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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.
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29 * This file is part of Lustre, http://www.lustre.org/
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32 * libcfs/include/libcfs/libcfs_hash.h
38 #ifndef __LIBCFS_HASH_H__
39 #define __LIBCFS_HASH_H__
41 #include <linux/hash.h>
44 * Knuth recommends primes in approximately golden ratio to the maximum
45 * integer representable by a machine word for multiplicative hashing.
46 * Chuck Lever verified the effectiveness of this technique:
47 * http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
49 * These primes are chosen to be bit-sparse, that is operations on
50 * them can use shifts and additions instead of multiplications for
51 * machines where multiplications are slow.
53 /* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
54 #define CFS_GOLDEN_RATIO_PRIME_32 0x9e370001UL
55 /* 2^63 + 2^61 - 2^57 + 2^54 - 2^51 - 2^18 + 1 */
56 #define CFS_GOLDEN_RATIO_PRIME_64 0x9e37fffffffc0001ULL
59 #define CFS_HASH_DEBUG_NONE 0
60 /** record hash depth and output to console when it's too deep,
61 * computing overhead is low but consume more memory */
62 #define CFS_HASH_DEBUG_1 1
63 /** expensive, check key validation */
64 #define CFS_HASH_DEBUG_2 2
66 #define CFS_HASH_DEBUG_LEVEL CFS_HASH_DEBUG_NONE
69 struct cfs_hash_lock_ops;
70 struct cfs_hash_hlist_ops;
73 rwlock_t rw; /**< rwlock */
74 spinlock_t spin; /**< spinlock */
78 * cfs_hash_bucket is a container of:
80 * - array of hash-head starting from hsb_head[0], hash-head can be one of
81 * . struct cfs_hash_head
82 * . struct cfs_hash_head_dep
83 * . struct cfs_hash_dhead
84 * . struct cfs_hash_dhead_dep
85 * which depends on requirement of user
86 * - some extra bytes (caller can require it while creating hash)
88 struct cfs_hash_bucket {
89 union cfs_hash_lock hsb_lock; /**< bucket lock */
90 __u32 hsb_count; /**< current entries */
91 __u32 hsb_version; /**< change version */
92 unsigned int hsb_index; /**< index of bucket */
93 int hsb_depmax; /**< max depth on bucket */
94 long hsb_head[0]; /**< hash-head array */
98 * cfs_hash bucket descriptor, it's normally in stack of caller
101 /**< address of bucket */
102 struct cfs_hash_bucket *bd_bucket;
103 /**< offset in bucket */
104 unsigned int bd_offset;
107 #define CFS_HASH_NAME_LEN 16 /**< default name length */
108 #define CFS_HASH_BIGNAME_LEN 64 /**< bigname for param tree */
110 #define CFS_HASH_BKT_BITS 3 /**< default bits of bucket */
111 #define CFS_HASH_BITS_MAX 30 /**< max bits of bucket */
112 #define CFS_HASH_BITS_MIN CFS_HASH_BKT_BITS
115 * common hash attributes.
