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.gnu.org/licenses/gpl-2.0.html
23 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2011, 2016, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
32 * libcfs/libcfs/hash.c
34 * Implement a hash class for hash process in lustre system.
36 * Author: YuZhangyong <yzy@clusterfs.com>
38 * 2008-08-15: Brian Behlendorf <behlendorf1@llnl.gov>
39 * - Simplified API and improved documentation
40 * - Added per-hash feature flags:
41 * * CFS_HASH_DEBUG additional validation
42 * * CFS_HASH_REHASH dynamic rehashing
43 * - Added per-hash statistics
44 * - General performance enhancements
46 * 2009-07-31: Liang Zhen <zhen.liang@sun.com>
47 * - move all stuff to libcfs
48 * - don't allow cur_bits != max_bits without setting of CFS_HASH_REHASH
49 * - ignore hs_rwlock if without CFS_HASH_REHASH setting
50 * - buckets are allocated one by one(instead of contiguous memory),
51 * to avoid unnecessary cacheline conflict
53 * 2010-03-01: Liang Zhen <zhen.liang@sun.com>
54 * - "bucket" is a group of hlist_head now, user can specify bucket size
55 * by bkt_bits of cfs_hash_create(), all hlist_heads in a bucket share
56 * one lock for reducing memory overhead.
58 * - support lockless hash, caller will take care of locks:
59 * avoid lock overhead for hash tables that are already protected
60 * by locking in the caller for another reason
62 * - support both spin_lock/rwlock for bucket:
63 * overhead of spinlock contention is lower than read/write
64 * contention of rwlock, so using spinlock to serialize operations on
65 * bucket is more reasonable for those frequently changed hash tables
67 * - support one-single lock mode:
68 * one lock to protect all hash operations to avoid overhead of
69 * multiple locks if hash table is always small
71 * - removed a lot of unnecessary addref & decref on hash element:
72 * addref & decref are atomic operations in many use-cases which
75 * - support non-blocking cfs_hash_add() and cfs_hash_findadd():
76 * some lustre use-cases require these functions to be strictly
77 * non-blocking, we need to schedule required rehash on a different
78 * thread on those cases.
80 * - safer rehash on large hash table
81 * In old implementation, rehash function will exclusively lock the
82 * hash table and finish rehash in one batch, it's dangerous on SMP
83 * system because rehash millions of elements could take long time.
84 * New implemented rehash can release lock and relax CPU in middle
85 * of rehash, it's safe for another thread to search/change on the
86 * hash table even it's in rehasing.
88 * - support two different refcount modes
89 * . hash table has refcount on element
90 * . hash table doesn't change refcount on adding/removing element
92 * - support long name hash table (for param-tree)
94 * - fix a bug for cfs_hash_rehash_key:
95 * in old implementation, cfs_hash_rehash_key could screw up the
96 * hash-table because @key is overwritten without any protection.
97 * Now we need user to define hs_keycpy for those rehash enabled
98 * hash tables, cfs_hash_rehash_key will overwrite hash-key
99 * inside lock by calling hs_keycpy.
101 * - better hash iteration:
102 * Now we support both locked iteration & lockless iteration of hash
103 * table. Also, user can break the iteration by return 1 in callback.
105 #include <linux/seq_file.h>
107 #include <libcfs/linux/linux-list.h>
108 #include <libcfs/libcfs.h>
110 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
111 static unsigned int warn_on_depth = 8;
112 module_param(warn_on_depth, uint, 0644);
113 MODULE_PARM_DESC(warn_on_depth, "warning when hash depth is high.");
116 struct cfs_wi_sched *cfs_sched_rehash;
119 cfs_hash_nl_lock(union cfs_hash_lock *lock, int exclusive) {}
122 cfs_hash_nl_unlock(union cfs_hash_lock *lock, int exclusive) {}
125 cfs_hash_spin_lock(union cfs_hash_lock *lock, int exclusive)
126 __acquires(&lock->spin)
128 spin_lock(&lock->spin);
132 cfs_hash_spin_unlock(union cfs_hash_lock *lock, int exclusive)
133 __releases(&lock->spin)
135 spin_unlock(&lock->spin);
139 cfs_hash_rw_lock(union cfs_hash_lock *lock, int exclusive)
140 __acquires(&lock->rw)
143 read_lock(&lock->rw);
145 write_lock(&lock->rw);
149 cfs_hash_rw_unlock(union cfs_hash_lock *lock, int exclusive)
150 __releases(&lock->rw)
153 read_unlock(&lock->rw);
155 write_unlock(&lock->rw);
159 static struct cfs_hash_lock_ops cfs_hash_nl_lops = {
160 .hs_lock = cfs_hash_nl_lock,
161 .hs_unlock = cfs_hash_nl_unlock,
162 .hs_bkt_lock = cfs_hash_nl_lock,
163 .hs_bkt_unlock = cfs_hash_nl_unlock,
166 /** no bucket lock, one spinlock to protect everything */
167 static struct cfs_hash_lock_ops 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 struct cfs_hash_lock_ops cfs_hash_bkt_spin_lops = {
176 .hs_lock = cfs_hash_rw_lock,
177 .hs_unlock = cfs_hash_rw_unlock,
178 .hs_bkt_lock = cfs_hash_spin_lock,
179 .hs_bkt_unlock = cfs_hash_spin_unlock,
182 /** rw bucket lock, rehash is enabled */
183 static struct cfs_hash_lock_ops cfs_hash_bkt_rw_lops = {
184 .hs_lock = cfs_hash_rw_lock,
185 .hs_unlock = cfs_hash_rw_unlock,
186 .hs_bkt_lock = cfs_hash_rw_lock,
187 .hs_bkt_unlock = cfs_hash_rw_unlock,
190 /** spin bucket lock, rehash is disabled */
191 static struct cfs_hash_lock_ops cfs_hash_nr_bkt_spin_lops = {
192 .hs_lock = cfs_hash_nl_lock,
193 .hs_unlock = cfs_hash_nl_unlock,
194 .hs_bkt_lock = cfs_hash_spin_lock,
195 .hs_bkt_unlock = cfs_hash_spin_unlock,
198 /** rw bucket lock, rehash is disabled */
199 static struct cfs_hash_lock_ops cfs_hash_nr_bkt_rw_lops = {
200 .hs_lock = cfs_hash_nl_lock,
201 .hs_unlock = cfs_hash_nl_unlock,
202 .hs_bkt_lock = cfs_hash_rw_lock,
203 .hs_bkt_unlock = cfs_hash_rw_unlock,
207 cfs_hash_lock_setup(struct cfs_hash *hs)
209 if (cfs_hash_with_no_lock(hs)) {
210 hs->hs_lops = &cfs_hash_nl_lops;
212 } else if (cfs_hash_with_no_bktlock(hs)) {
213 hs->hs_lops = &cfs_hash_nbl_lops;
214 spin_lock_init(&hs->hs_lock.spin);
216 } else if (cfs_hash_with_rehash(hs)) {
217 rwlock_init(&hs->hs_lock.rw);
219 if (cfs_hash_with_rw_bktlock(hs))
220 hs->hs_lops = &cfs_hash_bkt_rw_lops;
221 else if (cfs_hash_with_spin_bktlock(hs))
