4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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.
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).
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
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
27 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
30 * Copyright (c) 2011, 2013, Intel Corporation.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
36 * libcfs/libcfs/hash.c
38 * Implement a hash class for hash process in lustre system.
40 * Author: YuZhangyong <yzy@clusterfs.com>
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
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(intead of contiguous memory),
55 * to avoid unnecessary cacheline conflict
57 * 2010-03-01: Liang Zhen <zhen.liang@sun.com>
58 * - "bucket" is a group of hlist_head now, user can speicify bucket size
59 * by bkt_bits of cfs_hash_create(), all hlist_heads in a bucket share
60 * one lock for reducing memory overhead.
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
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
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
75 * - removed a lot of unnecessary addref & decref on hash element:
76 * addref & decref are atomic operations in many use-cases which
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.
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.
92 * - support two different refcount modes
93 * . hash table has refcount on element
94 * . hash table doesn't change refcount on adding/removing element
96 * - support long name hash table (for param-tree)
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.
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.
110 #include <libcfs/libcfs.h>
112 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
113 static unsigned int warn_on_depth = 8;
114 CFS_MODULE_PARM(warn_on_depth, "i", uint, 0644,
115 "warning when hash depth is high.");
118 struct cfs_wi_sched *cfs_sched_rehash;
121 cfs_hash_nl_lock(cfs_hash_lock_t *lock, int exclusive) {}
124 cfs_hash_nl_unlock(cfs_hash_lock_t *lock, int exclusive) {}
127 cfs_hash_spin_lock(cfs_hash_lock_t *lock, int exclusive)
129 spin_lock(&lock->spin);
133 cfs_hash_spin_unlock(cfs_hash_lock_t *lock, int exclusive)
135 spin_unlock(&lock->spin);
139 cfs_hash_rw_lock(cfs_hash_lock_t *lock, int exclusive)
142 read_lock(&lock->rw);
144 write_lock(&lock->rw);
148 cfs_hash_rw_unlock(cfs_hash_lock_t *lock, int exclusive)
151 read_unlock(&lock->rw);
153 write_unlock(&lock->rw);
157 static cfs_hash_lock_ops_t cfs_hash_nl_lops =
159 .hs_lock = cfs_hash_nl_lock,
160 .hs_unlock = cfs_hash_nl_unlock,
161 .hs_bkt_lock = cfs_hash_nl_lock,
162 .hs_bkt_unlock = cfs_hash_nl_unlock,
165 /** no bucket lock, one spinlock to protect everything */
166 static cfs_hash_lock_ops_t cfs_hash_nbl_lops =
168 .hs_lock = cfs_hash_spin_lock,
169 .hs_unlock = cfs_hash_spin_unlock,
170 .hs_bkt_lock = cfs_hash_nl_lock,
171 .hs_bkt_unlock = cfs_hash_nl_unlock,
174 /** spin bucket lock, rehash is enabled */
175 static cfs_hash_lock_ops_t cfs_hash_bkt_spin_lops =
177 .hs_lock = cfs_hash_rw_lock,
178 .hs_unlock = cfs_hash_rw_unlock,
179 .hs_bkt_lock = cfs_hash_spin_lock,
180 .hs_bkt_unlock = cfs_hash_spin_unlock,
183 /** rw bucket lock, rehash is enabled */
184 static cfs_hash_lock_ops_t cfs_hash_bkt_rw_lops =
186 .hs_lock = cfs_hash_rw_lock,
187 .hs_unlock = cfs_hash_rw_unlock,
188 .hs_bkt_lock = cfs_hash_rw_lock,
189 .hs_bkt_unlock = cfs_hash_rw_unlock,
192 /** spin bucket lock, rehash is disabled */
193 static cfs_hash_lock_ops_t 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,
201 /** rw bucket lock, rehash is disabled */
202 static cfs_hash_lock_ops_t cfs_hash_nr_bkt_rw_lops =
204 .hs_lock = cfs_hash_nl_lock,
205 .hs_unlock = cfs_hash_nl_unlock,
206 .hs_bkt_lock = cfs_hash_rw_lock,
207 .hs_bkt_unlock = cfs_hash_rw_unlock,
211 cfs_hash_lock_setup(cfs_hash_t *hs)
213 if (cfs_hash_with_no_lock(hs)) {
214 hs->hs_lops = &cfs_hash_nl_lops;
216 } else if (cfs_hash_with_no_bktlock(hs)) {
217 hs->hs_lops = &cfs_hash_nbl_lops;
218 spin_lock_init(&hs->hs_lock.spin);
220 } else if (cfs_hash_with_rehash(hs)) {
221 rwlock_init(&hs->hs_lock.rw);
223 if (cfs_hash_with_rw_bktlock(hs))
224 hs->hs_lops = &cfs_hash_bkt_rw_lops;
225 else if (cfs_hash_with_spin_bktlock(hs))
226 hs->hs_lops = &cfs_hash_bkt_spin_lops;
230 if (cfs_hash_with_rw_bktlock(hs))
231 hs->hs_lops = &cfs_hash_nr_bkt_rw_lops;
232 else if (cfs_hash_with_spin_bktlock(hs))
233 hs->hs_lops = &cfs_hash_nr_bkt_spin_lops;
240 * Simple hash head without depth tracking
241 * new element is always added to head of hlist
244 struct hlist_head hh_head; /**< entries list */
248 cfs_hash_hh_hhead_size(cfs_hash_t *hs)
250 return sizeof(cfs_hash_head_t);
253 static struct hlist_head *
254 cfs_hash_hh_hhead(cfs_hash_t *hs, cfs_hash_bd_t *bd)
256 cfs_hash_head_t *head = (cfs_hash_head_t *)&bd->bd_bucket->hsb_head[0];
258 return &head[bd->bd_offset].hh_head;
262 cfs_hash_hh_hnode_add(cfs_hash_t *hs, cfs_hash_bd_t *bd,
263 struct hlist_node *hnode)
265 hlist_add_head(hnode, cfs_hash_hh_hhead(hs, bd));
266 return -1; /* unknown depth */
270 cfs_hash_hh_hnode_del(cfs_hash_t *hs, cfs_hash_bd_t *bd,
271 struct hlist_node *hnode)
273 hlist_del_init(hnode);
274 return -1; /* unknown depth */
278 * Simple hash head with depth tracking
279 * new element is always added to head of hlist
282 struct hlist_head hd_head; /**< entries list */
283 unsigned int hd_depth; /**< list length */
284 } cfs_hash_head_dep_t;
287 cfs_hash_hd_hhead_size(cfs_hash_t *hs)
289 return sizeof(cfs_hash_head_dep_t);
292 static struct hlist_head *
293 cfs_hash_hd_hhead(cfs_hash_t *hs, cfs_hash_bd_t *bd)
295 cfs_hash_head_dep_t *head;
297 head = (cfs_hash_head_dep_t *)&bd->bd_bucket->hsb_head[0];
298 return &head[bd->bd_offset].hd_head;
302 cfs_hash_hd_hnode_add(cfs_hash_t *hs, cfs_hash_bd_t *bd,
303 struct hlist_node *hnode)
305 cfs_hash_head_dep_t *hh = container_of(cfs_hash_hd_hhead(hs, bd),
306 cfs_hash_head_dep_t, hd_head);
307 hlist_add_head(hnode, &hh->hd_head);
308 return ++hh->hd_depth;
312 cfs_hash_hd_hnode_del(cfs_hash_t *hs, cfs_hash_bd_t *bd,
313 struct hlist_node *hnode)
315 cfs_hash_head_dep_t *hh = container_of(cfs_hash_hd_hhead(hs, bd),
316 cfs_hash_head_dep_t, hd_head);
317 hlist_del_init(hnode);
318 return --hh->hd_depth;
322 * double links hash head without depth tracking
323 * new element is always added to tail of hlist
326 struct hlist_head dh_head; /**< entries list */
327 struct hlist_node *dh_tail; /**< the last entry */
331 cfs_hash_dh_hhead_size(cfs_hash_t *hs)
333 return sizeof(cfs_hash_dhead_t);
336 static struct hlist_head *
337 cfs_hash_dh_hhead(cfs_hash_t *hs, cfs_hash_bd_t *bd)
339 cfs_hash_dhead_t *head;
341 head = (cfs_hash_dhead_t *)&bd->bd_bucket->hsb_head[0];
342 return &head[bd->bd_offset].dh_head;
346 cfs_hash_dh_hnode_add(cfs_hash_t *hs, cfs_hash_bd_t *bd,
