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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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18 * http://www.gnu.org/licenses/gpl-2.0.html
23 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2012, 2015, Intel Corporation.
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 */
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 = 1 << 0,
129 /** no bucket lock, use one spinlock to protect the whole hash */
130 CFS_HASH_NO_BKTLOCK = 1 << 1,
131 /** rwlock to protect bucket */
132 CFS_HASH_RW_BKTLOCK = 1 << 2,
133 /** spinlock to protect bucket */
134 CFS_HASH_SPIN_BKTLOCK = 1 << 3,
135 /** always add new item to tail */
136 CFS_HASH_ADD_TAIL = 1 << 4,
137 /** hash-table doesn't have refcount on item */
138 CFS_HASH_NO_ITEMREF = 1 << 5,
139 /** big name for param-tree */
140 CFS_HASH_BIGNAME = 1 << 6,
141 /** track global count */
142 CFS_HASH_COUNTER = 1 << 7,
143 /** rehash item by new key */
144 CFS_HASH_REHASH_KEY = 1 << 8,
145 /** Enable dynamic hash resizing */
146 CFS_HASH_REHASH = 1 << 9,
147 /** can shrink hash-size */
148 CFS_HASH_SHRINK = 1 << 10,
149 /** assert hash is empty on exit */
150 CFS_HASH_ASSERT_EMPTY = 1 << 11,
151 /** record hlist depth */
152 CFS_HASH_DEPTH = 1 << 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 = 1 << 13,
158 /** NB, we typed hs_flags as __u16, please change it
159 * if you need to extend >=16 flags */
162 /** most used attributes */
163 #define CFS_HASH_DEFAULT (CFS_HASH_RW_BKTLOCK | \
164 CFS_HASH_COUNTER | CFS_HASH_REHASH)
167 * cfs_hash is a hash-table implementation for general purpose, it can support:
168 * . two refcount modes
169 * hash-table with & without refcount
171 * nolock, one-spinlock, rw-bucket-lock, spin-bucket-lock
172 * . general operations
173 * lookup, add(add_tail or add_head), delete
177 * locked iteration and unlocked iteration
179 * support long name hash
181 * trace max searching depth
184 * When the htable grows or shrinks, a separate task (cfs_hash_rehash_worker)
185 * is spawned to handle the rehash in the background, it's possible that other
186 * processes can concurrently perform additions, deletions, and lookups
187 * without being blocked on rehash completion, because rehash will release
188 * the global wrlock for each bucket.
190 * rehash and iteration can't run at the same time because it's too tricky
191 * to keep both of them safe and correct.
192 * As they are relatively rare operations, so:
193 * . if iteration is in progress while we try to launch rehash, then
194 * it just giveup, iterator will launch rehash at the end.
195 * . if rehash is in progress while we try to iterate the hash table,
196 * then we just wait (shouldn't be very long time), anyway, nobody
197 * should expect iteration of whole hash-table to be non-blocking.
199 * During rehashing, a (key,object) pair may be in one of two buckets,
200 * depending on whether the worker task has yet to transfer the object
201 * to its new location in the table. Lookups and deletions need to search both
202 * locations; additions must take care to only insert into the new bucket.
206 /** serialize with rehash, or serialize all operations if
207 * the hash-table has CFS_HASH_NO_BKTLOCK */
208 union cfs_hash_lock hs_lock;
209 /** hash operations */
210 struct cfs_hash_ops *hs_ops;
211 /** hash lock operations */
212 struct cfs_hash_lock_ops *hs_lops;
213 /** hash list operations */
214 struct cfs_hash_hlist_ops *hs_hops;
215 /** hash buckets-table */
216 struct cfs_hash_bucket **hs_buckets;
217 /** total number of items on this hash-table */
219 /** hash flags, see cfs_hash_tag for detail */
221 /** # of extra-bytes for bucket, for user saving extended attributes */
222 __u16 hs_extra_bytes;
223 /** wants to iterate */
225 /** hash-table is dying */
227 /** current hash bits */
233 /** bits for rehash */
235 /** bits for each bucket */
237 /** resize min threshold */
239 /** resize max threshold */
242 __u32 hs_rehash_count;
