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13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
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23 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
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29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
32 * libcfs/include/libcfs/libcfs_hash.h
38 #ifndef __LIBCFS_HASH_H__
39 #define __LIBCFS_HASH_H__
41 #include <linux/hash.h>
42 #include <linux/spinlock.h>
43 #include <linux/workqueue.h>
46 * Knuth recommends primes in approximately golden ratio to the maximum
47 * integer representable by a machine word for multiplicative hashing.
48 * Chuck Lever verified the effectiveness of this technique:
49 * http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
51 * These primes are chosen to be bit-sparse, that is operations on
52 * them can use shifts and additions instead of multiplications for
53 * machines where multiplications are slow.
55 /* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
56 #define CFS_GOLDEN_RATIO_PRIME_32 0x9e370001UL
57 /* 2^63 + 2^61 - 2^57 + 2^54 - 2^51 - 2^18 + 1 */
58 #define CFS_GOLDEN_RATIO_PRIME_64 0x9e37fffffffc0001ULL
61 #define CFS_HASH_DEBUG_NONE 0
62 /** record hash depth and output to console when it's too deep,
63 * computing overhead is low but consume more memory */
64 #define CFS_HASH_DEBUG_1 1
65 /** expensive, check key validation */
66 #define CFS_HASH_DEBUG_2 2
68 #define CFS_HASH_DEBUG_LEVEL CFS_HASH_DEBUG_NONE
71 struct cfs_hash_lock_ops;
72 struct cfs_hash_hlist_ops;
75 rwlock_t rw; /**< rwlock */
76 spinlock_t spin; /**< spinlock */
77 struct rw_semaphore rw_sem; /**< rwsem */
81 * cfs_hash_bucket is a container of:
83 * - array of hash-head starting from hsb_head[0], hash-head can be one of
84 * . struct cfs_hash_head
85 * . struct cfs_hash_head_dep
86 * . struct cfs_hash_dhead
87 * . struct cfs_hash_dhead_dep
88 * which depends on requirement of user
89 * - some extra bytes (caller can require it while creating hash)
91 struct cfs_hash_bucket {
92 union cfs_hash_lock hsb_lock; /**< bucket lock */
93 __u32 hsb_count; /**< current entries */
94 __u32 hsb_version; /**< change version */
95 unsigned int hsb_index; /**< index of bucket */
96 int hsb_depmax; /**< max depth on bucket */
97 long hsb_head[0]; /**< hash-head array */
101 * cfs_hash bucket descriptor, it's normally in stack of caller
104 /**< address of bucket */
105 struct cfs_hash_bucket *bd_bucket;
106 /**< offset in bucket */
107 unsigned int bd_offset;
110 #define CFS_HASH_NAME_LEN 16 /**< default name length */
111 #define CFS_HASH_BIGNAME_LEN 64 /**< bigname for param tree */
113 #define CFS_HASH_BKT_BITS 3 /**< default bits of bucket */
114 #define CFS_HASH_BITS_MAX 30 /**< max bits of bucket */
115 #define CFS_HASH_BITS_MIN CFS_HASH_BKT_BITS
118 * common hash attributes.
