kernel/drivers/staging/lustre/lustre/libcfs/hash.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) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 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/hash.c
  37  *
  38  * Implement a hash class for hash process in lustre system.
  39  *
  40  * Author: YuZhangyong <yzy@clusterfs.com>
  41  *
  42  * 2008-08-15: Brian Behlendorf <behlendorf1@llnl.gov>
  43  * - Simplified API and improved documentation
  44  * - Added per-hash feature flags:
  45  *   * CFS_HASH_DEBUG additional validation
  46  *   * CFS_HASH_REHASH dynamic rehashing
  47  * - Added per-hash statistics
  48  * - General performance enhancements
  49  *
  50  * 2009-07-31: Liang Zhen <zhen.liang@sun.com>
  51  * - move all stuff to libcfs
  52  * - don't allow cur_bits != max_bits without setting of CFS_HASH_REHASH
  53  * - ignore hs_rwlock if without CFS_HASH_REHASH setting
  54  * - buckets are allocated one by one(instead of contiguous memory),
  55  *   to avoid unnecessary cacheline conflict
  56  *
  57  * 2010-03-01: Liang Zhen <zhen.liang@sun.com>
  58  * - "bucket" is a group of hlist_head now, user can specify bucket size
  59  *   by bkt_bits of cfs_hash_create(), all hlist_heads in a bucket share
  60  *   one lock for reducing memory overhead.
  61  *
  62  * - support lockless hash, caller will take care of locks:
  63  *   avoid lock overhead for hash tables that are already protected
  64  *   by locking in the caller for another reason
  65  *
  66  * - support both spin_lock/rwlock for bucket:
  67  *   overhead of spinlock contention is lower than read/write
  68  *   contention of rwlock, so using spinlock to serialize operations on
  69  *   bucket is more reasonable for those frequently changed hash tables
  70  *
  71  * - support one-single lock mode:
  72  *   one lock to protect all hash operations to avoid overhead of
  73  *   multiple locks if hash table is always small
  74  *
  75  * - removed a lot of unnecessary addref & decref on hash element:
  76  *   addref & decref are atomic operations in many use-cases which
  77  *   are expensive.
  78  *
  79  * - support non-blocking cfs_hash_add() and cfs_hash_findadd():
  80  *   some lustre use-cases require these functions to be strictly
  81  *   non-blocking, we need to schedule required rehash on a different
  82  *   thread on those cases.
  83  *
  84  * - safer rehash on large hash table
  85  *   In old implementation, rehash function will exclusively lock the
  86  *   hash table and finish rehash in one batch, it's dangerous on SMP
  87  *   system because rehash millions of elements could take long time.
  88  *   New implemented rehash can release lock and relax CPU in middle
  89  *   of rehash, it's safe for another thread to search/change on the
  90  *   hash table even it's in rehasing.
  91  *
  92  * - support two different refcount modes
  93  *   . hash table has refcount on element
  94  *   . hash table doesn't change refcount on adding/removing element
  95  *
  96  * - support long name hash table (for param-tree)
  97  *
  98  * - fix a bug for cfs_hash_rehash_key:
  99  *   in old implementation, cfs_hash_rehash_key could screw up the
 100  *   hash-table because @key is overwritten without any protection.
 101  *   Now we need user to define hs_keycpy for those rehash enabled
 102  *   hash tables, cfs_hash_rehash_key will overwrite hash-key
 103  *   inside lock by calling hs_keycpy.
 104  *
 105  * - better hash iteration:
 106  *   Now we support both locked iteration & lockless iteration of hash
 107  *   table. Also, user can break the iteration by return 1 in callback.
 108  */
 109
 110 #include "../../include/linux/libcfs/libcfs.h"
 111 #include <linux/seq_file.h>
 112
 113 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
 114 static unsigned int warn_on_depth = 8;
 115 module_param(warn_on_depth, uint, 0644);
 116 MODULE_PARM_DESC(warn_on_depth, "warning when hash depth is high.");
 117 #endif
 118
 119 struct cfs_wi_sched *cfs_sched_rehash;
 120
 121 static inline void
 122 cfs_hash_nl_lock(union cfs_hash_lock *lock, int exclusive) {}
 123
 124 static inline void
 125 cfs_hash_nl_unlock(union cfs_hash_lock *lock, int exclusive) {}
 126
 127 static inline void
 128 cfs_hash_spin_lock(union cfs_hash_lock *lock, int exclusive)
 129         __acquires(&lock->spin)
 130 {
 131         spin_lock(&lock->spin);
 132 }
 133
 134 static inline void
 135 cfs_hash_spin_unlock(union cfs_hash_lock *lock, int exclusive)
 136         __releases(&lock->spin)
 137 {
 138         spin_unlock(&lock->spin);
 139 }
 140
 141 static inline void
 142 cfs_hash_rw_lock(union cfs_hash_lock *lock, int exclusive)
 143         __acquires(&lock->rw)
 144 {
 145         if (!exclusive)
 146                 read_lock(&lock->rw);
 147         else
 148                 write_lock(&lock->rw);
 149 }
 150
 151 static inline void
 152 cfs_hash_rw_unlock(union cfs_hash_lock *lock, int exclusive)
 153         __releases(&lock->rw)
 154 {
 155         if (!exclusive)
 156                 read_unlock(&lock->rw);
 157         else
 158                 write_unlock(&lock->rw);
 159 }
 160
 161 /** No lock hash */
 162 static struct cfs_hash_lock_ops cfs_hash_nl_lops = {
 163         .hs_lock        = cfs_hash_nl_lock,
 164         .hs_unlock      = cfs_hash_nl_unlock,
 165         .hs_bkt_lock    = cfs_hash_nl_lock,
 166         .hs_bkt_unlock  = cfs_hash_nl_unlock,
 167 };
 168
 169 /** no bucket lock, one spinlock to protect everything */
 170 static struct cfs_hash_lock_ops cfs_hash_nbl_lops = {
 171         .hs_lock        = cfs_hash_spin_lock,
 172         .hs_unlock      = cfs_hash_spin_unlock,
 173         .hs_bkt_lock    = cfs_hash_nl_lock,
 174         .hs_bkt_unlock  = cfs_hash_nl_unlock,
 175 };
 176
 177 /** spin bucket lock, rehash is enabled */
 178 static struct cfs_hash_lock_ops cfs_hash_bkt_spin_lops = {
 179         .hs_lock        = cfs_hash_rw_lock,
 180         .hs_unlock      = cfs_hash_rw_unlock,
 181         .hs_bkt_lock    = cfs_hash_spin_lock,
 182         .hs_bkt_unlock  = cfs_hash_spin_unlock,
 183 };
 184
 185 /** rw bucket lock, rehash is enabled */
 186 static struct cfs_hash_lock_ops cfs_hash_bkt_rw_lops = {
 187         .hs_lock        = cfs_hash_rw_lock,
 188         .hs_unlock      = cfs_hash_rw_unlock,
 189         .hs_bkt_lock    = cfs_hash_rw_lock,
 190         .hs_bkt_unlock  = cfs_hash_rw_unlock,
 191 };
 192
 193 /** spin bucket lock, rehash is disabled */
 194 static struct cfs_hash_lock_ops cfs_hash_nr_bkt_spin_lops = {
 195         .hs_lock        = cfs_hash_nl_lock,
 196         .hs_unlock      = cfs_hash_nl_unlock,
 197         .hs_bkt_lock    = cfs_hash_spin_lock,
 198         .hs_bkt_unlock  = cfs_hash_spin_unlock,
 199 };
 200
 201 /** rw bucket lock, rehash is disabled */
 202 static struct cfs_hash_lock_ops cfs_hash_nr_bkt_rw_lops = {
 203         .hs_lock        = cfs_hash_nl_lock,
 204         .hs_unlock      = cfs_hash_nl_unlock,
 205         .hs_bkt_lock    = cfs_hash_rw_lock,
 206         .hs_bkt_unlock  = cfs_hash_rw_unlock,
 207 };
 208
 209 static void
 210 cfs_hash_lock_setup(struct cfs_hash *hs)
 211 {
 212         if (cfs_hash_with_no_lock(hs)) {
 213                 hs->hs_lops = &cfs_hash_nl_lops;
 214
 215         } else if (cfs_hash_with_no_bktlock(hs)) {
 216                 hs->hs_lops = &cfs_hash_nbl_lops;
 217                 spin_lock_init(&hs->hs_lock.spin);
 218
 219         } else if (cfs_hash_with_rehash(hs)) {
 220                 rwlock_init(&hs->hs_lock.rw);
 221
 222                 if (cfs_hash_with_rw_bktlock(hs))
 223                         hs->hs_lops = &cfs_hash_bkt_rw_lops;
 224                 else if (cfs_hash_with_spin_bktlock(hs))
 225                         hs->hs_lops = &cfs_hash_bkt_spin_lops;
 226                 else
 227                         LBUG();
 228         } else {
 229                 if (cfs_hash_with_rw_bktlock(hs))
 230                         hs->hs_lops = &cfs_hash_nr_bkt_rw_lops;
 231                 else if (cfs_hash_with_spin_bktlock(hs))
 232                         hs->hs_lops = &cfs_hash_nr_bkt_spin_lops;
 233                 else
 234                         LBUG();
 235         }
 236 }
