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, 2014, 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(instead 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 specify bucket size
59 * by bkt_bits of cfs_hash_create(), all hlist_heads in a bucket share
60 * one lock for reducing memory overhead.
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.
109 #include <linux/seq_file.h>
111 #include <libcfs/libcfs.h>
113 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
114 static unsigned int warn_on_depth = 8;
115 module_param(warn_on_depth, uint, 0644);
116 MODULE_PARM_DESC(warn_on_depth, "warning when hash depth is high.");
119 struct cfs_wi_sched *cfs_sched_rehash;
122 cfs_hash_nl_lock(union cfs_hash_lock *lock, int exclusive) {}
125 cfs_hash_nl_unlock(union cfs_hash_lock *lock, int exclusive) {}
128 cfs_hash_spin_lock(union cfs_hash_lock *lock, int exclusive)
129 __acquires(&lock->spin)
131 spin_lock(&lock->spin);
135 cfs_hash_spin_unlock(union cfs_hash_lock *lock, int exclusive)
136 __releases(&lock->spin)
138 spin_unlock(&lock->spin);
142 cfs_hash_rw_lock(union cfs_hash_lock *lock, int exclusive)
143 __acquires(&lock->rw)
146 read_lock(&lock->rw);
148 write_lock(&lock->rw);
152 cfs_hash_rw_unlock(union cfs_hash_lock *lock, int exclusive)
153 __releases(&lock->rw)
156 read_unlock(&lock->rw);
158 write_unlock(&lock->rw);
162 static struct cfs_hash_lock_ops cfs_hash_nl_lops = {
163 .hs_lock = cfs_hash_nl_lock,
164 .hs_unlock = cfs_hash_nl_unlock,
165 .hs_bkt_lock = cfs_hash_nl_lock,
166 .hs_bkt_unlock = cfs_hash_nl_unlock,
169 /** no bucket lock, one spinlock to protect everything */
170 static struct cfs_hash_lock_ops cfs_hash_nbl_lops = {
171 .hs_lock = cfs_hash_spin_lock,
172 .hs_unlock = cfs_hash_spin_unlock,
173 .hs_bkt_lock = cfs_hash_nl_lock,
174 .hs_bkt_unlock = cfs_hash_nl_unlock,
177 /** spin bucket lock, rehash is enabled */
178 static struct cfs_hash_lock_ops cfs_hash_bkt_spin_lops = {
179 .hs_lock = cfs_hash_rw_lock,
180 .hs_unlock = cfs_hash_rw_unlock,
181 .hs_bkt_lock = cfs_hash_spin_lock,
182 .hs_bkt_unlock = cfs_hash_spin_unlock,
185 /** rw bucket lock, rehash is enabled */
186 static struct cfs_hash_lock_ops cfs_hash_bkt_rw_lops = {
187 .hs_lock = cfs_hash_rw_lock,
188 .hs_unlock = cfs_hash_rw_unlock,
189 .hs_bkt_lock = cfs_hash_rw_lock,
190 .hs_bkt_unlock = cfs_hash_rw_unlock,
193 /** spin bucket lock, rehash is disabled */
194 static struct cfs_hash_lock_ops cfs_hash_nr_bkt_spin_lops = {
195 .hs_lock = cfs_hash_nl_lock,
196 .hs_unlock = cfs_hash_nl_unlock,
197 .hs_bkt_lock = cfs_hash_spin_lock,
198 .hs_bkt_unlock = cfs_hash_spin_unlock,
201 /** rw bucket lock, rehash is disabled */
202 static struct cfs_hash_lock_ops cfs_hash_nr_bkt_rw_lops = {
203 .hs_lock = cfs_hash_nl_lock,
204 .hs_unlock = cfs_hash_nl_unlock,
205 .hs_bkt_lock = cfs_hash_rw_lock,
206 .hs_bkt_unlock = cfs_hash_rw_unlock,
210 cfs_hash_lock_setup(struct cfs_hash *hs)
212 if (cfs_hash_with_no_lock(hs)) {
213 hs->hs_lops = &cfs_hash_nl_lops;
215 } else if (cfs_hash_with_no_bktlock(hs)) {
216 hs->hs_lops = &cfs_hash_nbl_lops;
217 spin_lock_init(&hs->hs_lock.spin);
219 } else if (cfs_hash_with_rehash(hs)) {
220 rwlock_init(&hs->hs_lock.rw);
222 if (cfs_hash_with_rw_bktlock(hs))
223 hs->hs_lops = &cfs_hash_bkt_rw_lops;
224 else if (cfs_hash_with_spin_bktlock(hs))
225 hs->hs_lops = &cfs_hash_bkt_spin_lops;
229 if (cfs_hash_with_rw_bktlock(hs))
230 hs->hs_lops = &cfs_hash_nr_bkt_rw_lops;
231 else if (cfs_hash_with_spin_bktlock(hs))
232 hs->hs_lops = &cfs_hash_nr_bkt_spin_lops;
239 * Simple hash head without depth tracking
240 * new element is always added to head of hlist
242 struct cfs_hash_head {
243 struct hlist_head hh_head; /**< entries list */
247 cfs_hash_hh_hhead_size(struct cfs_hash *hs)
249 return sizeof(struct cfs_hash_head);
252 static struct hlist_head *
253 cfs_hash_hh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
255 struct cfs_hash_head *head;
257 head = (struct cfs_hash_head *)&bd->bd_bucket->hsb_head[0];
258 return &head[bd->bd_offset].hh_head;
262 cfs_hash_hh_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *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(struct cfs_hash *hs, struct cfs_hash_bd *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
281 struct cfs_hash_head_dep {
282 struct hlist_head hd_head; /**< entries list */
283 unsigned int hd_depth; /**< list length */
287 cfs_hash_hd_hhead_size(struct cfs_hash *hs)
289 return sizeof(struct cfs_hash_head_dep);
292 static struct hlist_head *
293 cfs_hash_hd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
295 struct cfs_hash_head_dep *head;
297 head = (struct cfs_hash_head_dep *)&bd->bd_bucket->hsb_head[0];
298 return &head[bd->bd_offset].hd_head;
302 cfs_hash_hd_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
303 struct hlist_node *hnode)
305 struct cfs_hash_head_dep *hh;
307 hh = container_of(cfs_hash_hd_hhead(hs, bd),
308 struct cfs_hash_head_dep, hd_head);
309 hlist_add_head(hnode, &hh->hd_head);
310 return ++hh->hd_depth;
314 cfs_hash_hd_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
315 struct hlist_node *hnode)
317 struct cfs_hash_head_dep *hh;
319 hh = container_of(cfs_hash_hd_hhead(hs, bd),
320 struct cfs_hash_head_dep, hd_head);
321 hlist_del_init(hnode);
322 return --hh->hd_depth;
326 * double links hash head without depth tracking
327 * new element is always added to tail of hlist
329 struct cfs_hash_dhead {
330 struct hlist_head dh_head; /**< entries list */
331 struct hlist_node *dh_tail; /**< the last entry */
335 cfs_hash_dh_hhead_size(struct cfs_hash *hs)
337 return sizeof(struct cfs_hash_dhead);
340 static struct hlist_head *
341 cfs_hash_dh_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
343 struct cfs_hash_dhead *head;
345 head = (struct cfs_hash_dhead *)&bd->bd_bucket->hsb_head[0];
346 return &head[bd->bd_offset].dh_head;
350 cfs_hash_dh_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
351 struct hlist_node *hnode)
353 struct cfs_hash_dhead *dh;
355 dh = container_of(cfs_hash_dh_hhead(hs, bd),
356 struct cfs_hash_dhead, dh_head);
357 if (dh->dh_tail != NULL) /* not empty */
358 hlist_add_behind(hnode, dh->dh_tail);
359 else /* empty list */
360 hlist_add_head(hnode, &dh->dh_head);
362 return -1; /* unknown depth */
366 cfs_hash_dh_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
367 struct hlist_node *hnd)
369 struct cfs_hash_dhead *dh;
371 dh = container_of(cfs_hash_dh_hhead(hs, bd),
372 struct cfs_hash_dhead, dh_head);
373 if (hnd->next == NULL) { /* it's the tail */
374 dh->dh_tail = (hnd->pprev == &dh->dh_head.first) ? NULL :