347 struct hlist_node *hnode)
349 cfs_hash_dhead_t *dh = container_of(cfs_hash_dh_hhead(hs, bd),
350 cfs_hash_dhead_t, dh_head);
352 if (dh->dh_tail != NULL) /* not empty */
353 hlist_add_after(dh->dh_tail, hnode);
354 else /* empty list */
355 hlist_add_head(hnode, &dh->dh_head);
357 return -1; /* unknown depth */
361 cfs_hash_dh_hnode_del(cfs_hash_t *hs, cfs_hash_bd_t *bd,
362 struct hlist_node *hnd)
364 cfs_hash_dhead_t *dh = container_of(cfs_hash_dh_hhead(hs, bd),
365 cfs_hash_dhead_t, dh_head);
367 if (hnd->next == NULL) { /* it's the tail */
368 dh->dh_tail = (hnd->pprev == &dh->dh_head.first) ? NULL :
369 container_of(hnd->pprev, struct hlist_node, next);
372 return -1; /* unknown depth */
376 * double links hash head with depth tracking
377 * new element is always added to tail of hlist
380 struct hlist_head dd_head; /**< entries list */
381 struct hlist_node *dd_tail; /**< the last entry */
382 unsigned int dd_depth; /**< list length */
383 } cfs_hash_dhead_dep_t;
386 cfs_hash_dd_hhead_size(cfs_hash_t *hs)
388 return sizeof(cfs_hash_dhead_dep_t);
391 static struct hlist_head *
392 cfs_hash_dd_hhead(cfs_hash_t *hs, cfs_hash_bd_t *bd)
394 cfs_hash_dhead_dep_t *head;
396 head = (cfs_hash_dhead_dep_t *)&bd->bd_bucket->hsb_head[0];
397 return &head[bd->bd_offset].dd_head;
401 cfs_hash_dd_hnode_add(cfs_hash_t *hs, cfs_hash_bd_t *bd,
402 struct hlist_node *hnode)
404 cfs_hash_dhead_dep_t *dh = container_of(cfs_hash_dd_hhead(hs, bd),
405 cfs_hash_dhead_dep_t, dd_head);
407 if (dh->dd_tail != NULL) /* not empty */
408 hlist_add_after(dh->dd_tail, hnode);
409 else /* empty list */
410 hlist_add_head(hnode, &dh->dd_head);
412 return ++dh->dd_depth;
416 cfs_hash_dd_hnode_del(cfs_hash_t *hs, cfs_hash_bd_t *bd,
417 struct hlist_node *hnd)
419 cfs_hash_dhead_dep_t *dh = container_of(cfs_hash_dd_hhead(hs, bd),
420 cfs_hash_dhead_dep_t, dd_head);
422 if (hnd->next == NULL) { /* it's the tail */
423 dh->dd_tail = (hnd->pprev == &dh->dd_head.first) ? NULL :
424 container_of(hnd->pprev, struct hlist_node, next);
427 return --dh->dd_depth;
430 static cfs_hash_hlist_ops_t cfs_hash_hh_hops = {
431 .hop_hhead = cfs_hash_hh_hhead,
432 .hop_hhead_size = cfs_hash_hh_hhead_size,
433 .hop_hnode_add = cfs_hash_hh_hnode_add,
434 .hop_hnode_del = cfs_hash_hh_hnode_del,
437 static cfs_hash_hlist_ops_t cfs_hash_hd_hops = {
438 .hop_hhead = cfs_hash_hd_hhead,
439 .hop_hhead_size = cfs_hash_hd_hhead_size,
440 .hop_hnode_add = cfs_hash_hd_hnode_add,
441 .hop_hnode_del = cfs_hash_hd_hnode_del,
444 static cfs_hash_hlist_ops_t cfs_hash_dh_hops = {
445 .hop_hhead = cfs_hash_dh_hhead,
446 .hop_hhead_size = cfs_hash_dh_hhead_size,
447 .hop_hnode_add = cfs_hash_dh_hnode_add,
448 .hop_hnode_del = cfs_hash_dh_hnode_del,
451 static cfs_hash_hlist_ops_t cfs_hash_dd_hops = {
452 .hop_hhead = cfs_hash_dd_hhead,
453 .hop_hhead_size = cfs_hash_dd_hhead_size,
454 .hop_hnode_add = cfs_hash_dd_hnode_add,
455 .hop_hnode_del = cfs_hash_dd_hnode_del,
459 cfs_hash_hlist_setup(cfs_hash_t *hs)
461 if (cfs_hash_with_add_tail(hs)) {
462 hs->hs_hops = cfs_hash_with_depth(hs) ?
463 &cfs_hash_dd_hops : &cfs_hash_dh_hops;
465 hs->hs_hops = cfs_hash_with_depth(hs) ?
466 &cfs_hash_hd_hops : &cfs_hash_hh_hops;
471 cfs_hash_bd_from_key(cfs_hash_t *hs, cfs_hash_bucket_t **bkts,
472 unsigned int bits, const void *key, cfs_hash_bd_t *bd)
474 unsigned int index = cfs_hash_id(hs, key, (1U << bits) - 1);
476 LASSERT(bits == hs->hs_cur_bits || bits == hs->hs_rehash_bits);
478 bd->bd_bucket = bkts[index & ((1U << (bits - hs->hs_bkt_bits)) - 1)];
479 bd->bd_offset = index >> (bits - hs->hs_bkt_bits);
483 cfs_hash_bd_get(cfs_hash_t *hs, const void *key, cfs_hash_bd_t *bd)
485 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
486 if (likely(hs->hs_rehash_buckets == NULL)) {
487 cfs_hash_bd_from_key(hs, hs->hs_buckets,
488 hs->hs_cur_bits, key, bd);
490 LASSERT(hs->hs_rehash_bits != 0);
491 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
492 hs->hs_rehash_bits, key, bd);
495 EXPORT_SYMBOL(cfs_hash_bd_get);
498 cfs_hash_bd_dep_record(cfs_hash_t *hs, cfs_hash_bd_t *bd, int dep_cur)
500 if (likely(dep_cur <= bd->bd_bucket->hsb_depmax))
503 bd->bd_bucket->hsb_depmax = dep_cur;
504 # if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
505 if (likely(warn_on_depth == 0 ||
506 max(warn_on_depth, hs->hs_dep_max) >= dep_cur))
509 spin_lock(&hs->hs_dep_lock);
510 hs->hs_dep_max = dep_cur;
511 hs->hs_dep_bkt = bd->bd_bucket->hsb_index;
512 hs->hs_dep_off = bd->bd_offset;
513 hs->hs_dep_bits = hs->hs_cur_bits;
514 spin_unlock(&hs->hs_dep_lock);
516 cfs_wi_schedule(cfs_sched_rehash, &hs->hs_dep_wi);
521 cfs_hash_bd_add_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd,
522 struct hlist_node *hnode)
526 rc = hs->hs_hops->hop_hnode_add(hs, bd, hnode);
527 cfs_hash_bd_dep_record(hs, bd, rc);
528 bd->bd_bucket->hsb_version++;
529 if (unlikely(bd->bd_bucket->hsb_version == 0))
530 bd->bd_bucket->hsb_version++;
531 bd->bd_bucket->hsb_count++;
533 if (cfs_hash_with_counter(hs))
534 atomic_inc(&hs->hs_count);
535 if (!cfs_hash_with_no_itemref(hs))
536 cfs_hash_get(hs, hnode);
538 EXPORT_SYMBOL(cfs_hash_bd_add_locked);
541 cfs_hash_bd_del_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd,
542 struct hlist_node *hnode)
544 hs->hs_hops->hop_hnode_del(hs, bd, hnode);
546 LASSERT(bd->bd_bucket->hsb_count > 0);
547 bd->bd_bucket->hsb_count--;
548 bd->bd_bucket->hsb_version++;
549 if (unlikely(bd->bd_bucket->hsb_version == 0))
550 bd->bd_bucket->hsb_version++;
552 if (cfs_hash_with_counter(hs)) {
553 LASSERT(atomic_read(&hs->hs_count) > 0);
554 atomic_dec(&hs->hs_count);
556 if (!cfs_hash_with_no_itemref(hs))
557 cfs_hash_put_locked(hs, hnode);
559 EXPORT_SYMBOL(cfs_hash_bd_del_locked);
562 cfs_hash_bd_move_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd_old,
563 cfs_hash_bd_t *bd_new, struct hlist_node *hnode)
565 cfs_hash_bucket_t *obkt = bd_old->bd_bucket;
566 cfs_hash_bucket_t *nbkt = bd_new->bd_bucket;
569 if (cfs_hash_bd_compare(bd_old, bd_new) == 0)
572 /* use cfs_hash_bd_hnode_add/del, to avoid atomic & refcount ops
573 * in cfs_hash_bd_del/add_locked */
574 hs->hs_hops->hop_hnode_del(hs, bd_old, hnode);
575 rc = hs->hs_hops->hop_hnode_add(hs, bd_new, hnode);
576 cfs_hash_bd_dep_record(hs, bd_new, rc);
578 LASSERT(obkt->hsb_count > 0);
581 if (unlikely(obkt->hsb_version == 0))
585 if (unlikely(nbkt->hsb_version == 0))
588 EXPORT_SYMBOL(cfs_hash_bd_move_locked);
591 /** always set, for sanity (avoid ZERO intent) */
592 CFS_HS_LOOKUP_MASK_FIND = 1 << 0,
593 /** return entry with a ref */
594 CFS_HS_LOOKUP_MASK_REF = 1 << 1,
595 /** add entry if not existing */
596 CFS_HS_LOOKUP_MASK_ADD = 1 << 2,
597 /** delete entry, ignore other masks */
598 CFS_HS_LOOKUP_MASK_DEL = 1 << 3,
601 typedef enum cfs_hash_lookup_intent {
602 /** return item w/o refcount */
603 CFS_HS_LOOKUP_IT_PEEK = CFS_HS_LOOKUP_MASK_FIND,
