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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
61 * record hash depth and output to console when it's too deep,
62 * 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 */
80 * cfs_hash_bucket is a container of:
82 * - array of hash-head starting from hsb_head[0], hash-head can be one of
83 * . struct cfs_hash_head
84 * . struct cfs_hash_head_dep
85 * . struct cfs_hash_dhead
86 * . struct cfs_hash_dhead_dep
87 * which depends on requirement of user
88 * - some extra bytes (caller can require it while creating hash)
90 struct cfs_hash_bucket {
91 union cfs_hash_lock hsb_lock; /**< bucket lock */
92 u32 hsb_count; /**< current entries */
93 u32 hsb_version; /**< change version */
94 unsigned int hsb_index; /**< index of bucket */
95 int hsb_depmax; /**< max depth on bucket */
96 long hsb_head[0]; /**< hash-head array */
100 * cfs_hash bucket descriptor, it's normally in stack of caller
103 /* address of bucket */
104 struct cfs_hash_bucket *bd_bucket;
105 /* offset in bucket */
106 unsigned int bd_offset;
109 #define CFS_HASH_NAME_LEN 16 /**< default name length */
110 #define CFS_HASH_BIGNAME_LEN 64 /**< bigname for param tree */
112 #define CFS_HASH_BKT_BITS 3 /**< default bits of bucket */
113 #define CFS_HASH_BITS_MAX 30 /**< max bits of bucket */
114 #define CFS_HASH_BITS_MIN CFS_HASH_BKT_BITS
117 * common hash attributes.
121 * don't need any lock, caller will protect operations with it's
122 * own lock. With this flag:
123 * . CFS_HASH_NO_BKTLOCK, CFS_HASH_RW_BKTLOCK, CFS_HASH_SPIN_BKTLOCK
125 * . Some functions will be disabled with this flag, i.e:
126 * cfs_hash_for_each_empty, cfs_hash_rehash
128 CFS_HASH_NO_LOCK = BIT(0),
129 /** no bucket lock, use one spinlock to protect the whole hash */
130 CFS_HASH_NO_BKTLOCK = BIT(1),
131 /** rwlock to protect bucket */
132 CFS_HASH_RW_BKTLOCK = BIT(2),
133 /** spinlock to protect bucket */
134 CFS_HASH_SPIN_BKTLOCK = BIT(3),
135 /** always add new item to tail */
136 CFS_HASH_ADD_TAIL = BIT(4),
137 /** hash-table doesn't have refcount on item */
138 CFS_HASH_NO_ITEMREF = BIT(5),
139 /** big name for param-tree */
140 CFS_HASH_BIGNAME = BIT(6),
141 /** track global count */
142 CFS_HASH_COUNTER = BIT(7),
143 /** rehash item by new key */
144 CFS_HASH_REHASH_KEY = BIT(8),
145 /** Enable dynamic hash resizing */
146 CFS_HASH_REHASH = BIT(9),
147 /** can shrink hash-size */
148 CFS_HASH_SHRINK = BIT(10),
149 /** assert hash is empty on exit */
150 CFS_HASH_ASSERT_EMPTY = BIT(11),
151 /** record hlist depth */
152 CFS_HASH_DEPTH = BIT(12),
154 * rehash is always scheduled in a different thread, so current
155 * change on hash table is non-blocking
157 CFS_HASH_NBLK_CHANGE = BIT(13),
159 * NB, we typed hs_flags as u16, please change it
160 * if you need to extend >=16 flags
164 /** most used attributes */
165 #define CFS_HASH_DEFAULT (CFS_HASH_RW_BKTLOCK | \
166 CFS_HASH_COUNTER | CFS_HASH_REHASH)
169 * cfs_hash is a hash-table implementation for general purpose, it can support:
170 * . two refcount modes
171 * hash-table with & without refcount
173 * nolock, one-spinlock, rw-bucket-lock, spin-bucket-lock
174 * . general operations
175 * lookup, add(add_tail or add_head), delete
179 * locked iteration and unlocked iteration
181 * support long name hash
183 * trace max searching depth
186 * When the htable grows or shrinks, a separate task (cfs_hash_rehash_worker)
187 * is spawned to handle the rehash in the background, it's possible that other
188 * processes can concurrently perform additions, deletions, and lookups
189 * without being blocked on rehash completion, because rehash will release
190 * the global wrlock for each bucket.
