {
 377         cache_flush(cache, 0);
 378 }
 379 EXPORT_SYMBOL(upcall_cache_flush_idle);
 380
 381 void upcall_cache_flush_all(struct upcall_cache *cache)
 382 {
 383         cache_flush(cache, 1);
 384 }
 385 EXPORT_SYMBOL(upcall_cache_flush_all);
 386
 387 void upcall_cache_flush_one(struct upcall_cache *cache, __u64 key, void *args)
 388 {
 389         struct list_head *head;
 390         struct upcall_cache_entry *entry;
 391         int found = 0;
 392
 393         head = &cache->uc_hashtable[UC_CACHE_HASH_INDEX(key)];
 394
 395         spin_lock(&cache->uc_lock);
 396         list_for_each_entry(entry, head, ue_hash) {
 397                 if (upcall_compare(cache, entry, key, args) == 0) {
 398                         found = 1;
 399                         break;
 400                 }
 401         }
 402
 403         if (found) {
 404                 CWARN("%s: flush entry %p: key "LPU64", ref %d, fl %x, "
 405                       "cur %lu, ex %ld/%ld\n",
 406                       cache->uc_name, entry, entry->ue_key,
 407                       atomic_read(&entry->ue_refcount), entry->ue_flags,
 408                       get_seconds(), entry->ue_acquire_expire,
 409                       entry->ue_expire);
 410                 UC_CACHE_SET_EXPIRED(entry);
 411                 if (!atomic_read(&entry->ue_refcount))
 412                         free_entry(cache, entry);
 413         }
 414         spin_unlock(&cache->uc_lock);
 415 }
 416 EXPORT_SYMBOL(upcall_cache_flush_one);
 417
 418 struct upcall_cache *upcall_cache_init(const char *name, const char *upcall,
 419                                        struct upcall_cache_ops *ops)
 420 {
 421         struct upcall_cache *cache;
 422         int i;
 423
 424         LIBCFS_ALLOC(cache, sizeof(*cache));
 425         if (!cache)
 426                 return ERR_PTR(-ENOMEM);
 427
 428         spin_lock_init(&cache->uc_lock);
 429         rwlock_init(&cache->uc_upcall_rwlock);
 430         for (i = 0; i < UC_CACHE_HASH_SIZE; i++)
 431                 INIT_LIST_HEAD(&cache->uc_hashtable[i]);
 432         strncpy(cache->uc_name, name, sizeof(cache->uc_name) - 1);
 433         /* upcall pathname proc tunable */
 434         strncpy(cache->uc_upcall, upcall, sizeof(cache->uc_upcall) - 1);
 435         cache->uc_entry_expire = 20 * 60;
 436         cache->uc_acquire_expire = 30;
 437         cache->uc_ops = ops;
 438
 439         return cache;
 440 }
 441 EXPORT_SYMBOL(upcall_cache_init);
 442
 443 void upcall_cache_cleanup(struct upcall_cache *cache)
 444 {
 445         if (!cache)
 446                 return;
 447         upcall_cache_flush_all(cache);
 448         LIBCFS_FREE(cache, sizeof(*cache));
 449 }
 450 EXPORT_SYMBOL(upcall_cache_cleanup);