375 container_of(hnd->pprev, struct hlist_node, next);
378 return -1; /* unknown depth */
382 * double links hash head with depth tracking
383 * new element is always added to tail of hlist
385 struct cfs_hash_dhead_dep {
386 struct hlist_head dd_head; /**< entries list */
387 struct hlist_node *dd_tail; /**< the last entry */
388 unsigned int dd_depth; /**< list length */
392 cfs_hash_dd_hhead_size(struct cfs_hash *hs)
394 return sizeof(struct cfs_hash_dhead_dep);
397 static struct hlist_head *
398 cfs_hash_dd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
400 struct cfs_hash_dhead_dep *head;
402 head = (struct cfs_hash_dhead_dep *)&bd->bd_bucket->hsb_head[0];
403 return &head[bd->bd_offset].dd_head;
407 cfs_hash_dd_hnode_add(struct cfs_hash *hs, struct cfs_hash_bd *bd,
408 struct hlist_node *hnode)
410 struct cfs_hash_dhead_dep *dh;
412 dh = container_of(cfs_hash_dd_hhead(hs, bd),
413 struct cfs_hash_dhead_dep, dd_head);
414 if (dh->dd_tail != NULL) /* not empty */
415 hlist_add_behind(hnode, dh->dd_tail);
416 else /* empty list */
417 hlist_add_head(hnode, &dh->dd_head);
419 return ++dh->dd_depth;
423 cfs_hash_dd_hnode_del(struct cfs_hash *hs, struct cfs_hash_bd *bd,
424 struct hlist_node *hnd)
426 struct cfs_hash_dhead_dep *dh;
428 dh = container_of(cfs_hash_dd_hhead(hs, bd),
429 struct cfs_hash_dhead_dep, dd_head);
430 if (hnd->next == NULL) { /* it's the tail */
431 dh->dd_tail = (hnd->pprev == &dh->dd_head.first) ? NULL :
432 container_of(hnd->pprev, struct hlist_node, next);
435 return --dh->dd_depth;
438 static struct cfs_hash_hlist_ops cfs_hash_hh_hops = {
439 .hop_hhead = cfs_hash_hh_hhead,
440 .hop_hhead_size = cfs_hash_hh_hhead_size,
441 .hop_hnode_add = cfs_hash_hh_hnode_add,
442 .hop_hnode_del = cfs_hash_hh_hnode_del,
445 static struct cfs_hash_hlist_ops cfs_hash_hd_hops = {
446 .hop_hhead = cfs_hash_hd_hhead,
447 .hop_hhead_size = cfs_hash_hd_hhead_size,
448 .hop_hnode_add = cfs_hash_hd_hnode_add,
449 .hop_hnode_del = cfs_hash_hd_hnode_del,
452 static struct cfs_hash_hlist_ops cfs_hash_dh_hops = {
453 .hop_hhead = cfs_hash_dh_hhead,
454 .hop_hhead_size = cfs_hash_dh_hhead_size,
455 .hop_hnode_add = cfs_hash_dh_hnode_add,
456 .hop_hnode_del = cfs_hash_dh_hnode_del,
459 static struct cfs_hash_hlist_ops cfs_hash_dd_hops = {
460 .hop_hhead = cfs_hash_dd_hhead,
461 .hop_hhead_size = cfs_hash_dd_hhead_size,
462 .hop_hnode_add = cfs_hash_dd_hnode_add,
463 .hop_hnode_del = cfs_hash_dd_hnode_del,
467 cfs_hash_hlist_setup(struct cfs_hash *hs)
469 if (cfs_hash_with_add_tail(hs)) {
470 hs->hs_hops = cfs_hash_with_depth(hs) ?
471 &cfs_hash_dd_hops : &cfs_hash_dh_hops;
473 hs->hs_hops = cfs_hash_with_depth(hs) ?
474 &cfs_hash_hd_hops : &cfs_hash_hh_hops;
479 cfs_hash_bd_from_key(struct cfs_hash *hs, struct cfs_hash_bucket **bkts,
480 unsigned int bits, const void *key, struct cfs_hash_bd *bd)
482 unsigned int index = cfs_hash_id(hs, key, (1U << bits) - 1);
484 LASSERT(bits == hs->hs_cur_bits || bits == hs->hs_rehash_bits);
486 bd->bd_bucket = bkts[index & ((1U << (bits - hs->hs_bkt_bits)) - 1)];
487 bd->bd_offset = index >> (bits - hs->hs_bkt_bits);
491 cfs_hash_bd_get(struct cfs_hash *hs, const void *key, struct cfs_hash_bd *bd)
493 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
494 if (likely(hs->hs_rehash_buckets == NULL)) {
495 cfs_hash_bd_from_key(hs, hs->hs_buckets,
496 hs->hs_cur_bits, key, bd);
498 LASSERT(hs->hs_rehash_bits != 0);
499 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
500 hs->hs_rehash_bits, key, bd);
503 EXPORT_SYMBOL(cfs_hash_bd_get);
506 cfs_hash_bd_dep_record(struct cfs_hash *hs, struct cfs_hash_bd *bd, int dep_cur)
508 if (likely(dep_cur <= bd->bd_bucket->hsb_depmax))
511 bd->bd_bucket->hsb_depmax = dep_cur;
512 # if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
513 if (likely(warn_on_depth == 0 ||
514 max(warn_on_depth, hs->hs_dep_max) >= dep_cur))
517 spin_lock(&hs->hs_dep_lock);
518 hs->hs_dep_max = dep_cur;
519 hs->hs_dep_bkt = bd->bd_bucket->hsb_index;
520 hs->hs_dep_off = bd->bd_offset;
521 hs->hs_dep_bits = hs->hs_cur_bits;
522 spin_unlock(&hs->hs_dep_lock);
524 cfs_wi_schedule(cfs_sched_rehash, &hs->hs_dep_wi);
529 cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
530 struct hlist_node *hnode)
534 rc = hs->hs_hops->hop_hnode_add(hs, bd, hnode);
535 cfs_hash_bd_dep_record(hs, bd, rc);
536 bd->bd_bucket->hsb_version++;
537 if (unlikely(bd->bd_bucket->hsb_version == 0))
538 bd->bd_bucket->hsb_version++;
539 bd->bd_bucket->hsb_count++;
541 if (cfs_hash_with_counter(hs))
542 atomic_inc(&hs->hs_count);
543 if (!cfs_hash_with_no_itemref(hs))
544 cfs_hash_get(hs, hnode);
546 EXPORT_SYMBOL(cfs_hash_bd_add_locked);
549 cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
550 struct hlist_node *hnode)
552 hs->hs_hops->hop_hnode_del(hs, bd, hnode);
554 LASSERT(bd->bd_bucket->hsb_count > 0);
555 bd->bd_bucket->hsb_count--;
556 bd->bd_bucket->hsb_version++;
557 if (unlikely(bd->bd_bucket->hsb_version == 0))
558 bd->bd_bucket->hsb_version++;
560 if (cfs_hash_with_counter(hs)) {
561 LASSERT(atomic_read(&hs->hs_count) > 0);
562 atomic_dec(&hs->hs_count);
564 if (!cfs_hash_with_no_itemref(hs))
565 cfs_hash_put_locked(hs, hnode);
567 EXPORT_SYMBOL(cfs_hash_bd_del_locked);
570 cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
571 struct cfs_hash_bd *bd_new, struct hlist_node *hnode)
573 struct cfs_hash_bucket *obkt = bd_old->bd_bucket;
574 struct cfs_hash_bucket *nbkt = bd_new->bd_bucket;
577 if (cfs_hash_bd_compare(bd_old, bd_new) == 0)
580 /* use cfs_hash_bd_hnode_add/del, to avoid atomic & refcount ops
581 * in cfs_hash_bd_del/add_locked */
582 hs->hs_hops->hop_hnode_del(hs, bd_old, hnode);
583 rc = hs->hs_hops->hop_hnode_add(hs, bd_new, hnode);
584 cfs_hash_bd_dep_record(hs, bd_new, rc);
586 LASSERT(obkt->hsb_count > 0);
589 if (unlikely(obkt->hsb_version == 0))
593 if (unlikely(nbkt->hsb_version == 0))
596 EXPORT_SYMBOL(cfs_hash_bd_move_locked);
599 /** always set, for sanity (avoid ZERO intent) */
600 CFS_HS_LOOKUP_MASK_FIND = 1 << 0,
601 /** return entry with a ref */
602 CFS_HS_LOOKUP_MASK_REF = 1 << 1,
603 /** add entry if not existing */
604 CFS_HS_LOOKUP_MASK_ADD = 1 << 2,
605 /** delete entry, ignore other masks */
606 CFS_HS_LOOKUP_MASK_DEL = 1 << 3,
609 enum cfs_hash_lookup_intent {
610 /** return item w/o refcount */
611 CFS_HS_LOOKUP_IT_PEEK = CFS_HS_LOOKUP_MASK_FIND,
612 /** return item with refcount */
613 CFS_HS_LOOKUP_IT_FIND = (CFS_HS_LOOKUP_MASK_FIND |
614 CFS_HS_LOOKUP_MASK_REF),
615 /** return item w/o refcount if existed, otherwise add */
616 CFS_HS_LOOKUP_IT_ADD = (CFS_HS_LOOKUP_MASK_FIND |