192 * rehash and iteration can't run at the same time because it's too tricky
193 * to keep both of them safe and correct.
194 * As they are relatively rare operations, so:
195 * . if iteration is in progress while we try to launch rehash, then
196 * it just giveup, iterator will launch rehash at the end.
197 * . if rehash is in progress while we try to iterate the hash table,
198 * then we just wait (shouldn't be very long time), anyway, nobody
199 * should expect iteration of whole hash-table to be non-blocking.
201 * During rehashing, a (key,object) pair may be in one of two buckets,
202 * depending on whether the worker task has yet to transfer the object
203 * to its new location in the table. Lookups and deletions need to search both
204 * locations; additions must take care to only insert into the new bucket.
209 * serialize with rehash, or serialize all operations if
210 * 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 */
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 */
247 /** # of iterators (caller of cfs_hash_for_each_*) */
249 /** rehash workitem */
250 struct cfs_workitem hs_rehash_wi;
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 cfs_workitem hs_dep_wi;
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,
287 struct cfs_hash_bd *bd);
288 /** return hash-head size */
289 int (*hop_hhead_size)(struct cfs_hash *hs);
290 /** add @hnode to hash-head of @bd */
291 int (*hop_hnode_add)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
292 struct hlist_node *hnode);
293 /** remove @hnode from hash-head of @bd */
294 int (*hop_hnode_del)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
295 struct hlist_node *hnode);
298 struct cfs_hash_ops {
299 /** return hashed value from @key */
300 unsigned int (*hs_hash)(struct cfs_hash *hs, const void *key,
302 /** return key address of @hnode */
303 void * (*hs_key)(struct hlist_node *hnode);
304 /** copy key from @hnode to @key */
305 void (*hs_keycpy)(struct hlist_node *hnode, void *key);
307 * compare @key with key of @hnode
308 * returns 1 on a match
310 int (*hs_keycmp)(const void *key, struct hlist_node *hnode);
311 /** return object address of @hnode, i.e: container_of(...hnode) */
312 void * (*hs_object)(struct hlist_node *hnode);
313 /** get refcount of item, always called with holding bucket-lock */
314 void (*hs_get)(struct cfs_hash *hs, struct hlist_node *hnode);
315 /** release refcount of item */
316 void (*hs_put)(struct cfs_hash *hs, struct hlist_node *hnode);
317 /** release refcount of item, always called with holding bucket-lock */
318 void (*hs_put_locked)(struct cfs_hash *hs,
319 struct hlist_node *hnode);
320 /** it's called before removing of @hnode */
321 void (*hs_exit)(struct cfs_hash *hs, struct hlist_node *hnode);
324 /** total number of buckets in @hs */
325 #define CFS_HASH_NBKT(hs) \
326 BIT((hs)->hs_cur_bits - (hs)->hs_bkt_bits)
328 /** total number of buckets in @hs while rehashing */
329 #define CFS_HASH_RH_NBKT(hs) \
330 BIT((hs)->hs_rehash_bits - (hs)->hs_bkt_bits)
332 /** number of hlist for in bucket */
333 #define CFS_HASH_BKT_NHLIST(hs) BIT((hs)->hs_bkt_bits)