222 hs->hs_lops = &cfs_hash_bkt_spin_lops;
226 if (cfs_hash_with_rw_bktlock(hs))
227 hs->hs_lops = &cfs_hash_nr_bkt_rw_lops;
228 else if (cfs_hash_with_spin_bktlock(hs))
229 hs->hs_lops = &cfs_hash_nr_bkt_spin_lops;
236 * Simple hash head without depth tracking
237 * new element is always added to head of hlist
239 struct cfs_hash_head {
240 struct hlist_head hh_head; /**< entries list */
244 cfs_hash_hh_hhead_size(struct cfs_hash *hs)
246 return sizeof(struct cfs_hash_head);
249 static struct hlist_head *
250 cfs_hash_hh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
252 struct cfs_hash_head *head;
254 head = (struct cfs_hash_head *)&bd->bd_bucket->hsb_head[0];
255 return &head[bd->bd_offset].hh_head;
259 cfs_hash_hh_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
260 struct hlist_node *hnode)
262 hlist_add_head(hnode, cfs_hash_hh_hhead(hs, bd));
263 return -1; /* unknown depth */
267 cfs_hash_hh_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
268 struct hlist_node *hnode)
270 hlist_del_init(hnode);
271 return -1; /* unknown depth */
275 * Simple hash head with depth tracking
276 * new element is always added to head of hlist
278 struct cfs_hash_head_dep {
279 struct hlist_head hd_head; /**< entries list */
280 unsigned int hd_depth; /**< list length */
284 cfs_hash_hd_hhead_size(struct cfs_hash *hs)
286 return sizeof(struct cfs_hash_head_dep);
289 static struct hlist_head *
290 cfs_hash_hd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
292 struct cfs_hash_head_dep *head;
294 head = (struct cfs_hash_head_dep *)&bd->bd_bucket->hsb_head[0];
295 return &head[bd->bd_offset].hd_head;
299 cfs_hash_hd_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
300 struct hlist_node *hnode)
302 struct cfs_hash_head_dep *hh;
304 hh = container_of(cfs_hash_hd_hhead(hs, bd),
305 struct cfs_hash_head_dep, hd_head);
306 hlist_add_head(hnode, &hh->hd_head);
307 return ++hh->hd_depth;
311 cfs_hash_hd_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
312 struct hlist_node *hnode)
314 struct cfs_hash_head_dep *hh;
316 hh = container_of(cfs_hash_hd_hhead(hs, bd),
317 struct cfs_hash_head_dep, hd_head);
318 hlist_del_init(hnode);
319 return --hh->hd_depth;
323 * double links hash head without depth tracking
324 * new element is always added to tail of hlist
326 struct cfs_hash_dhead {
327 struct hlist_head dh_head; /**< entries list */
328 struct hlist_node *dh_tail; /**< the last entry */
332 cfs_hash_dh_hhead_size(struct cfs_hash *hs)
334 return sizeof(struct cfs_hash_dhead);
337 static struct hlist_head *
338 cfs_hash_dh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
340 struct cfs_hash_dhead *head;
342 head = (struct cfs_hash_dhead *)&bd->bd_bucket->hsb_head[0];
343 return &head[bd->bd_offset].dh_head;
347 cfs_hash_dh_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
348 struct hlist_node *hnode)
350 struct cfs_hash_dhead *dh;
352 dh = container_of(cfs_hash_dh_hhead(hs, bd),
353 struct cfs_hash_dhead, dh_head);
354 if (dh->dh_tail != NULL) /* not empty */
355 hlist_add_behind(hnode, dh->dh_tail);
356 else /* empty list */
357 hlist_add_head(hnode, &dh->dh_head);
359 return -1; /* unknown depth */
363 cfs_hash_dh_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
364 struct hlist_node *hnd)
366 struct cfs_hash_dhead *dh;
368 dh = container_of(cfs_hash_dh_hhead(hs, bd),
369 struct cfs_hash_dhead, dh_head);
370 if (hnd->next == NULL) { /* it's the tail */
371 dh->dh_tail = (hnd->pprev == &dh->dh_head.first) ? NULL :
372 container_of(hnd->pprev, struct hlist_node, next);
375 return -1; /* unknown depth */
379 * double links hash head with depth tracking
380 * new element is always added to tail of hlist
382 struct cfs_hash_dhead_dep {
383 struct hlist_head dd_head; /**< entries list */
384 struct hlist_node *dd_tail; /**< the last entry */
385 unsigned int dd_depth; /**< list length */
389 cfs_hash_dd_hhead_size(struct cfs_hash *hs)
391 return sizeof(struct cfs_hash_dhead_dep);
394 static struct hlist_head *
395 cfs_hash_dd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
397 struct cfs_hash_dhead_dep *head;
399 head = (struct cfs_hash_dhead_dep *)&bd->bd_bucket->hsb_head[0];
400 return &head[bd->bd_offset].dd_head;
404 cfs_hash_dd_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
405 struct hlist_node *hnode)
407 struct cfs_hash_dhead_dep *dh;
409 dh = container_of(cfs_hash_dd_hhead(hs, bd),
410 struct cfs_hash_dhead_dep, dd_head);
411 if (dh->dd_tail != NULL) /* not empty */
412 hlist_add_behind(hnode, dh->dd_tail);
413 else /* empty list */
414 hlist_add_head(hnode, &dh->dd_head);
416 return ++dh->dd_depth;
420 cfs_hash_dd_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
421 struct hlist_node *hnd)
423 struct cfs_hash_dhead_dep *dh;
425 dh = container_of(cfs_hash_dd_hhead(hs, bd),
426 struct cfs_hash_dhead_dep, dd_head);
427 if (hnd->next == NULL) { /* it's the tail */
428 dh->dd_tail = (hnd->pprev == &dh->dd_head.first) ? NULL :
429 container_of(hnd->pprev, struct hlist_node, next);
432 return --dh->dd_depth;
435 static struct cfs_hash_hlist_ops cfs_hash_hh_hops = {
436 .hop_hhead = cfs_hash_hh_hhead,
437 .hop_hhead_size = cfs_hash_hh_hhead_size,
438 .hop_hnode_add = cfs_hash_hh_hnode_add,
439 .hop_hnode_del = cfs_hash_hh_hnode_del,
442 static struct cfs_hash_hlist_ops cfs_hash_hd_hops = {
443 .hop_hhead = cfs_hash_hd_hhead,
444 .hop_hhead_size = cfs_hash_hd_hhead_size,
445 .hop_hnode_add = cfs_hash_hd_hnode_add,
446 .hop_hnode_del = cfs_hash_hd_hnode_del,
449 static struct cfs_hash_hlist_ops cfs_hash_dh_hops = {
450 .hop_hhead = cfs_hash_dh_hhead,
451 .hop_hhead_size = cfs_hash_dh_hhead_size,
452 .hop_hnode_add = cfs_hash_dh_hnode_add,
453 .hop_hnode_del = cfs_hash_dh_hnode_del,
456 static struct cfs_hash_hlist_ops cfs_hash_dd_hops = {
457 .hop_hhead = cfs_hash_dd_hhead,
458 .hop_hhead_size = cfs_hash_dd_hhead_size,
459 .hop_hnode_add = cfs_hash_dd_hnode_add,
460 .hop_hnode_del = cfs_hash_dd_hnode_del,
464 cfs_hash_hlist_setup(struct cfs_hash *hs)
466 if (cfs_hash_with_add_tail(hs)) {
467 hs->hs_hops = cfs_hash_with_depth(hs) ?
468 &cfs_hash_dd_hops : &cfs_hash_dh_hops;
470 hs->hs_hops = cfs_hash_with_depth(hs) ?