604 /** return item with refcount */
605 CFS_HS_LOOKUP_IT_FIND = (CFS_HS_LOOKUP_MASK_FIND |
606 CFS_HS_LOOKUP_MASK_REF),
607 /** return item w/o refcount if existed, otherwise add */
608 CFS_HS_LOOKUP_IT_ADD = (CFS_HS_LOOKUP_MASK_FIND |
609 CFS_HS_LOOKUP_MASK_ADD),
610 /** return item with refcount if existed, otherwise add */
611 CFS_HS_LOOKUP_IT_FINDADD = (CFS_HS_LOOKUP_IT_FIND |
612 CFS_HS_LOOKUP_MASK_ADD),
613 /** delete if existed */
614 CFS_HS_LOOKUP_IT_FINDDEL = (CFS_HS_LOOKUP_MASK_FIND |
615 CFS_HS_LOOKUP_MASK_DEL)
616 } cfs_hash_lookup_intent_t;
618 static struct hlist_node *
619 cfs_hash_bd_lookup_intent(cfs_hash_t *hs, cfs_hash_bd_t *bd,
620 const void *key, struct hlist_node *hnode,
621 cfs_hash_lookup_intent_t intent)
624 struct hlist_head *hhead = cfs_hash_bd_hhead(hs, bd);
625 struct hlist_node *ehnode;
626 struct hlist_node *match;
627 int intent_add = (intent & CFS_HS_LOOKUP_MASK_ADD) != 0;
629 /* with this function, we can avoid a lot of useless refcount ops,
630 * which are expensive atomic operations most time. */
631 match = intent_add ? NULL : hnode;
632 hlist_for_each(ehnode, hhead) {
633 if (!cfs_hash_keycmp(hs, key, ehnode))
636 if (match != NULL && match != ehnode) /* can't match */
640 if ((intent & CFS_HS_LOOKUP_MASK_DEL) != 0) {
641 cfs_hash_bd_del_locked(hs, bd, ehnode);
645 /* caller wants refcount? */
646 if ((intent & CFS_HS_LOOKUP_MASK_REF) != 0)
647 cfs_hash_get(hs, ehnode);
654 LASSERT(hnode != NULL);
655 cfs_hash_bd_add_locked(hs, bd, hnode);
660 cfs_hash_bd_lookup_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd, const void *key)
662 return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
663 CFS_HS_LOOKUP_IT_FIND);
665 EXPORT_SYMBOL(cfs_hash_bd_lookup_locked);
668 cfs_hash_bd_peek_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd, const void *key)
670 return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
671 CFS_HS_LOOKUP_IT_PEEK);
673 EXPORT_SYMBOL(cfs_hash_bd_peek_locked);
676 cfs_hash_bd_findadd_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd,
677 const void *key, struct hlist_node *hnode,
680 return cfs_hash_bd_lookup_intent(hs, bd, key, hnode,
681 CFS_HS_LOOKUP_IT_ADD |
682 (!noref * CFS_HS_LOOKUP_MASK_REF));
684 EXPORT_SYMBOL(cfs_hash_bd_findadd_locked);
687 cfs_hash_bd_finddel_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd,
688 const void *key, struct hlist_node *hnode)
690 /* hnode can be NULL, we find the first item with @key */
691 return cfs_hash_bd_lookup_intent(hs, bd, key, hnode,
692 CFS_HS_LOOKUP_IT_FINDDEL);
694 EXPORT_SYMBOL(cfs_hash_bd_finddel_locked);
697 cfs_hash_multi_bd_lock(cfs_hash_t *hs, cfs_hash_bd_t *bds,
698 unsigned n, int excl)
700 cfs_hash_bucket_t *prev = NULL;
704 * bds must be ascendantly ordered by bd->bd_bucket->hsb_index.
705 * NB: it's possible that several bds point to the same bucket but
706 * have different bd::bd_offset, so need take care of deadlock.
708 cfs_hash_for_each_bd(bds, n, i) {
709 if (prev == bds[i].bd_bucket)
712 LASSERT(prev == NULL ||
713 prev->hsb_index < bds[i].bd_bucket->hsb_index);
714 cfs_hash_bd_lock(hs, &bds[i], excl);
715 prev = bds[i].bd_bucket;
720 cfs_hash_multi_bd_unlock(cfs_hash_t *hs, cfs_hash_bd_t *bds,
721 unsigned n, int excl)
723 cfs_hash_bucket_t *prev = NULL;
726 cfs_hash_for_each_bd(bds, n, i) {
727 if (prev != bds[i].bd_bucket) {
728 cfs_hash_bd_unlock(hs, &bds[i], excl);
729 prev = bds[i].bd_bucket;
734 static struct hlist_node *
735 cfs_hash_multi_bd_lookup_locked(cfs_hash_t *hs, cfs_hash_bd_t *bds,
736 unsigned n, const void *key)
738 struct hlist_node *ehnode;
741 cfs_hash_for_each_bd(bds, n, i) {
742 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, NULL,
743 CFS_HS_LOOKUP_IT_FIND);
750 static struct hlist_node *
751 cfs_hash_multi_bd_findadd_locked(cfs_hash_t *hs,
752 cfs_hash_bd_t *bds, unsigned n, const void *key,
753 struct hlist_node *hnode, int noref)
755 struct hlist_node *ehnode;
759 LASSERT(hnode != NULL);
760 intent = CFS_HS_LOOKUP_IT_PEEK | (!noref * CFS_HS_LOOKUP_MASK_REF);
762 cfs_hash_for_each_bd(bds, n, i) {
763 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key,
769 if (i == 1) { /* only one bucket */
770 cfs_hash_bd_add_locked(hs, &bds[0], hnode);
774 cfs_hash_bd_get(hs, key, &mybd);
775 cfs_hash_bd_add_locked(hs, &mybd, hnode);
781 static struct hlist_node *
782 cfs_hash_multi_bd_finddel_locked(cfs_hash_t *hs, cfs_hash_bd_t *bds,
783 unsigned n, const void *key,
784 struct hlist_node *hnode)
786 struct hlist_node *ehnode;
789 cfs_hash_for_each_bd(bds, n, i) {
790 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, hnode,
791 CFS_HS_LOOKUP_IT_FINDDEL);
799 cfs_hash_bd_order(cfs_hash_bd_t *bd1, cfs_hash_bd_t *bd2)
803 if (bd2->bd_bucket == NULL)
806 if (bd1->bd_bucket == NULL) {
808 bd2->bd_bucket = NULL;
812 rc = cfs_hash_bd_compare(bd1, bd2);
814 bd2->bd_bucket = NULL;
816 } else if (rc > 0) { /* swab bd1 and bd2 */
826 cfs_hash_dual_bd_get(cfs_hash_t *hs, const void *key, cfs_hash_bd_t *bds)
828 /* NB: caller should hold hs_lock.rw if REHASH is set */
829 cfs_hash_bd_from_key(hs, hs->hs_buckets,
830 hs->hs_cur_bits, key, &bds[0]);
831 if (likely(hs->hs_rehash_buckets == NULL)) {
832 /* no rehash or not rehashing */
833 bds[1].bd_bucket = NULL;
837 LASSERT(hs->hs_rehash_bits != 0);
838 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
839 hs->hs_rehash_bits, key, &bds[1]);
841 cfs_hash_bd_order(&bds[0], &bds[1]);
843 EXPORT_SYMBOL(cfs_hash_dual_bd_get);
846 cfs_hash_dual_bd_lock(cfs_hash_t *hs, cfs_hash_bd_t *bds, int excl)
848 cfs_hash_multi_bd_lock(hs, bds, 2, excl);
850 EXPORT_SYMBOL(cfs_hash_dual_bd_lock);
853 cfs_hash_dual_bd_unlock(cfs_hash_t *hs, cfs_hash_bd_t *bds, int excl)
855 cfs_hash_multi_bd_unlock(hs, bds, 2, excl);
857 EXPORT_SYMBOL(cfs_hash_dual_bd_unlock);
860 cfs_hash_dual_bd_lookup_locked(cfs_hash_t *hs, cfs_hash_bd_t *bds,
863 return cfs_hash_multi_bd_lookup_locked(hs, bds, 2, key);
865 EXPORT_SYMBOL(cfs_hash_dual_bd_lookup_locked);
868 cfs_hash_dual_bd_findadd_locked(cfs_hash_t *hs, cfs_hash_bd_t *bds,
869 const void *key, struct hlist_node *hnode,
872 return cfs_hash_multi_bd_findadd_locked(hs, bds, 2, key,
875 EXPORT_SYMBOL(cfs_hash_dual_bd_findadd_locked);
878 cfs_hash_dual_bd_finddel_locked(cfs_hash_t *hs, cfs_hash_bd_t *bds,
879 const void *key, struct hlist_node *hnode)
881 return cfs_hash_multi_bd_finddel_locked(hs, bds, 2, key, hnode);
883 EXPORT_SYMBOL(cfs_hash_dual_bd_finddel_locked);
886 cfs_hash_buckets_free(cfs_hash_bucket_t **buckets,
887 int bkt_size, int prev_size, int size)
891 for (i = prev_size; i < size; i++) {
892 if (buckets[i] != NULL)
893 LIBCFS_FREE(buckets[i], bkt_size);
896 LIBCFS_FREE(buckets, sizeof(buckets[0]) * size);
900 * Create or grow bucket memory. Return old_buckets if no allocation was
901 * needed, the newly allocated buckets if allocation was needed and
902 * successful, and NULL on error.