122 * don't need any lock, caller will protect operations with it's
123 * own lock. With this flag:
124 * . CFS_HASH_NO_BKTLOCK, CFS_HASH_RW_BKTLOCK, CFS_HASH_SPIN_BKTLOCK
126 * . Some functions will be disabled with this flag, i.e:
127 * cfs_hash_for_each_empty, cfs_hash_rehash
129 CFS_HASH_NO_LOCK = BIT(0),
130 /** no bucket lock, use one spinlock to protect the whole hash */
131 CFS_HASH_NO_BKTLOCK = BIT(1),
132 /** rwlock to protect bucket */
133 CFS_HASH_RW_BKTLOCK = BIT(2),
134 /** spinlock to protect bucket */
135 CFS_HASH_SPIN_BKTLOCK = BIT(3),
136 /** always add new item to tail */
137 CFS_HASH_ADD_TAIL = BIT(4),
138 /** hash-table doesn't have refcount on item */
139 CFS_HASH_NO_ITEMREF = BIT(5),
140 /** big name for param-tree */
141 CFS_HASH_BIGNAME = BIT(6),
142 /** track global count */
143 CFS_HASH_COUNTER = BIT(7),
144 /** rehash item by new key */
145 CFS_HASH_REHASH_KEY = BIT(8),
146 /** Enable dynamic hash resizing */
147 CFS_HASH_REHASH = BIT(9),
148 /** can shrink hash-size */
149 CFS_HASH_SHRINK = BIT(10),
150 /** assert hash is empty on exit */
151 CFS_HASH_ASSERT_EMPTY = BIT(11),
152 /** record hlist depth */
153 CFS_HASH_DEPTH = BIT(12),
155 * rehash is always scheduled in a different thread, so current
156 * change on hash table is non-blocking
158 CFS_HASH_NBLK_CHANGE = BIT(13),
159 /** rw semaphore lock to protect bucket */
160 CFS_HASH_RW_SEM_BKTLOCK = BIT(14),
161 /** NB, we typed hs_flags as __u16, please change it
162 * if you need to extend >=16 flags
166 /** most used attributes */
167 #define CFS_HASH_DEFAULT (CFS_HASH_RW_BKTLOCK | \
168 CFS_HASH_COUNTER | CFS_HASH_REHASH)
171 * cfs_hash is a hash-table implementation for general purpose, it can support:
172 * . two refcount modes
173 * hash-table with & without refcount
175 * nolock, one-spinlock, rw-bucket-lock, spin-bucket-lock
176 * . general operations
177 * lookup, add(add_tail or add_head), delete
181 * locked iteration and unlocked iteration
183 * support long name hash
185 * trace max searching depth
188 * When the htable grows or shrinks, a separate task (cfs_hash_rehash_worker)
189 * is spawned to handle the rehash in the background, it's possible that other
190 * processes can concurrently perform additions, deletions, and lookups
191 * without being blocked on rehash completion, because rehash will release
192 * the global wrlock for each bucket.
194 * rehash and iteration can't run at the same time because it's too tricky
195 * to keep both of them safe and correct.
196 * As they are relatively rare operations, so:
197 * . if iteration is in progress while we try to launch rehash, then
198 * it just giveup, iterator will launch rehash at the end.
199 * . if rehash is in progress while we try to iterate the hash table,
200 * then we just wait (shouldn't be very long time), anyway, nobody
201 * should expect iteration of whole hash-table to be non-blocking.
203 * During rehashing, a (key,object) pair may be in one of two buckets,
204 * depending on whether the worker task has yet to transfer the object
205 * to its new location in the table. Lookups and deletions need to search both
206 * locations; additions must take care to only insert into the new bucket.