617 CFS_HS_LOOKUP_MASK_ADD),
618 /** return item with refcount if existed, otherwise add */
619 CFS_HS_LOOKUP_IT_FINDADD = (CFS_HS_LOOKUP_IT_FIND |
620 CFS_HS_LOOKUP_MASK_ADD),
621 /** delete if existed */
622 CFS_HS_LOOKUP_IT_FINDDEL = (CFS_HS_LOOKUP_MASK_FIND |
623 CFS_HS_LOOKUP_MASK_DEL)
626 static struct hlist_node *
627 cfs_hash_bd_lookup_intent(struct cfs_hash *hs, struct cfs_hash_bd *bd,
628 const void *key, struct hlist_node *hnode,
629 enum cfs_hash_lookup_intent intent)
632 struct hlist_head *hhead = cfs_hash_bd_hhead(hs, bd);
633 struct hlist_node *ehnode;
634 struct hlist_node *match;
635 int intent_add = (intent & CFS_HS_LOOKUP_MASK_ADD) != 0;
637 /* with this function, we can avoid a lot of useless refcount ops,
638 * which are expensive atomic operations most time. */
639 match = intent_add ? NULL : hnode;
640 hlist_for_each(ehnode, hhead) {
641 if (!cfs_hash_keycmp(hs, key, ehnode))
644 if (match != NULL && match != ehnode) /* can't match */
648 if ((intent & CFS_HS_LOOKUP_MASK_DEL) != 0) {
649 cfs_hash_bd_del_locked(hs, bd, ehnode);
653 /* caller wants refcount? */
654 if ((intent & CFS_HS_LOOKUP_MASK_REF) != 0)
655 cfs_hash_get(hs, ehnode);
662 LASSERT(hnode != NULL);
663 cfs_hash_bd_add_locked(hs, bd, hnode);
668 cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
671 return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
672 CFS_HS_LOOKUP_IT_FIND);
674 EXPORT_SYMBOL(cfs_hash_bd_lookup_locked);
677 cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
680 return cfs_hash_bd_lookup_intent(hs, bd, key, NULL,
681 CFS_HS_LOOKUP_IT_PEEK);
683 EXPORT_SYMBOL(cfs_hash_bd_peek_locked);
686 cfs_hash_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
687 const void *key, struct hlist_node *hnode,
690 return cfs_hash_bd_lookup_intent(hs, bd, key, hnode,
691 CFS_HS_LOOKUP_IT_ADD |
692 (!noref * CFS_HS_LOOKUP_MASK_REF));
694 EXPORT_SYMBOL(cfs_hash_bd_findadd_locked);
697 cfs_hash_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
698 const void *key, struct hlist_node *hnode)
700 /* hnode can be NULL, we find the first item with @key */
701 return cfs_hash_bd_lookup_intent(hs, bd, key, hnode,
702 CFS_HS_LOOKUP_IT_FINDDEL);
704 EXPORT_SYMBOL(cfs_hash_bd_finddel_locked);
707 cfs_hash_multi_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
708 unsigned n, int excl)
710 struct cfs_hash_bucket *prev = NULL;
714 * bds must be ascendantly ordered by bd->bd_bucket->hsb_index.
715 * NB: it's possible that several bds point to the same bucket but
716 * have different bd::bd_offset, so need take care of deadlock.
718 cfs_hash_for_each_bd(bds, n, i) {
719 if (prev == bds[i].bd_bucket)
722 LASSERT(prev == NULL ||
723 prev->hsb_index < bds[i].bd_bucket->hsb_index);
724 cfs_hash_bd_lock(hs, &bds[i], excl);
725 prev = bds[i].bd_bucket;
730 cfs_hash_multi_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
731 unsigned n, int excl)
733 struct cfs_hash_bucket *prev = NULL;
736 cfs_hash_for_each_bd(bds, n, i) {
737 if (prev != bds[i].bd_bucket) {
738 cfs_hash_bd_unlock(hs, &bds[i], excl);
739 prev = bds[i].bd_bucket;
744 static struct hlist_node *
745 cfs_hash_multi_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
746 unsigned n, const void *key)
748 struct hlist_node *ehnode;
751 cfs_hash_for_each_bd(bds, n, i) {
752 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, NULL,
753 CFS_HS_LOOKUP_IT_FIND);
760 static struct hlist_node *
761 cfs_hash_multi_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
762 unsigned n, const void *key,
763 struct hlist_node *hnode, int noref)
765 struct hlist_node *ehnode;
769 LASSERT(hnode != NULL);
770 intent = CFS_HS_LOOKUP_IT_PEEK | (!noref * CFS_HS_LOOKUP_MASK_REF);
772 cfs_hash_for_each_bd(bds, n, i) {
773 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key,
779 if (i == 1) { /* only one bucket */
780 cfs_hash_bd_add_locked(hs, &bds[0], hnode);
782 struct cfs_hash_bd mybd;
784 cfs_hash_bd_get(hs, key, &mybd);
785 cfs_hash_bd_add_locked(hs, &mybd, hnode);
791 static struct hlist_node *
792 cfs_hash_multi_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
793 unsigned n, const void *key,
794 struct hlist_node *hnode)
796 struct hlist_node *ehnode;
799 cfs_hash_for_each_bd(bds, n, i) {
800 ehnode = cfs_hash_bd_lookup_intent(hs, &bds[i], key, hnode,
801 CFS_HS_LOOKUP_IT_FINDDEL);
809 cfs_hash_bd_order(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
813 if (bd2->bd_bucket == NULL)
816 if (bd1->bd_bucket == NULL) {
818 bd2->bd_bucket = NULL;
822 rc = cfs_hash_bd_compare(bd1, bd2);
824 bd2->bd_bucket = NULL;
826 } else if (rc > 0) { /* swab bd1 and bd2 */
827 struct cfs_hash_bd tmp;
836 cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key,
837 struct cfs_hash_bd *bds)
839 /* NB: caller should hold hs_lock.rw if REHASH is set */
840 cfs_hash_bd_from_key(hs, hs->hs_buckets,
841 hs->hs_cur_bits, key, &bds[0]);
842 if (likely(hs->hs_rehash_buckets == NULL)) {
843 /* no rehash or not rehashing */
844 bds[1].bd_bucket = NULL;
848 LASSERT(hs->hs_rehash_bits != 0);
849 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
850 hs->hs_rehash_bits, key, &bds[1]);
852 cfs_hash_bd_order(&bds[0], &bds[1]);
854 EXPORT_SYMBOL(cfs_hash_dual_bd_get);
857 cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds, int excl)
859 cfs_hash_multi_bd_lock(hs, bds, 2, excl);
861 EXPORT_SYMBOL(cfs_hash_dual_bd_lock);
864 cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds, int excl)
866 cfs_hash_multi_bd_unlock(hs, bds, 2, excl);
868 EXPORT_SYMBOL(cfs_hash_dual_bd_unlock);
871 cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
874 return cfs_hash_multi_bd_lookup_locked(hs, bds, 2, key);
876 EXPORT_SYMBOL(cfs_hash_dual_bd_lookup_locked);
879 cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
880 const void *key, struct hlist_node *hnode,
883 return cfs_hash_multi_bd_findadd_locked(hs, bds, 2, key,
886 EXPORT_SYMBOL(cfs_hash_dual_bd_findadd_locked);
889 cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
890 const void *key, struct hlist_node *hnode)
892 return cfs_hash_multi_bd_finddel_locked(hs, bds, 2, key, hnode);
894 EXPORT_SYMBOL(cfs_hash_dual_bd_finddel_locked);
897 cfs_hash_buckets_free(struct cfs_hash_bucket **buckets,
898 int bkt_size, int prev_size, int size)
902 for (i = prev_size; i < size; i++) {
903 if (buckets[i] != NULL)
904 LIBCFS_FREE(buckets[i], bkt_size);
907 LIBCFS_FREE(buckets, sizeof(buckets[0]) * size);
911 * Create or grow bucket memory. Return old_buckets if no allocation was
912 * needed, the newly allocated buckets if allocation was needed and
913 * successful, and NULL on error.