 237
 238 /**
 239  * Simple hash head without depth tracking
 240  * new element is always added to head of hlist
 241  */
 242 struct cfs_hash_head {
 243         struct hlist_head       hh_head;        /**< entries list */
 244 };
 245
 246 static int
 247 cfs_hash_hh_hhead_size(struct cfs_hash *hs)
 248 {
 249         return sizeof(struct cfs_hash_head);
 250 }
 251
 252 static struct hlist_head *
 253 cfs_hash_hh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
 254 {
 255         struct cfs_hash_head *head;
 256
 257         head = (struct cfs_hash_head *)&bd->bd_bucket->hsb_head[0];
 258         return &head[bd->bd_offset].hh_head;
 259 }
 260
 261 static int
 262 cfs_hash_hh_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 263                       struct hlist_node *hnode)
 264 {
 265         hlist_add_head(hnode, cfs_hash_hh_hhead(hs, bd));
 266         return -1; /* unknown depth */
 267 }
 268
 269 static int
 270 cfs_hash_hh_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 271                       struct hlist_node *hnode)
 272 {
 273         hlist_del_init(hnode);
 274         return -1; /* unknown depth */
 275 }
 276
 277 /**
 278  * Simple hash head with depth tracking
 279  * new element is always added to head of hlist
 280  */
 281 struct cfs_hash_head_dep {
 282         struct hlist_head       hd_head;        /**< entries list */
 283         unsigned int            hd_depth;       /**< list length */
 284 };
 285
 286 static int
 287 cfs_hash_hd_hhead_size(struct cfs_hash *hs)
 288 {
 289         return sizeof(struct cfs_hash_head_dep);
 290 }
 291
 292 static struct hlist_head *
 293 cfs_hash_hd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
 294 {
 295         struct cfs_hash_head_dep   *head;
 296
 297         head = (struct cfs_hash_head_dep *)&bd->bd_bucket->hsb_head[0];
 298         return &head[bd->bd_offset].hd_head;
 299 }
 300
 301 static int
 302 cfs_hash_hd_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 303                       struct hlist_node *hnode)
 304 {
 305         struct cfs_hash_head_dep *hh;
 306
 307         hh = container_of(cfs_hash_hd_hhead(hs, bd),
 308                           struct cfs_hash_head_dep, hd_head);
 309         hlist_add_head(hnode, &hh->hd_head);
 310         return ++hh->hd_depth;
 311 }
 312
 313 static int
 314 cfs_hash_hd_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 315                       struct hlist_node *hnode)
 316 {
 317         struct cfs_hash_head_dep *hh;
 318
 319         hh = container_of(cfs_hash_hd_hhead(hs, bd),
 320                           struct cfs_hash_head_dep, hd_head);
 321         hlist_del_init(hnode);
 322         return --hh->hd_depth;
 323 }
 324
 325 /**
 326  * double links hash head without depth tracking
 327  * new element is always added to tail of hlist
 328  */
 329 struct cfs_hash_dhead {
 330         struct hlist_head       dh_head;        /**< entries list */
 331         struct hlist_node       *dh_tail;       /**< the last entry */
 332 };
 333
 334 static int
 335 cfs_hash_dh_hhead_size(struct cfs_hash *hs)
 336 {
 337         return sizeof(struct cfs_hash_dhead);
 338 }
 339
 340 static struct hlist_head *
 341 cfs_hash_dh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
 342 {
 343         struct cfs_hash_dhead *head;
 344
 345         head = (struct cfs_hash_dhead *)&bd->bd_bucket->hsb_head[0];
 346         return &head[bd->bd_offset].dh_head;
 347 }
 348
 349 static int
 350 cfs_hash_dh_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 351                       struct hlist_node *hnode)
 352 {
 353         struct cfs_hash_dhead *dh;
 354
 355         dh = container_of(cfs_hash_dh_hhead(hs, bd),
 356                           struct cfs_hash_dhead, dh_head);
 357         if (dh->dh_tail != NULL) /* not empty */
 358                 hlist_add_behind(hnode, dh->dh_tail);
 359         else /* empty list */
 360                 hlist_add_head(hnode, &dh->dh_head);
 361         dh->dh_tail = hnode;
 362         return -1; /* unknown depth */
 363 }
 364
 365 static int
 366 cfs_hash_dh_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 367                       struct hlist_node *hnd)
 368 {
 369         struct cfs_hash_dhead *dh;
 370
 371         dh = container_of(cfs_hash_dh_hhead(hs, bd),
 372                           struct cfs_hash_dhead, dh_head);
 373         if (hnd->next == NULL) { /* it's the tail */
 374                 dh->dh_tail = (hnd->pprev == &dh->dh_head.first) ? NULL :
 375                               container_of(hnd->pprev, struct hlist_node, next);
 376         }
 377         hlist_del_init(hnd);
 378         return -1; /* unknown depth */
 379 }
 380
 381 /**
 382  * double links hash head with depth tracking
 383  * new element is always added to tail of hlist
 384  */
 385 struct cfs_hash_dhead_dep {
 386         struct hlist_head       dd_head;        /**< entries list */
 387         struct hlist_node       *dd_tail;       /**< the last entry */
 388         unsigned int        dd_depth;       /**< list length */
 389 };
 390
 391 static int
 392 cfs_hash_dd_hhead_size(struct cfs_hash *hs)
 393 {
 394         return sizeof(struct cfs_hash_dhead_dep);
 395 }
 396
 397 static struct hlist_head *
 398 cfs_hash_dd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
 399 {
 400         struct cfs_hash_dhead_dep *head;
 401
 402         head = (struct cfs_hash_dhead_dep *)&bd->bd_bucket->hsb_head[0];
 403         return &head[bd->bd_offset].dd_head;
 404 }
 405
 406 static int
 407 cfs_hash_dd_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 408                       struct hlist_node *hnode)
 409 {
 410         struct cfs_hash_dhead_dep *dh;
 411
 412         dh = container_of(cfs_hash_dd_hhead(hs, bd),
 413                           struct cfs_hash_dhead_dep, dd_head);
 414         if (dh->dd_tail != NULL) /* not empty */
 415                 hlist_add_behind(hnode, dh->dd_tail);
 416         else /* empty list */
 417                 hlist_add_head(hnode, &dh->dd_head);
 418         dh->dd_tail = hnode;
 419         return ++dh->dd_depth;
 420 }
 421
 422 static int
 423 cfs_hash_dd_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 424                       struct hlist_node *hnd)
 425 {
 426         struct cfs_hash_dhead_dep *dh;
 427
 428         dh = container_of(cfs_hash_dd_hhead(hs, bd),
 429                           struct cfs_hash_dhead_dep, dd_head);
 430         if (hnd->next == NULL) { /* it's the tail */
 431                 dh->dd_tail = (hnd->pprev == &dh->dd_head.first) ? NULL :
 432                               container_of(hnd->pprev, struct hlist_node, next);
 433         }
 434         hlist_del_init(hnd);
 435         return --dh->dd_depth;
 436 }
 437
 438 static struct cfs_hash_hlist_ops cfs_hash_hh_hops = {
 439         .hop_hhead      = cfs_hash_hh_hhead,
 440         .hop_hhead_size = cfs_hash_hh_hhead_size,
 441         .hop_hnode_add  = cfs_hash_hh_hnode_add,
 442         .hop_hnode_del  = cfs_hash_hh_hnode_del,
 443 };
 444
 445 static struct cfs_hash_hlist_ops cfs_hash_hd_hops = {
 446         .hop_hhead      = cfs_hash_hd_hhead,
 447         .hop_hhead_size = cfs_hash_hd_hhead_size,
 448         .hop_hnode_add  = cfs_hash_hd_hnode_add,
 449         .hop_hnode_del  = cfs_hash_hd_hnode_del,
 450 };
 451
 452 static struct cfs_hash_hlist_ops cfs_hash_dh_hops = {
 453         .hop_hhead      = cfs_hash_dh_hhead,
 454         .hop_hhead_size = cfs_hash_dh_hhead_size,
 455         .hop_hnode_add  = cfs_hash_dh_hnode_add,
 456         .hop_hnode_del  = cfs_hash_dh_hnode_del,
 457 };
 458
 459 static struct cfs_hash_hlist_ops cfs_hash_dd_hops = {
 460         .hop_hhead      = cfs_hash_dd_hhead,
 461         .hop_hhead_size = cfs_hash_dd_hhead_size,
 462         .hop_hnode_add  = cfs_hash_dd_hnode_add,
 463         .hop_hnode_del  = cfs_hash_dd_hnode_del,
 464 };
 465
 466 static void
 467 cfs_hash_hlist_setup(struct cfs_hash *hs)
 468 {
 469         if (cfs_hash_with_add_tail(hs)) {
 470                 hs->hs_hops = cfs_hash_with_depth(hs) ?
 471                               &cfs_hash_dd_hops : &cfs_hash_dh_hops;
 472         } else {
 473                 hs->hs_hops = cfs_hash_with_depth(hs) ?