904 static cfs_hash_bucket_t **
905 cfs_hash_buckets_realloc(cfs_hash_t *hs, cfs_hash_bucket_t **old_bkts,
906 unsigned int old_size, unsigned int new_size)
908 cfs_hash_bucket_t **new_bkts;
911 LASSERT(old_size == 0 || old_bkts != NULL);
913 if (old_bkts != NULL && old_size == new_size)
916 LIBCFS_ALLOC(new_bkts, sizeof(new_bkts[0]) * new_size);
917 if (new_bkts == NULL)
920 if (old_bkts != NULL) {
921 memcpy(new_bkts, old_bkts,
922 min(old_size, new_size) * sizeof(*old_bkts));
925 for (i = old_size; i < new_size; i++) {
926 struct hlist_head *hhead;
929 LIBCFS_ALLOC(new_bkts[i], cfs_hash_bkt_size(hs));
930 if (new_bkts[i] == NULL) {
931 cfs_hash_buckets_free(new_bkts, cfs_hash_bkt_size(hs),
936 new_bkts[i]->hsb_index = i;
937 new_bkts[i]->hsb_version = 1; /* shouldn't be zero */
938 new_bkts[i]->hsb_depmax = -1; /* unknown */
939 bd.bd_bucket = new_bkts[i];
940 cfs_hash_bd_for_each_hlist(hs, &bd, hhead)
941 INIT_HLIST_HEAD(hhead);
943 if (cfs_hash_with_no_lock(hs) ||
944 cfs_hash_with_no_bktlock(hs))
947 if (cfs_hash_with_rw_bktlock(hs))
948 rwlock_init(&new_bkts[i]->hsb_lock.rw);
949 else if (cfs_hash_with_spin_bktlock(hs))
950 spin_lock_init(&new_bkts[i]->hsb_lock.spin);
952 LBUG(); /* invalid use-case */
958 * Initialize new libcfs hash, where:
959 * @name - Descriptive hash name
960 * @cur_bits - Initial hash table size, in bits
961 * @max_bits - Maximum allowed hash table resize, in bits
962 * @ops - Registered hash table operations
963 * @flags - CFS_HASH_REHASH enable synamic hash resizing
964 * - CFS_HASH_SORT enable chained hash sort
966 static int cfs_hash_rehash_worker(cfs_workitem_t *wi);
968 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
969 static int cfs_hash_dep_print(cfs_workitem_t *wi)
971 cfs_hash_t *hs = container_of(wi, cfs_hash_t, hs_dep_wi);
977 spin_lock(&hs->hs_dep_lock);
978 dep = hs->hs_dep_max;
979 bkt = hs->hs_dep_bkt;
980 off = hs->hs_dep_off;
981 bits = hs->hs_dep_bits;
982 spin_unlock(&hs->hs_dep_lock);
984 LCONSOLE_WARN("#### HASH %s (bits: %d): max depth %d at bucket %d/%d\n",
985 hs->hs_name, bits, dep, bkt, off);
986 spin_lock(&hs->hs_dep_lock);
987 hs->hs_dep_bits = 0; /* mark as workitem done */
988 spin_unlock(&hs->hs_dep_lock);
992 static void cfs_hash_depth_wi_init(cfs_hash_t *hs)
994 spin_lock_init(&hs->hs_dep_lock);
995 cfs_wi_init(&hs->hs_dep_wi, hs, cfs_hash_dep_print);
998 static void cfs_hash_depth_wi_cancel(cfs_hash_t *hs)
1000 if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_dep_wi))
1003 spin_lock(&hs->hs_dep_lock);
1004 while (hs->hs_dep_bits != 0) {
1005 spin_unlock(&hs->hs_dep_lock);
1007 spin_lock(&hs->hs_dep_lock);
1009 spin_unlock(&hs->hs_dep_lock);
1012 #else /* CFS_HASH_DEBUG_LEVEL < CFS_HASH_DEBUG_1 */
1014 static inline void cfs_hash_depth_wi_init(cfs_hash_t *hs) {}
1015 static inline void cfs_hash_depth_wi_cancel(cfs_hash_t *hs) {}
1017 #endif /* CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1 */
1020 cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits,
1021 unsigned bkt_bits, unsigned extra_bytes,
1022 unsigned min_theta, unsigned max_theta,
1023 cfs_hash_ops_t *ops, unsigned flags)
1030 CLASSERT(CFS_HASH_THETA_BITS < 15);
1032 LASSERT(name != NULL);
1033 LASSERT(ops != NULL);
1034 LASSERT(ops->hs_key);
1035 LASSERT(ops->hs_hash);
1036 LASSERT(ops->hs_object);
1037 LASSERT(ops->hs_keycmp);
1038 LASSERT(ops->hs_get != NULL);
1039 LASSERT(ops->hs_put_locked != NULL);
1041 if ((flags & CFS_HASH_REHASH) != 0)
1042 flags |= CFS_HASH_COUNTER; /* must have counter */
1044 LASSERT(cur_bits > 0);
1045 LASSERT(cur_bits >= bkt_bits);
1046 LASSERT(max_bits >= cur_bits && max_bits < 31);
1047 LASSERT(ergo((flags & CFS_HASH_REHASH) == 0, cur_bits == max_bits));
1048 LASSERT(ergo((flags & CFS_HASH_REHASH) != 0,
1049 (flags & CFS_HASH_NO_LOCK) == 0));
1050 LASSERT(ergo((flags & CFS_HASH_REHASH_KEY) != 0,
1051 ops->hs_keycpy != NULL));
1053 len = (flags & CFS_HASH_BIGNAME) == 0 ?
1054 CFS_HASH_NAME_LEN : CFS_HASH_BIGNAME_LEN;
1055 LIBCFS_ALLOC(hs, offsetof(cfs_hash_t, hs_name[len]));
1059 strncpy(hs->hs_name, name, len);
1060 hs->hs_name[len - 1] = '\0';
1061 hs->hs_flags = flags;
1063 atomic_set(&hs->hs_refcount, 1);
1064 atomic_set(&hs->hs_count, 0);
1066 cfs_hash_lock_setup(hs);
1067 cfs_hash_hlist_setup(hs);
1069 hs->hs_cur_bits = (__u8)cur_bits;
1070 hs->hs_min_bits = (__u8)cur_bits;
1071 hs->hs_max_bits = (__u8)max_bits;
1072 hs->hs_bkt_bits = (__u8)bkt_bits;
1075 hs->hs_extra_bytes = extra_bytes;
1076 hs->hs_rehash_bits = 0;
1077 cfs_wi_init(&hs->hs_rehash_wi, hs, cfs_hash_rehash_worker);
1078 cfs_hash_depth_wi_init(hs);
1080 if (cfs_hash_with_rehash(hs))
1081 __cfs_hash_set_theta(hs, min_theta, max_theta);
1083 hs->hs_buckets = cfs_hash_buckets_realloc(hs, NULL, 0,
1085 if (hs->hs_buckets != NULL)
1088 LIBCFS_FREE(hs, offsetof(cfs_hash_t, hs_name[len]));
1091 EXPORT_SYMBOL(cfs_hash_create);
1094 * Cleanup libcfs hash @hs.