915 static struct cfs_hash_bucket **
916 cfs_hash_buckets_realloc(struct cfs_hash *hs, struct cfs_hash_bucket **old_bkts,
917 unsigned int old_size, unsigned int new_size)
919 struct cfs_hash_bucket **new_bkts;
922 LASSERT(old_size == 0 || old_bkts != NULL);
924 if (old_bkts != NULL && old_size == new_size)
927 LIBCFS_ALLOC(new_bkts, sizeof(new_bkts[0]) * new_size);
928 if (new_bkts == NULL)
931 if (old_bkts != NULL) {
932 memcpy(new_bkts, old_bkts,
933 min(old_size, new_size) * sizeof(*old_bkts));
936 for (i = old_size; i < new_size; i++) {
937 struct hlist_head *hhead;
938 struct cfs_hash_bd bd;
940 LIBCFS_ALLOC(new_bkts[i], cfs_hash_bkt_size(hs));
941 if (new_bkts[i] == NULL) {
942 cfs_hash_buckets_free(new_bkts, cfs_hash_bkt_size(hs),
947 new_bkts[i]->hsb_index = i;
948 new_bkts[i]->hsb_version = 1; /* shouldn't be zero */
949 new_bkts[i]->hsb_depmax = -1; /* unknown */
950 bd.bd_bucket = new_bkts[i];
951 cfs_hash_bd_for_each_hlist(hs, &bd, hhead)
952 INIT_HLIST_HEAD(hhead);
954 if (cfs_hash_with_no_lock(hs) ||
955 cfs_hash_with_no_bktlock(hs))
958 if (cfs_hash_with_rw_bktlock(hs))
959 rwlock_init(&new_bkts[i]->hsb_lock.rw);
960 else if (cfs_hash_with_spin_bktlock(hs))
961 spin_lock_init(&new_bkts[i]->hsb_lock.spin);
963 LBUG(); /* invalid use-case */
969 * Initialize new libcfs hash, where:
970 * @name - Descriptive hash name
971 * @cur_bits - Initial hash table size, in bits
972 * @max_bits - Maximum allowed hash table resize, in bits
973 * @ops - Registered hash table operations
974 * @flags - CFS_HASH_REHASH enable synamic hash resizing
975 * - CFS_HASH_SORT enable chained hash sort
977 static int cfs_hash_rehash_worker(cfs_workitem_t *wi);
979 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
980 static int cfs_hash_dep_print(cfs_workitem_t *wi)
982 struct cfs_hash *hs = container_of(wi, struct cfs_hash, hs_dep_wi);
988 spin_lock(&hs->hs_dep_lock);
989 dep = hs->hs_dep_max;
990 bkt = hs->hs_dep_bkt;
991 off = hs->hs_dep_off;
992 bits = hs->hs_dep_bits;
993 spin_unlock(&hs->hs_dep_lock);
995 LCONSOLE_WARN("#### HASH %s (bits: %d): max depth %d at bucket %d/%d\n",
996 hs->hs_name, bits, dep, bkt, off);
997 spin_lock(&hs->hs_dep_lock);
998 hs->hs_dep_bits = 0; /* mark as workitem done */
999 spin_unlock(&hs->hs_dep_lock);
1003 static void cfs_hash_depth_wi_init(struct cfs_hash *hs)
1005 spin_lock_init(&hs->hs_dep_lock);
1006 cfs_wi_init(&hs->hs_dep_wi, hs, cfs_hash_dep_print);
1009 static void cfs_hash_depth_wi_cancel(struct cfs_hash *hs)
1011 if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_dep_wi))
1014 spin_lock(&hs->hs_dep_lock);
1015 while (hs->hs_dep_bits != 0) {
1016 spin_unlock(&hs->hs_dep_lock);
1018 spin_lock(&hs->hs_dep_lock);
1020 spin_unlock(&hs->hs_dep_lock);
1023 #else /* CFS_HASH_DEBUG_LEVEL < CFS_HASH_DEBUG_1 */
1025 static inline void cfs_hash_depth_wi_init(struct cfs_hash *hs) {}
1026 static inline void cfs_hash_depth_wi_cancel(struct cfs_hash *hs) {}
1028 #endif /* CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1 */
1031 cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits,
1032 unsigned bkt_bits, unsigned extra_bytes,
1033 unsigned min_theta, unsigned max_theta,
1034 struct cfs_hash_ops *ops, unsigned flags)
1036 struct cfs_hash *hs;
1041 CLASSERT(CFS_HASH_THETA_BITS < 15);
1043 LASSERT(name != NULL);
1044 LASSERT(ops != NULL);
1045 LASSERT(ops->hs_key);
1046 LASSERT(ops->hs_hash);
1047 LASSERT(ops->hs_object);
1048 LASSERT(ops->hs_keycmp);
1049 LASSERT(ops->hs_get != NULL);
1050 LASSERT(ops->hs_put_locked != NULL);
1052 if ((flags & CFS_HASH_REHASH) != 0)
1053 flags |= CFS_HASH_COUNTER; /* must have counter */
1055 LASSERT(cur_bits > 0);
1056 LASSERT(cur_bits >= bkt_bits);
1057 LASSERT(max_bits >= cur_bits && max_bits < 31);
1058 LASSERT(ergo((flags & CFS_HASH_REHASH) == 0, cur_bits == max_bits));
1059 LASSERT(ergo((flags & CFS_HASH_REHASH) != 0,
1060 (flags & CFS_HASH_NO_LOCK) == 0));
1061 LASSERT(ergo((flags & CFS_HASH_REHASH_KEY) != 0,
1062 ops->hs_keycpy != NULL));
1064 len = (flags & CFS_HASH_BIGNAME) == 0 ?
1065 CFS_HASH_NAME_LEN : CFS_HASH_BIGNAME_LEN;
1066 LIBCFS_ALLOC(hs, offsetof(struct cfs_hash, hs_name[len]));
1070 strlcpy(hs->hs_name, name, len);
1071 hs->hs_flags = flags;
1073 atomic_set(&hs->hs_refcount, 1);
1074 atomic_set(&hs->hs_count, 0);
1076 cfs_hash_lock_setup(hs);
1077 cfs_hash_hlist_setup(hs);
1079 hs->hs_cur_bits = (__u8)cur_bits;
1080 hs->hs_min_bits = (__u8)cur_bits;
1081 hs->hs_max_bits = (__u8)max_bits;
1082 hs->hs_bkt_bits = (__u8)bkt_bits;
1085 hs->hs_extra_bytes = extra_bytes;
1086 hs->hs_rehash_bits = 0;
1087 cfs_wi_init(&hs->hs_rehash_wi, hs, cfs_hash_rehash_worker);
1088 cfs_hash_depth_wi_init(hs);
1090 if (cfs_hash_with_rehash(hs))
1091 __cfs_hash_set_theta(hs, min_theta, max_theta);
1093 hs->hs_buckets = cfs_hash_buckets_realloc(hs, NULL, 0,
1095 if (hs->hs_buckets != NULL)
1098 LIBCFS_FREE(hs, offsetof(struct cfs_hash, hs_name[len]));
1101 EXPORT_SYMBOL(cfs_hash_create);
1104 * Cleanup libcfs hash @hs.
1107 cfs_hash_destroy(struct cfs_hash *hs)
1109 struct hlist_node *hnode;
1110 struct hlist_node *pos;
1111 struct cfs_hash_bd bd;
1115 LASSERT(hs != NULL);
1116 LASSERT(!cfs_hash_is_exiting(hs) &&
1117 !cfs_hash_is_iterating(hs));
1120 * prohibit further rehashes, don't need any lock because
1121 * I'm the only (last) one can change it.