335 /** total number of hlist in @hs */
336 #define CFS_HASH_NHLIST(hs) BIT((hs)->hs_cur_bits)
338 /** total number of hlist in @hs while rehashing */
339 #define CFS_HASH_RH_NHLIST(hs) BIT((hs)->hs_rehash_bits)
342 cfs_hash_with_no_lock(struct cfs_hash *hs)
344 /* caller will serialize all operations for this hash-table */
345 return hs->hs_flags & CFS_HASH_NO_LOCK;
349 cfs_hash_with_no_bktlock(struct cfs_hash *hs)
351 /* no bucket lock, one single lock to protect the hash-table */
352 return hs->hs_flags & CFS_HASH_NO_BKTLOCK;
356 cfs_hash_with_rw_bktlock(struct cfs_hash *hs)
358 /* rwlock to protect hash bucket */
359 return hs->hs_flags & CFS_HASH_RW_BKTLOCK;
363 cfs_hash_with_spin_bktlock(struct cfs_hash *hs)
365 /* spinlock to protect hash bucket */
366 return hs->hs_flags & CFS_HASH_SPIN_BKTLOCK;
370 cfs_hash_with_add_tail(struct cfs_hash *hs)
372 return hs->hs_flags & CFS_HASH_ADD_TAIL;
376 cfs_hash_with_no_itemref(struct cfs_hash *hs)
379 * hash-table doesn't keep refcount on item,
380 * item can't be removed from hash unless it's
383 return hs->hs_flags & CFS_HASH_NO_ITEMREF;
387 cfs_hash_with_bigname(struct cfs_hash *hs)
389 return hs->hs_flags & CFS_HASH_BIGNAME;
393 cfs_hash_with_counter(struct cfs_hash *hs)
395 return hs->hs_flags & CFS_HASH_COUNTER;
399 cfs_hash_with_rehash(struct cfs_hash *hs)
401 return hs->hs_flags & CFS_HASH_REHASH;
405 cfs_hash_with_rehash_key(struct cfs_hash *hs)
407 return hs->hs_flags & CFS_HASH_REHASH_KEY;
411 cfs_hash_with_shrink(struct cfs_hash *hs)
413 return hs->hs_flags & CFS_HASH_SHRINK;
417 cfs_hash_with_assert_empty(struct cfs_hash *hs)
419 return hs->hs_flags & CFS_HASH_ASSERT_EMPTY;
423 cfs_hash_with_depth(struct cfs_hash *hs)
425 return hs->hs_flags & CFS_HASH_DEPTH;
429 cfs_hash_with_nblk_change(struct cfs_hash *hs)
431 return hs->hs_flags & CFS_HASH_NBLK_CHANGE;
435 cfs_hash_is_exiting(struct cfs_hash *hs)
437 /* cfs_hash_destroy is called */
438 return hs->hs_exiting;
442 cfs_hash_is_rehashing(struct cfs_hash *hs)
444 /* rehash is launched */
445 return !!hs->hs_rehash_bits;
449 cfs_hash_is_iterating(struct cfs_hash *hs)
451 /* someone is calling cfs_hash_for_each_* */
452 return hs->hs_iterating || hs->hs_iterators;
456 cfs_hash_bkt_size(struct cfs_hash *hs)
458 return offsetof(struct cfs_hash_bucket, hsb_head[0]) +
459 hs->hs_hops->hop_hhead_size(hs) * CFS_HASH_BKT_NHLIST(hs) +
463 static inline unsigned
464 cfs_hash_id(struct cfs_hash *hs, const void *key, unsigned int mask)
466 return hs->hs_ops->hs_hash(hs, key, mask);
470 cfs_hash_key(struct cfs_hash *hs, struct hlist_node *hnode)
472 return hs->hs_ops->hs_key(hnode);
476 cfs_hash_keycpy(struct cfs_hash *hs, struct hlist_node *hnode, void *key)
478 if (hs->hs_ops->hs_keycpy)
479 hs->hs_ops->hs_keycpy(hnode, key);
483 * Returns 1 on a match,
486 cfs_hash_keycmp(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
488 return hs->hs_ops->hs_keycmp(key, hnode);
492 cfs_hash_object(struct cfs_hash *hs, struct hlist_node *hnode)
494 return hs->hs_ops->hs_object(hnode);
498 cfs_hash_get(struct cfs_hash *hs, struct hlist_node *hnode)
500 return hs->hs_ops->hs_get(hs, hnode);