210 /** serialize with rehash, or serialize all operations if
211 * the hash-table has CFS_HASH_NO_BKTLOCK */
212 union cfs_hash_lock hs_lock;
213 /** hash operations */
214 struct cfs_hash_ops *hs_ops;
215 /** hash lock operations */
216 struct cfs_hash_lock_ops *hs_lops;
217 /** hash list operations */
218 struct cfs_hash_hlist_ops *hs_hops;
219 /** hash buckets-table */
220 struct cfs_hash_bucket **hs_buckets;
221 /** total number of items on this hash-table */
223 /** hash flags, see cfs_hash_tag for detail */
225 /** # of extra-bytes for bucket, for user saving extended attributes */
226 __u16 hs_extra_bytes;
227 /** wants to iterate */
229 /** hash-table is dying */
231 /** current hash bits */
237 /** bits for rehash */
239 /** bits for each bucket */
241 /** resize min threshold */
243 /** resize max threshold */
246 __u32 hs_rehash_count;
247 /** # of iterators (caller of cfs_hash_for_each_*) */
249 /** rehash workitem */
250 struct work_struct hs_rehash_work;
251 /** refcount on this hash table */
252 atomic_t hs_refcount;
253 /** rehash buckets-table */
254 struct cfs_hash_bucket **hs_rehash_buckets;
255 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
256 /** serialize debug members */
257 spinlock_t hs_dep_lock;
259 unsigned int hs_dep_max;
260 /** id of the deepest bucket */
261 unsigned int hs_dep_bkt;
262 /** offset in the deepest bucket */
263 unsigned int hs_dep_off;
264 /** bits when we found the max depth */
265 unsigned int hs_dep_bits;
266 /** workitem to output max depth */
267 struct work_struct hs_dep_work;
269 /** name of htable */
273 struct cfs_hash_lock_ops {
274 /** lock the hash table */
275 void (*hs_lock)(union cfs_hash_lock *lock, int exclusive);
276 /** unlock the hash table */
277 void (*hs_unlock)(union cfs_hash_lock *lock, int exclusive);
278 /** lock the hash bucket */
279 void (*hs_bkt_lock)(union cfs_hash_lock *lock, int exclusive);
280 /** unlock the hash bucket */
281 void (*hs_bkt_unlock)(union cfs_hash_lock *lock, int exclusive);
284 struct cfs_hash_hlist_ops {
285 /** return hlist_head of hash-head of @bd */
286 struct hlist_head *(*hop_hhead)(struct cfs_hash *hs, struct cfs_hash_bd *bd);
287 /** return hash-head size */
288 int (*hop_hhead_size)(struct cfs_hash *hs);
289 /** add @hnode to hash-head of @bd */
290 int (*hop_hnode_add)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
291 struct hlist_node *hnode);
292 /** remove @hnode from hash-head of @bd */
293 int (*hop_hnode_del)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
294 struct hlist_node *hnode);
297 struct cfs_hash_ops {
298 /** return hashed value from @key */
299 unsigned (*hs_hash)(struct cfs_hash *hs, const void *key, unsigned mask);
300 /** return key address of @hnode */
301 void * (*hs_key)(struct hlist_node *hnode);
302 /** copy key from @hnode to @key */
303 void (*hs_keycpy)(struct hlist_node *hnode, void *key);
305 * compare @key with key of @hnode
306 * returns 1 on a match
308 int (*hs_keycmp)(const void *key, struct hlist_node *hnode);
309 /** return object address of @hnode, i.e: container_of(...hnode) */
310 void * (*hs_object)(struct hlist_node *hnode);
311 /** get refcount of item, always called with holding bucket-lock */
312 void (*hs_get)(struct cfs_hash *hs, struct hlist_node *hnode);
313 /** release refcount of item */
314 void (*hs_put)(struct cfs_hash *hs, struct hlist_node *hnode);
315 /** release refcount of item, always called with holding bucket-lock */