119 * don't need any lock, caller will protect operations with it's
120 * own lock. With this flag:
121 * . CFS_HASH_NO_BKTLOCK, CFS_HASH_RW_BKTLOCK, CFS_HASH_SPIN_BKTLOCK
123 * . Some functions will be disabled with this flag, i.e:
124 * cfs_hash_for_each_empty, cfs_hash_rehash
126 CFS_HASH_NO_LOCK = 1 << 0,
127 /** no bucket lock, use one spinlock to protect the whole hash */
128 CFS_HASH_NO_BKTLOCK = 1 << 1,
129 /** rwlock to protect bucket */
130 CFS_HASH_RW_BKTLOCK = 1 << 2,
131 /** spinlock to protect bucket */
132 CFS_HASH_SPIN_BKTLOCK = 1 << 3,
133 /** always add new item to tail */
134 CFS_HASH_ADD_TAIL = 1 << 4,
135 /** hash-table doesn't have refcount on item */
136 CFS_HASH_NO_ITEMREF = 1 << 5,
137 /** big name for param-tree */
138 CFS_HASH_BIGNAME = 1 << 6,
139 /** track global count */
140 CFS_HASH_COUNTER = 1 << 7,
141 /** rehash item by new key */
142 CFS_HASH_REHASH_KEY = 1 << 8,
143 /** Enable dynamic hash resizing */
144 CFS_HASH_REHASH = 1 << 9,
145 /** can shrink hash-size */
146 CFS_HASH_SHRINK = 1 << 10,
147 /** assert hash is empty on exit */
148 CFS_HASH_ASSERT_EMPTY = 1 << 11,
149 /** record hlist depth */
150 CFS_HASH_DEPTH = 1 << 12,
152 * rehash is always scheduled in a different thread, so current
153 * change on hash table is non-blocking
155 CFS_HASH_NBLK_CHANGE = 1 << 13,
156 /** NB, we typed hs_flags as __u16, please change it
157 * if you need to extend >=16 flags */
160 /** most used attributes */
161 #define CFS_HASH_DEFAULT (CFS_HASH_RW_BKTLOCK | \
162 CFS_HASH_COUNTER | CFS_HASH_REHASH)
165 * cfs_hash is a hash-table implementation for general purpose, it can support:
166 * . two refcount modes
167 * hash-table with & without refcount
169 * nolock, one-spinlock, rw-bucket-lock, spin-bucket-lock
170 * . general operations
171 * lookup, add(add_tail or add_head), delete
175 * locked iteration and unlocked iteration
177 * support long name hash
179 * trace max searching depth
182 * When the htable grows or shrinks, a separate task (cfs_hash_rehash_worker)
183 * is spawned to handle the rehash in the background, it's possible that other
184 * processes can concurrently perform additions, deletions, and lookups
185 * without being blocked on rehash completion, because rehash will release
186 * the global wrlock for each bucket.
188 * rehash and iteration can't run at the same time because it's too tricky
189 * to keep both of them safe and correct.
190 * As they are relatively rare operations, so:
191 * . if iteration is in progress while we try to launch rehash, then
192 * it just giveup, iterator will launch rehash at the end.
193 * . if rehash is in progress while we try to iterate the hash table,
194 * then we just wait (shouldn't be very long time), anyway, nobody
195 * should expect iteration of whole hash-table to be non-blocking.
197 * During rehashing, a (key,object) pair may be in one of two buckets,
198 * depending on whether the worker task has yet to transfer the object
199 * to its new location in the table. Lookups and deletions need to search both
200 * locations; additions must take care to only insert into the new bucket.
204 /** serialize with rehash, or serialize all operations if
205 * the hash-table has CFS_HASH_NO_BKTLOCK */
206 union cfs_hash_lock hs_lock;
207 /** hash operations */
208 struct cfs_hash_ops *hs_ops;
209 /** hash lock operations */