504 cfs_hash_put_locked(struct cfs_hash *hs, struct hlist_node *hnode)
506 return hs->hs_ops->hs_put_locked(hs, hnode);
510 cfs_hash_put(struct cfs_hash *hs, struct hlist_node *hnode)
512 return hs->hs_ops->hs_put(hs, hnode);
516 cfs_hash_exit(struct cfs_hash *hs, struct hlist_node *hnode)
518 if (hs->hs_ops->hs_exit)
519 hs->hs_ops->hs_exit(hs, hnode);
522 static inline void cfs_hash_lock(struct cfs_hash *hs, int excl)
524 hs->hs_lops->hs_lock(&hs->hs_lock, excl);
527 static inline void cfs_hash_unlock(struct cfs_hash *hs, int excl)
529 hs->hs_lops->hs_unlock(&hs->hs_lock, excl);
532 static inline int cfs_hash_dec_and_lock(struct cfs_hash *hs,
535 LASSERT(cfs_hash_with_no_bktlock(hs));
536 return atomic_dec_and_lock(condition, &hs->hs_lock.spin);
539 static inline void cfs_hash_bd_lock(struct cfs_hash *hs,
540 struct cfs_hash_bd *bd, int excl)
542 hs->hs_lops->hs_bkt_lock(&bd->bd_bucket->hsb_lock, excl);
545 static inline void cfs_hash_bd_unlock(struct cfs_hash *hs,
546 struct cfs_hash_bd *bd, int excl)
548 hs->hs_lops->hs_bkt_unlock(&bd->bd_bucket->hsb_lock, excl);
552 * operations on cfs_hash bucket (bd: bucket descriptor),
553 * they are normally for hash-table without rehash
555 void cfs_hash_bd_get(struct cfs_hash *hs, const void *key,
556 struct cfs_hash_bd *bd);
559 cfs_hash_bd_get_and_lock(struct cfs_hash *hs, const void *key,
560 struct cfs_hash_bd *bd, int excl)
562 cfs_hash_bd_get(hs, key, bd);
563 cfs_hash_bd_lock(hs, bd, excl);
566 static inline unsigned
567 cfs_hash_bd_index_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
569 return bd->bd_offset | (bd->bd_bucket->hsb_index << hs->hs_bkt_bits);
573 cfs_hash_bd_index_set(struct cfs_hash *hs, unsigned int index,
574 struct cfs_hash_bd *bd)
576 bd->bd_bucket = hs->hs_buckets[index >> hs->hs_bkt_bits];
577 bd->bd_offset = index & (CFS_HASH_BKT_NHLIST(hs) - 1U);
581 cfs_hash_bd_extra_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
583 return (void *)bd->bd_bucket +
584 cfs_hash_bkt_size(hs) - hs->hs_extra_bytes;
588 cfs_hash_bd_version_get(struct cfs_hash_bd *bd)
590 /* need hold cfs_hash_bd_lock */
591 return bd->bd_bucket->hsb_version;
595 cfs_hash_bd_count_get(struct cfs_hash_bd *bd)
597 /* need hold cfs_hash_bd_lock */
598 return bd->bd_bucket->hsb_count;
602 cfs_hash_bd_depmax_get(struct cfs_hash_bd *bd)
604 return bd->bd_bucket->hsb_depmax;
608 cfs_hash_bd_compare(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
610 if (bd1->bd_bucket->hsb_index != bd2->bd_bucket->hsb_index)
611 return bd1->bd_bucket->hsb_index - bd2->bd_bucket->hsb_index;
613 if (bd1->bd_offset != bd2->bd_offset)
614 return bd1->bd_offset - bd2->bd_offset;
619 void cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
620 struct hlist_node *hnode);
621 void cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
622 struct hlist_node *hnode);
623 void cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
624 struct cfs_hash_bd *bd_new,
625 struct hlist_node *hnode);
628 cfs_hash_bd_dec_and_lock(struct cfs_hash *hs, struct cfs_hash_bd *bd,
631 LASSERT(cfs_hash_with_spin_bktlock(hs));
632 return atomic_dec_and_lock(condition, &bd->bd_bucket->hsb_lock.spin);