471 &cfs_hash_hd_hops : &cfs_hash_hh_hops;
476 cfs_hash_bd_from_key(struct cfs_hash *hs, struct cfs_hash_bucket **bkts,
477 unsigned int bits, const void *key, struct cfs_hash_bd *bd)
479 unsigned int index = cfs_hash_id(hs, key, (1U << bits) - 1);
481 LASSERT(bits == hs->hs_cur_bits || bits == hs->hs_rehash_bits);
483 bd->bd_bucket = bkts[index & ((1U << (bits - hs->hs_bkt_bits)) - 1)];
484 bd->bd_offset = index >> (bits - hs->hs_bkt_bits);
488 cfs_hash_bd_get(struct cfs_hash *hs, const void *key, struct cfs_hash_bd *bd)
490 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
491 if (likely(hs->hs_rehash_buckets == NULL)) {
492 cfs_hash_bd_from_key(hs, hs->hs_buckets,
493 hs->hs_cur_bits, key, bd);
495 LASSERT(hs->hs_rehash_bits != 0);
496 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
497 hs->hs_rehash_bits, key, bd);
500 EXPORT_SYMBOL(cfs_hash_bd_get);
503 cfs_hash_bd_dep_record(struct cfs_hash *hs, struct cfs_hash_bd *bd, int dep_cur)
505 if (likely(dep_cur <= bd->bd_bucket->hsb_depmax))
508 bd->bd_bucket->hsb_depmax = dep_cur;
509 # if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
510 if (likely(warn_on_depth == 0 ||
511 max(warn_on_depth, hs->hs_dep_max) >= dep_cur))
514 spin_lock(&hs->hs_dep_lock);
515 hs->hs_dep_max = dep_cur;
516 hs->hs_dep_bkt = bd->bd_bucket->hsb_index;
517 hs->hs_dep_off = bd->bd_offset;
518 hs->hs_dep_bits = hs->hs_cur_bits;
519 spin_unlock(&hs->hs_dep_lock);
521 cfs_wi_schedule(cfs_sched_rehash, &hs->hs_dep_wi);
526 cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
527 struct hlist_node *hnode)
531 rc = hs->hs_hops->hop_hnode_add(hs, bd, hnode);
532 cfs_hash_bd_dep_record(hs, bd, rc);
533 bd->bd_bucket->hsb_version++;
534 if (unlikely(bd->bd_bucket->hsb_version == 0))
535 bd->bd_bucket->hsb_version++;
536 bd->bd_bucket->hsb_count++;
538 if (cfs_hash_with_counter(hs))
539 atomic_inc(&hs->hs_count);
540 if (!cfs_hash_with_no_itemref(hs))
541 cfs_hash_get(hs, hnode);
543 EXPORT_SYMBOL(cfs_hash_bd_add_locked);
546 cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
547 struct hlist_node *hnode)
549 hs->hs_hops->hop_hnode_del(hs, bd, hnode);
551 LASSERT(bd->bd_bucket->hsb_count > 0);
552 bd->bd_bucket->hsb_count--;
553 bd->bd_bucket->hsb_version++;
554 if (unlikely(bd->bd_bucket->hsb_version == 0))
555 bd->bd_bucket->hsb_version++;
557 if (cfs_hash_with_counter(hs)) {
558 LASSERT(atomic_read(&hs->hs_count) > 0);
559 atomic_dec(&hs->hs_count);
561 if (!cfs_hash_with_no_itemref(hs))
562 cfs_hash_put_locked(hs, hnode);
564 EXPORT_SYMBOL(cfs_hash_bd_del_locked);
567 cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
568 struct cfs_hash_bd *bd_new, struct hlist_node *hnode)
570 struct cfs_hash_bucket *obkt = bd_old->bd_bucket;
571 struct cfs_hash_bucket *nbkt = bd_new->bd_bucket;
574 if (cfs_hash_bd_compare(bd_old, bd_new) == 0)
577 /* use cfs_hash_bd_hnode_add/del, to avoid atomic & refcount ops
578 * in cfs_hash_bd_del/add_locked */
579 hs->hs_hops->hop_hnode_del(hs, bd_old, hnode);
580 rc = hs->hs_hops->hop_hnode_add(hs, bd_new, hnode);
581 cfs_hash_bd_dep_record(hs, bd_new, rc);
583 LASSERT(obkt->hsb_count > 0);
586 if (unlikely(obkt->hsb_version == 0))
590 if (unlikely(nbkt->hsb_version == 0))
595 /** always set, for sanity (avoid ZERO intent) */
596 CFS_HS_LOOKUP_MASK_FIND = 1 << 0,
597 /** return entry with a ref */
598 CFS_HS_LOOKUP_MASK_REF = 1 << 1,
599 /** add entry if not existing */
600 CFS_HS_LOOKUP_MASK_ADD = 1 << 2,
601 /** delete entry, ignore other masks */
602 CFS_HS_LOOKUP_MASK_DEL = 1 << 3,
605 enum cfs_hash_lookup_intent {
606 /** return item w/o refcount */
607 CFS_HS_LOOKUP_IT_PEEK = CFS_HS_LOOKUP_MASK_FIND,
608 /** return item with refcount */
609 CFS_HS_LOOKUP_IT_FIND = (CFS_HS_LOOKUP_MASK_FIND |
610 CFS_HS_LOOKUP_MASK_REF),
611 /** return item w/o refcount if existed, otherwise add */
612 CFS_HS_LOOKUP_IT_ADD = (CFS_HS_LOOKUP_MASK_FIND |
613 CFS_HS_LOOKUP_MASK_ADD),
614 /** return item with refcount if existed, otherwise add */
615 CFS_HS_LOOKUP_IT_FINDADD = (CFS_HS_LOOKUP_IT_FIND |
616 CFS_HS_LOOKUP_MASK_ADD),
617 /** delete if existed */
618 CFS_HS_LOOKUP_IT_FINDDEL = (CFS_HS_LOOKUP_MASK_FIND |
619 CFS_HS_LOOKUP_MASK_DEL)
622 static struct hlist_node *
623 cfs_hash_bd_lookup_intent(struct cfs_hash *hs, struct cfs_hash_bd *bd,
624 const void *key, struct hlist_node *hnode,
625 enum cfs_hash_lookup_intent intent)
628 struct hlist_head *hhead = cfs_hash_bd_hhead(hs, bd);
629 struct hlist_node *ehnode;
630 struct hlist_node *match;
631 int intent_add = (intent & CFS_HS_LOOKUP_MASK_ADD) != 0;
633 /* with this function, we can avoid a lot of useless refcount ops,
634 * which are expensive atomic operations most time. */
635 match = intent_add ? NULL : hnode;
636 hlist_for_each(ehnode, hhead) {
637 if (!cfs_hash_keycmp(hs, key, ehnode))
640 if (match != NULL && match != ehnode) /* can't match */
644 if ((intent & CFS_HS_LOOKUP_MASK_DEL) != 0) {
645 cfs_hash_bd_del_locked(hs, bd, ehnode);
649 /* caller wants refcount? */
650 if ((intent & CFS_HS_LOOKUP_MASK_REF) != 0)
651 cfs_hash_get(hs, ehnode);
658 LASSERT(hnode != NULL);
659 cfs_hash_bd_add_locked(hs, bd, hnode);
664 cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
667 return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
668 CFS_HS_LOOKUP_IT_FIND);
670 EXPORT_SYMBOL(cfs_hash_bd_lookup_locked);
673 cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
676 return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
677 CFS_HS_LOOKUP_IT_PEEK);
679 EXPORT_SYMBOL(cfs_hash_bd_peek_locked);
682 cfs_hash_multi_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
683 unsigned n, int excl)
685 struct cfs_hash_bucket *prev = NULL;
689 * bds must be ascendantly ordered by bd->bd_bucket->hsb_index.
690 * NB: it's possible that several bds point to the same bucket but
691 * have different bd::bd_offset, so need take care of deadlock.
693 cfs_hash_for_each_bd(bds, n, i) {
694 if (prev == bds[i].bd_bucket)
697 LASSERT(prev == NULL ||
698 prev->hsb_index < bds[i].bd_bucket->hsb_index);
699 cfs_hash_bd_lock(hs, &bds[i], excl);
700 prev = bds[i].bd_bucket;
705 cfs_hash_multi_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
706 unsigned n, int excl)
708 struct cfs_hash_bucket *prev = NULL;
711 cfs_hash_for_each_bd(bds, n, i) {
712 if (prev != bds[i].bd_bucket) {
713 cfs_hash_bd_unlock(hs, &bds[i], excl);
714 prev = bds[i].bd_bucket;
719 static struct hlist_node *
720 cfs_hash_multi_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
721 unsigned n, const void *key)
723 struct hlist_node *ehnode;
726 cfs_hash_for_each_bd(bds, n, i) {
727 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, NULL,
728 CFS_HS_LOOKUP_IT_FIND);
735 static struct hlist_node *
736 cfs_hash_multi_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
737 unsigned n, const void *key,
738 struct hlist_node *hnode, int noref)
740 struct hlist_node *ehnode;
744 LASSERT(hnode != NULL);
745 intent = CFS_HS_LOOKUP_IT_PEEK | (!noref * CFS_HS_LOOKUP_MASK_REF);
747 cfs_hash_for_each_bd(bds, n, i) {
748 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key,
754 if (i == 1) { /* only one bucket */
755 cfs_hash_bd_add_locked(hs, &bds[0], hnode);
757 struct cfs_hash_bd mybd;
759 cfs_hash_bd_get(hs, key, &mybd);
760 cfs_hash_bd_add_locked(hs, &mybd, hnode);
766 static struct hlist_node *
767 cfs_hash_multi_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
768 unsigned n, const void *key,
769 struct hlist_node *hnode)
771 struct hlist_node *ehnode;
774 cfs_hash_for_each_bd(bds, n, i) {
775 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, hnode,
776 CFS_HS_LOOKUP_IT_FINDDEL);
784 cfs_hash_bd_order(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
788 if (bd2->bd_bucket == NULL)
791 if (bd1->bd_bucket == NULL) {
793 bd2->bd_bucket = NULL;
797 rc = cfs_hash_bd_compare(bd1, bd2);
799 bd2->bd_bucket = NULL;
802 swap(*bd1, *bd2); /* swab bd1 and bd2 */
807 cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key,
808 struct cfs_hash_bd *bds)
810 /* NB: caller should hold hs_lock.rw if REHASH is set */
811 cfs_hash_bd_from_key(hs, hs->hs_buckets,
812 hs->hs_cur_bits, key, &bds[0]);
813 if (likely(hs->hs_rehash_buckets == NULL)) {
814 /* no rehash or not rehashing */
815 bds[1].bd_bucket = NULL;
819 LASSERT(hs->hs_rehash_bits != 0);
820 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
821 hs->hs_rehash_bits, key, &bds[1]);
823 cfs_hash_bd_order(&bds[0], &bds[1]);
827 cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds, int excl)
829 cfs_hash_multi_bd_lock(hs, bds, 2, excl);
833 cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds, int excl)
835 cfs_hash_multi_bd_unlock(hs, bds, 2, excl);
839 cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
842 return cfs_hash_multi_bd_lookup_locked(hs, bds, 2, key);
846 cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
847 const void *key, struct hlist_node *hnode,
850 return cfs_hash_multi_bd_findadd_locked(hs, bds, 2, key,
855 cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
856 const void *key, struct hlist_node *hnode)
858 return cfs_hash_multi_bd_finddel_locked(hs, bds, 2, key, hnode);
862 cfs_hash_buckets_free(struct cfs_hash_bucket **buckets,
863 int bkt_size, int prev_size, int size)
867 for (i = prev_size; i < size; i++) {
868 if (buckets[i] != NULL)
869 LIBCFS_FREE(buckets[i], bkt_size);
872 LIBCFS_FREE(buckets, sizeof(buckets[0]) * size);
876 * Create or grow bucket memory. Return old_buckets if no allocation was
877 * needed, the newly allocated buckets if allocation was needed and
878 * successful, and NULL on error.