 474                               &cfs_hash_hd_hops : &cfs_hash_hh_hops;
 475         }
 476 }
 477
 478 static void
 479 cfs_hash_bd_from_key(struct cfs_hash *hs, struct cfs_hash_bucket **bkts,
 480                      unsigned int bits, const void *key, struct cfs_hash_bd *bd)
 481 {
 482         unsigned int index = cfs_hash_id(hs, key, (1U << bits) - 1);
 483
 484         LASSERT(bits == hs->hs_cur_bits || bits == hs->hs_rehash_bits);
 485
 486         bd->bd_bucket = bkts[index & ((1U << (bits - hs->hs_bkt_bits)) - 1)];
 487         bd->bd_offset = index >> (bits - hs->hs_bkt_bits);
 488 }
 489
 490 void
 491 cfs_hash_bd_get(struct cfs_hash *hs, const void *key, struct cfs_hash_bd *bd)
 492 {
 493         /* NB: caller should hold hs->hs_rwlock if REHASH is set */
 494         if (likely(hs->hs_rehash_buckets == NULL)) {
 495                 cfs_hash_bd_from_key(hs, hs->hs_buckets,
 496                                      hs->hs_cur_bits, key, bd);
 497         } else {
 498                 LASSERT(hs->hs_rehash_bits != 0);
 499                 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
 500                                      hs->hs_rehash_bits, key, bd);
 501         }
 502 }
 503 EXPORT_SYMBOL(cfs_hash_bd_get);
 504
 505 static inline void
 506 cfs_hash_bd_dep_record(struct cfs_hash *hs, struct cfs_hash_bd *bd, int dep_cur)
 507 {
 508         if (likely(dep_cur <= bd->bd_bucket->hsb_depmax))
 509                 return;
 510
 511         bd->bd_bucket->hsb_depmax = dep_cur;
 512 # if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
 513         if (likely(warn_on_depth == 0 ||
 514                    max(warn_on_depth, hs->hs_dep_max) >= dep_cur))
 515                 return;
 516
 517         spin_lock(&hs->hs_dep_lock);
 518         hs->hs_dep_max  = dep_cur;
 519         hs->hs_dep_bkt  = bd->bd_bucket->hsb_index;
 520         hs->hs_dep_off  = bd->bd_offset;
 521         hs->hs_dep_bits = hs->hs_cur_bits;
 522         spin_unlock(&hs->hs_dep_lock);
 523
 524         cfs_wi_schedule(cfs_sched_rehash, &hs->hs_dep_wi);
 525 # endif
 526 }
 527
 528 void
 529 cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 530                        struct hlist_node *hnode)
 531 {
 532         int             rc;
 533
 534         rc = hs->hs_hops->hop_hnode_add(hs, bd, hnode);
 535         cfs_hash_bd_dep_record(hs, bd, rc);
 536         bd->bd_bucket->hsb_version++;
 537         if (unlikely(bd->bd_bucket->hsb_version == 0))
 538                 bd->bd_bucket->hsb_version++;
 539         bd->bd_bucket->hsb_count++;
 540
 541         if (cfs_hash_with_counter(hs))
 542                 atomic_inc(&hs->hs_count);
 543         if (!cfs_hash_with_no_itemref(hs))
 544                 cfs_hash_get(hs, hnode);
 545 }
 546 EXPORT_SYMBOL(cfs_hash_bd_add_locked);
 547
 548 void
 549 cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 550                        struct hlist_node *hnode)
 551 {
 552         hs->hs_hops->hop_hnode_del(hs, bd, hnode);
 553
 554         LASSERT(bd->bd_bucket->hsb_count > 0);
 555         bd->bd_bucket->hsb_count--;
 556         bd->bd_bucket->hsb_version++;
 557         if (unlikely(bd->bd_bucket->hsb_version == 0))
 558                 bd->bd_bucket->hsb_version++;
 559
 560         if (cfs_hash_with_counter(hs)) {
 561                 LASSERT(atomic_read(&hs->hs_count) > 0);
 562                 atomic_dec(&hs->hs_count);
 563         }
 564         if (!cfs_hash_with_no_itemref(hs))
 565                 cfs_hash_put_locked(hs, hnode);
 566 }
 567 EXPORT_SYMBOL(cfs_hash_bd_del_locked);
 568
 569 void
 570 cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
 571                         struct cfs_hash_bd *bd_new, struct hlist_node *hnode)
 572 {
 573         struct cfs_hash_bucket *obkt = bd_old->bd_bucket;
 574         struct cfs_hash_bucket *nbkt = bd_new->bd_bucket;
 575         int             rc;
 576
 577         if (cfs_hash_bd_compare(bd_old, bd_new) == 0)
 578                 return;
 579
 580         /* use cfs_hash_bd_hnode_add/del, to avoid atomic & refcount ops
 581          * in cfs_hash_bd_del/add_locked */
 582         hs->hs_hops->hop_hnode_del(hs, bd_old, hnode);
 583         rc = hs->hs_hops->hop_hnode_add(hs, bd_new, hnode);
 584         cfs_hash_bd_dep_record(hs, bd_new, rc);
 585
 586         LASSERT(obkt->hsb_count > 0);
 587         obkt->hsb_count--;
 588         obkt->hsb_version++;
 589         if (unlikely(obkt->hsb_version == 0))
 590                 obkt->hsb_version++;
 591         nbkt->hsb_count++;
 592         nbkt->hsb_version++;
 593         if (unlikely(nbkt->hsb_version == 0))
 594                 nbkt->hsb_version++;
 595 }
 596 EXPORT_SYMBOL(cfs_hash_bd_move_locked);
 597
 598 enum {
 599         /** always set, for sanity (avoid ZERO intent) */
 600         CFS_HS_LOOKUP_MASK_FIND     = BIT(0),
 601         /** return entry with a ref */
 602         CFS_HS_LOOKUP_MASK_REF      = BIT(1),
 603         /** add entry if not existing */
 604         CFS_HS_LOOKUP_MASK_ADD      = BIT(2),
 605         /** delete entry, ignore other masks */
 606         CFS_HS_LOOKUP_MASK_DEL      = BIT(3),
 607 };
 608
 609 enum cfs_hash_lookup_intent {
 610         /** return item w/o refcount */
 611         CFS_HS_LOOKUP_IT_PEEK       = CFS_HS_LOOKUP_MASK_FIND,
 612         /** return item with refcount */
 613         CFS_HS_LOOKUP_IT_FIND       = (CFS_HS_LOOKUP_MASK_FIND |
 614                                        CFS_HS_LOOKUP_MASK_REF),
 615         /** return item w/o refcount if existed, otherwise add */
 616         CFS_HS_LOOKUP_IT_ADD    = (CFS_HS_LOOKUP_MASK_FIND |
 617                                        CFS_HS_LOOKUP_MASK_ADD),
 618         /** return item with refcount if existed, otherwise add */
 619         CFS_HS_LOOKUP_IT_FINDADD    = (CFS_HS_LOOKUP_IT_FIND |
 620                                        CFS_HS_LOOKUP_MASK_ADD),
 621         /** delete if existed */
 622         CFS_HS_LOOKUP_IT_FINDDEL    = (CFS_HS_LOOKUP_MASK_FIND |
 623                                        CFS_HS_LOOKUP_MASK_DEL)
 624 };
 625
 626 static struct hlist_node *
 627 cfs_hash_bd_lookup_intent(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 628                           const void *key, struct hlist_node *hnode,
 629                           enum cfs_hash_lookup_intent intent)
 630
 631 {
 632         struct hlist_head  *hhead = cfs_hash_bd_hhead(hs, bd);
 633         struct hlist_node  *ehnode;
 634         struct hlist_node  *match;
 635         int  intent_add = (intent & CFS_HS_LOOKUP_MASK_ADD) != 0;
 636
 637         /* with this function, we can avoid a lot of useless refcount ops,
 638          * which are expensive atomic operations most time. */
 639         match = intent_add ? NULL : hnode;
 640         hlist_for_each(ehnode, hhead) {
 641                 if (!cfs_hash_keycmp(hs, key, ehnode))
 642                         continue;
 643
 644                 if (match != NULL && match != ehnode) /* can't match */
 645                         continue;
 646
 647                 /* match and ... */
 648                 if ((intent & CFS_HS_LOOKUP_MASK_DEL) != 0) {
 649                         cfs_hash_bd_del_locked(hs, bd, ehnode);
 650                         return ehnode;
 651                 }
 652
 653                 /* caller wants refcount? */
 654                 if ((intent & CFS_HS_LOOKUP_MASK_REF) != 0)
 655                         cfs_hash_get(hs, ehnode);
 656                 return ehnode;
 657         }
 658         /* no match item */
 659         if (!intent_add)
 660                 return NULL;
 661
 662         LASSERT(hnode != NULL);
 663         cfs_hash_bd_add_locked(hs, bd, hnode);
 664         return hnode;
 665 }
 666
 667 struct hlist_node *
 668 cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd, const void *key)
 669 {
 670         return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
 671                                          CFS_HS_LOOKUP_IT_FIND);
 672 }
 673 EXPORT_SYMBOL(cfs_hash_bd_lookup_locked);
 674
 675 struct hlist_node *
 676 cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd, const void *key)
 677 {
 678         return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
 679                                          CFS_HS_LOOKUP_IT_PEEK);
 680 }
 681 EXPORT_SYMBOL(cfs_hash_bd_peek_locked);
 682
 683 struct hlist_node *
 684 cfs_hash_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 685                            const void *key, struct hlist_node *hnode,
 686                            int noref)
 687 {
 688         return cfs_hash_bd_lookup_intent(hs, bd, key, hnode,
 689                                          (!noref * CFS_HS_LOOKUP_MASK_REF) |
 690                                          CFS_HS_LOOKUP_IT_ADD);
 691 }
 692 EXPORT_SYMBOL(cfs_hash_bd_findadd_locked);
 693
 694 struct hlist_node *
 695 cfs_hash_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
 696                            const void *key, struct hlist_node *hnode)
 697 {
 698         /* hnode can be NULL, we find the first item with @key */
 699         return cfs_hash_bd_lookup_intent(hs, bd, key, hnode,
 700                                          CFS_HS_LOOKUP_IT_FINDDEL);
 701 }
 702 EXPORT_SYMBOL(cfs_hash_bd_finddel_locked);
 703
 704 static void
 705 cfs_hash_multi_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
 706                        unsigned n, int excl)
 707 {
 708         struct cfs_hash_bucket *prev = NULL;
 709         int             i;
 710
 711         /**
 712          * bds must be ascendantly ordered by bd->bd_bucket->hsb_index.
 713          * NB: it's possible that several bds point to the same bucket but
 714          * have different bd::bd_offset, so need take care of deadlock.