210 struct cfs_hash_lock_ops *hs_lops;
211 /** hash list operations */
212 struct cfs_hash_hlist_ops *hs_hops;
213 /** hash buckets-table */
214 struct cfs_hash_bucket **hs_buckets;
215 /** total number of items on this hash-table */
217 /** hash flags, see cfs_hash_tag for detail */
219 /** # of extra-bytes for bucket, for user saving extended attributes */
220 __u16 hs_extra_bytes;
221 /** wants to iterate */
223 /** hash-table is dying */
225 /** current hash bits */
231 /** bits for rehash */
233 /** bits for each bucket */
235 /** resize min threshold */
237 /** resize max threshold */
240 __u32 hs_rehash_count;
241 /** # of iterators (caller of cfs_hash_for_each_*) */
243 /** rehash workitem */
244 struct cfs_workitem hs_rehash_wi;
245 /** refcount on this hash table */
246 atomic_t hs_refcount;
247 /** rehash buckets-table */
248 struct cfs_hash_bucket **hs_rehash_buckets;
249 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
250 /** serialize debug members */
251 spinlock_t hs_dep_lock;
253 unsigned int hs_dep_max;
254 /** id of the deepest bucket */
255 unsigned int hs_dep_bkt;
256 /** offset in the deepest bucket */
257 unsigned int hs_dep_off;
258 /** bits when we found the max depth */
259 unsigned int hs_dep_bits;
260 /** workitem to output max depth */
261 struct cfs_workitem hs_dep_wi;
263 /** name of htable */
267 struct cfs_hash_lock_ops {
268 /** lock the hash table */
269 void (*hs_lock)(union cfs_hash_lock *lock, int exclusive);
270 /** unlock the hash table */
271 void (*hs_unlock)(union cfs_hash_lock *lock, int exclusive);
272 /** lock the hash bucket */
273 void (*hs_bkt_lock)(union cfs_hash_lock *lock, int exclusive);
274 /** unlock the hash bucket */
275 void (*hs_bkt_unlock)(union cfs_hash_lock *lock, int exclusive);
278 struct cfs_hash_hlist_ops {
279 /** return hlist_head of hash-head of @bd */
280 struct hlist_head *(*hop_hhead)(struct cfs_hash *hs, struct cfs_hash_bd *bd);
281 /** return hash-head size */
282 int (*hop_hhead_size)(struct cfs_hash *hs);
283 /** add @hnode to hash-head of @bd */
284 int (*hop_hnode_add)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
285 struct hlist_node *hnode);
286 /** remove @hnode from hash-head of @bd */
287 int (*hop_hnode_del)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
288 struct hlist_node *hnode);
291 struct cfs_hash_ops {
292 /** return hashed value from @key */
293 unsigned (*hs_hash)(struct cfs_hash *hs, const void *key, unsigned mask);
294 /** return key address of @hnode */
295 void * (*hs_key)(struct hlist_node *hnode);
296 /** copy key from @hnode to @key */
297 void (*hs_keycpy)(struct hlist_node *hnode, void *key);
299 * compare @key with key of @hnode
300 * returns 1 on a match
302 int (*hs_keycmp)(const void *key, struct hlist_node *hnode);
303 /** return object address of @hnode, i.e: container_of(...hnode) */
304 void * (*hs_object)(struct hlist_node *hnode);
305 /** get refcount of item, always called with holding bucket-lock */
306 void (*hs_get)(struct cfs_hash *hs, struct hlist_node *hnode);
307 /** release refcount of item */
308 void (*hs_put)(struct cfs_hash *hs, struct hlist_node *hnode);
309 /** release refcount of item, always called with holding bucket-lock */
310 void (*hs_put_locked)(struct cfs_hash *hs, struct hlist_node *hnode);
311 /** it's called before removing of @hnode */
312 void (*hs_exit)(struct cfs_hash *hs, struct hlist_node *hnode);