880 static struct cfs_hash_bucket **
881 cfs_hash_buckets_realloc(struct cfs_hash *hs, struct cfs_hash_bucket **old_bkts,
882 unsigned int old_size, unsigned int new_size)
884 struct cfs_hash_bucket **new_bkts;
887 LASSERT(old_size == 0 || old_bkts != NULL);
889 if (old_bkts != NULL && old_size == new_size)
892 LIBCFS_ALLOC(new_bkts, sizeof(new_bkts[0]) * new_size);
893 if (new_bkts == NULL)
896 if (old_bkts != NULL) {
897 memcpy(new_bkts, old_bkts,
898 min(old_size, new_size) * sizeof(*old_bkts));
901 for (i = old_size; i < new_size; i++) {
902 struct hlist_head *hhead;
903 struct cfs_hash_bd bd;
905 LIBCFS_ALLOC(new_bkts[i], cfs_hash_bkt_size(hs));
906 if (new_bkts[i] == NULL) {
907 cfs_hash_buckets_free(new_bkts, cfs_hash_bkt_size(hs),
912 new_bkts[i]->hsb_index = i;
913 new_bkts[i]->hsb_version = 1; /* shouldn't be zero */
914 new_bkts[i]->hsb_depmax = -1; /* unknown */
915 bd.bd_bucket = new_bkts[i];
916 cfs_hash_bd_for_each_hlist(hs, &bd, hhead)
917 INIT_HLIST_HEAD(hhead);
919 if (cfs_hash_with_no_lock(hs) ||
920 cfs_hash_with_no_bktlock(hs))
923 if (cfs_hash_with_rw_bktlock(hs))
924 rwlock_init(&new_bkts[i]->hsb_lock.rw);
925 else if (cfs_hash_with_spin_bktlock(hs))
926 spin_lock_init(&new_bkts[i]->hsb_lock.spin);
928 LBUG(); /* invalid use-case */
934 * Initialize new libcfs hash, where:
935 * @name - Descriptive hash name
936 * @cur_bits - Initial hash table size, in bits
937 * @max_bits - Maximum allowed hash table resize, in bits
938 * @ops - Registered hash table operations
939 * @flags - CFS_HASH_REHASH enable synamic hash resizing
940 * - CFS_HASH_SORT enable chained hash sort
942 static int cfs_hash_rehash_worker(struct cfs_workitem *wi);
944 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
945 static int cfs_hash_dep_print(struct cfs_workitem *wi)
947 struct cfs_hash *hs = container_of(wi, struct cfs_hash, hs_dep_wi);
953 spin_lock(&hs->hs_dep_lock);
954 dep = hs->hs_dep_max;
955 bkt = hs->hs_dep_bkt;
956 off = hs->hs_dep_off;
957 bits = hs->hs_dep_bits;
958 spin_unlock(&hs->hs_dep_lock);
960 LCONSOLE_WARN("#### HASH %s (bits: %d): max depth %d at bucket %d/%d\n",
961 hs->hs_name, bits, dep, bkt, off);
962 spin_lock(&hs->hs_dep_lock);
963 hs->hs_dep_bits = 0; /* mark as workitem done */
964 spin_unlock(&hs->hs_dep_lock);
968 static void cfs_hash_depth_wi_init(struct cfs_hash *hs)
970 spin_lock_init(&hs->hs_dep_lock);
971 cfs_wi_init(&hs->hs_dep_wi, hs, cfs_hash_dep_print);
974 static void cfs_hash_depth_wi_cancel(struct cfs_hash *hs)
976 if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_dep_wi))
979 spin_lock(&hs->hs_dep_lock);
980 while (hs->hs_dep_bits != 0) {
981 spin_unlock(&hs->hs_dep_lock);
983 spin_lock(&hs->hs_dep_lock);
985 spin_unlock(&hs->hs_dep_lock);
988 #else /* CFS_HASH_DEBUG_LEVEL < CFS_HASH_DEBUG_1 */
990 static inline void cfs_hash_depth_wi_init(struct cfs_hash *hs) {}
991 static inline void cfs_hash_depth_wi_cancel(struct cfs_hash *hs) {}
993 #endif /* CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1 */
996 cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits,
997 unsigned bkt_bits, unsigned extra_bytes,
998 unsigned min_theta, unsigned max_theta,
999 struct cfs_hash_ops *ops, unsigned flags)
1001 struct cfs_hash *hs;
1006 CLASSERT(CFS_HASH_THETA_BITS < 15);
1008 LASSERT(name != NULL);
1009 LASSERT(ops != NULL);
1010 LASSERT(ops->hs_key);
1011 LASSERT(ops->hs_hash);
1012 LASSERT(ops->hs_object);
1013 LASSERT(ops->hs_keycmp);
1014 LASSERT(ops->hs_get != NULL);
1015 LASSERT(ops->hs_put != NULL || ops->hs_put_locked != NULL);
1017 if ((flags & CFS_HASH_REHASH) != 0)
1018 flags |= CFS_HASH_COUNTER; /* must have counter */
1020 LASSERT(cur_bits > 0);
1021 LASSERT(cur_bits >= bkt_bits);
1022 LASSERT(max_bits >= cur_bits && max_bits < 31);
1023 LASSERT(ergo((flags & CFS_HASH_REHASH) == 0, cur_bits == max_bits));
1024 LASSERT(ergo((flags & CFS_HASH_REHASH) != 0,
1025 (flags & CFS_HASH_NO_LOCK) == 0));
1026 LASSERT(ergo((flags & CFS_HASH_REHASH_KEY) != 0,
1027 ops->hs_keycpy != NULL));
1029 len = (flags & CFS_HASH_BIGNAME) == 0 ?
1030 CFS_HASH_NAME_LEN : CFS_HASH_BIGNAME_LEN;
1031 LIBCFS_ALLOC(hs, offsetof(struct cfs_hash, hs_name[len]));
1035 strlcpy(hs->hs_name, name, len);
1036 hs->hs_flags = flags;
1038 atomic_set(&hs->hs_refcount, 1);
1039 atomic_set(&hs->hs_count, 0);
1041 cfs_hash_lock_setup(hs);
1042 cfs_hash_hlist_setup(hs);
1044 hs->hs_cur_bits = (__u8)cur_bits;
1045 hs->hs_min_bits = (__u8)cur_bits;
1046 hs->hs_max_bits = (__u8)max_bits;
1047 hs->hs_bkt_bits = (__u8)bkt_bits;
1050 hs->hs_extra_bytes = extra_bytes;
1051 hs->hs_rehash_bits = 0;
1052 cfs_wi_init(&hs->hs_rehash_wi, hs, cfs_hash_rehash_worker);
1053 cfs_hash_depth_wi_init(hs);
1055 if (cfs_hash_with_rehash(hs))
1056 __cfs_hash_set_theta(hs, min_theta, max_theta);
1058 hs->hs_buckets = cfs_hash_buckets_realloc(hs, NULL, 0,
1060 if (hs->hs_buckets != NULL)
1063 LIBCFS_FREE(hs, offsetof(struct cfs_hash, hs_name[len]));
1066 EXPORT_SYMBOL(cfs_hash_create);
1069 * Cleanup libcfs hash @hs.