635 static inline struct hlist_head *
636 cfs_hash_bd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
638 return hs->hs_hops->hop_hhead(hs, bd);
642 cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
645 cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
649 * operations on cfs_hash bucket (bd: bucket descriptor),
650 * they are safe for hash-table with rehash
652 void cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key,
653 struct cfs_hash_bd *bds);
654 void cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
656 void cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
660 cfs_hash_dual_bd_get_and_lock(struct cfs_hash *hs, const void *key,
661 struct cfs_hash_bd *bds, int excl)
663 cfs_hash_dual_bd_get(hs, key, bds);
664 cfs_hash_dual_bd_lock(hs, bds, excl);
668 cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
671 cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
672 const void *key, struct hlist_node *hnode,
675 cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
676 const void *key, struct hlist_node *hnode);
678 /* Hash init/cleanup functions */
680 cfs_hash_create(char *name, unsigned int cur_bits, unsigned int max_bits,
681 unsigned int bkt_bits, unsigned int extra_bytes,
682 unsigned int min_theta, unsigned int max_theta,
683 struct cfs_hash_ops *ops, unsigned int flags);
685 struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs);
686 void cfs_hash_putref(struct cfs_hash *hs);
688 /* Hash addition functions */
689 void cfs_hash_add(struct cfs_hash *hs, const void *key,
690 struct hlist_node *hnode);
691 int cfs_hash_add_unique(struct cfs_hash *hs, const void *key,
692 struct hlist_node *hnode);
693 void *cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
694 struct hlist_node *hnode);
696 /* Hash deletion functions */
697 void *cfs_hash_del(struct cfs_hash *hs, const void *key,
698 struct hlist_node *hnode);
699 void *cfs_hash_del_key(struct cfs_hash *hs, const void *key);
701 /* Hash lookup/for_each functions */
702 #define CFS_HASH_LOOP_HOG 1024
704 typedef int (*cfs_hash_for_each_cb_t)(struct cfs_hash *hs,
705 struct cfs_hash_bd *bd,
706 struct hlist_node *node,
709 cfs_hash_lookup(struct cfs_hash *hs, const void *key);
711 cfs_hash_for_each(struct cfs_hash *hs, cfs_hash_for_each_cb_t cb, void *data);
713 cfs_hash_for_each_safe(struct cfs_hash *hs, cfs_hash_for_each_cb_t cb,
716 cfs_hash_for_each_nolock(struct cfs_hash *hs, cfs_hash_for_each_cb_t cb,
717 void *data, int start);
719 cfs_hash_for_each_empty(struct cfs_hash *hs, cfs_hash_for_each_cb_t cb,
722 cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
723 cfs_hash_for_each_cb_t cb, void *data);
724 typedef int (*cfs_hash_cond_opt_cb_t)(void *obj, void *data);
726 cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t cb, void *data);
729 cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned int hindex,
730 cfs_hash_for_each_cb_t cb, void *data);
731 int cfs_hash_is_empty(struct cfs_hash *hs);
732 u64 cfs_hash_size_get(struct cfs_hash *hs);
735 * Rehash - Theta is calculated to be the average chained
736 * hash depth assuming a perfectly uniform hash function.