 715          */
 716         cfs_hash_for_each_bd(bds, n, i) {
 717                 if (prev == bds[i].bd_bucket)
 718                         continue;
 719
 720                 LASSERT(prev == NULL ||
 721                         prev->hsb_index < bds[i].bd_bucket->hsb_index);
 722                 cfs_hash_bd_lock(hs, &bds[i], excl);
 723                 prev = bds[i].bd_bucket;
 724         }
 725 }
 726
 727 static void
 728 cfs_hash_multi_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
 729                          unsigned n, int excl)
 730 {
 731         struct cfs_hash_bucket *prev = NULL;
 732         int             i;
 733
 734         cfs_hash_for_each_bd(bds, n, i) {
 735                 if (prev != bds[i].bd_bucket) {
 736                         cfs_hash_bd_unlock(hs, &bds[i], excl);
 737                         prev = bds[i].bd_bucket;
 738                 }
 739         }
 740 }
 741
 742 static struct hlist_node *
 743 cfs_hash_multi_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
 744                                 unsigned n, const void *key)
 745 {
 746         struct hlist_node  *ehnode;
 747         unsigned           i;
 748
 749         cfs_hash_for_each_bd(bds, n, i) {
 750                 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, NULL,
 751                                                    CFS_HS_LOOKUP_IT_FIND);
 752                 if (ehnode != NULL)
 753                         return ehnode;
 754         }
 755         return NULL;
 756 }
 757
 758 static struct hlist_node *
 759 cfs_hash_multi_bd_findadd_locked(struct cfs_hash *hs,
 760                                  struct cfs_hash_bd *bds, unsigned n, const void *key,
 761                                  struct hlist_node *hnode, int noref)
 762 {
 763         struct hlist_node  *ehnode;
 764         int             intent;
 765         unsigned           i;
 766
 767         LASSERT(hnode != NULL);
 768         intent = (!noref * CFS_HS_LOOKUP_MASK_REF) | CFS_HS_LOOKUP_IT_PEEK;
 769
 770         cfs_hash_for_each_bd(bds, n, i) {
 771                 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key,
 772                                                    NULL, intent);
 773                 if (ehnode != NULL)
 774                         return ehnode;
 775         }
 776
 777         if (i == 1) { /* only one bucket */
 778                 cfs_hash_bd_add_locked(hs, &bds[0], hnode);
 779         } else {
 780                 struct cfs_hash_bd      mybd;
 781
 782                 cfs_hash_bd_get(hs, key, &mybd);
 783                 cfs_hash_bd_add_locked(hs, &mybd, hnode);
 784         }
 785
 786         return hnode;
 787 }
 788
 789 static struct hlist_node *
 790 cfs_hash_multi_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
 791                                  unsigned n, const void *key,
 792                                  struct hlist_node *hnode)
 793 {
 794         struct hlist_node  *ehnode;
 795         unsigned           i;
 796
 797         cfs_hash_for_each_bd(bds, n, i) {
 798                 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, hnode,
 799                                                    CFS_HS_LOOKUP_IT_FINDDEL);
 800                 if (ehnode != NULL)
 801                         return ehnode;
 802         }
 803         return NULL;
 804 }
 805
 806 static void
 807 cfs_hash_bd_order(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
 808 {
 809         int     rc;
 810
 811         if (bd2->bd_bucket == NULL)
 812                 return;
 813
 814         if (bd1->bd_bucket == NULL) {
 815                 *bd1 = *bd2;
 816                 bd2->bd_bucket = NULL;
 817                 return;
 818         }
 819
 820         rc = cfs_hash_bd_compare(bd1, bd2);
 821         if (rc == 0) {
 822                 bd2->bd_bucket = NULL;
 823
 824         } else if (rc > 0) { /* swab bd1 and bd2 */
 825                 struct cfs_hash_bd tmp;
 826
 827                 tmp = *bd2;
 828                 *bd2 = *bd1;
 829                 *bd1 = tmp;
 830         }
 831 }
 832
 833 void
 834 cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key, struct cfs_hash_bd *bds)
 835 {
 836         /* NB: caller should hold hs_lock.rw if REHASH is set */
 837         cfs_hash_bd_from_key(hs, hs->hs_buckets,
 838                              hs->hs_cur_bits, key, &bds[0]);
 839         if (likely(hs->hs_rehash_buckets == NULL)) {
 840                 /* no rehash or not rehashing */
 841                 bds[1].bd_bucket = NULL;
 842                 return;
 843         }
 844
 845         LASSERT(hs->hs_rehash_bits != 0);
 846         cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
 847                              hs->hs_rehash_bits, key, &bds[1]);
 848
 849         cfs_hash_bd_order(&bds[0], &bds[1]);
 850 }
 851 EXPORT_SYMBOL(cfs_hash_dual_bd_get);
 852
 853 void
 854 cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds, int excl)
 855 {
 856         cfs_hash_multi_bd_lock(hs, bds, 2, excl);
 857 }
 858 EXPORT_SYMBOL(cfs_hash_dual_bd_lock);
 859
 860 void
 861 cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds, int excl)
 862 {
 863         cfs_hash_multi_bd_unlock(hs, bds, 2, excl);
 864 }
 865 EXPORT_SYMBOL(cfs_hash_dual_bd_unlock);
 866
 867 struct hlist_node *
 868 cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
 869                                const void *key)
 870 {
 871         return cfs_hash_multi_bd_lookup_locked(hs, bds, 2, key);
 872 }
 873 EXPORT_SYMBOL(cfs_hash_dual_bd_lookup_locked);
 874
 875 struct hlist_node *
 876 cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
 877                                 const void *key, struct hlist_node *hnode,
 878                                 int noref)
 879 {
 880         return cfs_hash_multi_bd_findadd_locked(hs, bds, 2, key,
 881                                                 hnode, noref);
 882 }
 883 EXPORT_SYMBOL(cfs_hash_dual_bd_findadd_locked);
 884
 885 struct hlist_node *
 886 cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
 887                                 const void *key, struct hlist_node *hnode)
 888 {
 889         return cfs_hash_multi_bd_finddel_locked(hs, bds, 2, key, hnode);
 890 }
 891 EXPORT_SYMBOL(cfs_hash_dual_bd_finddel_locked);
 892
 893 static void
 894 cfs_hash_buckets_free(struct cfs_hash_bucket **buckets,
 895                       int bkt_size, int prev_size, int size)
 896 {
 897         int     i;
 898
 899         for (i = prev_size; i < size; i++) {
 900                 if (buckets[i] != NULL)
 901                         LIBCFS_FREE(buckets[i], bkt_size);
 902         }
 903
 904         LIBCFS_FREE(buckets, sizeof(buckets[0]) * size);
 905 }
 906
 907 /*
 908  * Create or grow bucket memory. Return old_buckets if no allocation was
 909  * needed, the newly allocated buckets if allocation was needed and
 910  * successful, and NULL on error.
 911  */
 912 static struct cfs_hash_bucket **
 913 cfs_hash_buckets_realloc(struct cfs_hash *hs, struct cfs_hash_bucket **old_bkts,
 914                          unsigned int old_size, unsigned int new_size)
 915 {
 916         struct cfs_hash_bucket **new_bkts;
 917         int              i;
 918
 919         LASSERT(old_size == 0 || old_bkts != NULL);
 920
 921         if (old_bkts != NULL && old_size == new_size)
 922                 return old_bkts;
 923
 924         LIBCFS_ALLOC(new_bkts, sizeof(new_bkts[0]) * new_size);
 925         if (new_bkts == NULL)
 926                 return NULL;
 927
 928         if (old_bkts != NULL) {
 929                 memcpy(new_bkts, old_bkts,
 930                        min(old_size, new_size) * sizeof(*old_bkts));
 931         }
 932
 933         for (i = old_size; i < new_size; i++) {
 934                 struct hlist_head *hhead;
 935                 struct cfs_hash_bd     bd;
 936
 937                 LIBCFS_ALLOC(new_bkts[i], cfs_hash_bkt_size(hs));
 938                 if (new_bkts[i] == NULL) {
 939                         cfs_hash_buckets_free(new_bkts, cfs_hash_bkt_size(hs),
 940                                               old_size, new_size);
 941                         return NULL;
 942                 }
 943
 944                 new_bkts[i]->hsb_index   = i;
 945                 new_bkts[i]->hsb_version = 1;  /* shouldn't be zero */
 946                 new_bkts[i]->hsb_depmax  = -1; /* unknown */
 947                 bd.bd_bucket = new_bkts[i];
 948                 cfs_hash_bd_for_each_hlist(hs, &bd, hhead)
 949                         INIT_HLIST_HEAD(hhead);
 950
 951                 if (cfs_hash_with_no_lock(hs) ||
 952                     cfs_hash_with_no_bktlock(hs))
 953                         continue;
 954
 955                 if (cfs_hash_with_rw_bktlock(hs))
 956                         rwlock_init(&new_bkts[i]->hsb_lock.rw);
 957                 else if (cfs_hash_with_spin_bktlock(hs))
 958                         spin_lock_init(&new_bkts[i]->hsb_lock.spin);
 959                 else
 960                         LBUG(); /* invalid use-case */
 961         }
 962         return new_bkts;
 963 }
 964
 965 /**
 966  * Initialize new libcfs hash, where:
 967  * @name     - Descriptive hash name
 968  * @cur_bits - Initial hash table size, in bits
 969  * @max_bits - Maximum allowed hash table resize, in bits
 970  * @ops      - Registered hash table operations
 971  * @flags    - CFS_HASH_REHASH enable synamic hash resizing
 972  *         - CFS_HASH_SORT enable chained hash sort
 973  */
 974 static int cfs_hash_rehash_worker(cfs_workitem_t *wi);
 975
 976 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
 977 static int cfs_hash_dep_print(cfs_workitem_t *wi)
 978 {
 979         struct cfs_hash *hs = container_of(wi, struct cfs_hash, hs_dep_wi);
 980         int      dep;
 981         int      bkt;
 982         int      off;
 983         int      bits;
 984
 985         spin_lock(&hs->hs_dep_lock);
 986         dep  = hs->hs_dep_max;
 987         bkt  = hs->hs_dep_bkt;
 988         off  = hs->hs_dep_off;
 989         bits = hs->hs_dep_bits;
 990         spin_unlock(&hs->hs_dep_lock);
 991
 992         LCONSOLE_WARN("#### HASH %s (bits: %d): max depth %d at bucket %d/%d\n",
 993                       hs->hs_name, bits, dep, bkt, off);
 994         spin_lock(&hs->hs_dep_lock);
 995         hs->hs_dep_bits = 0; /* mark as workitem done */
 996         spin_unlock(&hs->hs_dep_lock);
 997         return 0;
 998 }
 999
1000 static void cfs_hash_depth_wi_init(struct cfs_hash *hs)
1001 {
1002         spin_lock_init(&hs->hs_dep_lock);
1003         cfs_wi_init(&hs->hs_dep_wi, hs, cfs_hash_dep_print);
1004 }
1005
1006 static void cfs_hash_depth_wi_cancel(struct cfs_hash *hs)
1007 {
1008         if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_dep_wi))
1009                 return;
1010
1011         spin_lock(&hs->hs_dep_lock);
1012         while (hs->hs_dep_bits != 0) {
1013                 spin_unlock(&hs->hs_dep_lock);
1014                 cond_resched();
1015                 spin_lock(&hs->hs_dep_lock);
1016         }
1017         spin_unlock(&hs->hs_dep_lock);
1018 }
1019
1020 #else /* CFS_HASH_DEBUG_LEVEL < CFS_HASH_DEBUG_1 */
1021
1022 static inline void cfs_hash_depth_wi_init(struct cfs_hash *hs) {}
1023 static inline void cfs_hash_depth_wi_cancel(struct cfs_hash *hs) {}
1024
1025 #endif /* CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1 */
1026
1027 struct cfs_hash *
1028 cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits,
1029                 unsigned bkt_bits, unsigned extra_bytes,
1030                 unsigned min_theta, unsigned max_theta,
1031                 struct cfs_hash_ops *ops, unsigned flags)
1032 {
1033         struct cfs_hash *hs;
1034         int      len;
1035
1036         CLASSERT(CFS_HASH_THETA_BITS < 15);
1037
1038         LASSERT(name != NULL);
1039         LASSERT(ops != NULL);
1040         LASSERT(ops->hs_key);
1041         LASSERT(ops->hs_hash);
1042         LASSERT(ops->hs_object);
1043         LASSERT(ops->hs_keycmp);
1044         LASSERT(ops->hs_get != NULL);
1045         LASSERT(ops->hs_put_locked != NULL);
1046
1047         if ((flags & CFS_HASH_REHASH) != 0)
1048                 flags |= CFS_HASH_COUNTER; /* must have counter */
1049
1050         LASSERT(cur_bits > 0);
1051         LASSERT(cur_bits >= bkt_bits);
1052         LASSERT(max_bits >= cur_bits && max_bits < 31);
1053         LASSERT(ergo((flags & CFS_HASH_REHASH) == 0, cur_bits == max_bits));
1054         LASSERT(ergo((flags & CFS_HASH_REHASH) != 0,
1055                      (flags & CFS_HASH_NO_LOCK) == 0));
1056         LASSERT(ergo((flags & CFS_HASH_REHASH_KEY) != 0,
1057                       ops->hs_keycpy != NULL));
1058
1059         len = (flags & CFS_HASH_BIGNAME) == 0 ?