315 /** total number of buckets in @hs */
316 #define CFS_HASH_NBKT(hs) \
317 (1U << ((hs)->hs_cur_bits - (hs)->hs_bkt_bits))
319 /** total number of buckets in @hs while rehashing */
320 #define CFS_HASH_RH_NBKT(hs) \
321 (1U << ((hs)->hs_rehash_bits - (hs)->hs_bkt_bits))
323 /** number of hlist for in bucket */
324 #define CFS_HASH_BKT_NHLIST(hs) (1U << (hs)->hs_bkt_bits)
326 /** total number of hlist in @hs */
327 #define CFS_HASH_NHLIST(hs) (1U << (hs)->hs_cur_bits)
329 /** total number of hlist in @hs while rehashing */
330 #define CFS_HASH_RH_NHLIST(hs) (1U << (hs)->hs_rehash_bits)
333 cfs_hash_with_no_lock(struct cfs_hash *hs)
335 /* caller will serialize all operations for this hash-table */
336 return (hs->hs_flags & CFS_HASH_NO_LOCK) != 0;
340 cfs_hash_with_no_bktlock(struct cfs_hash *hs)
342 /* no bucket lock, one single lock to protect the hash-table */
343 return (hs->hs_flags & CFS_HASH_NO_BKTLOCK) != 0;
347 cfs_hash_with_rw_bktlock(struct cfs_hash *hs)
349 /* rwlock to protect hash bucket */
350 return (hs->hs_flags & CFS_HASH_RW_BKTLOCK) != 0;
354 cfs_hash_with_spin_bktlock(struct cfs_hash *hs)
356 /* spinlock to protect hash bucket */
357 return (hs->hs_flags & CFS_HASH_SPIN_BKTLOCK) != 0;
361 cfs_hash_with_add_tail(struct cfs_hash *hs)
363 return (hs->hs_flags & CFS_HASH_ADD_TAIL) != 0;
367 cfs_hash_with_no_itemref(struct cfs_hash *hs)
369 /* hash-table doesn't keep refcount on item,
370 * item can't be removed from hash unless it's
372 return (hs->hs_flags & CFS_HASH_NO_ITEMREF) != 0;
376 cfs_hash_with_bigname(struct cfs_hash *hs)
378 return (hs->hs_flags & CFS_HASH_BIGNAME) != 0;
382 cfs_hash_with_counter(struct cfs_hash *hs)
384 return (hs->hs_flags & CFS_HASH_COUNTER) != 0;
388 cfs_hash_with_rehash(struct cfs_hash *hs)
390 return (hs->hs_flags & CFS_HASH_REHASH) != 0;
394 cfs_hash_with_rehash_key(struct cfs_hash *hs)
396 return (hs->hs_flags & CFS_HASH_REHASH_KEY) != 0;
400 cfs_hash_with_shrink(struct cfs_hash *hs)
402 return (hs->hs_flags & CFS_HASH_SHRINK) != 0;
406 cfs_hash_with_assert_empty(struct cfs_hash *hs)
408 return (hs->hs_flags & CFS_HASH_ASSERT_EMPTY) != 0;
412 cfs_hash_with_depth(struct cfs_hash *hs)
414 return (hs->hs_flags & CFS_HASH_DEPTH) != 0;
418 cfs_hash_with_nblk_change(struct cfs_hash *hs)
420 return (hs->hs_flags & CFS_HASH_NBLK_CHANGE) != 0;
424 cfs_hash_is_exiting(struct cfs_hash *hs)
425 { /* cfs_hash_destroy is called */
426 return hs->hs_exiting;
430 cfs_hash_is_rehashing(struct cfs_hash *hs)
431 { /* rehash is launched */
432 return hs->hs_rehash_bits != 0;
436 cfs_hash_is_iterating(struct cfs_hash *hs)
437 { /* someone is calling cfs_hash_for_each_* */
438 return hs->hs_iterating || hs->hs_iterators != 0;
442 cfs_hash_bkt_size(struct cfs_hash *hs)
444 return offsetof(struct cfs_hash_bucket, hsb_head[0]) +
445 hs->hs_hops->hop_hhead_size(hs) * CFS_HASH_BKT_NHLIST(hs) +
449 static inline unsigned
450 cfs_hash_id(struct cfs_hash *hs, const void *key, unsigned mask)
452 return hs->hs_ops->hs_hash(hs, key, mask);
456 cfs_hash_key(struct cfs_hash *hs, struct hlist_node *hnode)
458 return hs->hs_ops->hs_key(hnode);
462 cfs_hash_keycpy(struct cfs_hash *hs, struct hlist_node *hnode, void *key)
464 if (hs->hs_ops->hs_keycpy != NULL)
465 hs->hs_ops->hs_keycpy(hnode, key);
469 * Returns 1 on a match,
472 cfs_hash_keycmp(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