1072 cfs_hash_destroy(struct cfs_hash *hs)
1074 struct hlist_node *hnode;
1075 struct hlist_node *pos;
1076 struct cfs_hash_bd bd;
1080 LASSERT(hs != NULL);
1081 LASSERT(!cfs_hash_is_exiting(hs) &&
1082 !cfs_hash_is_iterating(hs));
1085 * prohibit further rehashes, don't need any lock because
1086 * I'm the only (last) one can change it.
1089 if (cfs_hash_with_rehash(hs))
1090 cfs_hash_rehash_cancel(hs);
1092 cfs_hash_depth_wi_cancel(hs);
1093 /* rehash should be done/canceled */
1094 LASSERT(hs->hs_buckets != NULL &&
1095 hs->hs_rehash_buckets == NULL);
1097 cfs_hash_for_each_bucket(hs, &bd, i) {
1098 struct hlist_head *hhead;
1100 LASSERT(bd.bd_bucket != NULL);
1101 /* no need to take this lock, just for consistent code */
1102 cfs_hash_bd_lock(hs, &bd, 1);
1104 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1105 hlist_for_each_safe(hnode, pos, hhead) {
1106 LASSERTF(!cfs_hash_with_assert_empty(hs),
1107 "hash %s bucket %u(%u) is not "
1108 " empty: %u items left\n",
1109 hs->hs_name, bd.bd_bucket->hsb_index,
1110 bd.bd_offset, bd.bd_bucket->hsb_count);
1111 /* can't assert key valicate, because we
1112 * can interrupt rehash */
1113 cfs_hash_bd_del_locked(hs, &bd, hnode);
1114 cfs_hash_exit(hs, hnode);
1117 LASSERT(bd.bd_bucket->hsb_count == 0);
1118 cfs_hash_bd_unlock(hs, &bd, 1);
1122 LASSERT(atomic_read(&hs->hs_count) == 0);
1124 cfs_hash_buckets_free(hs->hs_buckets, cfs_hash_bkt_size(hs),
1125 0, CFS_HASH_NBKT(hs));
1126 i = cfs_hash_with_bigname(hs) ?
1127 CFS_HASH_BIGNAME_LEN : CFS_HASH_NAME_LEN;
1128 LIBCFS_FREE(hs, offsetof(struct cfs_hash, hs_name[i]));
1133 struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs)
1135 if (atomic_inc_not_zero(&hs->hs_refcount))
1139 EXPORT_SYMBOL(cfs_hash_getref);
1141 void cfs_hash_putref(struct cfs_hash *hs)
1143 if (atomic_dec_and_test(&hs->hs_refcount))
1144 cfs_hash_destroy(hs);
1146 EXPORT_SYMBOL(cfs_hash_putref);
1149 cfs_hash_rehash_bits(struct cfs_hash *hs)
1151 if (cfs_hash_with_no_lock(hs) ||
1152 !cfs_hash_with_rehash(hs))
1155 if (unlikely(cfs_hash_is_exiting(hs)))
1158 if (unlikely(cfs_hash_is_rehashing(hs)))
1161 if (unlikely(cfs_hash_is_iterating(hs)))
1164 /* XXX: need to handle case with max_theta != 2.0
1165 * and the case with min_theta != 0.5 */
1166 if ((hs->hs_cur_bits < hs->hs_max_bits) &&
1167 (__cfs_hash_theta(hs) > hs->hs_max_theta))
1168 return hs->hs_cur_bits + 1;
1170 if (!cfs_hash_with_shrink(hs))
1173 if ((hs->hs_cur_bits > hs->hs_min_bits) &&
1174 (__cfs_hash_theta(hs) < hs->hs_min_theta))
1175 return hs->hs_cur_bits - 1;
1181 * don't allow inline rehash if:
1182 * - user wants non-blocking change (add/del) on hash table
1183 * - too many elements
1186 cfs_hash_rehash_inline(struct cfs_hash *hs)
1188 return !cfs_hash_with_nblk_change(hs) &&
1189 atomic_read(&hs->hs_count) < CFS_HASH_LOOP_HOG;
1193 * Add item @hnode to libcfs hash @hs using @key. The registered
1194 * ops->hs_get function will be called when the item is added.
1197 cfs_hash_add(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
1199 struct cfs_hash_bd bd;
1202 LASSERT(hlist_unhashed(hnode));
1204 cfs_hash_lock(hs, 0);
1205 cfs_hash_bd_get_and_lock(hs, key, &bd, 1);
1207 cfs_hash_key_validate(hs, key, hnode);
1208 cfs_hash_bd_add_locked(hs, &bd, hnode);
1210 cfs_hash_bd_unlock(hs, &bd, 1);
1212 bits = cfs_hash_rehash_bits(hs);
1213 cfs_hash_unlock(hs, 0);
1215 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1217 EXPORT_SYMBOL(cfs_hash_add);
1219 static struct hlist_node *
1220 cfs_hash_find_or_add(struct cfs_hash *hs, const void *key,
1221 struct hlist_node *hnode, int noref)
1223 struct hlist_node *ehnode;
1224 struct cfs_hash_bd bds[2];
1227 LASSERTF(hlist_unhashed(hnode), "hnode = %p\n", hnode);
1229 cfs_hash_lock(hs, 0);
1230 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
1232 cfs_hash_key_validate(hs, key, hnode);
1233 ehnode = cfs_hash_dual_bd_findadd_locked(hs, bds, key,
1235 cfs_hash_dual_bd_unlock(hs, bds, 1);
1237 if (ehnode == hnode) /* new item added */
1238 bits = cfs_hash_rehash_bits(hs);
1239 cfs_hash_unlock(hs, 0);
1241 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1247 * Add item @hnode to libcfs hash @hs using @key. The registered
1248 * ops->hs_get function will be called if the item was added.
1249 * Returns 0 on success or -EALREADY on key collisions.
1252 cfs_hash_add_unique(struct cfs_hash *hs, const void *key,
1253 struct hlist_node *hnode)
1255 return cfs_hash_find_or_add(hs, key, hnode, 1) != hnode ?
1258 EXPORT_SYMBOL(cfs_hash_add_unique);
1261 * Add item @hnode to libcfs hash @hs using @key. If this @key
1262 * already exists in the hash then ops->hs_get will be called on the
1263 * conflicting entry and that entry will be returned to the caller.
1264 * Otherwise ops->hs_get is called on the item which was added.
1267 cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
1268 struct hlist_node *hnode)
1270 hnode = cfs_hash_find_or_add(hs, key, hnode, 0);
1272 return cfs_hash_object(hs, hnode);
1274 EXPORT_SYMBOL(cfs_hash_findadd_unique);
1277 * Delete item @hnode from the libcfs hash @hs using @key. The @key
1278 * is required to ensure the correct hash bucket is locked since there
1279 * is no direct linkage from the item to the bucket. The object
1280 * removed from the hash will be returned and obs->hs_put is called
1281 * on the removed object.
1284 cfs_hash_del(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
1288 struct cfs_hash_bd bds[2];
1290 cfs_hash_lock(hs, 0);
1291 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
1293 /* NB: do nothing if @hnode is not in hash table */
1294 if (hnode == NULL || !hlist_unhashed(hnode)) {
1295 if (bds[1].bd_bucket == NULL && hnode != NULL) {
1296 cfs_hash_bd_del_locked(hs, &bds[0], hnode);
1298 hnode = cfs_hash_dual_bd_finddel_locked(hs, bds,
1303 if (hnode != NULL) {
1304 obj = cfs_hash_object(hs, hnode);
1305 bits = cfs_hash_rehash_bits(hs);
1308 cfs_hash_dual_bd_unlock(hs, bds, 1);
1309 cfs_hash_unlock(hs, 0);
1311 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1315 EXPORT_SYMBOL(cfs_hash_del);
1318 * Delete item given @key in libcfs hash @hs. The first @key found in
1319 * the hash will be removed, if the key exists multiple times in the hash
1320 * @hs this function must be called once per key. The removed object
1321 * will be returned and ops->hs_put is called on the removed object.
1324 cfs_hash_del_key(struct cfs_hash *hs, const void *key)
1326 return cfs_hash_del(hs, key, NULL);
1328 EXPORT_SYMBOL(cfs_hash_del_key);
1331 * Lookup an item using @key in the libcfs hash @hs and return it.