1060               CFS_HASH_NAME_LEN : CFS_HASH_BIGNAME_LEN;
1061         LIBCFS_ALLOC(hs, offsetof(struct cfs_hash, hs_name[len]));
1062         if (hs == NULL)
1063                 return NULL;
1064
1065         strncpy(hs->hs_name, name, len);
1066         hs->hs_name[len - 1] = '\0';
1067         hs->hs_flags = flags;
1068
1069         atomic_set(&hs->hs_refcount, 1);
1070         atomic_set(&hs->hs_count, 0);
1071
1072         cfs_hash_lock_setup(hs);
1073         cfs_hash_hlist_setup(hs);
1074
1075         hs->hs_cur_bits = (__u8)cur_bits;
1076         hs->hs_min_bits = (__u8)cur_bits;
1077         hs->hs_max_bits = (__u8)max_bits;
1078         hs->hs_bkt_bits = (__u8)bkt_bits;
1079
1080         hs->hs_ops       = ops;
1081         hs->hs_extra_bytes = extra_bytes;
1082         hs->hs_rehash_bits = 0;
1083         cfs_wi_init(&hs->hs_rehash_wi, hs, cfs_hash_rehash_worker);
1084         cfs_hash_depth_wi_init(hs);
1085
1086         if (cfs_hash_with_rehash(hs))
1087                 __cfs_hash_set_theta(hs, min_theta, max_theta);
1088
1089         hs->hs_buckets = cfs_hash_buckets_realloc(hs, NULL, 0,
1090                                                   CFS_HASH_NBKT(hs));
1091         if (hs->hs_buckets != NULL)
1092                 return hs;
1093
1094         LIBCFS_FREE(hs, offsetof(struct cfs_hash, hs_name[len]));
1095         return NULL;
1096 }
1097 EXPORT_SYMBOL(cfs_hash_create);
1098
1099 /**
1100  * Cleanup libcfs hash @hs.
1101  */
1102 static void
1103 cfs_hash_destroy(struct cfs_hash *hs)
1104 {
1105         struct hlist_node     *hnode;
1106         struct hlist_node     *pos;
1107         struct cfs_hash_bd       bd;
1108         int                i;
1109
1110         LASSERT(hs != NULL);
1111         LASSERT(!cfs_hash_is_exiting(hs) &&
1112                 !cfs_hash_is_iterating(hs));
1113
1114         /**
1115          * prohibit further rehashes, don't need any lock because
1116          * I'm the only (last) one can change it.
1117          */
1118         hs->hs_exiting = 1;
1119         if (cfs_hash_with_rehash(hs))
1120                 cfs_hash_rehash_cancel(hs);
1121
1122         cfs_hash_depth_wi_cancel(hs);
1123         /* rehash should be done/canceled */
1124         LASSERT(hs->hs_buckets != NULL &&
1125                 hs->hs_rehash_buckets == NULL);
1126
1127         cfs_hash_for_each_bucket(hs, &bd, i) {
1128                 struct hlist_head *hhead;
1129
1130                 LASSERT(bd.bd_bucket != NULL);
1131                 /* no need to take this lock, just for consistent code */
1132                 cfs_hash_bd_lock(hs, &bd, 1);
1133
1134                 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1135                         hlist_for_each_safe(hnode, pos, hhead) {
1136                                 LASSERTF(!cfs_hash_with_assert_empty(hs),
1137                                          "hash %s bucket %u(%u) is not empty: %u items left\n",
1138                                          hs->hs_name, bd.bd_bucket->hsb_index,
1139                                          bd.bd_offset, bd.bd_bucket->hsb_count);
1140                                 /* can't assert key valicate, because we
1141                                  * can interrupt rehash */
1142                                 cfs_hash_bd_del_locked(hs, &bd, hnode);
1143                                 cfs_hash_exit(hs, hnode);
1144                         }
1145                 }
1146                 LASSERT(bd.bd_bucket->hsb_count == 0);
1147                 cfs_hash_bd_unlock(hs, &bd, 1);
1148                 cond_resched();
1149         }
1150
1151         LASSERT(atomic_read(&hs->hs_count) == 0);
1152
1153         cfs_hash_buckets_free(hs->hs_buckets, cfs_hash_bkt_size(hs),
1154                               0, CFS_HASH_NBKT(hs));
1155         i = cfs_hash_with_bigname(hs) ?
1156             CFS_HASH_BIGNAME_LEN : CFS_HASH_NAME_LEN;
1157         LIBCFS_FREE(hs, offsetof(struct cfs_hash, hs_name[i]));
1158 }
1159
1160 struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs)
1161 {
1162         if (atomic_inc_not_zero(&hs->hs_refcount))
1163                 return hs;
1164         return NULL;
1165 }
1166 EXPORT_SYMBOL(cfs_hash_getref);
1167
1168 void cfs_hash_putref(struct cfs_hash *hs)
1169 {
1170         if (atomic_dec_and_test(&hs->hs_refcount))
1171                 cfs_hash_destroy(hs);
1172 }
1173 EXPORT_SYMBOL(cfs_hash_putref);
1174
1175 static inline int
1176 cfs_hash_rehash_bits(struct cfs_hash *hs)
1177 {
1178         if (cfs_hash_with_no_lock(hs) ||
1179             !cfs_hash_with_rehash(hs))
1180                 return -EOPNOTSUPP;
1181
1182         if (unlikely(cfs_hash_is_exiting(hs)))
1183                 return -ESRCH;
1184
1185         if (unlikely(cfs_hash_is_rehashing(hs)))
1186                 return -EALREADY;
1187
1188         if (unlikely(cfs_hash_is_iterating(hs)))
1189                 return -EAGAIN;
1190
1191         /* XXX: need to handle case with max_theta != 2.0
1192          *      and the case with min_theta != 0.5 */
1193         if ((hs->hs_cur_bits < hs->hs_max_bits) &&
1194             (__cfs_hash_theta(hs) > hs->hs_max_theta))
1195                 return hs->hs_cur_bits + 1;
1196
1197         if (!cfs_hash_with_shrink(hs))
1198                 return 0;
1199
1200         if ((hs->hs_cur_bits > hs->hs_min_bits) &&
1201             (__cfs_hash_theta(hs) < hs->hs_min_theta))
1202                 return hs->hs_cur_bits - 1;
1203
1204         return 0;
1205 }
1206
1207 /**
1208  * don't allow inline rehash if:
1209  * - user wants non-blocking change (add/del) on hash table
1210  * - too many elements
1211  */
1212 static inline int
1213 cfs_hash_rehash_inline(struct cfs_hash *hs)
1214 {
1215         return !cfs_hash_with_nblk_change(hs) &&
1216                atomic_read(&hs->hs_count) < CFS_HASH_LOOP_HOG;
1217 }
1218
1219 /**
1220  * Add item @hnode to libcfs hash @hs using @key.  The registered
1221  * ops->hs_get function will be called when the item is added.
1222  */
1223 void
1224 cfs_hash_add(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
1225 {
1226         struct cfs_hash_bd   bd;
1227         int          bits;
1228
1229         LASSERT(hlist_unhashed(hnode));
1230
1231         cfs_hash_lock(hs, 0);
1232         cfs_hash_bd_get_and_lock(hs, key, &bd, 1);
1233
1234         cfs_hash_key_validate(hs, key, hnode);
1235         cfs_hash_bd_add_locked(hs, &bd, hnode);
1236
1237         cfs_hash_bd_unlock(hs, &bd, 1);
1238
1239         bits = cfs_hash_rehash_bits(hs);
1240         cfs_hash_unlock(hs, 0);
1241         if (bits > 0)
1242                 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1243 }
1244 EXPORT_SYMBOL(cfs_hash_add);
1245
1246 static struct hlist_node *
1247 cfs_hash_find_or_add(struct cfs_hash *hs, const void *key,
1248                      struct hlist_node *hnode, int noref)
1249 {
1250         struct hlist_node *ehnode;
1251         struct cfs_hash_bd     bds[2];
1252         int            bits = 0;
1253
1254         LASSERT(hlist_unhashed(hnode));
1255
1256         cfs_hash_lock(hs, 0);
1257         cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
1258
1259         cfs_hash_key_validate(hs, key, hnode);
1260         ehnode = cfs_hash_dual_bd_findadd_locked(hs, bds, key,
1261                                                  hnode, noref);
1262         cfs_hash_dual_bd_unlock(hs, bds, 1);
1263
1264         if (ehnode == hnode) /* new item added */
1265                 bits = cfs_hash_rehash_bits(hs);
1266         cfs_hash_unlock(hs, 0);
1267         if (bits > 0)
1268                 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1269
1270         return ehnode;
1271 }
1272
1273 /**
1274  * Add item @hnode to libcfs hash @hs using @key.  The registered
1275  * ops->hs_get function will be called if the item was added.
1276  * Returns 0 on success or -EALREADY on key collisions.
1277  */
1278 int
1279 cfs_hash_add_unique(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
1280 {
1281         return cfs_hash_find_or_add(hs, key, hnode, 1) != hnode ?
1282                -EALREADY : 0;
1283 }
1284 EXPORT_SYMBOL(cfs_hash_add_unique);
1285
1286 /**
1287  * Add item @hnode to libcfs hash @hs using @key.  If this @key
1288  * already exists in the hash then ops->hs_get will be called on the
1289  * conflicting entry and that entry will be returned to the caller.
1290  * Otherwise ops->hs_get is called on the item which was added.
1291  */
1292 void *
1293 cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
1294                         struct hlist_node *hnode)
1295 {
1296         hnode = cfs_hash_find_or_add(hs, key, hnode, 0);
1297
1298         return cfs_hash_object(hs, hnode);
1299 }
1300 EXPORT_SYMBOL(cfs_hash_findadd_unique);
1301
1302 /**
1303  * Delete item @hnode from the libcfs hash @hs using @key.  The @key
1304  * is required to ensure the correct hash bucket is locked since there
1305  * is no direct linkage from the item to the bucket.  The object
1306  * removed from the hash will be returned and obs->hs_put is called
1307  * on the removed object.
1308  */
1309 void *
1310 cfs_hash_del(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
1311 {
1312         void       *obj  = NULL;
1313         int          bits = 0;
1314         struct cfs_hash_bd   bds[2];
1315
1316         cfs_hash_lock(hs, 0);
1317         cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
1318
1319         /* NB: do nothing if @hnode is not in hash table */
1320         if (hnode == NULL || !hlist_unhashed(hnode)) {
1321                 if (bds[1].bd_bucket == NULL && hnode != NULL) {
1322                         cfs_hash_bd_del_locked(hs, &bds[0], hnode);
1323                 } else {
1324                         hnode = cfs_hash_dual_bd_finddel_locked(hs, bds,
1325                                                                 key, hnode);
1326                 }
1327         }
1328
1329         if (hnode != NULL) {
1330                 obj  = cfs_hash_object(hs, hnode);
1331                 bits = cfs_hash_rehash_bits(hs);
1332         }
1333
1334         cfs_hash_dual_bd_unlock(hs, bds, 1);
1335         cfs_hash_unlock(hs, 0);
1336         if (bits > 0)
1337                 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1338
1339         return obj;
1340 }
1341 EXPORT_SYMBOL(cfs_hash_del);
1342
1343 /**
1344  * Delete item given @key in libcfs hash @hs.  The first @key found in
1345  * the hash will be removed, if the key exists multiple times in the hash
1346  * @hs this function must be called once per key.  The removed object
1347  * will be returned and ops->hs_put is called on the removed object.