316 void (*hs_put_locked)(struct cfs_hash *hs, struct hlist_node *hnode);
317 /** it's called before removing of @hnode */
318 void (*hs_exit)(struct cfs_hash *hs, struct hlist_node *hnode);
321 /** total number of buckets in @hs */
322 #define CFS_HASH_NBKT(hs) \
323 (1U << ((hs)->hs_cur_bits - (hs)->hs_bkt_bits))
325 /** total number of buckets in @hs while rehashing */
326 #define CFS_HASH_RH_NBKT(hs) \
327 (1U << ((hs)->hs_rehash_bits - (hs)->hs_bkt_bits))
329 /** number of hlist for in bucket */
330 #define CFS_HASH_BKT_NHLIST(hs) (1U << (hs)->hs_bkt_bits)
332 /** total number of hlist in @hs */
333 #define CFS_HASH_NHLIST(hs) (1U << (hs)->hs_cur_bits)
335 /** total number of hlist in @hs while rehashing */
336 #define CFS_HASH_RH_NHLIST(hs) (1U << (hs)->hs_rehash_bits)
339 cfs_hash_with_no_lock(struct cfs_hash *hs)
341 /* caller will serialize all operations for this hash-table */
342 return (hs->hs_flags & CFS_HASH_NO_LOCK) != 0;
346 cfs_hash_with_no_bktlock(struct cfs_hash *hs)
348 /* no bucket lock, one single lock to protect the hash-table */
349 return (hs->hs_flags & CFS_HASH_NO_BKTLOCK) != 0;
353 cfs_hash_with_rw_bktlock(struct cfs_hash *hs)
355 /* rwlock to protect hash bucket */
356 return (hs->hs_flags & CFS_HASH_RW_BKTLOCK) != 0;
360 cfs_hash_with_spin_bktlock(struct cfs_hash *hs)
362 /* spinlock to protect hash bucket */
363 return (hs->hs_flags & CFS_HASH_SPIN_BKTLOCK) != 0;
367 cfs_hash_with_rw_sem_bktlock(struct cfs_hash *hs)
369 /* rw sem lock to protect hash bucket */
370 return (hs->hs_flags & CFS_HASH_RW_SEM_BKTLOCK) != 0;
374 cfs_hash_with_add_tail(struct cfs_hash *hs)
376 return (hs->hs_flags & CFS_HASH_ADD_TAIL) != 0;
380 cfs_hash_with_no_itemref(struct cfs_hash *hs)
382 /* hash-table doesn't keep refcount on item,
383 * item can't be removed from hash unless it's
385 return (hs->hs_flags & CFS_HASH_NO_ITEMREF) != 0;
389 cfs_hash_with_bigname(struct cfs_hash *hs)
391 return (hs->hs_flags & CFS_HASH_BIGNAME) != 0;
395 cfs_hash_with_counter(struct cfs_hash *hs)
397 return (hs->hs_flags & CFS_HASH_COUNTER) != 0;
401 cfs_hash_with_rehash(struct cfs_hash *hs)
403 return (hs->hs_flags & CFS_HASH_REHASH) != 0;
407 cfs_hash_with_rehash_key(struct cfs_hash *hs)
409 return (hs->hs_flags & CFS_HASH_REHASH_KEY) != 0;
413 cfs_hash_with_shrink(struct cfs_hash *hs)
415 return (hs->hs_flags & CFS_HASH_SHRINK) != 0;
419 cfs_hash_with_assert_empty(struct cfs_hash *hs)
421 return (hs->hs_flags & CFS_HASH_ASSERT_EMPTY) != 0;
425 cfs_hash_with_depth(struct cfs_hash *hs)
427 return (hs->hs_flags & CFS_HASH_DEPTH) != 0;
431 cfs_hash_with_nblk_change(struct cfs_hash *hs)
433 return (hs->hs_flags & CFS_HASH_NBLK_CHANGE) != 0;
437 cfs_hash_is_exiting(struct cfs_hash *hs)
438 { /* cfs_hash_destroy is called */
439 return hs->hs_exiting;
443 cfs_hash_is_rehashing(struct cfs_hash *hs)
444 { /* rehash is launched */
445 return hs->hs_rehash_bits != 0;
449 cfs_hash_is_iterating(struct cfs_hash *hs)
450 { /* someone is calling cfs_hash_for_each_* */
451 return hs->hs_iterating || hs->hs_iterators != 0;
455 cfs_hash_bkt_size(struct cfs_hash *hs)
457 return offsetof(struct cfs_hash_bucket, hsb_head[0]) +
458 hs->hs_hops->hop_hhead_size(hs) * CFS_HASH_BKT_NHLIST(hs) +
462 static inline unsigned
463 cfs_hash_id(struct cfs_hash *hs, const void *key, unsigned mask)
465 return hs->hs_ops->hs_hash(hs, key, mask);
469 cfs_hash_key(struct cfs_hash *hs, struct hlist_node *hnode)
471 return hs->hs_ops->hs_key(hnode);