1332 * If the @key is found in the hash hs->hs_get() is called and the
1333 * matching objects is returned. It is the callers responsibility
1334 * to call the counterpart ops->hs_put using the cfs_hash_put() macro
1335 * when when finished with the object. If the @key was not found
1336 * in the hash @hs NULL is returned.
1339 cfs_hash_lookup(struct cfs_hash *hs, const void *key)
1342 struct hlist_node *hnode;
1343 struct cfs_hash_bd bds[2];
1345 cfs_hash_lock(hs, 0);
1346 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
1348 hnode = cfs_hash_dual_bd_lookup_locked(hs, bds, key);
1350 obj = cfs_hash_object(hs, hnode);
1352 cfs_hash_dual_bd_unlock(hs, bds, 0);
1353 cfs_hash_unlock(hs, 0);
1357 EXPORT_SYMBOL(cfs_hash_lookup);
1360 cfs_hash_for_each_enter(struct cfs_hash *hs)
1362 LASSERT(!cfs_hash_is_exiting(hs));
1364 if (!cfs_hash_with_rehash(hs))
1367 * NB: it's race on cfs_has_t::hs_iterating, but doesn't matter
1368 * because it's just an unreliable signal to rehash-thread,
1369 * rehash-thread will try to finish rehash ASAP when seeing this.
1371 hs->hs_iterating = 1;
1373 cfs_hash_lock(hs, 1);
1376 /* NB: iteration is mostly called by service thread,
1377 * we tend to cancel pending rehash-request, instead of
1378 * blocking service thread, we will relaunch rehash request
1379 * after iteration */
1380 if (cfs_hash_is_rehashing(hs))
1381 cfs_hash_rehash_cancel_locked(hs);
1382 cfs_hash_unlock(hs, 1);
1386 cfs_hash_for_each_exit(struct cfs_hash *hs)
1391 if (!cfs_hash_with_rehash(hs))
1393 cfs_hash_lock(hs, 1);
1394 remained = --hs->hs_iterators;
1395 bits = cfs_hash_rehash_bits(hs);
1396 cfs_hash_unlock(hs, 1);
1397 /* NB: it's race on cfs_has_t::hs_iterating, see above */
1399 hs->hs_iterating = 0;
1401 cfs_hash_rehash(hs, atomic_read(&hs->hs_count) <
1407 * For each item in the libcfs hash @hs call the passed callback @func
1408 * and pass to it as an argument each hash item and the private @data.
1410 * a) the function may sleep!
1411 * b) during the callback:
1412 * . the bucket lock is held so the callback must never sleep.
1413 * . if @removal_safe is true, use can remove current item by
1414 * cfs_hash_bd_del_locked
1417 cfs_hash_for_each_tight(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
1418 void *data, int remove_safe)
1420 struct hlist_node *hnode;
1421 struct hlist_node *pos;
1422 struct cfs_hash_bd bd;
1424 int excl = !!remove_safe;
1429 cfs_hash_for_each_enter(hs);
1431 cfs_hash_lock(hs, 0);
1432 LASSERT(!cfs_hash_is_rehashing(hs));
1434 cfs_hash_for_each_bucket(hs, &bd, i) {
1435 struct hlist_head *hhead;
1437 cfs_hash_bd_lock(hs, &bd, excl);
1438 if (func == NULL) { /* only glimpse size */
1439 count += bd.bd_bucket->hsb_count;
1440 cfs_hash_bd_unlock(hs, &bd, excl);
1444 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1445 hlist_for_each_safe(hnode, pos, hhead) {
1446 cfs_hash_bucket_validate(hs, &bd, hnode);
1449 if (func(hs, &bd, hnode, data)) {
1450 cfs_hash_bd_unlock(hs, &bd, excl);
1455 cfs_hash_bd_unlock(hs, &bd, excl);
1456 if (loop < CFS_HASH_LOOP_HOG)
1459 cfs_hash_unlock(hs, 0);
1461 cfs_hash_lock(hs, 0);
1464 cfs_hash_unlock(hs, 0);
1466 cfs_hash_for_each_exit(hs);
1470 struct cfs_hash_cond_arg {
1471 cfs_hash_cond_opt_cb_t func;
1476 cfs_hash_cond_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
1477 struct hlist_node *hnode, void *data)
1479 struct cfs_hash_cond_arg *cond = data;
1481 if (cond->func(cfs_hash_object(hs, hnode), cond->arg))
1482 cfs_hash_bd_del_locked(hs, bd, hnode);
1487 * Delete item from the libcfs hash @hs when @func return true.
1488 * The write lock being hold during loop for each bucket to avoid
1489 * any object be reference.
1492 cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t func, void *data)
1494 struct cfs_hash_cond_arg arg = {
1499 cfs_hash_for_each_tight(hs, cfs_hash_cond_del_locked, &arg, 1);
1501 EXPORT_SYMBOL(cfs_hash_cond_del);
1504 cfs_hash_for_each(struct cfs_hash *hs,
1505 cfs_hash_for_each_cb_t func, void *data)
1507 cfs_hash_for_each_tight(hs, func, data, 0);
1509 EXPORT_SYMBOL(cfs_hash_for_each);
1512 cfs_hash_for_each_safe(struct cfs_hash *hs,
1513 cfs_hash_for_each_cb_t func, void *data)
1515 cfs_hash_for_each_tight(hs, func, data, 1);
1517 EXPORT_SYMBOL(cfs_hash_for_each_safe);
1520 cfs_hash_peek(struct cfs_hash *hs, struct cfs_hash_bd *bd,
1521 struct hlist_node *hnode, void *data)
1524 return 1; /* return 1 to break the loop */
1528 cfs_hash_is_empty(struct cfs_hash *hs)
1532 cfs_hash_for_each_tight(hs, cfs_hash_peek, &empty, 0);
1535 EXPORT_SYMBOL(cfs_hash_is_empty);
1538 cfs_hash_size_get(struct cfs_hash *hs)
1540 return cfs_hash_with_counter(hs) ?
1541 atomic_read(&hs->hs_count) :
1542 cfs_hash_for_each_tight(hs, NULL, NULL, 0);
1544 EXPORT_SYMBOL(cfs_hash_size_get);
1547 * cfs_hash_for_each_relax:
1548 * Iterate the hash table and call @func on each item without
1549 * any lock. This function can't guarantee to finish iteration
1550 * if these features are enabled:
1552 * a. if rehash_key is enabled, an item can be moved from
1553 * one bucket to another bucket
1554 * b. user can remove non-zero-ref item from hash-table,
1555 * so the item can be removed from hash-table, even worse,
1556 * it's possible that user changed key and insert to another
1558 * there's no way for us to finish iteration correctly on previous
1559 * two cases, so iteration has to be stopped on change.
1562 cfs_hash_for_each_relax(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
1563 void *data, int start)
1565 struct hlist_node *hnode;
1566 struct hlist_node *next = NULL;
1567 struct cfs_hash_bd bd;
1576 stop_on_change = cfs_hash_with_rehash_key(hs) ||
1577 !cfs_hash_with_no_itemref(hs);
1578 has_put_locked = hs->hs_ops->hs_put_locked != NULL;
1579 cfs_hash_lock(hs, 0);
1581 LASSERT(!cfs_hash_is_rehashing(hs));
1583 cfs_hash_for_each_bucket(hs, &bd, i) {
1584 struct hlist_head *hhead;
1588 else if (end > 0 && i >= end)
1591 cfs_hash_bd_lock(hs, &bd, 0);
1592 version = cfs_hash_bd_version_get(&bd);
1594 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1595 hnode = hhead->first;
1598 cfs_hash_get(hs, hnode);
1599 for (; hnode != NULL; hnode = next) {
1600 cfs_hash_bucket_validate(hs, &bd, hnode);
1603 cfs_hash_get(hs, next);
1604 cfs_hash_bd_unlock(hs, &bd, 0);
1605 cfs_hash_unlock(hs, 0);
1607 rc = func(hs, &bd, hnode, data);
1608 if (stop_on_change || !has_put_locked)
1609 cfs_hash_put(hs, hnode);
1614 cfs_hash_lock(hs, 0);
1615 cfs_hash_bd_lock(hs, &bd, 0);
1616 if (stop_on_change) {
1618 cfs_hash_bd_version_get(&bd))
1620 } else if (has_put_locked) {
1621 cfs_hash_put_locked(hs, hnode);
1623 if (rc) /* callback wants to break iteration */
1627 if (has_put_locked) {
1628 cfs_hash_put_locked(hs, next);
1632 } else if (rc != 0) {
1636 cfs_hash_bd_unlock(hs, &bd, 0);
1637 if (next != NULL && !has_put_locked) {
1638 cfs_hash_put(hs, next);
1641 if (rc) /* callback wants to break iteration */
1645 if (start > 0 && rc == 0) {
1651 cfs_hash_unlock(hs, 0);
1656 cfs_hash_for_each_nolock(struct cfs_hash *hs,
1657 cfs_hash_for_each_cb_t func, void *data, int start)
1661 if (cfs_hash_with_no_lock(hs) ||
1662 cfs_hash_with_rehash_key(hs) ||
1663 !cfs_hash_with_no_itemref(hs))
1664 RETURN(-EOPNOTSUPP);
1666 if (hs->hs_ops->hs_get == NULL ||
1667 (hs->hs_ops->hs_put == NULL &&
1668 hs->hs_ops->hs_put_locked == NULL))
1669 RETURN(-EOPNOTSUPP);
1671 cfs_hash_for_each_enter(hs);
1672 cfs_hash_for_each_relax(hs, func, data, start);
1673 cfs_hash_for_each_exit(hs);
1677 EXPORT_SYMBOL(cfs_hash_for_each_nolock);
1680 * For each hash bucket in the libcfs hash @hs call the passed callback
1681 * @func until all the hash buckets are empty. The passed callback @func
1682 * or the previously registered callback hs->hs_put must remove the item
1683 * from the hash. You may either use the cfs_hash_del() or hlist_del()
1684 * functions. No rwlocks will be held during the callback @func it is
1685 * safe to sleep if needed. This function will not terminate until the
1686 * hash is empty. Note it is still possible to concurrently add new
1687 * items in to the hash. It is the callers responsibility to ensure
1688 * the required locking is in place to prevent concurrent insertions.