1348  */
1349 void *
1350 cfs_hash_del_key(struct cfs_hash *hs, const void *key)
1351 {
1352         return cfs_hash_del(hs, key, NULL);
1353 }
1354 EXPORT_SYMBOL(cfs_hash_del_key);
1355
1356 /**
1357  * Lookup an item using @key in the libcfs hash @hs and return it.
1358  * If the @key is found in the hash hs->hs_get() is called and the
1359  * matching objects is returned.  It is the callers responsibility
1360  * to call the counterpart ops->hs_put using the cfs_hash_put() macro
1361  * when when finished with the object.  If the @key was not found
1362  * in the hash @hs NULL is returned.
1363  */
1364 void *
1365 cfs_hash_lookup(struct cfs_hash *hs, const void *key)
1366 {
1367         void             *obj = NULL;
1368         struct hlist_node     *hnode;
1369         struct cfs_hash_bd       bds[2];
1370
1371         cfs_hash_lock(hs, 0);
1372         cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
1373
1374         hnode = cfs_hash_dual_bd_lookup_locked(hs, bds, key);
1375         if (hnode != NULL)
1376                 obj = cfs_hash_object(hs, hnode);
1377
1378         cfs_hash_dual_bd_unlock(hs, bds, 0);
1379         cfs_hash_unlock(hs, 0);
1380
1381         return obj;
1382 }
1383 EXPORT_SYMBOL(cfs_hash_lookup);
1384
1385 static void
1386 cfs_hash_for_each_enter(struct cfs_hash *hs) {
1387         LASSERT(!cfs_hash_is_exiting(hs));
1388
1389         if (!cfs_hash_with_rehash(hs))
1390                 return;
1391         /*
1392          * NB: it's race on cfs_has_t::hs_iterating, but doesn't matter
1393          * because it's just an unreliable signal to rehash-thread,
1394          * rehash-thread will try to finish rehash ASAP when seeing this.
1395          */
1396         hs->hs_iterating = 1;
1397
1398         cfs_hash_lock(hs, 1);
1399         hs->hs_iterators++;
1400
1401         /* NB: iteration is mostly called by service thread,
1402          * we tend to cancel pending rehash-request, instead of
1403          * blocking service thread, we will relaunch rehash request
1404          * after iteration */
1405         if (cfs_hash_is_rehashing(hs))
1406                 cfs_hash_rehash_cancel_locked(hs);
1407         cfs_hash_unlock(hs, 1);
1408 }
1409
1410 static void
1411 cfs_hash_for_each_exit(struct cfs_hash *hs) {
1412         int remained;
1413         int bits;
1414
1415         if (!cfs_hash_with_rehash(hs))
1416                 return;
1417         cfs_hash_lock(hs, 1);
1418         remained = --hs->hs_iterators;
1419         bits = cfs_hash_rehash_bits(hs);
1420         cfs_hash_unlock(hs, 1);
1421         /* NB: it's race on cfs_has_t::hs_iterating, see above */
1422         if (remained == 0)
1423                 hs->hs_iterating = 0;
1424         if (bits > 0) {
1425                 cfs_hash_rehash(hs, atomic_read(&hs->hs_count) <
1426                                     CFS_HASH_LOOP_HOG);
1427         }
1428 }
1429
1430 /**
1431  * For each item in the libcfs hash @hs call the passed callback @func
1432  * and pass to it as an argument each hash item and the private @data.
1433  *
1434  * a) the function may sleep!
1435  * b) during the callback:
1436  *    . the bucket lock is held so the callback must never sleep.
1437  *    . if @removal_safe is true, use can remove current item by
1438  *      cfs_hash_bd_del_locked
1439  */
1440 static __u64
1441 cfs_hash_for_each_tight(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
1442                         void *data, int remove_safe) {
1443         struct hlist_node     *hnode;
1444         struct hlist_node     *pos;
1445         struct cfs_hash_bd       bd;
1446         __u64            count = 0;
1447         int                excl  = !!remove_safe;
1448         int                loop  = 0;
1449         int                i;
1450
1451         cfs_hash_for_each_enter(hs);
1452
1453         cfs_hash_lock(hs, 0);
1454         LASSERT(!cfs_hash_is_rehashing(hs));
1455
1456         cfs_hash_for_each_bucket(hs, &bd, i) {
1457                 struct hlist_head *hhead;
1458
1459                 cfs_hash_bd_lock(hs, &bd, excl);
1460                 if (func == NULL) { /* only glimpse size */
1461                         count += bd.bd_bucket->hsb_count;
1462                         cfs_hash_bd_unlock(hs, &bd, excl);
1463                         continue;
1464                 }
1465
1466                 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1467                         hlist_for_each_safe(hnode, pos, hhead) {
1468                                 cfs_hash_bucket_validate(hs, &bd, hnode);
1469                                 count++;
1470                                 loop++;
1471                                 if (func(hs, &bd, hnode, data)) {
1472                                         cfs_hash_bd_unlock(hs, &bd, excl);
1473                                         goto out;
1474                                 }
1475                         }
1476                 }
1477                 cfs_hash_bd_unlock(hs, &bd, excl);
1478                 if (loop < CFS_HASH_LOOP_HOG)
1479                         continue;
1480                 loop = 0;
1481                 cfs_hash_unlock(hs, 0);
1482                 cond_resched();
1483                 cfs_hash_lock(hs, 0);
1484         }
1485  out:
1486         cfs_hash_unlock(hs, 0);
1487
1488         cfs_hash_for_each_exit(hs);
1489         return count;
1490 }
1491
1492 struct cfs_hash_cond_arg {
1493         cfs_hash_cond_opt_cb_t  func;
1494         void                    *arg;
1495 };
1496
1497 static int
1498 cfs_hash_cond_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
1499                          struct hlist_node *hnode, void *data)
1500 {
1501         struct cfs_hash_cond_arg *cond = data;
1502
1503         if (cond->func(cfs_hash_object(hs, hnode), cond->arg))
1504                 cfs_hash_bd_del_locked(hs, bd, hnode);
1505         return 0;
1506 }
1507
1508 /**
1509  * Delete item from the libcfs hash @hs when @func return true.
1510  * The write lock being hold during loop for each bucket to avoid
1511  * any object be reference.
1512  */
1513 void
1514 cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t func, void *data)
1515 {
1516         struct cfs_hash_cond_arg arg = {
1517                 .func   = func,
1518                 .arg    = data,
1519         };
1520
1521         cfs_hash_for_each_tight(hs, cfs_hash_cond_del_locked, &arg, 1);
1522 }
1523 EXPORT_SYMBOL(cfs_hash_cond_del);
1524
1525 void
1526 cfs_hash_for_each(struct cfs_hash *hs,
1527                   cfs_hash_for_each_cb_t func, void *data)
1528 {
1529         cfs_hash_for_each_tight(hs, func, data, 0);
1530 }
1531 EXPORT_SYMBOL(cfs_hash_for_each);
1532
1533 void
1534 cfs_hash_for_each_safe(struct cfs_hash *hs,
1535                        cfs_hash_for_each_cb_t func, void *data) {
1536         cfs_hash_for_each_tight(hs, func, data, 1);
1537 }
1538 EXPORT_SYMBOL(cfs_hash_for_each_safe);
1539
1540 static int
1541 cfs_hash_peek(struct cfs_hash *hs, struct cfs_hash_bd *bd,
1542               struct hlist_node *hnode, void *data)
1543 {
1544         *(int *)data = 0;
1545         return 1; /* return 1 to break the loop */
1546 }
1547
1548 int
1549 cfs_hash_is_empty(struct cfs_hash *hs)
1550 {
1551         int empty = 1;
1552
1553         cfs_hash_for_each_tight(hs, cfs_hash_peek, &empty, 0);
1554         return empty;
1555 }
1556 EXPORT_SYMBOL(cfs_hash_is_empty);
1557
1558 __u64
1559 cfs_hash_size_get(struct cfs_hash *hs)
1560 {
1561         return cfs_hash_with_counter(hs) ?
1562                atomic_read(&hs->hs_count) :
1563                cfs_hash_for_each_tight(hs, NULL, NULL, 0);
1564 }
1565 EXPORT_SYMBOL(cfs_hash_size_get);
1566
1567 /*
1568  * cfs_hash_for_each_relax:
1569  * Iterate the hash table and call @func on each item without
1570  * any lock. This function can't guarantee to finish iteration
1571  * if these features are enabled:
1572  *
1573  *  a. if rehash_key is enabled, an item can be moved from
1574  *     one bucket to another bucket
1575  *  b. user can remove non-zero-ref item from hash-table,
1576  *     so the item can be removed from hash-table, even worse,
1577  *     it's possible that user changed key and insert to another
1578  *     hash bucket.
1579  * there's no way for us to finish iteration correctly on previous
1580  * two cases, so iteration has to be stopped on change.