474 return hs->hs_ops->hs_keycmp(key, hnode);
478 cfs_hash_object(struct cfs_hash *hs, struct hlist_node *hnode)
480 return hs->hs_ops->hs_object(hnode);
484 cfs_hash_get(struct cfs_hash *hs, struct hlist_node *hnode)
486 return hs->hs_ops->hs_get(hs, hnode);
490 cfs_hash_put_locked(struct cfs_hash *hs, struct hlist_node *hnode)
492 return hs->hs_ops->hs_put_locked(hs, hnode);
496 cfs_hash_put(struct cfs_hash *hs, struct hlist_node *hnode)
498 return hs->hs_ops->hs_put(hs, hnode);
502 cfs_hash_exit(struct cfs_hash *hs, struct hlist_node *hnode)
504 if (hs->hs_ops->hs_exit)
505 hs->hs_ops->hs_exit(hs, hnode);
508 static inline void cfs_hash_lock(struct cfs_hash *hs, int excl)
510 hs->hs_lops->hs_lock(&hs->hs_lock, excl);
513 static inline void cfs_hash_unlock(struct cfs_hash *hs, int excl)
515 hs->hs_lops->hs_unlock(&hs->hs_lock, excl);
518 static inline int cfs_hash_dec_and_lock(struct cfs_hash *hs,
521 LASSERT(cfs_hash_with_no_bktlock(hs));
522 return atomic_dec_and_lock(condition, &hs->hs_lock.spin);
525 static inline void cfs_hash_bd_lock(struct cfs_hash *hs,
526 struct cfs_hash_bd *bd, int excl)
528 hs->hs_lops->hs_bkt_lock(&bd->bd_bucket->hsb_lock, excl);
531 static inline void cfs_hash_bd_unlock(struct cfs_hash *hs,
532 struct cfs_hash_bd *bd, int excl)
534 hs->hs_lops->hs_bkt_unlock(&bd->bd_bucket->hsb_lock, excl);
538 * operations on cfs_hash bucket (bd: bucket descriptor),
539 * they are normally for hash-table without rehash
541 void cfs_hash_bd_get(struct cfs_hash *hs, const void *key,
542 struct cfs_hash_bd *bd);
545 cfs_hash_bd_get_and_lock(struct cfs_hash *hs, const void *key,
546 struct cfs_hash_bd *bd, int excl)
548 cfs_hash_bd_get(hs, key, bd);
549 cfs_hash_bd_lock(hs, bd, excl);
552 static inline unsigned
553 cfs_hash_bd_index_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
555 return bd->bd_offset | (bd->bd_bucket->hsb_index << hs->hs_bkt_bits);
559 cfs_hash_bd_index_set(struct cfs_hash *hs, unsigned index,
560 struct cfs_hash_bd *bd)
562 bd->bd_bucket = hs->hs_buckets[index >> hs->hs_bkt_bits];
563 bd->bd_offset = index & (CFS_HASH_BKT_NHLIST(hs) - 1U);
567 cfs_hash_bd_extra_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
569 return (void *)bd->bd_bucket +
570 cfs_hash_bkt_size(hs) - hs->hs_extra_bytes;
574 cfs_hash_bd_version_get(struct cfs_hash_bd *bd)
576 /* need hold cfs_hash_bd_lock */
577 return bd->bd_bucket->hsb_version;
581 cfs_hash_bd_count_get(struct cfs_hash_bd *bd)
583 /* need hold cfs_hash_bd_lock */
584 return bd->bd_bucket->hsb_count;
588 cfs_hash_bd_depmax_get(struct cfs_hash_bd *bd)
590 return bd->bd_bucket->hsb_depmax;
594 cfs_hash_bd_compare(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
596 if (bd1->bd_bucket->hsb_index != bd2->bd_bucket->hsb_index)
597 return bd1->bd_bucket->hsb_index - bd2->bd_bucket->hsb_index;
599 if (bd1->bd_offset != bd2->bd_offset)
600 return bd1->bd_offset - bd2->bd_offset;
605 void cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
606 struct hlist_node *hnode);
607 void cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
608 struct hlist_node *hnode);
609 void cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
610 struct cfs_hash_bd *bd_new,
611 struct hlist_node *hnode);
614 cfs_hash_bd_dec_and_lock(struct cfs_hash *hs, struct cfs_hash_bd *bd,
617 LASSERT(cfs_hash_with_spin_bktlock(hs));