1097 cfs_hash_destroy(cfs_hash_t *hs)
1099 struct hlist_node *hnode;
1100 struct hlist_node *pos;
1105 LASSERT(hs != NULL);
1106 LASSERT(!cfs_hash_is_exiting(hs) &&
1107 !cfs_hash_is_iterating(hs));
1110 * prohibit further rehashes, don't need any lock because
1111 * I'm the only (last) one can change it.
1114 if (cfs_hash_with_rehash(hs))
1115 cfs_hash_rehash_cancel(hs);
1117 cfs_hash_depth_wi_cancel(hs);
1118 /* rehash should be done/canceled */
1119 LASSERT(hs->hs_buckets != NULL &&
1120 hs->hs_rehash_buckets == NULL);
1122 cfs_hash_for_each_bucket(hs, &bd, i) {
1123 struct hlist_head *hhead;
1125 LASSERT(bd.bd_bucket != NULL);
1126 /* no need to take this lock, just for consistent code */
1127 cfs_hash_bd_lock(hs, &bd, 1);
1129 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1130 hlist_for_each_safe(hnode, pos, hhead) {
1131 LASSERTF(!cfs_hash_with_assert_empty(hs),
1132 "hash %s bucket %u(%u) is not "
1133 " empty: %u items left\n",
1134 hs->hs_name, bd.bd_bucket->hsb_index,
1135 bd.bd_offset, bd.bd_bucket->hsb_count);
1136 /* can't assert key valicate, because we
1137 * can interrupt rehash */
1138 cfs_hash_bd_del_locked(hs, &bd, hnode);
1139 cfs_hash_exit(hs, hnode);
1142 LASSERT(bd.bd_bucket->hsb_count == 0);
1143 cfs_hash_bd_unlock(hs, &bd, 1);
1147 LASSERT(atomic_read(&hs->hs_count) == 0);
1149 cfs_hash_buckets_free(hs->hs_buckets, cfs_hash_bkt_size(hs),
1150 0, CFS_HASH_NBKT(hs));
1151 i = cfs_hash_with_bigname(hs) ?
1152 CFS_HASH_BIGNAME_LEN : CFS_HASH_NAME_LEN;
1153 LIBCFS_FREE(hs, offsetof(cfs_hash_t, hs_name[i]));
1158 cfs_hash_t *cfs_hash_getref(cfs_hash_t *hs)
1160 if (atomic_inc_not_zero(&hs->hs_refcount))
1164 EXPORT_SYMBOL(cfs_hash_getref);
1166 void cfs_hash_putref(cfs_hash_t *hs)
1168 if (atomic_dec_and_test(&hs->hs_refcount))
1169 cfs_hash_destroy(hs);
1171 EXPORT_SYMBOL(cfs_hash_putref);
1174 cfs_hash_rehash_bits(cfs_hash_t *hs)
1176 if (cfs_hash_with_no_lock(hs) ||
1177 !cfs_hash_with_rehash(hs))
1180 if (unlikely(cfs_hash_is_exiting(hs)))
1183 if (unlikely(cfs_hash_is_rehashing(hs)))
1186 if (unlikely(cfs_hash_is_iterating(hs)))
1189 /* XXX: need to handle case with max_theta != 2.0
1190 * and the case with min_theta != 0.5 */
1191 if ((hs->hs_cur_bits < hs->hs_max_bits) &&
1192 (__cfs_hash_theta(hs) > hs->hs_max_theta))
1193 return hs->hs_cur_bits + 1;
1195 if (!cfs_hash_with_shrink(hs))
1198 if ((hs->hs_cur_bits > hs->hs_min_bits) &&
1199 (__cfs_hash_theta(hs) < hs->hs_min_theta))
1200 return hs->hs_cur_bits - 1;
1206 * don't allow inline rehash if:
1207 * - user wants non-blocking change (add/del) on hash table
1208 * - too many elements
1211 cfs_hash_rehash_inline(cfs_hash_t *hs)
1213 return !cfs_hash_with_nblk_change(hs) &&
1214 atomic_read(&hs->hs_count) < CFS_HASH_LOOP_HOG;
1218 * Add item @hnode to libcfs hash @hs using @key. The registered
1219 * ops->hs_get function will be called when the item is added.
1222 cfs_hash_add(cfs_hash_t *hs, const void *key, struct hlist_node *hnode)
1227 LASSERT(hlist_unhashed(hnode));
1229 cfs_hash_lock(hs, 0);
1230 cfs_hash_bd_get_and_lock(hs, key, &bd, 1);
1232 cfs_hash_key_validate(hs, key, hnode);
1233 cfs_hash_bd_add_locked(hs, &bd, hnode);
1235 cfs_hash_bd_unlock(hs, &bd, 1);
1237 bits = cfs_hash_rehash_bits(hs);
1238 cfs_hash_unlock(hs, 0);
1240 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1242 EXPORT_SYMBOL(cfs_hash_add);
1244 static struct hlist_node *
1245 cfs_hash_find_or_add(cfs_hash_t *hs, const void *key,
1246 struct hlist_node *hnode, int noref)
1248 struct hlist_node *ehnode;
1249 cfs_hash_bd_t bds[2];
1252 LASSERT(hlist_unhashed(hnode));
1254 cfs_hash_lock(hs, 0);
1255 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
1257 cfs_hash_key_validate(hs, key, hnode);
1258 ehnode = cfs_hash_dual_bd_findadd_locked(hs, bds, key,
1260 cfs_hash_dual_bd_unlock(hs, bds, 1);
1262 if (ehnode == hnode) /* new item added */
1263 bits = cfs_hash_rehash_bits(hs);
1264 cfs_hash_unlock(hs, 0);
1266 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1272 * Add item @hnode to libcfs hash @hs using @key. The registered
1273 * ops->hs_get function will be called if the item was added.
1274 * Returns 0 on success or -EALREADY on key collisions.
1277 cfs_hash_add_unique(cfs_hash_t *hs, const void *key, struct hlist_node *hnode)
1279 return cfs_hash_find_or_add(hs, key, hnode, 1) != hnode ?
1282 EXPORT_SYMBOL(cfs_hash_add_unique);
1285 * Add item @hnode to libcfs hash @hs using @key. If this @key
1286 * already exists in the hash then ops->hs_get will be called on the
1287 * conflicting entry and that entry will be returned to the caller.
1288 * Otherwise ops->hs_get is called on the item which was added.
1291 cfs_hash_findadd_unique(cfs_hash_t *hs, const void *key,
1292 struct hlist_node *hnode)
1294 hnode = cfs_hash_find_or_add(hs, key, hnode, 0);
1296 return cfs_hash_object(hs, hnode);
1298 EXPORT_SYMBOL(cfs_hash_findadd_unique);
1301 * Delete item @hnode from the libcfs hash @hs using @key. The @key
1302 * is required to ensure the correct hash bucket is locked since there
1303 * is no direct linkage from the item to the bucket. The object
1304 * removed from the hash will be returned and obs->hs_put is called
1305 * on the removed object.
1308 cfs_hash_del(cfs_hash_t *hs, const void *key, struct hlist_node *hnode)
1312 cfs_hash_bd_t bds[2];
1314 cfs_hash_lock(hs, 0);
1315 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
1317 /* NB: do nothing if @hnode is not in hash table */
1318 if (hnode == NULL || !hlist_unhashed(hnode)) {
1319 if (bds[1].bd_bucket == NULL && hnode != NULL) {
1320 cfs_hash_bd_del_locked(hs, &bds[0], hnode);
1322 hnode = cfs_hash_dual_bd_finddel_locked(hs, bds,
1327 if (hnode != NULL) {
1328 obj = cfs_hash_object(hs, hnode);
1329 bits = cfs_hash_rehash_bits(hs);
1332 cfs_hash_dual_bd_unlock(hs, bds, 1);
1333 cfs_hash_unlock(hs, 0);
1335 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1339 EXPORT_SYMBOL(cfs_hash_del);
1342 * Delete item given @key in libcfs hash @hs. The first @key found in
1343 * the hash will be removed, if the key exists multiple times in the hash
1344 * @hs this function must be called once per key. The removed object
1345 * will be returned and ops->hs_put is called on the removed object.