1124 if (cfs_hash_with_rehash(hs))
1125 cfs_hash_rehash_cancel(hs);
1127 cfs_hash_depth_wi_cancel(hs);
1128 /* rehash should be done/canceled */
1129 LASSERT(hs->hs_buckets != NULL &&
1130 hs->hs_rehash_buckets == NULL);
1132 cfs_hash_for_each_bucket(hs, &bd, i) {
1133 struct hlist_head *hhead;
1135 LASSERT(bd.bd_bucket != NULL);
1136 /* no need to take this lock, just for consistent code */
1137 cfs_hash_bd_lock(hs, &bd, 1);
1139 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1140 hlist_for_each_safe(hnode, pos, hhead) {
1141 LASSERTF(!cfs_hash_with_assert_empty(hs),
1142 "hash %s bucket %u(%u) is not "
1143 " empty: %u items left\n",
1144 hs->hs_name, bd.bd_bucket->hsb_index,
1145 bd.bd_offset, bd.bd_bucket->hsb_count);
1146 /* can't assert key valicate, because we
1147 * can interrupt rehash */
1148 cfs_hash_bd_del_locked(hs, &bd, hnode);
1149 cfs_hash_exit(hs, hnode);
1152 LASSERT(bd.bd_bucket->hsb_count == 0);
1153 cfs_hash_bd_unlock(hs, &bd, 1);
1157 LASSERT(atomic_read(&hs->hs_count) == 0);
1159 cfs_hash_buckets_free(hs->hs_buckets, cfs_hash_bkt_size(hs),
1160 0, CFS_HASH_NBKT(hs));
1161 i = cfs_hash_with_bigname(hs) ?
1162 CFS_HASH_BIGNAME_LEN : CFS_HASH_NAME_LEN;
1163 LIBCFS_FREE(hs, offsetof(struct cfs_hash, hs_name[i]));
1168 struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs)
1170 if (atomic_inc_not_zero(&hs->hs_refcount))
1174 EXPORT_SYMBOL(cfs_hash_getref);
1176 void cfs_hash_putref(struct cfs_hash *hs)
1178 if (atomic_dec_and_test(&hs->hs_refcount))
1179 cfs_hash_destroy(hs);
1181 EXPORT_SYMBOL(cfs_hash_putref);
1184 cfs_hash_rehash_bits(struct cfs_hash *hs)
1186 if (cfs_hash_with_no_lock(hs) ||
1187 !cfs_hash_with_rehash(hs))
1190 if (unlikely(cfs_hash_is_exiting(hs)))
1193 if (unlikely(cfs_hash_is_rehashing(hs)))
1196 if (unlikely(cfs_hash_is_iterating(hs)))
1199 /* XXX: need to handle case with max_theta != 2.0
1200 * and the case with min_theta != 0.5 */
1201 if ((hs->hs_cur_bits < hs->hs_max_bits) &&
1202 (__cfs_hash_theta(hs) > hs->hs_max_theta))
1203 return hs->hs_cur_bits + 1;
1205 if (!cfs_hash_with_shrink(hs))
1208 if ((hs->hs_cur_bits > hs->hs_min_bits) &&
1209 (__cfs_hash_theta(hs) < hs->hs_min_theta))
1210 return hs->hs_cur_bits - 1;
1216 * don't allow inline rehash if:
1217 * - user wants non-blocking change (add/del) on hash table
1218 * - too many elements
1221 cfs_hash_rehash_inline(struct cfs_hash *hs)
1223 return !cfs_hash_with_nblk_change(hs) &&
1224 atomic_read(&hs->hs_count) < CFS_HASH_LOOP_HOG;
1228 * Add item @hnode to libcfs hash @hs using @key. The registered
1229 * ops->hs_get function will be called when the item is added.
1232 cfs_hash_add(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
1234 struct cfs_hash_bd bd;
1237 LASSERT(hlist_unhashed(hnode));
1239 cfs_hash_lock(hs, 0);
1240 cfs_hash_bd_get_and_lock(hs, key, &bd, 1);
1242 cfs_hash_key_validate(hs, key, hnode);
1243 cfs_hash_bd_add_locked(hs, &bd, hnode);
1245 cfs_hash_bd_unlock(hs, &bd, 1);
1247 bits = cfs_hash_rehash_bits(hs);
1248 cfs_hash_unlock(hs, 0);
1250 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1252 EXPORT_SYMBOL(cfs_hash_add);
1254 static struct hlist_node *
1255 cfs_hash_find_or_add(struct cfs_hash *hs, const void *key,
1256 struct hlist_node *hnode, int noref)
1258 struct hlist_node *ehnode;
1259 struct cfs_hash_bd bds[2];
1262 LASSERT(hlist_unhashed(hnode));
1264 cfs_hash_lock(hs, 0);
1265 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
1267 cfs_hash_key_validate(hs, key, hnode);
1268 ehnode = cfs_hash_dual_bd_findadd_locked(hs, bds, key,
1270 cfs_hash_dual_bd_unlock(hs, bds, 1);
1272 if (ehnode == hnode) /* new item added */
1273 bits = cfs_hash_rehash_bits(hs);
1274 cfs_hash_unlock(hs, 0);
1276 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1282 * Add item @hnode to libcfs hash @hs using @key. The registered
1283 * ops->hs_get function will be called if the item was added.
1284 * Returns 0 on success or -EALREADY on key collisions.
1287 cfs_hash_add_unique(struct cfs_hash *hs, const void *key,
1288 struct hlist_node *hnode)
1290 return cfs_hash_find_or_add(hs, key, hnode, 1) != hnode ?
1293 EXPORT_SYMBOL(cfs_hash_add_unique);
1296 * Add item @hnode to libcfs hash @hs using @key. If this @key
1297 * already exists in the hash then ops->hs_get will be called on the
1298 * conflicting entry and that entry will be returned to the caller.
1299 * Otherwise ops->hs_get is called on the item which was added.
1302 cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
1303 struct hlist_node *hnode)
1305 hnode = cfs_hash_find_or_add(hs, key, hnode, 0);
1307 return cfs_hash_object(hs, hnode);
1309 EXPORT_SYMBOL(cfs_hash_findadd_unique);
1312 * Delete item @hnode from the libcfs hash @hs using @key. The @key
1313 * is required to ensure the correct hash bucket is locked since there
1314 * is no direct linkage from the item to the bucket. The object
1315 * removed from the hash will be returned and obs->hs_put is called
1316 * on the removed object.
1319 cfs_hash_del(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
1323 struct cfs_hash_bd bds[2];
1325 cfs_hash_lock(hs, 0);
1326 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 1);
1328 /* NB: do nothing if @hnode is not in hash table */
1329 if (hnode == NULL || !hlist_unhashed(hnode)) {
1330 if (bds[1].bd_bucket == NULL && hnode != NULL) {
1331 cfs_hash_bd_del_locked(hs, &bds[0], hnode);
1333 hnode = cfs_hash_dual_bd_finddel_locked(hs, bds,
1338 if (hnode != NULL) {
1339 obj = cfs_hash_object(hs, hnode);
1340 bits = cfs_hash_rehash_bits(hs);
1343 cfs_hash_dual_bd_unlock(hs, bds, 1);
1344 cfs_hash_unlock(hs, 0);
1346 cfs_hash_rehash(hs, cfs_hash_rehash_inline(hs));
1350 EXPORT_SYMBOL(cfs_hash_del);
1353 * Delete item given @key in libcfs hash @hs. The first @key found in
1354 * the hash will be removed, if the key exists multiple times in the hash
1355 * @hs this function must be called once per key. The removed object
1356 * will be returned and ops->hs_put is called on the removed object.
1359 cfs_hash_del_key(struct cfs_hash *hs, const void *key)
1361 return cfs_hash_del(hs, key, NULL);
1363 EXPORT_SYMBOL(cfs_hash_del_key);
1366 * Lookup an item using @key in the libcfs hash @hs and return it.
1367 * If the @key is found in the hash hs->hs_get() is called and the
1368 * matching objects is returned. It is the callers responsibility
1369 * to call the counterpart ops->hs_put using the cfs_hash_put() macro
1370 * when when finished with the object. If the @key was not found
1371 * in the hash @hs NULL is returned.
1374 cfs_hash_lookup(struct cfs_hash *hs, const void *key)
1377 struct hlist_node *hnode;
1378 struct cfs_hash_bd bds[2];
1380 cfs_hash_lock(hs, 0);
1381 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
1383 hnode = cfs_hash_dual_bd_lookup_locked(hs, bds, key);
1385 obj = cfs_hash_object(hs, hnode);
1387 cfs_hash_dual_bd_unlock(hs, bds, 0);
1388 cfs_hash_unlock(hs, 0);
1392 EXPORT_SYMBOL(cfs_hash_lookup);
1395 cfs_hash_for_each_enter(struct cfs_hash *hs)
1397 LASSERT(!cfs_hash_is_exiting(hs));
1399 if (!cfs_hash_with_rehash(hs))
1402 * NB: it's race on cfs_has_t::hs_iterating, but doesn't matter
1403 * because it's just an unreliable signal to rehash-thread,
1404 * rehash-thread will try to finish rehash ASAP when seeing this.