618 return atomic_dec_and_lock(condition, &bd->bd_bucket->hsb_lock.spin);
621 static inline struct hlist_head *
622 cfs_hash_bd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
624 return hs->hs_hops->hop_hhead(hs, bd);
628 cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
631 cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
634 cfs_hash_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
635 const void *key, struct hlist_node *hnode,
638 cfs_hash_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
639 const void *key, struct hlist_node *hnode);
642 * operations on cfs_hash bucket (bd: bucket descriptor),
643 * they are safe for hash-table with rehash
645 void cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key,
646 struct cfs_hash_bd *bds);
647 void cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
649 void cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
653 cfs_hash_dual_bd_get_and_lock(struct cfs_hash *hs, const void *key,
654 struct cfs_hash_bd *bds, int excl)
656 cfs_hash_dual_bd_get(hs, key, bds);
657 cfs_hash_dual_bd_lock(hs, bds, excl);
661 cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
664 cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
665 const void *key, struct hlist_node *hnode,
668 cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
669 const void *key, struct hlist_node *hnode);
671 /* Hash init/cleanup functions */
673 cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits,
674 unsigned bkt_bits, unsigned extra_bytes,
675 unsigned min_theta, unsigned max_theta,
676 struct cfs_hash_ops *ops, unsigned flags);
678 struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs);
679 void cfs_hash_putref(struct cfs_hash *hs);
681 /* Hash addition functions */
682 void cfs_hash_add(struct cfs_hash *hs, const void *key,
683 struct hlist_node *hnode);
684 int cfs_hash_add_unique(struct cfs_hash *hs, const void *key,
685 struct hlist_node *hnode);
686 void *cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
687 struct hlist_node *hnode);
689 /* Hash deletion functions */
690 void *cfs_hash_del(struct cfs_hash *hs, const void *key,
691 struct hlist_node *hnode);
692 void *cfs_hash_del_key(struct cfs_hash *hs, const void *key);
694 /* Hash lookup/for_each functions */
695 #define CFS_HASH_LOOP_HOG 1024
697 typedef int (*cfs_hash_for_each_cb_t)(struct cfs_hash *hs,
698 struct cfs_hash_bd *bd,
699 struct hlist_node *node,
702 cfs_hash_lookup(struct cfs_hash *hs, const void *key);
704 cfs_hash_for_each(struct cfs_hash *hs, cfs_hash_for_each_cb_t, void *data);
706 cfs_hash_for_each_safe(struct cfs_hash *hs, cfs_hash_for_each_cb_t, void *data);
708 cfs_hash_for_each_nolock(struct cfs_hash *hs, cfs_hash_for_each_cb_t,
709 void *data, int start);
711 cfs_hash_for_each_empty(struct cfs_hash *hs, cfs_hash_for_each_cb_t,
714 cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
715 cfs_hash_for_each_cb_t, void *data);
716 typedef int (*cfs_hash_cond_opt_cb_t)(void *obj, void *data);
718 cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t, void *data);
721 cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned hindex,
722 cfs_hash_for_each_cb_t, void *data);
723 int cfs_hash_is_empty(struct cfs_hash *hs);
724 __u64 cfs_hash_size_get(struct cfs_hash *hs);
727 * Rehash - Theta is calculated to be the average chained
728 * hash depth assuming a perfectly uniform hash function.