475 cfs_hash_keycpy(struct cfs_hash *hs, struct hlist_node *hnode, void *key)
477 if (hs->hs_ops->hs_keycpy != NULL)
478 hs->hs_ops->hs_keycpy(hnode, key);
482 * Returns 1 on a match,
485 cfs_hash_keycmp(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
487 return hs->hs_ops->hs_keycmp(key, hnode);
491 cfs_hash_object(struct cfs_hash *hs, struct hlist_node *hnode)
493 return hs->hs_ops->hs_object(hnode);
497 cfs_hash_get(struct cfs_hash *hs, struct hlist_node *hnode)
499 return hs->hs_ops->hs_get(hs, hnode);
503 cfs_hash_put_locked(struct cfs_hash *hs, struct hlist_node *hnode)
505 return hs->hs_ops->hs_put_locked(hs, hnode);
509 cfs_hash_put(struct cfs_hash *hs, struct hlist_node *hnode)
511 return hs->hs_ops->hs_put(hs, hnode);
515 cfs_hash_exit(struct cfs_hash *hs, struct hlist_node *hnode)
517 if (hs->hs_ops->hs_exit)
518 hs->hs_ops->hs_exit(hs, hnode);
521 static inline void cfs_hash_lock(struct cfs_hash *hs, int excl)
523 hs->hs_lops->hs_lock(&hs->hs_lock, excl);
526 static inline void cfs_hash_unlock(struct cfs_hash *hs, int excl)
528 hs->hs_lops->hs_unlock(&hs->hs_lock, excl);
531 static inline int cfs_hash_dec_and_lock(struct cfs_hash *hs,
534 LASSERT(cfs_hash_with_no_bktlock(hs));
535 return atomic_dec_and_lock(condition, &hs->hs_lock.spin);
538 static inline void cfs_hash_bd_lock(struct cfs_hash *hs,
539 struct cfs_hash_bd *bd, int excl)
541 hs->hs_lops->hs_bkt_lock(&bd->bd_bucket->hsb_lock, excl);
544 static inline void cfs_hash_bd_unlock(struct cfs_hash *hs,
545 struct cfs_hash_bd *bd, int excl)
547 hs->hs_lops->hs_bkt_unlock(&bd->bd_bucket->hsb_lock, excl);
551 * operations on cfs_hash bucket (bd: bucket descriptor),
552 * they are normally for hash-table without rehash
554 void cfs_hash_bd_get(struct cfs_hash *hs, const void *key,
555 struct cfs_hash_bd *bd);
558 cfs_hash_bd_get_and_lock(struct cfs_hash *hs, const void *key,
559 struct cfs_hash_bd *bd, int excl)
561 cfs_hash_bd_get(hs, key, bd);
562 cfs_hash_bd_lock(hs, bd, excl);
565 static inline unsigned
566 cfs_hash_bd_index_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
568 return bd->bd_offset | (bd->bd_bucket->hsb_index << hs->hs_bkt_bits);
572 cfs_hash_bd_index_set(struct cfs_hash *hs, unsigned index,
573 struct cfs_hash_bd *bd)
575 bd->bd_bucket = hs->hs_buckets[index >> hs->hs_bkt_bits];
576 bd->bd_offset = index & (CFS_HASH_BKT_NHLIST(hs) - 1U);
580 cfs_hash_bd_extra_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
582 return (void *)bd->bd_bucket +
583 cfs_hash_bkt_size(hs) - hs->hs_extra_bytes;
587 cfs_hash_bd_version_get(struct cfs_hash_bd *bd)
589 /* need hold cfs_hash_bd_lock */
590 return bd->bd_bucket->hsb_version;
594 cfs_hash_bd_count_get(struct cfs_hash_bd *bd)
596 /* need hold cfs_hash_bd_lock */
597 return bd->bd_bucket->hsb_count;
601 cfs_hash_bd_depmax_get(struct cfs_hash_bd *bd)
603 return bd->bd_bucket->hsb_depmax;
607 cfs_hash_bd_compare(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
609 if (bd1->bd_bucket->hsb_index != bd2->bd_bucket->hsb_index)
610 return bd1->bd_bucket->hsb_index - bd2->bd_bucket->hsb_index;
612 if (bd1->bd_offset != bd2->bd_offset)
613 return bd1->bd_offset - bd2->bd_offset;
618 void cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
619 struct hlist_node *hnode);
620 void cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
621 struct hlist_node *hnode);
622 void cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
623 struct cfs_hash_bd *bd_new,
624 struct hlist_node *hnode);