1406 hs->hs_iterating = 1;
1408 cfs_hash_lock(hs, 1);
1411 /* NB: iteration is mostly called by service thread,
1412 * we tend to cancel pending rehash-request, instead of
1413 * blocking service thread, we will relaunch rehash request
1414 * after iteration */
1415 if (cfs_hash_is_rehashing(hs))
1416 cfs_hash_rehash_cancel_locked(hs);
1417 cfs_hash_unlock(hs, 1);
1421 cfs_hash_for_each_exit(struct cfs_hash *hs)
1426 if (!cfs_hash_with_rehash(hs))
1428 cfs_hash_lock(hs, 1);
1429 remained = --hs->hs_iterators;
1430 bits = cfs_hash_rehash_bits(hs);
1431 cfs_hash_unlock(hs, 1);
1432 /* NB: it's race on cfs_has_t::hs_iterating, see above */
1434 hs->hs_iterating = 0;
1436 cfs_hash_rehash(hs, atomic_read(&hs->hs_count) <
1442 * For each item in the libcfs hash @hs call the passed callback @func
1443 * and pass to it as an argument each hash item and the private @data.
1445 * a) the function may sleep!
1446 * b) during the callback:
1447 * . the bucket lock is held so the callback must never sleep.
1448 * . if @removal_safe is true, use can remove current item by
1449 * cfs_hash_bd_del_locked
1452 cfs_hash_for_each_tight(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
1453 void *data, int remove_safe)
1455 struct hlist_node *hnode;
1456 struct hlist_node *pos;
1457 struct cfs_hash_bd bd;
1459 int excl = !!remove_safe;
1464 cfs_hash_for_each_enter(hs);
1466 cfs_hash_lock(hs, 0);
1467 LASSERT(!cfs_hash_is_rehashing(hs));
1469 cfs_hash_for_each_bucket(hs, &bd, i) {
1470 struct hlist_head *hhead;
1472 cfs_hash_bd_lock(hs, &bd, excl);
1473 if (func == NULL) { /* only glimpse size */
1474 count += bd.bd_bucket->hsb_count;
1475 cfs_hash_bd_unlock(hs, &bd, excl);
1479 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1480 hlist_for_each_safe(hnode, pos, hhead) {
1481 cfs_hash_bucket_validate(hs, &bd, hnode);
1484 if (func(hs, &bd, hnode, data)) {
1485 cfs_hash_bd_unlock(hs, &bd, excl);
1490 cfs_hash_bd_unlock(hs, &bd, excl);
1491 if (loop < CFS_HASH_LOOP_HOG)
1494 cfs_hash_unlock(hs, 0);
1496 cfs_hash_lock(hs, 0);
1499 cfs_hash_unlock(hs, 0);
1501 cfs_hash_for_each_exit(hs);
1505 struct cfs_hash_cond_arg {
1506 cfs_hash_cond_opt_cb_t func;
1511 cfs_hash_cond_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
1512 struct hlist_node *hnode, void *data)
1514 struct cfs_hash_cond_arg *cond = data;
1516 if (cond->func(cfs_hash_object(hs, hnode), cond->arg))
1517 cfs_hash_bd_del_locked(hs, bd, hnode);
1522 * Delete item from the libcfs hash @hs when @func return true.
1523 * The write lock being hold during loop for each bucket to avoid
1524 * any object be reference.
1527 cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t func, void *data)
1529 struct cfs_hash_cond_arg arg = {
1534 cfs_hash_for_each_tight(hs, cfs_hash_cond_del_locked, &arg, 1);
1536 EXPORT_SYMBOL(cfs_hash_cond_del);
1539 cfs_hash_for_each(struct cfs_hash *hs,
1540 cfs_hash_for_each_cb_t func, void *data)
1542 cfs_hash_for_each_tight(hs, func, data, 0);
1544 EXPORT_SYMBOL(cfs_hash_for_each);
1547 cfs_hash_for_each_safe(struct cfs_hash *hs,
1548 cfs_hash_for_each_cb_t func, void *data)
1550 cfs_hash_for_each_tight(hs, func, data, 1);
1552 EXPORT_SYMBOL(cfs_hash_for_each_safe);
1555 cfs_hash_peek(struct cfs_hash *hs, struct cfs_hash_bd *bd,
1556 struct hlist_node *hnode, void *data)
1559 return 1; /* return 1 to break the loop */
1563 cfs_hash_is_empty(struct cfs_hash *hs)
1567 cfs_hash_for_each_tight(hs, cfs_hash_peek, &empty, 0);
1570 EXPORT_SYMBOL(cfs_hash_is_empty);
1573 cfs_hash_size_get(struct cfs_hash *hs)
1575 return cfs_hash_with_counter(hs) ?
1576 atomic_read(&hs->hs_count) :
1577 cfs_hash_for_each_tight(hs, NULL, NULL, 0);
1579 EXPORT_SYMBOL(cfs_hash_size_get);
1582 * cfs_hash_for_each_relax:
1583 * Iterate the hash table and call @func on each item without
1584 * any lock. This function can't guarantee to finish iteration
1585 * if these features are enabled:
1587 * a. if rehash_key is enabled, an item can be moved from
1588 * one bucket to another bucket
1589 * b. user can remove non-zero-ref item from hash-table,
1590 * so the item can be removed from hash-table, even worse,
1591 * it's possible that user changed key and insert to another
1593 * there's no way for us to finish iteration correctly on previous
1594 * two cases, so iteration has to be stopped on change.
1597 cfs_hash_for_each_relax(struct cfs_hash *hs, cfs_hash_for_each_cb_t func,
1600 struct hlist_node *hnode;
1601 struct hlist_node *tmp;
1602 struct cfs_hash_bd bd;
1610 stop_on_change = cfs_hash_with_rehash_key(hs) ||
1611 !cfs_hash_with_no_itemref(hs) ||
1612 hs->hs_ops->hs_put_locked == NULL;
1613 cfs_hash_lock(hs, 0);
1614 LASSERT(!cfs_hash_is_rehashing(hs));
1616 cfs_hash_for_each_bucket(hs, &bd, i) {
1617 struct hlist_head *hhead;
1619 cfs_hash_bd_lock(hs, &bd, 0);
1620 version = cfs_hash_bd_version_get(&bd);
1622 cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
1623 for (hnode = hhead->first; hnode != NULL;) {
1624 cfs_hash_bucket_validate(hs, &bd, hnode);
1625 cfs_hash_get(hs, hnode);
1626 cfs_hash_bd_unlock(hs, &bd, 0);
1627 cfs_hash_unlock(hs, 0);
1629 rc = func(hs, &bd, hnode, data);
1631 cfs_hash_put(hs, hnode);
1635 cfs_hash_lock(hs, 0);
1636 cfs_hash_bd_lock(hs, &bd, 0);
1637 if (!stop_on_change) {
1639 cfs_hash_put_locked(hs, hnode);
1641 } else { /* bucket changed? */
1643 cfs_hash_bd_version_get(&bd))
1645 /* safe to continue because no change */
1646 hnode = hnode->next;
1648 if (rc) /* callback wants to break iteration */
1652 cfs_hash_bd_unlock(hs, &bd, 0);
1654 cfs_hash_unlock(hs, 0);
1660 cfs_hash_for_each_nolock(struct cfs_hash *hs,
1661 cfs_hash_for_each_cb_t func, void *data)
1665 if (cfs_hash_with_no_lock(hs) ||
1666 cfs_hash_with_rehash_key(hs) ||
1667 !cfs_hash_with_no_itemref(hs))
1668 RETURN(-EOPNOTSUPP);
1670 if (hs->hs_ops->hs_get == NULL ||
1671 (hs->hs_ops->hs_put == NULL &&
1672 hs->hs_ops->hs_put_locked == NULL))
1673 RETURN(-EOPNOTSUPP);
1675 cfs_hash_for_each_enter(hs);
1676 cfs_hash_for_each_relax(hs, func, data);
1677 cfs_hash_for_each_exit(hs);
1681 EXPORT_SYMBOL(cfs_hash_for_each_nolock);
1684 * For each hash bucket in the libcfs hash @hs call the passed callback
1685 * @func until all the hash buckets are empty. The passed callback @func
1686 * or the previously registered callback hs->hs_put must remove the item
1687 * from the hash. You may either use the cfs_hash_del() or hlist_del()
1688 * functions. No rwlocks will be held during the callback @func it is
1689 * safe to sleep if needed. This function will not terminate until the
1690 * hash is empty. Note it is still possible to concurrently add new
1691 * items in to the hash. It is the callers responsibility to ensure
1692 * the required locking is in place to prevent concurrent insertions.