1348 cfs_hash_del_key(cfs_hash_t *hs, const void *key)
1350 return cfs_hash_del(hs, key, NULL);
1352 EXPORT_SYMBOL(cfs_hash_del_key);
1355 * Lookup an item using @key in the libcfs hash @hs and return it.
1356 * If the @key is found in the hash hs->hs_get() is called and the
1357 * matching objects is returned. It is the callers responsibility
1358 * to call the counterpart ops->hs_put using the cfs_hash_put() macro
1359 * when when finished with the object. If the @key was not found
1360 * in the hash @hs NULL is returned.
1363 cfs_hash_lookup(cfs_hash_t *hs, const void *key)
1366 struct hlist_node *hnode;
1367 cfs_hash_bd_t bds[2];
1369 cfs_hash_lock(hs, 0);
1370 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
1372 hnode = cfs_hash_dual_bd_lookup_locked(hs, bds, key);
1374 obj = cfs_hash_object(hs, hnode);
1376 cfs_hash_dual_bd_unlock(hs, bds, 0);
1377 cfs_hash_unlock(hs, 0);
1381 EXPORT_SYMBOL(cfs_hash_lookup);
1384 cfs_hash_for_each_enter(cfs_hash_t *hs)
1386 LASSERT(!cfs_hash_is_exiting(hs));
1388 if (!cfs_hash_with_rehash(hs))
1391 * NB: it's race on cfs_has_t::hs_iterating, but doesn't matter
1392 * because it's just an unreliable signal to rehash-thread,
1393 * rehash-thread will try to finsih rehash ASAP when seeing this.
1395 hs->hs_iterating = 1;
1397 cfs_hash_lock(hs, 1);
1400 /* NB: iteration is mostly called by service thread,
1401 * we tend to cancel pending rehash-requst, instead of
1402 * blocking service thread, we will relaunch rehash request
1403 * after iteration */
1404 if (cfs_hash_is_rehashing(hs))
1405 cfs_hash_rehash_cancel_locked(hs);
1406 cfs_hash_unlock(hs, 1);
1410 cfs_hash_for_each_exit(cfs_hash_t *hs)
1415 if (!cfs_hash_with_rehash(hs))
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 */
1423 hs->hs_iterating = 0;
1425 cfs_hash_rehash(hs, atomic_read(&hs->hs_count) <
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.
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
1441 cfs_hash_for_each_tight(cfs_hash_t *hs, cfs_hash_for_each_cb_t func,
1442 void *data, int remove_safe)
1444 struct hlist_node *hnode;
1445 struct hlist_node *pos;
1448 int excl = !!remove_safe;
1453 cfs_hash_for_each_enter(hs);
1455 cfs_hash_lock(hs, 0);
1456 LASSERT(!cfs_hash_is_rehashing(hs));
1458 cfs_hash_for_each_bucket(hs, &bd, i) {
1459 struct hlist_head *hhead;
1461 cfs_hash_bd_lock(hs, &bd, excl);
1462 if (func == NULL) { /* only glimpse size */
1463 count += bd.bd_bucket->hsb_count;
1464 cfs_hash_bd_unlock(hs, &bd, excl);
1468 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1469 hlist_for_each_safe(hnode, pos, hhead) {
1470 cfs_hash_bucket_validate(hs, &bd, hnode);
1473 if (func(hs, &bd, hnode, data)) {
1474 cfs_hash_bd_unlock(hs, &bd, excl);
1479 cfs_hash_bd_unlock(hs, &bd, excl);
1480 if (loop < CFS_HASH_LOOP_HOG)
1483 cfs_hash_unlock(hs, 0);
1485 cfs_hash_lock(hs, 0);
1488 cfs_hash_unlock(hs, 0);
1490 cfs_hash_for_each_exit(hs);
1495 cfs_hash_cond_opt_cb_t func;
1497 } cfs_hash_cond_arg_t;
1500 cfs_hash_cond_del_locked(cfs_hash_t *hs, cfs_hash_bd_t *bd,
1501 struct hlist_node *hnode, void *data)
1503 cfs_hash_cond_arg_t *cond = data;
1505 if (cond->func(cfs_hash_object(hs, hnode), cond->arg))
1506 cfs_hash_bd_del_locked(hs, bd, hnode);
1511 * Delete item from the libcfs hash @hs when @func return true.
1512 * The write lock being hold during loop for each bucket to avoid
1513 * any object be reference.
1516 cfs_hash_cond_del(cfs_hash_t *hs, cfs_hash_cond_opt_cb_t func, void *data)
1518 cfs_hash_cond_arg_t arg = {
1523 cfs_hash_for_each_tight(hs, cfs_hash_cond_del_locked, &arg, 1);
1525 EXPORT_SYMBOL(cfs_hash_cond_del);
1528 cfs_hash_for_each(cfs_hash_t *hs,
1529 cfs_hash_for_each_cb_t func, void *data)
1531 cfs_hash_for_each_tight(hs, func, data, 0);
1533 EXPORT_SYMBOL(cfs_hash_for_each);
1536 cfs_hash_for_each_safe(cfs_hash_t *hs,
1537 cfs_hash_for_each_cb_t func, void *data)
1539 cfs_hash_for_each_tight(hs, func, data, 1);
1541 EXPORT_SYMBOL(cfs_hash_for_each_safe);
1544 cfs_hash_peek(cfs_hash_t *hs, cfs_hash_bd_t *bd,
1545 struct hlist_node *hnode, void *data)
1548 return 1; /* return 1 to break the loop */
1552 cfs_hash_is_empty(cfs_hash_t *hs)
1556 cfs_hash_for_each_tight(hs, cfs_hash_peek, &empty, 0);
1559 EXPORT_SYMBOL(cfs_hash_is_empty);
1562 cfs_hash_size_get(cfs_hash_t *hs)
1564 return cfs_hash_with_counter(hs) ?
1565 atomic_read(&hs->hs_count) :
1566 cfs_hash_for_each_tight(hs, NULL, NULL, 0);
1568 EXPORT_SYMBOL(cfs_hash_size_get);
1571 * cfs_hash_for_each_relax:
1572 * Iterate the hash table and call @func on each item without
1573 * any lock. This function can't guarantee to finish iteration
1574 * if these features are enabled:
1576 * a. if rehash_key is enabled, an item can be moved from
1577 * one bucket to another bucket
1578 * b. user can remove non-zero-ref item from hash-table,
1579 * so the item can be removed from hash-table, even worse,
1580 * it's possible that user changed key and insert to another
1582 * there's no way for us to finish iteration correctly on previous
1583 * two cases, so iteration has to be stopped on change.
1586 cfs_hash_for_each_relax(cfs_hash_t *hs, cfs_hash_for_each_cb_t func, void *data)
1588 struct hlist_node *hnode;
1589 struct hlist_node *tmp;
1598 stop_on_change = cfs_hash_with_rehash_key(hs) ||
1599 !cfs_hash_with_no_itemref(hs) ||
1600 CFS_HOP(hs, put_locked) == NULL;
1601 cfs_hash_lock(hs, 0);
1602 LASSERT(!cfs_hash_is_rehashing(hs));
1604 cfs_hash_for_each_bucket(hs, &bd, i) {
1605 struct hlist_head *hhead;
1607 cfs_hash_bd_lock(hs, &bd, 0);
1608 version = cfs_hash_bd_version_get(&bd);
1610 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1611 for (hnode = hhead->first; hnode != NULL;) {
1612 cfs_hash_bucket_validate(hs, &bd, hnode);
1613 cfs_hash_get(hs, hnode);
1614 cfs_hash_bd_unlock(hs, &bd, 0);
1615 cfs_hash_unlock(hs, 0);
1617 rc = func(hs, &bd, hnode, data);
1619 cfs_hash_put(hs, hnode);
1623 cfs_hash_lock(hs, 0);
1624 cfs_hash_bd_lock(hs, &bd, 0);
1625 if (!stop_on_change) {
1627 cfs_hash_put_locked(hs, hnode);
1629 } else { /* bucket changed? */
1631 cfs_hash_bd_version_get(&bd))
1633 /* safe to continue because no change */
1634 hnode = hnode->next;
1636 if (rc) /* callback wants to break iteration */
1640 cfs_hash_bd_unlock(hs, &bd, 0);
1642 cfs_hash_unlock(hs, 0);
1648 cfs_hash_for_each_nolock(cfs_hash_t *hs,
1649 cfs_hash_for_each_cb_t func, void *data)
1653 if (cfs_hash_with_no_lock(hs) ||
1654 cfs_hash_with_rehash_key(hs) ||
1655 !cfs_hash_with_no_itemref(hs))
1656 RETURN(-EOPNOTSUPP);
1658 if (CFS_HOP(hs, get) == NULL ||
1659 (CFS_HOP(hs, put) == NULL &&
1660 CFS_HOP(hs, put_locked) == NULL))
1661 RETURN(-EOPNOTSUPP);
1663 cfs_hash_for_each_enter(hs);
1664 cfs_hash_for_each_relax(hs, func, data);
1665 cfs_hash_for_each_exit(hs);
1669 EXPORT_SYMBOL(cfs_hash_for_each_nolock);
1672 * For each hash bucket in the libcfs hash @hs call the passed callback
1673 * @func until all the hash buckets are empty. The passed callback @func
1674 * or the previously registered callback hs->hs_put must remove the item
1675 * from the hash. You may either use the cfs_hash_del() or hlist_del()
1676 * functions. No rwlocks will be held during the callback @func it is
1677 * safe to sleep if needed. This function will not terminate until the
1678 * hash is empty. Note it is still possible to concurrently add new
1679 * items in to the hash. It is the callers responsibility to ensure
1680 * the required locking is in place to prevent concurrent insertions.