627 cfs_hash_bd_dec_and_lock(struct cfs_hash *hs, struct cfs_hash_bd *bd,
630 LASSERT(cfs_hash_with_spin_bktlock(hs));
631 return atomic_dec_and_lock(condition, &bd->bd_bucket->hsb_lock.spin);
634 static inline struct hlist_head *
635 cfs_hash_bd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
637 return hs->hs_hops->hop_hhead(hs, bd);
641 cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
644 cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
647 cfs_hash_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
648 const void *key, struct hlist_node *hnode,
651 cfs_hash_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
652 const void *key, struct hlist_node *hnode);
655 * operations on cfs_hash bucket (bd: bucket descriptor),
656 * they are safe for hash-table with rehash
658 void cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key,
659 struct cfs_hash_bd *bds);
660 void cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
662 void cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
666 cfs_hash_dual_bd_get_and_lock(struct cfs_hash *hs, const void *key,
667 struct cfs_hash_bd *bds, int excl)
669 cfs_hash_dual_bd_get(hs, key, bds);
670 cfs_hash_dual_bd_lock(hs, bds, excl);
674 cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
677 cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
678 const void *key, struct hlist_node *hnode,
681 cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
682 const void *key, struct hlist_node *hnode);
684 /* Hash init/cleanup functions */
686 cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits,
687 unsigned bkt_bits, unsigned extra_bytes,
688 unsigned min_theta, unsigned max_theta,
689 struct cfs_hash_ops *ops, unsigned flags);
691 struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs);
692 void cfs_hash_putref(struct cfs_hash *hs);
694 /* Hash addition functions */
695 void cfs_hash_add(struct cfs_hash *hs, const void *key,
696 struct hlist_node *hnode);
697 int cfs_hash_add_unique(struct cfs_hash *hs, const void *key,
698 struct hlist_node *hnode);
699 void *cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
700 struct hlist_node *hnode);
702 /* Hash deletion functions */
703 void *cfs_hash_del(struct cfs_hash *hs, const void *key,
704 struct hlist_node *hnode);
705 void *cfs_hash_del_key(struct cfs_hash *hs, const void *key);
707 /* Hash lookup/for_each functions */
708 #define CFS_HASH_LOOP_HOG 1024
710 typedef int (*cfs_hash_for_each_cb_t)(struct cfs_hash *hs,
711 struct cfs_hash_bd *bd,
712 struct hlist_node *node,
715 cfs_hash_lookup(struct cfs_hash *hs, const void *key);
717 cfs_hash_for_each(struct cfs_hash *hs, cfs_hash_for_each_cb_t, void *data);
719 cfs_hash_for_each_safe(struct cfs_hash *hs, cfs_hash_for_each_cb_t, void *data);
721 cfs_hash_for_each_nolock(struct cfs_hash *hs, cfs_hash_for_each_cb_t,
722 void *data, int start);
724 cfs_hash_for_each_empty(struct cfs_hash *hs, cfs_hash_for_each_cb_t,
727 cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
728 cfs_hash_for_each_cb_t, void *data);
729 typedef int (*cfs_hash_cond_opt_cb_t)(void *obj, void *data);
731 cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t, void *data);
734 cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned hindex,
735 cfs_hash_for_each_cb_t, void *data);
736 int cfs_hash_is_empty(struct cfs_hash *hs);
737 __u64 cfs_hash_size_get(struct cfs_hash *hs);
740 * Rehash - Theta is calculated to be the average chained
741 * hash depth assuming a perfectly uniform hash function.