1691 cfs_hash_for_each_empty(struct cfs_hash *hs,
1692 cfs_hash_for_each_cb_t func, void *data)
1697 if (cfs_hash_with_no_lock(hs))
1700 if (hs->hs_ops->hs_get == NULL ||
1701 (hs->hs_ops->hs_put == NULL &&
1702 hs->hs_ops->hs_put_locked == NULL))
1705 cfs_hash_for_each_enter(hs);
1706 while (cfs_hash_for_each_relax(hs, func, data, 0)) {
1707 CDEBUG(D_INFO, "Try to empty hash: %s, loop: %u\n",
1710 cfs_hash_for_each_exit(hs);
1713 EXPORT_SYMBOL(cfs_hash_for_each_empty);
1716 cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned hindex,
1717 cfs_hash_for_each_cb_t func, void *data)
1719 struct hlist_head *hhead;
1720 struct hlist_node *hnode;
1721 struct cfs_hash_bd bd;
1723 cfs_hash_for_each_enter(hs);
1724 cfs_hash_lock(hs, 0);
1725 if (hindex >= CFS_HASH_NHLIST(hs))
1728 cfs_hash_bd_index_set(hs, hindex, &bd);
1730 cfs_hash_bd_lock(hs, &bd, 0);
1731 hhead = cfs_hash_bd_hhead(hs, &bd);
1732 hlist_for_each(hnode, hhead) {
1733 if (func(hs, &bd, hnode, data))
1736 cfs_hash_bd_unlock(hs, &bd, 0);
1738 cfs_hash_unlock(hs, 0);
1739 cfs_hash_for_each_exit(hs);
1742 EXPORT_SYMBOL(cfs_hash_hlist_for_each);
1745 * For each item in the libcfs hash @hs which matches the @key call
1746 * the passed callback @func and pass to it as an argument each hash
1747 * item and the private @data. During the callback the bucket lock
1748 * is held so the callback must never sleep.
1751 cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
1752 cfs_hash_for_each_cb_t func, void *data)
1754 struct hlist_node *hnode;
1755 struct cfs_hash_bd bds[2];
1758 cfs_hash_lock(hs, 0);
1760 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
1762 cfs_hash_for_each_bd(bds, 2, i) {
1763 struct hlist_head *hlist = cfs_hash_bd_hhead(hs, &bds[i]);
1765 hlist_for_each(hnode, hlist) {
1766 cfs_hash_bucket_validate(hs, &bds[i], hnode);
1768 if (cfs_hash_keycmp(hs, key, hnode)) {
1769 if (func(hs, &bds[i], hnode, data))
1775 cfs_hash_dual_bd_unlock(hs, bds, 0);
1776 cfs_hash_unlock(hs, 0);
1778 EXPORT_SYMBOL(cfs_hash_for_each_key);
1781 * Rehash the libcfs hash @hs to the given @bits. This can be used
1782 * to grow the hash size when excessive chaining is detected, or to
1783 * shrink the hash when it is larger than needed. When the CFS_HASH_REHASH
1784 * flag is set in @hs the libcfs hash may be dynamically rehashed
1785 * during addition or removal if the hash's theta value exceeds
1786 * either the hs->hs_min_theta or hs->max_theta values. By default
1787 * these values are tuned to keep the chained hash depth small, and
1788 * this approach assumes a reasonably uniform hashing function. The
1789 * theta thresholds for @hs are tunable via cfs_hash_set_theta().
1792 cfs_hash_rehash_cancel_locked(struct cfs_hash *hs)
1796 /* need hold cfs_hash_lock(hs, 1) */
1797 LASSERT(cfs_hash_with_rehash(hs) &&
1798 !cfs_hash_with_no_lock(hs));
1800 if (!cfs_hash_is_rehashing(hs))
1803 if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_rehash_wi)) {
1804 hs->hs_rehash_bits = 0;
1808 for (i = 2; cfs_hash_is_rehashing(hs); i++) {
1809 cfs_hash_unlock(hs, 1);
1810 /* raise console warning while waiting too long */
1811 CDEBUG(IS_PO2(i >> 3) ? D_WARNING : D_INFO,
1812 "hash %s is still rehashing, rescheded %d\n",
1813 hs->hs_name, i - 1);
1815 cfs_hash_lock(hs, 1);
1820 cfs_hash_rehash_cancel(struct cfs_hash *hs)
1822 cfs_hash_lock(hs, 1);
1823 cfs_hash_rehash_cancel_locked(hs);
1824 cfs_hash_unlock(hs, 1);
1828 cfs_hash_rehash(struct cfs_hash *hs, int do_rehash)
1832 LASSERT(cfs_hash_with_rehash(hs) && !cfs_hash_with_no_lock(hs));
1834 cfs_hash_lock(hs, 1);
1836 rc = cfs_hash_rehash_bits(hs);
1838 cfs_hash_unlock(hs, 1);
1842 hs->hs_rehash_bits = rc;
1844 /* launch and return */
1845 cfs_wi_schedule(cfs_sched_rehash, &hs->hs_rehash_wi);
1846 cfs_hash_unlock(hs, 1);
1850 /* rehash right now */
1851 cfs_hash_unlock(hs, 1);
1853 return cfs_hash_rehash_worker(&hs->hs_rehash_wi);
1857 cfs_hash_rehash_bd(struct cfs_hash *hs, struct cfs_hash_bd *old)
1859 struct cfs_hash_bd new;
1860 struct hlist_head *hhead;
1861 struct hlist_node *hnode;
1862 struct hlist_node *pos;
1866 /* hold cfs_hash_lock(hs, 1), so don't need any bucket lock */
1867 cfs_hash_bd_for_each_hlist(hs, old, hhead) {
1868 hlist_for_each_safe(hnode, pos, hhead) {
1869 key = cfs_hash_key(hs, hnode);
1870 LASSERT(key != NULL);
1871 /* Validate hnode is in the correct bucket. */
1872 cfs_hash_bucket_validate(hs, old, hnode);
1874 * Delete from old hash bucket; move to new bucket.
1875 * ops->hs_key must be defined.
1877 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
1878 hs->hs_rehash_bits, key, &new);
1879 cfs_hash_bd_move_locked(hs, old, &new, hnode);
1887 cfs_hash_rehash_worker(struct cfs_workitem *wi)
1889 struct cfs_hash *hs =
1890 container_of(wi, struct cfs_hash, hs_rehash_wi);
1891 struct cfs_hash_bucket **bkts;
1892 struct cfs_hash_bd bd;
1893 unsigned int old_size;
1894 unsigned int new_size;
1900 LASSERT(hs != NULL && cfs_hash_with_rehash(hs));
1902 cfs_hash_lock(hs, 0);
1903 LASSERT(cfs_hash_is_rehashing(hs));
1905 old_size = CFS_HASH_NBKT(hs);
1906 new_size = CFS_HASH_RH_NBKT(hs);
1908 cfs_hash_unlock(hs, 0);
1911 * don't need hs::hs_rwlock for hs::hs_buckets,
1912 * because nobody can change bkt-table except me.