1695 cfs_hash_for_each_empty(struct cfs_hash *hs,
1696 cfs_hash_for_each_cb_t func, void *data)
1701 if (cfs_hash_with_no_lock(hs))
1704 if (hs->hs_ops->hs_get == NULL ||
1705 (hs->hs_ops->hs_put == NULL &&
1706 hs->hs_ops->hs_put_locked == NULL))
1709 cfs_hash_for_each_enter(hs);
1710 while (cfs_hash_for_each_relax(hs, func, data)) {
1711 CDEBUG(D_INFO, "Try to empty hash: %s, loop: %u\n",
1714 cfs_hash_for_each_exit(hs);
1717 EXPORT_SYMBOL(cfs_hash_for_each_empty);
1720 cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned hindex,
1721 cfs_hash_for_each_cb_t func, void *data)
1723 struct hlist_head *hhead;
1724 struct hlist_node *hnode;
1725 struct cfs_hash_bd bd;
1727 cfs_hash_for_each_enter(hs);
1728 cfs_hash_lock(hs, 0);
1729 if (hindex >= CFS_HASH_NHLIST(hs))
1732 cfs_hash_bd_index_set(hs, hindex, &bd);
1734 cfs_hash_bd_lock(hs, &bd, 0);
1735 hhead = cfs_hash_bd_hhead(hs, &bd);
1736 hlist_for_each(hnode, hhead) {
1737 if (func(hs, &bd, hnode, data))
1740 cfs_hash_bd_unlock(hs, &bd, 0);
1742 cfs_hash_unlock(hs, 0);
1743 cfs_hash_for_each_exit(hs);
1746 EXPORT_SYMBOL(cfs_hash_hlist_for_each);
1749 * For each item in the libcfs hash @hs which matches the @key call
1750 * the passed callback @func and pass to it as an argument each hash
1751 * item and the private @data. During the callback the bucket lock
1752 * is held so the callback must never sleep.
1755 cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
1756 cfs_hash_for_each_cb_t func, void *data)
1758 struct hlist_node *hnode;
1759 struct cfs_hash_bd bds[2];
1762 cfs_hash_lock(hs, 0);
1764 cfs_hash_dual_bd_get_and_lock(hs, key, bds, 0);
1766 cfs_hash_for_each_bd(bds, 2, i) {
1767 struct hlist_head *hlist = cfs_hash_bd_hhead(hs, &bds[i]);
1769 hlist_for_each(hnode, hlist) {
1770 cfs_hash_bucket_validate(hs, &bds[i], hnode);
1772 if (cfs_hash_keycmp(hs, key, hnode)) {
1773 if (func(hs, &bds[i], hnode, data))
1779 cfs_hash_dual_bd_unlock(hs, bds, 0);
1780 cfs_hash_unlock(hs, 0);
1782 EXPORT_SYMBOL(cfs_hash_for_each_key);
1785 * Rehash the libcfs hash @hs to the given @bits. This can be used
1786 * to grow the hash size when excessive chaining is detected, or to
1787 * shrink the hash when it is larger than needed. When the CFS_HASH_REHASH
1788 * flag is set in @hs the libcfs hash may be dynamically rehashed
1789 * during addition or removal if the hash's theta value exceeds
1790 * either the hs->hs_min_theta or hs->max_theta values. By default
1791 * these values are tuned to keep the chained hash depth small, and
1792 * this approach assumes a reasonably uniform hashing function. The
1793 * theta thresholds for @hs are tunable via cfs_hash_set_theta().
1796 cfs_hash_rehash_cancel_locked(struct cfs_hash *hs)
1800 /* need hold cfs_hash_lock(hs, 1) */
1801 LASSERT(cfs_hash_with_rehash(hs) &&
1802 !cfs_hash_with_no_lock(hs));
1804 if (!cfs_hash_is_rehashing(hs))
1807 if (cfs_wi_deschedule(cfs_sched_rehash, &hs->hs_rehash_wi)) {
1808 hs->hs_rehash_bits = 0;
1812 for (i = 2; cfs_hash_is_rehashing(hs); i++) {
1813 cfs_hash_unlock(hs, 1);
1814 /* raise console warning while waiting too long */
1815 CDEBUG(IS_PO2(i >> 3) ? D_WARNING : D_INFO,
1816 "hash %s is still rehashing, rescheded %d\n",
1817 hs->hs_name, i - 1);
1819 cfs_hash_lock(hs, 1);
1822 EXPORT_SYMBOL(cfs_hash_rehash_cancel_locked);
1825 cfs_hash_rehash_cancel(struct cfs_hash *hs)
1827 cfs_hash_lock(hs, 1);
1828 cfs_hash_rehash_cancel_locked(hs);
1829 cfs_hash_unlock(hs, 1);
1831 EXPORT_SYMBOL(cfs_hash_rehash_cancel);
1834 cfs_hash_rehash(struct cfs_hash *hs, int do_rehash)
1838 LASSERT(cfs_hash_with_rehash(hs) && !cfs_hash_with_no_lock(hs));
1840 cfs_hash_lock(hs, 1);
1842 rc = cfs_hash_rehash_bits(hs);
1844 cfs_hash_unlock(hs, 1);
1848 hs->hs_rehash_bits = rc;
1850 /* launch and return */
1851 cfs_wi_schedule(cfs_sched_rehash, &hs->hs_rehash_wi);
1852 cfs_hash_unlock(hs, 1);
1856 /* rehash right now */
1857 cfs_hash_unlock(hs, 1);
1859 return cfs_hash_rehash_worker(&hs->hs_rehash_wi);
1861 EXPORT_SYMBOL(cfs_hash_rehash);
1864 cfs_hash_rehash_bd(struct cfs_hash *hs, struct cfs_hash_bd *old)
1866 struct cfs_hash_bd new;
1867 struct hlist_head *hhead;
1868 struct hlist_node *hnode;
1869 struct hlist_node *pos;
1873 /* hold cfs_hash_lock(hs, 1), so don't need any bucket lock */
1874 cfs_hash_bd_for_each_hlist(hs, old, hhead) {
1875 hlist_for_each_safe(hnode, pos, hhead) {
1876 key = cfs_hash_key(hs, hnode);
1877 LASSERT(key != NULL);
1878 /* Validate hnode is in the correct bucket. */
1879 cfs_hash_bucket_validate(hs, old, hnode);
1881 * Delete from old hash bucket; move to new bucket.
1882 * ops->hs_key must be defined.
1884 cfs_hash_bd_from_key(hs, hs->hs_rehash_buckets,
1885 hs->hs_rehash_bits, key, &new);
1886 cfs_hash_bd_move_locked(hs, old, &new, hnode);
1894 cfs_hash_rehash_worker(cfs_workitem_t *wi)
1896 struct cfs_hash *hs =
1897 container_of(wi, struct cfs_hash, hs_rehash_wi);
1898 struct cfs_hash_bucket **bkts;
1899 struct cfs_hash_bd bd;
1900 unsigned int old_size;
1901 unsigned int new_size;
1907 LASSERT(hs != NULL && cfs_hash_with_rehash(hs));
1909 cfs_hash_lock(hs, 0);
1910 LASSERT(cfs_hash_is_rehashing(hs));
1912 old_size = CFS_HASH_NBKT(hs);
1913 new_size = CFS_HASH_RH_NBKT(hs);
1915 cfs_hash_unlock(hs, 0);
1918 * don't need hs::hs_rwlock for hs::hs_buckets,
1919 * because nobody can change bkt-table except me.