243 /** # of iterators (caller of cfs_hash_for_each_*) */
245 /** rehash workitem */
246 struct work_struct hs_rehash_work;
247 /** refcount on this hash table */
248 atomic_t hs_refcount;
249 /** rehash buckets-table */
250 struct cfs_hash_bucket **hs_rehash_buckets;
251 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
252 /** serialize debug members */
253 spinlock_t hs_dep_lock;
255 unsigned int hs_dep_max;
256 /** id of the deepest bucket */
257 unsigned int hs_dep_bkt;
258 /** offset in the deepest bucket */
259 unsigned int hs_dep_off;
260 /** bits when we found the max depth */
261 unsigned int hs_dep_bits;
262 /** workitem to output max depth */
263 struct work_struct hs_dep_work;
265 /** name of htable */
269 struct cfs_hash_lock_ops {
270 /** lock the hash table */
271 void (*hs_lock)(union cfs_hash_lock *lock, int exclusive);
272 /** unlock the hash table */
273 void (*hs_unlock)(union cfs_hash_lock *lock, int exclusive);
274 /** lock the hash bucket */
275 void (*hs_bkt_lock)(union cfs_hash_lock *lock, int exclusive);
276 /** unlock the hash bucket */
277 void (*hs_bkt_unlock)(union cfs_hash_lock *lock, int exclusive);
280 struct cfs_hash_hlist_ops {
281 /** return hlist_head of hash-head of @bd */
282 struct hlist_head *(*hop_hhead)(struct cfs_hash *hs, struct cfs_hash_bd *bd);
283 /** return hash-head size */
284 int (*hop_hhead_size)(struct cfs_hash *hs);
285 /** add @hnode to hash-head of @bd */
286 int (*hop_hnode_add)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
287 struct hlist_node *hnode);
288 /** remove @hnode from hash-head of @bd */
289 int (*hop_hnode_del)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
290 struct hlist_node *hnode);
293 struct cfs_hash_ops {
294 /** return hashed value from @key */
295 unsigned (*hs_hash)(struct cfs_hash *hs, const void *key, unsigned mask);
296 /** return key address of @hnode */
297 void * (*hs_key)(struct hlist_node *hnode);
298 /** copy key from @hnode to @key */
299 void (*hs_keycpy)(struct hlist_node *hnode, void *key);
301 * compare @key with key of @hnode
302 * returns 1 on a match
304 int (*hs_keycmp)(const void *key, struct hlist_node *hnode);
305 /** return object address of @hnode, i.e: container_of(...hnode) */
306 void * (*hs_object)(struct hlist_node *hnode);
307 /** get refcount of item, always called with holding bucket-lock */
308 void (*hs_get)(struct cfs_hash *hs, struct hlist_node *hnode);
309 /** release refcount of item */
310 void (*hs_put)(struct cfs_hash *hs, struct hlist_node *hnode);
311 /** release refcount of item, always called with holding bucket-lock */
312 void (*hs_put_locked)(struct cfs_hash *hs, struct hlist_node *hnode);
313 /** it's called before removing of @hnode */
314 void (*hs_exit)(struct cfs_hash *hs, struct hlist_node *hnode);
317 /** total number of buckets in @hs */
318 #define CFS_HASH_NBKT(hs) \
319 (1U << ((hs)->hs_cur_bits - (hs)->hs_bkt_bits))
321 /** total number of buckets in @hs while rehashing */
322 #define CFS_HASH_RH_NBKT(hs) \
323 (1U << ((hs)->hs_rehash_bits - (hs)->hs_bkt_bits))
325 /** number of hlist for in bucket */
326 #define CFS_HASH_BKT_NHLIST(hs) (1U << (hs)->hs_bkt_bits)
328 /** total number of hlist in @hs */
329 #define CFS_HASH_NHLIST(hs) (1U << (hs)->hs_cur_bits)
331 /** total number of hlist in @hs while rehashing */
332 #define CFS_HASH_RH_NHLIST(hs) (1U << (hs)->hs_rehash_bits)
335 cfs_hash_with_no_lock(struct cfs_hash *hs)
337 /* caller will serialize all operations for this hash-table */
338 return (hs->hs_flags & CFS_HASH_NO_LOCK) != 0;
342 cfs_hash_with_no_bktlock(struct cfs_hash *hs)
344 /* no bucket lock, one single lock to protect the hash-table */
345 return (hs->hs_flags & CFS_HASH_NO_BKTLOCK) != 0;
349 cfs_hash_with_rw_bktlock(struct cfs_hash *hs)
351 /* rwlock to protect hash bucket */
352 return (hs->hs_flags & CFS_HASH_RW_BKTLOCK) != 0;
356 cfs_hash_with_spin_bktlock(struct cfs_hash *hs)
358 /* spinlock to protect hash bucket */
359 return (hs->hs_flags & CFS_HASH_SPIN_BKTLOCK) != 0;