1581  */
1582 static int
1583 cfs_hash_for_each_relax(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
1584                         void *data) {
1585         struct hlist_node *hnode;
1586         struct hlist_node *tmp;
1587         struct cfs_hash_bd     bd;
1588         __u32        version;
1589         int            count = 0;
1590         int            stop_on_change;
1591         int            rc;
1592         int            i;
1593
1594         stop_on_change = cfs_hash_with_rehash_key(hs) ||
1595                          !cfs_hash_with_no_itemref(hs) ||
1596                          hs->hs_ops->hs_put_locked == NULL;
1597         cfs_hash_lock(hs, 0);
1598         LASSERT(!cfs_hash_is_rehashing(hs));
1599
1600         cfs_hash_for_each_bucket(hs, &bd, i) {
1601                 struct hlist_head *hhead;
1602
1603                 cfs_hash_bd_lock(hs, &bd, 0);
1604                 version = cfs_hash_bd_version_get(&bd);
1605
1606                 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1607                         for (hnode = hhead->first; hnode != NULL;) {
1608                                 cfs_hash_bucket_validate(hs, &bd, hnode);
1609                                 cfs_hash_get(hs, hnode);
1610                                 cfs_hash_bd_unlock(hs, &bd, 0);
1611                                 cfs_hash_unlock(hs, 0);
1612
1613                                 rc = func(hs, &bd, hnode, data);
1614                                 if (stop_on_change)
1615                                         cfs_hash_put(hs, hnode);
1616                                 cond_resched();
1617                                 count++;
1618
1619                                 cfs_hash_lock(hs, 0);
1620                                 cfs_hash_bd_lock(hs, &bd, 0);
1621                                 if (!stop_on_change) {
1622                                         tmp = hnode->next;
1623                                         cfs_hash_put_locked(hs, hnode);
1624                                         hnode = tmp;
1625                                 } else { /* bucket changed? */
1626                                         if (version !=
1627                                             cfs_hash_bd_version_get(&bd))
1628                                                 break;
1629                                         /* safe to continue because no change */
1630                                         hnode = hnode->next;
1631                                 }
1632                                 if (rc) /* callback wants to break iteration */
1633                                         break;
1634                         }
1635                         if (rc) /* callback wants to break iteration */
1636                                 break;
1637                 }
1638                 cfs_hash_bd_unlock(hs, &bd, 0);
1639                 if (rc) /* callback wants to break iteration */
1640                         break;
1641         }
1642         cfs_hash_unlock(hs, 0);
1643
1644         return count;
1645 }
1646
1647 int
1648 cfs_hash_for_each_nolock(struct cfs_hash *hs,
1649                          cfs_hash_for_each_cb_t func, void *data) {
1650         if (cfs_hash_with_no_lock(hs) ||
1651             cfs_hash_with_rehash_key(hs) ||
1652             !cfs_hash_with_no_itemref(hs))
1653                 return -EOPNOTSUPP;
1654
1655         if (hs->hs_ops->hs_get == NULL ||
1656             (hs->hs_ops->hs_put == NULL &&
1657              hs->hs_ops->hs_put_locked == NULL))
1658                 return -EOPNOTSUPP;
1659
1660         cfs_hash_for_each_enter(hs);
1661         cfs_hash_for_each_relax(hs, func, data);
1662         cfs_hash_for_each_exit(hs);
1663
1664         return 0;
1665 }
1666 EXPORT_SYMBOL(cfs_hash_for_each_nolock);
1667
1668 /**
1669  * For each hash bucket in the libcfs hash @hs call the passed callback
1670  * @func until all the hash buckets are empty.  The passed callback @func
1671  * or the previously registered callback hs->hs_put must remove the item
1672  * from the hash.  You may either use the cfs_hash_del() or hlist_del()
1673  * functions.  No rwlocks will be held during the callback @func it is
1674  * safe to sleep if needed.  This function will not terminate until the
1675  * hash is empty.  Note it is still possible to concurrently add new
1676  * items in to the hash.  It is the callers responsibility to ensure
1677  * the required locking is in place to prevent concurrent insertions.
1678  */
1679 int
1680 cfs_hash_for_each_empty(struct cfs_hash *hs,
1681                         cfs_hash_for_each_cb_t func, void *data) {
1682         unsigned  i = 0;
1683
1684         if (cfs_hash_with_no_lock(hs))
1685                 return -EOPNOTSUPP;
1686
1687         if (hs->hs_ops->hs_get == NULL ||
1688             (hs->hs_ops->hs_put == NULL &&
1689              hs->hs_ops->hs_put_locked == NULL))
1690                 return -EOPNOTSUPP;
1691
1692         cfs_hash_for_each_enter(hs);
1693         while (cfs_hash_for_each_relax(hs, func, data)) {
1694                 CDEBUG(D_INFO, "Try to empty hash: %s, loop: %u\n",
1695                        hs->hs_name, i++);
1696         }
1697         cfs_hash_for_each_exit(hs);
1698         return 0;
1699 }
1700 EXPORT_SYMBOL(cfs_hash_for_each_empty);
1701
1702 void
1703 cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned hindex,
1704                         cfs_hash_for_each_cb_t func, void *data)
1705 {
1706         struct hlist_head   *hhead;
1707         struct hlist_node   *hnode;
1708         struct cfs_hash_bd       bd;
1709
1710         cfs_hash_for_each_enter(hs);
1711         cfs_hash_lock(hs, 0);
1712         if (hindex >= CFS_HASH_NHLIST(hs))
1713                 goto out;
1714
1715         cfs_hash_bd_index_set(hs, hindex, &bd);
1716
1717         cfs_hash_bd_lock(hs, &bd, 0);
1718         hhead = cfs_hash_bd_hhead(hs, &bd);
1719         hlist_for_each(hnode, hhead) {
1720                 if (func(hs, &bd, hnode, data))
1721                         break;
1722         }
1723         cfs_hash_bd_unlock(hs, &bd, 0);
1724  out:
1725         cfs_hash_unlock(hs, 0);
1726         cfs_hash_for_each_exit(hs);
1727 }
1728
1729 EXPORT_SYMBOL(cfs_hash_hlist_for_each);
1730
1731 /*
1732  * For each item in the libcfs hash @hs which matches the @key call
1733  * the passed callback @func and pass to it as an argument each hash
1734  * item and the private @data. During the callback the bucket lock
1735  * is held so the callback must never sleep.
1736    */
1737 void
1738 cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
1739                       cfs_hash_for_each_cb_t func, void *data) {
1740         struct hlist_node   *hnode;
1741         struct cfs_hash_bd       bds[2];
1742         unsigned            i;
1743
1744         cfs_hash_lock(hs, 0);
1745
1746         cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
1747
1748         cfs_hash_for_each_bd(bds, 2, i) {
1749                 struct hlist_head *hlist = cfs_hash_bd_hhead(hs, &bds[i]);
1750
1751                 hlist_for_each(hnode, hlist) {
1752                         cfs_hash_bucket_validate(hs, &bds[i], hnode);
1753
1754                         if (cfs_hash_keycmp(hs, key, hnode)) {
1755                                 if (func(hs, &bds[i], hnode, data))
1756                                         break;
1757                         }
1758                 }
1759         }
1760
1761         cfs_hash_dual_bd_unlock(hs, bds, 0);
1762         cfs_hash_unlock(hs, 0);
1763 }
1764 EXPORT_SYMBOL(cfs_hash_for_each_key);
1765
1766 /**
1767  * Rehash the libcfs hash @hs to the given @bits.  This can be used
1768  * to grow the hash size when excessive chaining is detected, or to
1769  * shrink the hash when it is larger than needed.  When the CFS_HASH_REHASH
1770  * flag is set in @hs the libcfs hash may be dynamically rehashed
1771  * during addition or removal if the hash's theta value exceeds
1772  * either the hs->hs_min_theta or hs->max_theta values.  By default
1773  * these values are tuned to keep the chained hash depth small, and
1774  * this approach assumes a reasonably uniform hashing function.  The
1775  * theta thresholds for @hs are tunable via cfs_hash_set_theta().
1776  */
1777 void
1778 cfs_hash_rehash_cancel_locked(struct cfs_hash *hs)
1779 {
1780         int     i;
1781
1782         /* need hold cfs_hash_lock(hs, 1) */
1783         LASSERT(cfs_hash_with_rehash(hs) &&
1784                 !cfs_hash_with_no_lock(hs));
1785
1786         if (!cfs_hash_is_rehashing(hs))
1787                 return;
1788
1789         if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_rehash_wi)) {
1790                 hs->hs_rehash_bits = 0;
1791                 return;
1792         }
1793
1794         for (i = 2; cfs_hash_is_rehashing(hs); i++) {
1795                 cfs_hash_unlock(hs, 1);
1796                 /* raise console warning while waiting too long */
1797                 CDEBUG(IS_PO2(i >> 3) ? D_WARNING : D_INFO,
1798                        "hash %s is still rehashing, rescheded %d\n",
1799                        hs->hs_name, i - 1);
1800                 cond_resched();
1801                 cfs_hash_lock(hs, 1);
1802         }
1803 }
1804 EXPORT_SYMBOL(cfs_hash_rehash_cancel_locked);
1805
1806 void
1807 cfs_hash_rehash_cancel(struct cfs_hash *hs)
1808 {
1809         cfs_hash_lock(hs, 1);
1810         cfs_hash_rehash_cancel_locked(hs);
1811         cfs_hash_unlock(hs, 1);
1812 }
1813 EXPORT_SYMBOL(cfs_hash_rehash_cancel);
1814
1815 int
1816 cfs_hash_rehash(struct cfs_hash *hs, int do_rehash)
1817 {
1818         int     rc;
1819
1820         LASSERT(cfs_hash_with_rehash(hs) && !cfs_hash_with_no_lock(hs));
1821
1822         cfs_hash_lock(hs, 1);
1823
1824         rc = cfs_hash_rehash_bits(hs);
1825         if (rc <= 0) {
1826                 cfs_hash_unlock(hs, 1);
1827                 return rc;
1828         }
1829
1830         hs->hs_rehash_bits = rc;
1831         if (!do_rehash) {
1832                 /* launch and return */
1833                 cfs_wi_schedule(cfs_sched_rehash, &hs->hs_rehash_wi);
1834                 cfs_hash_unlock(hs, 1);
1835                 return 0;
1836         }
1837
1838         /* rehash right now */
1839         cfs_hash_unlock(hs, 1);
1840
1841         return cfs_hash_rehash_worker(&hs->hs_rehash_wi);
1842 }
1843 EXPORT_SYMBOL(cfs_hash_rehash);
1844
1845 static int
1846 cfs_hash_rehash_bd(struct cfs_hash *hs, struct cfs_hash_bd *old)
1847 {
1848         struct cfs_hash_bd      new;
1849         struct hlist_head  *hhead;
1850         struct hlist_node  *hnode;
1851         struct hlist_node  *pos;
1852         void          *key;
1853         int             c = 0;
1854
1855         /* hold cfs_hash_lock(hs, 1), so don't need any bucket lock */
1856         cfs_hash_bd_for_each_hlist(hs, old, hhead) {
1857                 hlist_for_each_safe(hnode, pos, hhead) {
1858                         key = cfs_hash_key(hs, hnode);
1859                         LASSERT(key != NULL);
1860                         /* Validate hnode is in the correct bucket. */
1861                         cfs_hash_bucket_validate(hs, old, hnode);
1862                         /*
1863                          * Delete from old hash bucket; move to new bucket.
1864                          * ops->hs_key must be defined.