1683 cfs_hash_for_each_empty(cfs_hash_t *hs,
1684 cfs_hash_for_each_cb_t func, void *data)
1689 if (cfs_hash_with_no_lock(hs))
1692 if (CFS_HOP(hs, get) == NULL ||
1693 (CFS_HOP(hs, put) == NULL &&
1694 CFS_HOP(hs, put_locked) == NULL))
1697 cfs_hash_for_each_enter(hs);
1698 while (cfs_hash_for_each_relax(hs, func, data)) {
1699 CDEBUG(D_INFO, "Try to empty hash: %s, loop: %u\n",
1702 cfs_hash_for_each_exit(hs);
1705 EXPORT_SYMBOL(cfs_hash_for_each_empty);
1708 cfs_hash_hlist_for_each(cfs_hash_t *hs, unsigned hindex,
1709 cfs_hash_for_each_cb_t func, void *data)
1711 struct hlist_head *hhead;
1712 struct hlist_node *hnode;
1715 cfs_hash_for_each_enter(hs);
1716 cfs_hash_lock(hs, 0);
1717 if (hindex >= CFS_HASH_NHLIST(hs))
1720 cfs_hash_bd_index_set(hs, hindex, &bd);
1722 cfs_hash_bd_lock(hs, &bd, 0);
1723 hhead = cfs_hash_bd_hhead(hs, &bd);
1724 hlist_for_each(hnode, hhead) {
1725 if (func(hs, &bd, hnode, data))
1728 cfs_hash_bd_unlock(hs, &bd, 0);
1730 cfs_hash_unlock(hs, 0);
1731 cfs_hash_for_each_exit(hs);
1734 EXPORT_SYMBOL(cfs_hash_hlist_for_each);
1737 * For each item in the libcfs hash @hs which matches the @key call
1738 * the passed callback @func and pass to it as an argument each hash
1739 * item and the private @data. During the callback the bucket lock
1740 * is held so the callback must never sleep.
1743 cfs_hash_for_each_key(cfs_hash_t *hs, const void *key,
1744 cfs_hash_for_each_cb_t func, void *data)
1746 struct hlist_node *hnode;
1747 cfs_hash_bd_t bds[2];
1750 cfs_hash_lock(hs, 0);
1752 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
1754 cfs_hash_for_each_bd(bds, 2, i) {
1755 struct hlist_head *hlist = cfs_hash_bd_hhead(hs, &bds[i]);
1757 hlist_for_each(hnode, hlist) {
1758 cfs_hash_bucket_validate(hs, &bds[i], hnode);
1760 if (cfs_hash_keycmp(hs, key, hnode)) {
1761 if (func(hs, &bds[i], hnode, data))
1767 cfs_hash_dual_bd_unlock(hs, bds, 0);
1768 cfs_hash_unlock(hs, 0);
1770 EXPORT_SYMBOL(cfs_hash_for_each_key);
1773 * Rehash the libcfs hash @hs to the given @bits. This can be used
1774 * to grow the hash size when excessive chaining is detected, or to
1775 * shrink the hash when it is larger than needed. When the CFS_HASH_REHASH
1776 * flag is set in @hs the libcfs hash may be dynamically rehashed
1777 * during addition or removal if the hash's theta value exceeds
1778 * either the hs->hs_min_theta or hs->max_theta values. By default
1779 * these values are tuned to keep the chained hash depth small, and
1780 * this approach assumes a reasonably uniform hashing function. The
1781 * theta thresholds for @hs are tunable via cfs_hash_set_theta().
1784 cfs_hash_rehash_cancel_locked(cfs_hash_t *hs)
1788 /* need hold cfs_hash_lock(hs, 1) */
1789 LASSERT(cfs_hash_with_rehash(hs) &&
1790 !cfs_hash_with_no_lock(hs));
1792 if (!cfs_hash_is_rehashing(hs))
1795 if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_rehash_wi)) {
1796 hs->hs_rehash_bits = 0;
1800 for (i = 2; cfs_hash_is_rehashing(hs); i++) {
1801 cfs_hash_unlock(hs, 1);
1802 /* raise console warning while waiting too long */
1803 CDEBUG(IS_PO2(i >> 3) ? D_WARNING : D_INFO,
1804 "hash %s is still rehashing, rescheded %d\n",
1805 hs->hs_name, i - 1);
1807 cfs_hash_lock(hs, 1);
1810 EXPORT_SYMBOL(cfs_hash_rehash_cancel_locked);
1813 cfs_hash_rehash_cancel(cfs_hash_t *hs)
1815 cfs_hash_lock(hs, 1);
1816 cfs_hash_rehash_cancel_locked(hs);
1817 cfs_hash_unlock(hs, 1);
1819 EXPORT_SYMBOL(cfs_hash_rehash_cancel);
1822 cfs_hash_rehash(cfs_hash_t *hs, int do_rehash)
1826 LASSERT(cfs_hash_with_rehash(hs) && !cfs_hash_with_no_lock(hs));
1828 cfs_hash_lock(hs, 1);
1830 rc = cfs_hash_rehash_bits(hs);
1832 cfs_hash_unlock(hs, 1);
1836 hs->hs_rehash_bits = rc;
1838 /* launch and return */
1839 cfs_wi_schedule(cfs_sched_rehash, &hs->hs_rehash_wi);
1840 cfs_hash_unlock(hs, 1);
1844 /* rehash right now */
1845 cfs_hash_unlock(hs, 1);
1847 return cfs_hash_rehash_worker(&hs->hs_rehash_wi);
1849 EXPORT_SYMBOL(cfs_hash_rehash);
1852 cfs_hash_rehash_bd(cfs_hash_t *hs, cfs_hash_bd_t *old)
1855 struct hlist_head *hhead;
1856 struct hlist_node *hnode;
1857 struct hlist_node *pos;
1861 /* hold cfs_hash_lock(hs, 1), so don't need any bucket lock */
1862 cfs_hash_bd_for_each_hlist(hs, old, hhead) {
1863 hlist_for_each_safe(hnode, pos, hhead) {
1864 key = cfs_hash_key(hs, hnode);
1865 LASSERT(key != NULL);
1866 /* Validate hnode is in the correct bucket. */
1867 cfs_hash_bucket_validate(hs, old, hnode);
1869 * Delete from old hash bucket; move to new bucket.
1870 * ops->hs_key must be defined.
1872 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
1873 hs->hs_rehash_bits, key, &new);
1874 cfs_hash_bd_move_locked(hs, old, &new, hnode);
1882 cfs_hash_rehash_worker(cfs_workitem_t *wi)
1884 cfs_hash_t *hs = container_of(wi, cfs_hash_t, hs_rehash_wi);
1885 cfs_hash_bucket_t **bkts;
1887 unsigned int old_size;
1888 unsigned int new_size;
1894 LASSERT (hs != NULL && cfs_hash_with_rehash(hs));
1896 cfs_hash_lock(hs, 0);
1897 LASSERT(cfs_hash_is_rehashing(hs));
1899 old_size = CFS_HASH_NBKT(hs);
1900 new_size = CFS_HASH_RH_NBKT(hs);
1902 cfs_hash_unlock(hs, 0);
1905 * don't need hs::hs_rwlock for hs::hs_buckets,
1906 * because nobody can change bkt-table except me.