730 void cfs_hash_rehash_cancel_locked(struct cfs_hash *hs);
731 void cfs_hash_rehash_cancel(struct cfs_hash *hs);
732 int cfs_hash_rehash(struct cfs_hash *hs, int do_rehash);
733 void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
734 void *new_key, struct hlist_node *hnode);
736 #if CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1
737 /* Validate hnode references the correct key */
739 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
740 struct hlist_node *hnode)
742 LASSERT(cfs_hash_keycmp(hs, key, hnode));
745 /* Validate hnode is in the correct bucket */
747 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
748 struct hlist_node *hnode)
750 struct cfs_hash_bd bds[2];
752 cfs_hash_dual_bd_get(hs, cfs_hash_key(hs, hnode), bds);
753 LASSERT(bds[0].bd_bucket == bd->bd_bucket ||
754 bds[1].bd_bucket == bd->bd_bucket);
757 #else /* CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1 */
760 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
761 struct hlist_node *hnode) {}
764 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
765 struct hlist_node *hnode) {}
767 #endif /* CFS_HASH_DEBUG_LEVEL */
769 #define CFS_HASH_THETA_BITS 10
770 #define CFS_HASH_MIN_THETA (1U << (CFS_HASH_THETA_BITS - 1))
771 #define CFS_HASH_MAX_THETA (1U << (CFS_HASH_THETA_BITS + 1))
773 /* Return integer component of theta */
774 static inline int __cfs_hash_theta_int(int theta)
776 return (theta >> CFS_HASH_THETA_BITS);
779 /* Return a fractional value between 0 and 999 */
780 static inline int __cfs_hash_theta_frac(int theta)
782 return ((theta * 1000) >> CFS_HASH_THETA_BITS) -
783 (__cfs_hash_theta_int(theta) * 1000);
786 static inline int __cfs_hash_theta(struct cfs_hash *hs)
788 return (atomic_read(&hs->hs_count) <<
789 CFS_HASH_THETA_BITS) >> hs->hs_cur_bits;
793 __cfs_hash_set_theta(struct cfs_hash *hs, int min, int max)
796 hs->hs_min_theta = (__u16)min;
797 hs->hs_max_theta = (__u16)max;
800 /* Generic debug formatting routines mainly for proc handler */
802 void cfs_hash_debug_header(struct seq_file *m);
803 void cfs_hash_debug_str(struct cfs_hash *hs, struct seq_file *m);
806 * Generic djb2 hash algorithm for character arrays.
808 static inline unsigned
809 cfs_hash_djb2_hash(const void *key, size_t size, unsigned mask)
811 unsigned i, hash = 5381;
813 LASSERT(key != NULL);
815 for (i = 0; i < size; i++)
816 hash = hash * 33 + ((char *)key)[i];
818 return (hash & mask);
822 * Generic u32 hash algorithm.
824 static inline unsigned
825 cfs_hash_u32_hash(const __u32 key, unsigned mask)
827 return ((key * CFS_GOLDEN_RATIO_PRIME_32) & mask);
831 * Generic u64 hash algorithm.
833 static inline unsigned
834 cfs_hash_u64_hash(const __u64 key, unsigned mask)
836 return ((unsigned)(key * CFS_GOLDEN_RATIO_PRIME_64) & mask);
839 /** iterate over all buckets in @bds (array of struct cfs_hash_bd) */
840 #define cfs_hash_for_each_bd(bds, n, i) \
841 for (i = 0; i < n && (bds)[i].bd_bucket != NULL; i++)
843 /** iterate over all buckets of @hs */
844 #define cfs_hash_for_each_bucket(hs, bd, pos) \
846 pos < CFS_HASH_NBKT(hs) && \
847 ((bd)->bd_bucket = (hs)->hs_buckets[pos]) != NULL; pos++)
849 /** iterate over all hlist of bucket @bd */
850 #define cfs_hash_bd_for_each_hlist(hs, bd, hlist) \
851 for ((bd)->bd_offset = 0; \
852 (bd)->bd_offset < CFS_HASH_BKT_NHLIST(hs) && \
853 (hlist = cfs_hash_bd_hhead(hs, bd)) != NULL; \
856 /* !__LIBCFS__HASH_H__ */