1914 bkts = cfs_hash_buckets_realloc(hs, hs->hs_buckets,
1915 old_size, new_size);
1916 cfs_hash_lock(hs, 1);
1922 if (bkts == hs->hs_buckets) {
1923 bkts = NULL; /* do nothing */
1927 rc = __cfs_hash_theta(hs);
1928 if ((rc >= hs->hs_min_theta) && (rc <= hs->hs_max_theta)) {
1929 /* free the new allocated bkt-table */
1930 old_size = new_size;
1931 new_size = CFS_HASH_NBKT(hs);
1936 LASSERT(hs->hs_rehash_buckets == NULL);
1937 hs->hs_rehash_buckets = bkts;
1940 cfs_hash_for_each_bucket(hs, &bd, i) {
1941 if (cfs_hash_is_exiting(hs)) {
1943 /* someone wants to destroy the hash, abort now */
1944 if (old_size < new_size) /* OK to free old bkt-table */
1946 /* it's shrinking, need free new bkt-table */
1947 hs->hs_rehash_buckets = NULL;
1948 old_size = new_size;
1949 new_size = CFS_HASH_NBKT(hs);
1953 count += cfs_hash_rehash_bd(hs, &bd);
1954 if (count < CFS_HASH_LOOP_HOG ||
1955 cfs_hash_is_iterating(hs)) { /* need to finish ASAP */
1960 cfs_hash_unlock(hs, 1);
1962 cfs_hash_lock(hs, 1);
1965 hs->hs_rehash_count++;
1967 bkts = hs->hs_buckets;
1968 hs->hs_buckets = hs->hs_rehash_buckets;
1969 hs->hs_rehash_buckets = NULL;
1971 hs->hs_cur_bits = hs->hs_rehash_bits;
1973 hs->hs_rehash_bits = 0;
1974 if (rc == -ESRCH) /* never be scheduled again */
1975 cfs_wi_exit(cfs_sched_rehash, wi);
1976 bsize = cfs_hash_bkt_size(hs);
1977 cfs_hash_unlock(hs, 1);
1978 /* can't refer to @hs anymore because it could be destroyed */
1980 cfs_hash_buckets_free(bkts, bsize, new_size, old_size);
1982 CDEBUG(D_INFO, "early quit of rehashing: %d\n", rc);
1983 /* return 1 only if cfs_wi_exit is called */
1984 return rc == -ESRCH;
1988 * Rehash the object referenced by @hnode in the libcfs hash @hs. The
1989 * @old_key must be provided to locate the objects previous location
1990 * in the hash, and the @new_key will be used to reinsert the object.
1991 * Use this function instead of a cfs_hash_add() + cfs_hash_del()
1992 * combo when it is critical that there is no window in time where the
1993 * object is missing from the hash. When an object is being rehashed
1994 * the registered cfs_hash_get() and cfs_hash_put() functions will
1997 void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
1998 void *new_key, struct hlist_node *hnode)
2000 struct cfs_hash_bd bds[3];
2001 struct cfs_hash_bd old_bds[2];
2002 struct cfs_hash_bd new_bd;
2004 LASSERT(!hlist_unhashed(hnode));
2006 cfs_hash_lock(hs, 0);
2008 cfs_hash_dual_bd_get(hs, old_key, old_bds);
2009 cfs_hash_bd_get(hs, new_key, &new_bd);
2011 bds[0] = old_bds[0];
2012 bds[1] = old_bds[1];
2015 /* NB: bds[0] and bds[1] are ordered already */
2016 cfs_hash_bd_order(&bds[1], &bds[2]);
2017 cfs_hash_bd_order(&bds[0], &bds[1]);
2019 cfs_hash_multi_bd_lock(hs, bds, 3, 1);
2020 if (likely(old_bds[1].bd_bucket == NULL)) {
2021 cfs_hash_bd_move_locked(hs, &old_bds[0], &new_bd, hnode);
2023 cfs_hash_dual_bd_finddel_locked(hs, old_bds, old_key, hnode);
2024 cfs_hash_bd_add_locked(hs, &new_bd, hnode);
2026 /* overwrite key inside locks, otherwise may screw up with
2027 * other operations, i.e: rehash */
2028 cfs_hash_keycpy(hs, hnode, new_key);
2030 cfs_hash_multi_bd_unlock(hs, bds, 3, 1);
2031 cfs_hash_unlock(hs, 0);
2033 EXPORT_SYMBOL(cfs_hash_rehash_key);
2035 void cfs_hash_debug_header(struct seq_file *m)
2037 seq_printf(m, "%-*s cur min max theta t-min t-max flags rehash count maxdep maxdepb distribution\n",
2038 CFS_HASH_BIGNAME_LEN, "name");
2040 EXPORT_SYMBOL(cfs_hash_debug_header);
2042 static struct cfs_hash_bucket **
2043 cfs_hash_full_bkts(struct cfs_hash *hs)
2045 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
2046 if (hs->hs_rehash_buckets == NULL)
2047 return hs->hs_buckets;
2049 LASSERT(hs->hs_rehash_bits != 0);
2050 return hs->hs_rehash_bits > hs->hs_cur_bits ?
2051 hs->hs_rehash_buckets : hs->hs_buckets;
2055 cfs_hash_full_nbkt(struct cfs_hash *hs)
2057 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
2058 if (hs->hs_rehash_buckets == NULL)
2059 return CFS_HASH_NBKT(hs);
2061 LASSERT(hs->hs_rehash_bits != 0);
2062 return hs->hs_rehash_bits > hs->hs_cur_bits ?
2063 CFS_HASH_RH_NBKT(hs) : CFS_HASH_NBKT(hs);
2066 void cfs_hash_debug_str(struct cfs_hash *hs, struct seq_file *m)
2068 int dist[8] = { 0, };
2075 cfs_hash_lock(hs, 0);
2076 theta = __cfs_hash_theta(hs);
2078 seq_printf(m, "%-*s %5d %5d %5d %d.%03d %d.%03d %d.%03d 0x%02x %6d ",
2079 CFS_HASH_BIGNAME_LEN, hs->hs_name,
2080 1 << hs->hs_cur_bits, 1 << hs->hs_min_bits,
2081 1 << hs->hs_max_bits,
2082 __cfs_hash_theta_int(theta), __cfs_hash_theta_frac(theta),
2083 __cfs_hash_theta_int(hs->hs_min_theta),
2084 __cfs_hash_theta_frac(hs->hs_min_theta),
2085 __cfs_hash_theta_int(hs->hs_max_theta),
2086 __cfs_hash_theta_frac(hs->hs_max_theta),
2087 hs->hs_flags, hs->hs_rehash_count);
2090 * The distribution is a summary of the chained hash depth in
2091 * each of the libcfs hash buckets. Each buckets hsb_count is
2092 * divided by the hash theta value and used to generate a
2093 * histogram of the hash distribution. A uniform hash will
2094 * result in all hash buckets being close to the average thus
2095 * only the first few entries in the histogram will be non-zero.
2096 * If you hash function results in a non-uniform hash the will
2097 * be observable by outlier bucks in the distribution histogram.
2099 * Uniform hash distribution: 128/128/0/0/0/0/0/0
2100 * Non-Uniform hash distribution: 128/125/0/0/0/0/2/1
2102 for (i = 0; i < cfs_hash_full_nbkt(hs); i++) {
2103 struct cfs_hash_bd bd;
2105 bd.bd_bucket = cfs_hash_full_bkts(hs)[i];
2106 cfs_hash_bd_lock(hs, &bd, 0);
2107 if (maxdep < bd.bd_bucket->hsb_depmax) {
2108 maxdep = bd.bd_bucket->hsb_depmax;
2109 maxdepb = ffz(~maxdep);
2111 total += bd.bd_bucket->hsb_count;
2112 dist[min(fls(bd.bd_bucket->hsb_count / max(theta, 1)), 7)]++;
2113 cfs_hash_bd_unlock(hs, &bd, 0);
2116 seq_printf(m, "%7d %7d %7d ", total, maxdep, maxdepb);
2117 for (i = 0; i < 8; i++)
2118 seq_printf(m, "%d%c", dist[i], (i == 7) ? '\n' : '/');
2120 cfs_hash_unlock(hs, 0);
2122 EXPORT_SYMBOL(cfs_hash_debug_str);