1908 bkts = cfs_hash_buckets_realloc(hs, hs->hs_buckets,
1909 old_size, new_size);
1910 cfs_hash_lock(hs, 1);
1916 if (bkts == hs->hs_buckets) {
1917 bkts = NULL; /* do nothing */
1921 rc = __cfs_hash_theta(hs);
1922 if ((rc >= hs->hs_min_theta) && (rc <= hs->hs_max_theta)) {
1923 /* free the new allocated bkt-table */
1924 old_size = new_size;
1925 new_size = CFS_HASH_NBKT(hs);
1930 LASSERT(hs->hs_rehash_buckets == NULL);
1931 hs->hs_rehash_buckets = bkts;
1934 cfs_hash_for_each_bucket(hs, &bd, i) {
1935 if (cfs_hash_is_exiting(hs)) {
1937 /* someone wants to destroy the hash, abort now */
1938 if (old_size < new_size) /* OK to free old bkt-table */
1940 /* it's shrinking, need free new bkt-table */
1941 hs->hs_rehash_buckets = NULL;
1942 old_size = new_size;
1943 new_size = CFS_HASH_NBKT(hs);
1947 count += cfs_hash_rehash_bd(hs, &bd);
1948 if (count < CFS_HASH_LOOP_HOG ||
1949 cfs_hash_is_iterating(hs)) { /* need to finish ASAP */
1954 cfs_hash_unlock(hs, 1);
1956 cfs_hash_lock(hs, 1);
1959 hs->hs_rehash_count++;
1961 bkts = hs->hs_buckets;
1962 hs->hs_buckets = hs->hs_rehash_buckets;
1963 hs->hs_rehash_buckets = NULL;
1965 hs->hs_cur_bits = hs->hs_rehash_bits;
1967 hs->hs_rehash_bits = 0;
1968 if (rc == -ESRCH) /* never be scheduled again */
1969 cfs_wi_exit(cfs_sched_rehash, wi);
1970 bsize = cfs_hash_bkt_size(hs);
1971 cfs_hash_unlock(hs, 1);
1972 /* can't refer to @hs anymore because it could be destroyed */
1974 cfs_hash_buckets_free(bkts, bsize, new_size, old_size);
1976 CDEBUG(D_INFO, "early quit of of rehashing: %d\n", rc);
1977 /* return 1 only if cfs_wi_exit is called */
1978 return rc == -ESRCH;
1982 * Rehash the object referenced by @hnode in the libcfs hash @hs. The
1983 * @old_key must be provided to locate the objects previous location
1984 * in the hash, and the @new_key will be used to reinsert the object.
1985 * Use this function instead of a cfs_hash_add() + cfs_hash_del()
1986 * combo when it is critical that there is no window in time where the
1987 * object is missing from the hash. When an object is being rehashed
1988 * the registered cfs_hash_get() and cfs_hash_put() functions will
1991 void cfs_hash_rehash_key(cfs_hash_t *hs, const void *old_key,
1992 void *new_key, struct hlist_node *hnode)
1994 cfs_hash_bd_t bds[3];
1995 cfs_hash_bd_t old_bds[2];
1996 cfs_hash_bd_t new_bd;
1998 LASSERT(!hlist_unhashed(hnode));
2000 cfs_hash_lock(hs, 0);
2002 cfs_hash_dual_bd_get(hs, old_key, old_bds);
2003 cfs_hash_bd_get(hs, new_key, &new_bd);
2005 bds[0] = old_bds[0];
2006 bds[1] = old_bds[1];
2009 /* NB: bds[0] and bds[1] are ordered already */
2010 cfs_hash_bd_order(&bds[1], &bds[2]);
2011 cfs_hash_bd_order(&bds[0], &bds[1]);
2013 cfs_hash_multi_bd_lock(hs, bds, 3, 1);
2014 if (likely(old_bds[1].bd_bucket == NULL)) {
2015 cfs_hash_bd_move_locked(hs, &old_bds[0], &new_bd, hnode);
2017 cfs_hash_dual_bd_finddel_locked(hs, old_bds, old_key, hnode);
2018 cfs_hash_bd_add_locked(hs, &new_bd, hnode);
2020 /* overwrite key inside locks, otherwise may screw up with
2021 * other operations, i.e: rehash */
2022 cfs_hash_keycpy(hs, hnode, new_key);
2024 cfs_hash_multi_bd_unlock(hs, bds, 3, 1);
2025 cfs_hash_unlock(hs, 0);
2027 EXPORT_SYMBOL(cfs_hash_rehash_key);
2029 int cfs_hash_debug_header(char *str, int size)
2031 return snprintf(str, size, "%-*s%6s%6s%6s%6s%6s%6s%6s%7s%8s%8s%8s%s\n",
2032 CFS_HASH_BIGNAME_LEN,
2033 "name", "cur", "min", "max", "theta", "t-min", "t-max",
2034 "flags", "rehash", "count", "maxdep", "maxdepb",
2037 EXPORT_SYMBOL(cfs_hash_debug_header);
2039 static cfs_hash_bucket_t **
2040 cfs_hash_full_bkts(cfs_hash_t *hs)
2042 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
2043 if (hs->hs_rehash_buckets == NULL)
2044 return hs->hs_buckets;
2046 LASSERT(hs->hs_rehash_bits != 0);
2047 return hs->hs_rehash_bits > hs->hs_cur_bits ?
2048 hs->hs_rehash_buckets : hs->hs_buckets;
2052 cfs_hash_full_nbkt(cfs_hash_t *hs)
2054 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
2055 if (hs->hs_rehash_buckets == NULL)
2056 return CFS_HASH_NBKT(hs);
2058 LASSERT(hs->hs_rehash_bits != 0);
2059 return hs->hs_rehash_bits > hs->hs_cur_bits ?
2060 CFS_HASH_RH_NBKT(hs) : CFS_HASH_NBKT(hs);
2063 int cfs_hash_debug_str(cfs_hash_t *hs, char *str, int size)
2065 int dist[8] = { 0, };
2073 if (str == NULL || size == 0)
2076 cfs_hash_lock(hs, 0);
2077 theta = __cfs_hash_theta(hs);
2079 c += snprintf(str + c, size - c, "%-*s ",
2080 CFS_HASH_BIGNAME_LEN, hs->hs_name);
2081 c += snprintf(str + c, size - c, "%5d ", 1 << hs->hs_cur_bits);
2082 c += snprintf(str + c, size - c, "%5d ", 1 << hs->hs_min_bits);
2083 c += snprintf(str + c, size - c, "%5d ", 1 << hs->hs_max_bits);
2084 c += snprintf(str + c, size - c, "%d.%03d ",
2085 __cfs_hash_theta_int(theta),
2086 __cfs_hash_theta_frac(theta));
2087 c += snprintf(str + c, size - c, "%d.%03d ",
2088 __cfs_hash_theta_int(hs->hs_min_theta),
2089 __cfs_hash_theta_frac(hs->hs_min_theta));
2090 c += snprintf(str + c, size - c, "%d.%03d ",
2091 __cfs_hash_theta_int(hs->hs_max_theta),
2092 __cfs_hash_theta_frac(hs->hs_max_theta));
2093 c += snprintf(str + c, size - c, " 0x%02x ", hs->hs_flags);
2094 c += snprintf(str + c, size - c, "%6d ", hs->hs_rehash_count);
2097 * The distribution is a summary of the chained hash depth in
2098 * each of the libcfs hash buckets. Each buckets hsb_count is
2099 * divided by the hash theta value and used to generate a
2100 * histogram of the hash distribution. A uniform hash will
2101 * result in all hash buckets being close to the average thus
2102 * only the first few entries in the histogram will be non-zero.
2103 * If you hash function results in a non-uniform hash the will
2104 * be observable by outlier bucks in the distribution histogram.
2106 * Uniform hash distribution: 128/128/0/0/0/0/0/0
2107 * Non-Uniform hash distribution: 128/125/0/0/0/0/2/1
2109 for (i = 0; i < cfs_hash_full_nbkt(hs); i++) {
2112 bd.bd_bucket = cfs_hash_full_bkts(hs)[i];
2113 cfs_hash_bd_lock(hs, &bd, 0);
2114 if (maxdep < bd.bd_bucket->hsb_depmax) {
2115 maxdep = bd.bd_bucket->hsb_depmax;
2117 maxdepb = ffz(~maxdep);
2120 total += bd.bd_bucket->hsb_count;
2121 dist[min(fls(bd.bd_bucket->hsb_count/max(theta,1)),7)]++;
2122 cfs_hash_bd_unlock(hs, &bd, 0);
2125 c += snprintf(str + c, size - c, "%7d ", total);
2126 c += snprintf(str + c, size - c, "%7d ", maxdep);
2127 c += snprintf(str + c, size - c, "%7d ", maxdepb);
2128 for (i = 0; i < 8; i++)
2129 c += snprintf(str + c, size - c, "%d%c", dist[i],
2130 (i == 7) ? '\n' : '/');
2132 cfs_hash_unlock(hs, 0);
2136 EXPORT_SYMBOL(cfs_hash_debug_str);