743 void cfs_hash_rehash_cancel_locked(struct cfs_hash *hs);
744 void cfs_hash_rehash_cancel(struct cfs_hash *hs);
745 void cfs_hash_rehash(struct cfs_hash *hs, int do_rehash);
746 void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
747 void *new_key, struct hlist_node *hnode);
749 #if CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1
750 /* Validate hnode references the correct key */
752 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
753 struct hlist_node *hnode)
755 LASSERT(cfs_hash_keycmp(hs, key, hnode));
758 /* Validate hnode is in the correct bucket */
760 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
761 struct hlist_node *hnode)
763 struct cfs_hash_bd bds[2];
765 cfs_hash_dual_bd_get(hs, cfs_hash_key(hs, hnode), bds);
766 LASSERT(bds[0].bd_bucket == bd->bd_bucket ||
767 bds[1].bd_bucket == bd->bd_bucket);
770 #else /* CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1 */
773 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
774 struct hlist_node *hnode) {}
777 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
778 struct hlist_node *hnode) {}
780 #endif /* CFS_HASH_DEBUG_LEVEL */
782 #define CFS_HASH_THETA_BITS 10
783 #define CFS_HASH_MIN_THETA (1U << (CFS_HASH_THETA_BITS - 1))
784 #define CFS_HASH_MAX_THETA (1U << (CFS_HASH_THETA_BITS + 1))
786 /* Return integer component of theta */
787 static inline int __cfs_hash_theta_int(int theta)
789 return (theta >> CFS_HASH_THETA_BITS);
792 /* Return a fractional value between 0 and 999 */
793 static inline int __cfs_hash_theta_frac(int theta)
795 return ((theta * 1000) >> CFS_HASH_THETA_BITS) -
796 (__cfs_hash_theta_int(theta) * 1000);
799 static inline int __cfs_hash_theta(struct cfs_hash *hs)
801 return (atomic_read(&hs->hs_count) <<
802 CFS_HASH_THETA_BITS) >> hs->hs_cur_bits;
806 __cfs_hash_set_theta(struct cfs_hash *hs, int min, int max)
809 hs->hs_min_theta = (__u16)min;
810 hs->hs_max_theta = (__u16)max;
813 /* Generic debug formatting routines mainly for proc handler */
815 void cfs_hash_debug_header(struct seq_file *m);
816 void cfs_hash_debug_str(struct cfs_hash *hs, struct seq_file *m);
819 * Generic djb2 hash algorithm for character arrays.
821 static inline unsigned
822 cfs_hash_djb2_hash(const void *key, size_t size, unsigned mask)
824 unsigned i, hash = 5381;
826 LASSERT(key != NULL);
828 for (i = 0; i < size; i++)
829 hash = hash * 33 + ((char *)key)[i];
831 return (hash & mask);
835 * Generic u32 hash algorithm.
837 static inline unsigned
838 cfs_hash_u32_hash(const __u32 key, unsigned mask)
840 return ((key * CFS_GOLDEN_RATIO_PRIME_32) & mask);
844 * Generic u64 hash algorithm.
846 static inline unsigned
847 cfs_hash_u64_hash(const __u64 key, unsigned mask)
849 return ((unsigned)(key * CFS_GOLDEN_RATIO_PRIME_64) & mask);
852 /** iterate over all buckets in @bds (array of struct cfs_hash_bd) */
853 #define cfs_hash_for_each_bd(bds, n, i) \
854 for (i = 0; i < n && (bds)[i].bd_bucket != NULL; i++)
856 /** iterate over all buckets of @hs */
857 #define cfs_hash_for_each_bucket(hs, bd, pos) \
859 pos < CFS_HASH_NBKT(hs) && \
860 ((bd)->bd_bucket = (hs)->hs_buckets[pos]) != NULL; pos++)
862 /** iterate over all hlist of bucket @bd */
863 #define cfs_hash_bd_for_each_hlist(hs, bd, hlist) \
864 for ((bd)->bd_offset = 0; \
865 (bd)->bd_offset < CFS_HASH_BKT_NHLIST(hs) && \
866 (hlist = cfs_hash_bd_hhead(hs, bd)) != NULL; \
869 /* !__LIBCFS__HASH_H__ */