738 void cfs_hash_rehash_cancel_locked(struct cfs_hash *hs);
739 void cfs_hash_rehash_cancel(struct cfs_hash *hs);
740 int cfs_hash_rehash(struct cfs_hash *hs, int do_rehash);
741 void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
742 void *new_key, struct hlist_node *hnode);
744 #if CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1
745 /* Validate hnode references the correct key */
747 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
748 struct hlist_node *hnode)
750 LASSERT(cfs_hash_keycmp(hs, key, hnode));
753 /* Validate hnode is in the correct bucket */
755 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
756 struct hlist_node *hnode)
758 struct cfs_hash_bd bds[2];
760 cfs_hash_dual_bd_get(hs, cfs_hash_key(hs, hnode), bds);
761 LASSERT(bds[0].bd_bucket == bd->bd_bucket ||
762 bds[1].bd_bucket == bd->bd_bucket);
765 #else /* CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1 */
768 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
769 struct hlist_node *hnode) {}
772 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
773 struct hlist_node *hnode) {}
775 #endif /* CFS_HASH_DEBUG_LEVEL */
777 #define CFS_HASH_THETA_BITS 10
778 #define CFS_HASH_MIN_THETA BIT(CFS_HASH_THETA_BITS - 1)
779 #define CFS_HASH_MAX_THETA BIT(CFS_HASH_THETA_BITS + 1)
781 /* Return integer component of theta */
782 static inline int __cfs_hash_theta_int(int theta)
784 return (theta >> CFS_HASH_THETA_BITS);
787 /* Return a fractional value between 0 and 999 */
788 static inline int __cfs_hash_theta_frac(int theta)
790 return ((theta * 1000) >> CFS_HASH_THETA_BITS) -
791 (__cfs_hash_theta_int(theta) * 1000);
794 static inline int __cfs_hash_theta(struct cfs_hash *hs)
796 return (atomic_read(&hs->hs_count) <<
797 CFS_HASH_THETA_BITS) >> hs->hs_cur_bits;
801 __cfs_hash_set_theta(struct cfs_hash *hs, int min, int max)
804 hs->hs_min_theta = (u16)min;
805 hs->hs_max_theta = (u16)max;
808 /* Generic debug formatting routines mainly for proc handler */
810 void cfs_hash_debug_header(struct seq_file *m);
811 void cfs_hash_debug_str(struct cfs_hash *hs, struct seq_file *m);
814 * Generic djb2 hash algorithm for character arrays.
816 static inline unsigned
817 cfs_hash_djb2_hash(const void *key, size_t size, unsigned int mask)
819 unsigned int i, hash = 5381;
823 for (i = 0; i < size; i++)
824 hash = hash * 33 + ((char *)key)[i];
826 return (hash & mask);
830 * Generic u32 hash algorithm.
832 static inline unsigned
833 cfs_hash_u32_hash(const u32 key, unsigned int mask)
835 return ((key * CFS_GOLDEN_RATIO_PRIME_32) & mask);
839 * Generic u64 hash algorithm.
841 static inline unsigned
842 cfs_hash_u64_hash(const u64 key, unsigned int mask)
844 return ((unsigned int)(key * CFS_GOLDEN_RATIO_PRIME_64) & mask);
847 /** iterate over all buckets in @bds (array of struct cfs_hash_bd) */
848 #define cfs_hash_for_each_bd(bds, n, i) \
849 for (i = 0; i < n && (bds)[i].bd_bucket != NULL; i++)
851 /** iterate over all buckets of @hs */
852 #define cfs_hash_for_each_bucket(hs, bd, pos) \
854 pos < CFS_HASH_NBKT(hs) && \
855 ((bd)->bd_bucket = (hs)->hs_buckets[pos]) != NULL; pos++)
857 /** iterate over all hlist of bucket @bd */
858 #define cfs_hash_bd_for_each_hlist(hs, bd, hlist) \
859 for ((bd)->bd_offset = 0; \
860 (bd)->bd_offset < CFS_HASH_BKT_NHLIST(hs) && \
861 (hlist = cfs_hash_bd_hhead(hs, bd)) != NULL; \
864 /* !__LIBCFS__HASH_H__ */