1921 bkts = cfs_hash_buckets_realloc(hs, hs->hs_buckets,
1922 old_size, new_size);
1923 cfs_hash_lock(hs, 1);
1929 if (bkts == hs->hs_buckets) {
1930 bkts = NULL; /* do nothing */
1934 rc = __cfs_hash_theta(hs);
1935 if ((rc >= hs->hs_min_theta) && (rc <= hs->hs_max_theta)) {
1936 /* free the new allocated bkt-table */
1937 old_size = new_size;
1938 new_size = CFS_HASH_NBKT(hs);
1943 LASSERT(hs->hs_rehash_buckets == NULL);
1944 hs->hs_rehash_buckets = bkts;
1947 cfs_hash_for_each_bucket(hs, &bd, i) {
1948 if (cfs_hash_is_exiting(hs)) {
1950 /* someone wants to destroy the hash, abort now */
1951 if (old_size < new_size) /* OK to free old bkt-table */
1953 /* it's shrinking, need free new bkt-table */
1954 hs->hs_rehash_buckets = NULL;
1955 old_size = new_size;
1956 new_size = CFS_HASH_NBKT(hs);
1960 count += cfs_hash_rehash_bd(hs, &bd);
1961 if (count < CFS_HASH_LOOP_HOG ||
1962 cfs_hash_is_iterating(hs)) { /* need to finish ASAP */
1967 cfs_hash_unlock(hs, 1);
1969 cfs_hash_lock(hs, 1);
1972 hs->hs_rehash_count++;
1974 bkts = hs->hs_buckets;
1975 hs->hs_buckets = hs->hs_rehash_buckets;
1976 hs->hs_rehash_buckets = NULL;
1978 hs->hs_cur_bits = hs->hs_rehash_bits;
1980 hs->hs_rehash_bits = 0;
1981 if (rc == -ESRCH) /* never be scheduled again */
1982 cfs_wi_exit(cfs_sched_rehash, wi);
1983 bsize = cfs_hash_bkt_size(hs);
1984 cfs_hash_unlock(hs, 1);
1985 /* can't refer to @hs anymore because it could be destroyed */
1987 cfs_hash_buckets_free(bkts, bsize, new_size, old_size);
1989 CDEBUG(D_INFO, "early quit of rehashing: %d\n", rc);
1990 /* return 1 only if cfs_wi_exit is called */
1991 return rc == -ESRCH;
1995 * Rehash the object referenced by @hnode in the libcfs hash @hs. The
1996 * @old_key must be provided to locate the objects previous location
1997 * in the hash, and the @new_key will be used to reinsert the object.
1998 * Use this function instead of a cfs_hash_add() + cfs_hash_del()
1999 * combo when it is critical that there is no window in time where the
2000 * object is missing from the hash. When an object is being rehashed
2001 * the registered cfs_hash_get() and cfs_hash_put() functions will
2004 void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
2005 void *new_key, struct hlist_node *hnode)
2007 struct cfs_hash_bd bds[3];
2008 struct cfs_hash_bd old_bds[2];
2009 struct cfs_hash_bd new_bd;
2011 LASSERT(!hlist_unhashed(hnode));
2013 cfs_hash_lock(hs, 0);
2015 cfs_hash_dual_bd_get(hs, old_key, old_bds);
2016 cfs_hash_bd_get(hs, new_key, &new_bd);
2018 bds[0] = old_bds[0];
2019 bds[1] = old_bds[1];
2022 /* NB: bds[0] and bds[1] are ordered already */
2023 cfs_hash_bd_order(&bds[1], &bds[2]);
2024 cfs_hash_bd_order(&bds[0], &bds[1]);
2026 cfs_hash_multi_bd_lock(hs, bds, 3, 1);
2027 if (likely(old_bds[1].bd_bucket == NULL)) {
2028 cfs_hash_bd_move_locked(hs, &old_bds[0], &new_bd, hnode);
2030 cfs_hash_dual_bd_finddel_locked(hs, old_bds, old_key, hnode);
2031 cfs_hash_bd_add_locked(hs, &new_bd, hnode);
2033 /* overwrite key inside locks, otherwise may screw up with
2034 * other operations, i.e: rehash */
2035 cfs_hash_keycpy(hs, hnode, new_key);
2037 cfs_hash_multi_bd_unlock(hs, bds, 3, 1);
2038 cfs_hash_unlock(hs, 0);
2040 EXPORT_SYMBOL(cfs_hash_rehash_key);
2042 int cfs_hash_debug_header(struct seq_file *m)
2044 return seq_printf(m, "%-*s%6s%6s%6s%6s%6s%6s%6s%7s%8s%8s%8s%s\n",
2045 CFS_HASH_BIGNAME_LEN,
2046 "name", "cur", "min", "max", "theta", "t-min", "t-max",
2047 "flags", "rehash", "count", "maxdep", "maxdepb",
2050 EXPORT_SYMBOL(cfs_hash_debug_header);
2052 static struct cfs_hash_bucket **
2053 cfs_hash_full_bkts(struct cfs_hash *hs)
2055 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
2056 if (hs->hs_rehash_buckets == NULL)
2057 return hs->hs_buckets;
2059 LASSERT(hs->hs_rehash_bits != 0);
2060 return hs->hs_rehash_bits > hs->hs_cur_bits ?
2061 hs->hs_rehash_buckets : hs->hs_buckets;
2065 cfs_hash_full_nbkt(struct cfs_hash *hs)
2067 /* NB: caller should hold hs->hs_rwlock if REHASH is set */
2068 if (hs->hs_rehash_buckets == NULL)
2069 return CFS_HASH_NBKT(hs);
2071 LASSERT(hs->hs_rehash_bits != 0);
2072 return hs->hs_rehash_bits > hs->hs_cur_bits ?
2073 CFS_HASH_RH_NBKT(hs) : CFS_HASH_NBKT(hs);
2076 int cfs_hash_debug_str(struct cfs_hash *hs, struct seq_file *m)
2078 int dist[8] = { 0, };
2086 cfs_hash_lock(hs, 0);
2087 theta = __cfs_hash_theta(hs);
2089 c += seq_printf(m, "%-*s ", CFS_HASH_BIGNAME_LEN, hs->hs_name);
2090 c += seq_printf(m, "%5d ", 1 << hs->hs_cur_bits);
2091 c += seq_printf(m, "%5d ", 1 << hs->hs_min_bits);
2092 c += seq_printf(m, "%5d ", 1 << hs->hs_max_bits);
2093 c += seq_printf(m, "%d.%03d ", __cfs_hash_theta_int(theta),
2094 __cfs_hash_theta_frac(theta));
2095 c += seq_printf(m, "%d.%03d ", __cfs_hash_theta_int(hs->hs_min_theta),
2096 __cfs_hash_theta_frac(hs->hs_min_theta));
2097 c += seq_printf(m, "%d.%03d ", __cfs_hash_theta_int(hs->hs_max_theta),
2098 __cfs_hash_theta_frac(hs->hs_max_theta));
2099 c += seq_printf(m, " 0x%02x ", hs->hs_flags);
2100 c += seq_printf(m, "%6d ", hs->hs_rehash_count);
2103 * The distribution is a summary of the chained hash depth in
2104 * each of the libcfs hash buckets. Each buckets hsb_count is
2105 * divided by the hash theta value and used to generate a
2106 * histogram of the hash distribution. A uniform hash will
2107 * result in all hash buckets being close to the average thus
2108 * only the first few entries in the histogram will be non-zero.
2109 * If you hash function results in a non-uniform hash the will
2110 * be observable by outlier bucks in the distribution histogram.
2112 * Uniform hash distribution: 128/128/0/0/0/0/0/0
2113 * Non-Uniform hash distribution: 128/125/0/0/0/0/2/1
2115 for (i = 0; i < cfs_hash_full_nbkt(hs); i++) {
2116 struct cfs_hash_bd bd;
2118 bd.bd_bucket = cfs_hash_full_bkts(hs)[i];
2119 cfs_hash_bd_lock(hs, &bd, 0);
2120 if (maxdep < bd.bd_bucket->hsb_depmax) {
2121 maxdep = bd.bd_bucket->hsb_depmax;
2122 maxdepb = ffz(~maxdep);
2124 total += bd.bd_bucket->hsb_count;
2125 dist[min(fls(bd.bd_bucket->hsb_count/max(theta,1)),7)]++;
2126 cfs_hash_bd_unlock(hs, &bd, 0);
2129 c += seq_printf(m, "%7d ", total);
2130 c += seq_printf(m, "%7d ", maxdep);
2131 c += seq_printf(m, "%7d ", maxdepb);
2132 for (i = 0; i < 8; i++)
2133 c += seq_printf(m, "%d%c", dist[i], (i == 7) ? '\n' : '/');
2135 cfs_hash_unlock(hs, 0);
2138 EXPORT_SYMBOL(cfs_hash_debug_str);