1865                          */
1866                         cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
1867                                              hs->hs_rehash_bits, key, &new);
1868                         cfs_hash_bd_move_locked(hs, old, &new, hnode);
1869                         c++;
1870                 }
1871         }
1872
1873         return c;
1874 }
1875
1876 static int
1877 cfs_hash_rehash_worker(cfs_workitem_t *wi)
1878 {
1879         struct cfs_hash  *hs = container_of(wi, struct cfs_hash, hs_rehash_wi);
1880         struct cfs_hash_bucket **bkts;
1881         struct cfs_hash_bd       bd;
1882         unsigned int    old_size;
1883         unsigned int    new_size;
1884         int              bsize;
1885         int              count = 0;
1886         int              rc = 0;
1887         int              i;
1888
1889         LASSERT (hs != NULL && cfs_hash_with_rehash(hs));
1890
1891         cfs_hash_lock(hs, 0);
1892         LASSERT(cfs_hash_is_rehashing(hs));
1893
1894         old_size = CFS_HASH_NBKT(hs);
1895         new_size = CFS_HASH_RH_NBKT(hs);
1896
1897         cfs_hash_unlock(hs, 0);
1898
1899         /*
1900          * don't need hs::hs_rwlock for hs::hs_buckets,
1901          * because nobody can change bkt-table except me.
1902          */
1903         bkts = cfs_hash_buckets_realloc(hs, hs->hs_buckets,
1904                                         old_size, new_size);
1905         cfs_hash_lock(hs, 1);
1906         if (bkts == NULL) {
1907                 rc = -ENOMEM;
1908                 goto out;
1909         }
1910
1911         if (bkts == hs->hs_buckets) {
1912                 bkts = NULL; /* do nothing */
1913                 goto out;
1914         }
1915
1916         rc = __cfs_hash_theta(hs);
1917         if ((rc >= hs->hs_min_theta) && (rc <= hs->hs_max_theta)) {
1918                 /* free the new allocated bkt-table */
1919                 old_size = new_size;
1920                 new_size = CFS_HASH_NBKT(hs);
1921                 rc = -EALREADY;
1922                 goto out;
1923         }
1924
1925         LASSERT(hs->hs_rehash_buckets == NULL);
1926         hs->hs_rehash_buckets = bkts;
1927
1928         rc = 0;
1929         cfs_hash_for_each_bucket(hs, &bd, i) {
1930                 if (cfs_hash_is_exiting(hs)) {
1931                         rc = -ESRCH;
1932                         /* someone wants to destroy the hash, abort now */
1933                         if (old_size < new_size) /* OK to free old bkt-table */
1934                                 break;
1935                         /* it's shrinking, need free new bkt-table */
1936                         hs->hs_rehash_buckets = NULL;
1937                         old_size = new_size;
1938                         new_size = CFS_HASH_NBKT(hs);
1939                         goto out;
1940                 }
1941
1942                 count += cfs_hash_rehash_bd(hs, &bd);
1943                 if (count < CFS_HASH_LOOP_HOG ||
1944                     cfs_hash_is_iterating(hs)) { /* need to finish ASAP */
1945                         continue;
1946                 }
1947
1948                 count = 0;
1949                 cfs_hash_unlock(hs, 1);
1950                 cond_resched();
1951                 cfs_hash_lock(hs, 1);
1952         }
1953
1954         hs->hs_rehash_count++;
1955
1956         bkts = hs->hs_buckets;
1957         hs->hs_buckets = hs->hs_rehash_buckets;
1958         hs->hs_rehash_buckets = NULL;
1959
1960         hs->hs_cur_bits = hs->hs_rehash_bits;
1961  out:
1962         hs->hs_rehash_bits = 0;
1963         if (rc == -ESRCH) /* never be scheduled again */
1964                 cfs_wi_exit(cfs_sched_rehash, wi);
1965         bsize = cfs_hash_bkt_size(hs);
1966         cfs_hash_unlock(hs, 1);
1967         /* can't refer to @hs anymore because it could be destroyed */
1968         if (bkts != NULL)
1969                 cfs_hash_buckets_free(bkts, bsize, new_size, old_size);
1970         if (rc != 0)
1971                 CDEBUG(D_INFO, "early quit of rehashing: %d\n", rc);
1972         /* return 1 only if cfs_wi_exit is called */
1973         return rc == -ESRCH;
1974 }
1975
1976 /**
1977  * Rehash the object referenced by @hnode in the libcfs hash @hs.  The
1978  * @old_key must be provided to locate the objects previous location
1979  * in the hash, and the @new_key will be used to reinsert the object.
1980  * Use this function instead of a cfs_hash_add() + cfs_hash_del()
1981  * combo when it is critical that there is no window in time where the
1982  * object is missing from the hash.  When an object is being rehashed
1983  * the registered cfs_hash_get() and cfs_hash_put() functions will
1984  * not be called.
1985  */
1986 void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
1987                          void *new_key, struct hlist_node *hnode)
1988 {
1989         struct cfs_hash_bd      bds[3];
1990         struct cfs_hash_bd      old_bds[2];
1991         struct cfs_hash_bd      new_bd;
1992
1993         LASSERT(!hlist_unhashed(hnode));
1994
1995         cfs_hash_lock(hs, 0);
1996
1997         cfs_hash_dual_bd_get(hs, old_key, old_bds);
1998         cfs_hash_bd_get(hs, new_key, &new_bd);
1999
2000         bds[0] = old_bds[0];
2001         bds[1] = old_bds[1];
2002         bds[2] = new_bd;
2003
2004         /* NB: bds[0] and bds[1] are ordered already */
2005         cfs_hash_bd_order(&bds[1], &bds[2]);
2006         cfs_hash_bd_order(&bds[0], &bds[1]);
2007
2008         cfs_hash_multi_bd_lock(hs, bds, 3, 1);
2009         if (likely(old_bds[1].bd_bucket == NULL)) {
2010                 cfs_hash_bd_move_locked(hs, &old_bds[0], &new_bd, hnode);
2011         } else {
2012                 cfs_hash_dual_bd_finddel_locked(hs, old_bds, old_key, hnode);
2013                 cfs_hash_bd_add_locked(hs, &new_bd, hnode);
2014         }
2015         /* overwrite key inside locks, otherwise may screw up with
2016          * other operations, i.e: rehash */
2017         cfs_hash_keycpy(hs, new_key, hnode);
2018
2019         cfs_hash_multi_bd_unlock(hs, bds, 3, 1);
2020         cfs_hash_unlock(hs, 0);
2021 }
2022 EXPORT_SYMBOL(cfs_hash_rehash_key);
2023
2024 void cfs_hash_debug_header(struct seq_file *m)
2025 {
2026         seq_printf(m, "%-*s   cur   min   max theta t-min t-max flags rehash   count  maxdep maxdepb distribution\n",
2027                    CFS_HASH_BIGNAME_LEN, "name");
2028 }
2029 EXPORT_SYMBOL(cfs_hash_debug_header);
2030
2031 static struct cfs_hash_bucket **
2032 cfs_hash_full_bkts(struct cfs_hash *hs)
2033 {
2034         /* NB: caller should hold hs->hs_rwlock if REHASH is set */
2035         if (hs->hs_rehash_buckets == NULL)
2036                 return hs->hs_buckets;
2037
2038         LASSERT(hs->hs_rehash_bits != 0);
2039         return hs->hs_rehash_bits > hs->hs_cur_bits ?
2040                hs->hs_rehash_buckets : hs->hs_buckets;
2041 }
2042
2043 static unsigned int
2044 cfs_hash_full_nbkt(struct cfs_hash *hs)
2045 {
2046         /* NB: caller should hold hs->hs_rwlock if REHASH is set */
2047         if (hs->hs_rehash_buckets == NULL)
2048                 return CFS_HASH_NBKT(hs);
2049
2050         LASSERT(hs->hs_rehash_bits != 0);
2051         return hs->hs_rehash_bits > hs->hs_cur_bits ?
2052                CFS_HASH_RH_NBKT(hs) : CFS_HASH_NBKT(hs);
2053 }
2054
2055 void cfs_hash_debug_str(struct cfs_hash *hs, struct seq_file *m)
2056 {
2057         int                 dist[8] = { 0, };
2058         int                 maxdep  = -1;
2059         int                 maxdepb = -1;
2060         int                 total   = 0;
2061         int                 theta;
2062         int                 i;
2063
2064         cfs_hash_lock(hs, 0);
2065         theta = __cfs_hash_theta(hs);
2066
2067         seq_printf(m, "%-*s %5d %5d %5d %d.%03d %d.%03d %d.%03d  0x%02x %6d ",
2068                       CFS_HASH_BIGNAME_LEN, hs->hs_name,
2069                       1 << hs->hs_cur_bits, 1 << hs->hs_min_bits,
2070                       1 << hs->hs_max_bits,
2071                       __cfs_hash_theta_int(theta), __cfs_hash_theta_frac(theta),
2072                       __cfs_hash_theta_int(hs->hs_min_theta),
2073                       __cfs_hash_theta_frac(hs->hs_min_theta),
2074                       __cfs_hash_theta_int(hs->hs_max_theta),
2075                       __cfs_hash_theta_frac(hs->hs_max_theta),
2076                       hs->hs_flags, hs->hs_rehash_count);
2077
2078         /*
2079          * The distribution is a summary of the chained hash depth in
2080          * each of the libcfs hash buckets.  Each buckets hsb_count is
2081          * divided by the hash theta value and used to generate a
2082          * histogram of the hash distribution.  A uniform hash will
2083          * result in all hash buckets being close to the average thus
2084          * only the first few entries in the histogram will be non-zero.
2085          * If you hash function results in a non-uniform hash the will
2086          * be observable by outlier bucks in the distribution histogram.
2087          *
2088          * Uniform hash distribution:      128/128/0/0/0/0/0/0
2089          * Non-Uniform hash distribution:  128/125/0/0/0/0/2/1
2090          */
2091         for (i = 0; i < cfs_hash_full_nbkt(hs); i++) {
2092                 struct cfs_hash_bd  bd;
2093
2094                 bd.bd_bucket = cfs_hash_full_bkts(hs)[i];
2095                 cfs_hash_bd_lock(hs, &bd, 0);
2096                 if (maxdep < bd.bd_bucket->hsb_depmax) {
2097                         maxdep  = bd.bd_bucket->hsb_depmax;
2098                         maxdepb = ffz(~maxdep);
2099                 }
2100                 total += bd.bd_bucket->hsb_count;
2101                 dist[min(fls(bd.bd_bucket->hsb_count / max(theta, 1)), 7)]++;
2102                 cfs_hash_bd_unlock(hs, &bd, 0);
2103         }
2104
2105         seq_printf(m, "%7d %7d %7d ", total, maxdep, maxdepb);
2106         for (i = 0; i < 8; i++)
2107                 seq_printf(m, "%d%c",  dist[i], (i == 7) ? '\n' : '/');
2108
2109         cfs_hash_unlock(hs, 0);
2110 }
2111 EXPORT_SYMBOL(cfs_hash_debug_str);