363 cfs_hash_with_add_tail(struct cfs_hash *hs)
365 return (hs->hs_flags & CFS_HASH_ADD_TAIL) != 0;
369 cfs_hash_with_no_itemref(struct cfs_hash *hs)
371 /* hash-table doesn't keep refcount on item,
372 * item can't be removed from hash unless it's
374 return (hs->hs_flags & CFS_HASH_NO_ITEMREF) != 0;
378 cfs_hash_with_bigname(struct cfs_hash *hs)
380 return (hs->hs_flags & CFS_HASH_BIGNAME) != 0;
384 cfs_hash_with_counter(struct cfs_hash *hs)
386 return (hs->hs_flags & CFS_HASH_COUNTER) != 0;
390 cfs_hash_with_rehash(struct cfs_hash *hs)
392 return (hs->hs_flags & CFS_HASH_REHASH) != 0;
396 cfs_hash_with_rehash_key(struct cfs_hash *hs)
398 return (hs->hs_flags & CFS_HASH_REHASH_KEY) != 0;
402 cfs_hash_with_shrink(struct cfs_hash *hs)
404 return (hs->hs_flags & CFS_HASH_SHRINK) != 0;
408 cfs_hash_with_assert_empty(struct cfs_hash *hs)
410 return (hs->hs_flags & CFS_HASH_ASSERT_EMPTY) != 0;
414 cfs_hash_with_depth(struct cfs_hash *hs)
416 return (hs->hs_flags & CFS_HASH_DEPTH) != 0;
420 cfs_hash_with_nblk_change(struct cfs_hash *hs)
422 return (hs->hs_flags & CFS_HASH_NBLK_CHANGE) != 0;
426 cfs_hash_is_exiting(struct cfs_hash *hs)
427 { /* cfs_hash_destroy is called */
428 return hs->hs_exiting;
432 cfs_hash_is_rehashing(struct cfs_hash *hs)
433 { /* rehash is launched */
434 return hs->hs_rehash_bits != 0;
438 cfs_hash_is_iterating(struct cfs_hash *hs)
439 { /* someone is calling cfs_hash_for_each_* */
440 return hs->hs_iterating || hs->hs_iterators != 0;
444 cfs_hash_bkt_size(struct cfs_hash *hs)
446 return offsetof(struct cfs_hash_bucket, hsb_head[0]) +
447 hs->hs_hops->hop_hhead_size(hs) * CFS_HASH_BKT_NHLIST(hs) +
451 static inline unsigned
452 cfs_hash_id(struct cfs_hash *hs, const void *key, unsigned mask)
454 return hs->hs_ops->hs_hash(hs, key, mask);
458 cfs_hash_key(struct cfs_hash *hs, struct hlist_node *hnode)
460 return hs->hs_ops->hs_key(hnode);
464 cfs_hash_keycpy(struct cfs_hash *hs, struct hlist_node *hnode, void *key)
466 if (hs->hs_ops->hs_keycpy != NULL)
467 hs->hs_ops->hs_keycpy(hnode, key);
471 * Returns 1 on a match,
474 cfs_hash_keycmp(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
476 return hs->hs_ops->hs_keycmp(key, hnode);
480 cfs_hash_object(struct cfs_hash *hs, struct hlist_node *hnode)
482 return hs->hs_ops->hs_object(hnode);
486 cfs_hash_get(struct cfs_hash *hs, struct hlist_node *hnode)
488 return hs->hs_ops->hs_get(hs, hnode);
492 cfs_hash_put_locked(struct cfs_hash *hs, struct hlist_node *hnode)
494 return hs->hs_ops->hs_put_locked(hs, hnode);
498 cfs_hash_put(struct cfs_hash *hs, struct hlist_node *hnode)
500 return hs->hs_ops->hs_put(hs, hnode);
504 cfs_hash_exit(struct cfs_hash *hs, struct hlist_node *hnode)
506 if (hs->hs_ops->hs_exit)
507 hs->hs_ops->hs_exit(hs, hnode);
510 static inline void cfs_hash_lock(struct cfs_hash *hs, int excl)
512 hs->hs_lops->hs_lock(&hs->hs_lock, excl);
515 static inline void cfs_hash_unlock(struct cfs_hash *hs, int excl)
517 hs->hs_lops->hs_unlock(&hs->hs_lock, excl);
520 static inline int cfs_hash_dec_and_lock(struct cfs_hash *hs,
523 LASSERT(cfs_hash_with_no_bktlock(hs));
524 return atomic_dec_and_lock(condition, &hs->hs_lock.spin);
527 static inline void cfs_hash_bd_lock(struct cfs_hash *hs,
528 struct cfs_hash_bd *bd, int excl)
530 hs->hs_lops->hs_bkt_lock(&bd->bd_bucket->hsb_lock, excl);
533 static inline void cfs_hash_bd_unlock(struct cfs_hash *hs,
534 struct cfs_hash_bd *bd, int excl)
536 hs->hs_lops->hs_bkt_unlock(&bd->bd_bucket->hsb_lock, excl);
540 * operations on cfs_hash bucket (bd: bucket descriptor),
541 * they are normally for hash-table without rehash
543 void cfs_hash_bd_get(struct cfs_hash *hs, const void *key,
544 struct cfs_hash_bd *bd);
547 cfs_hash_bd_get_and_lock(struct cfs_hash *hs, const void *key,
548 struct cfs_hash_bd *bd, int excl)
550 cfs_hash_bd_get(hs, key, bd);
551 cfs_hash_bd_lock(hs, bd, excl);
554 static inline unsigned
555 cfs_hash_bd_index_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
557 return bd->bd_offset | (bd->bd_bucket->hsb_index << hs->hs_bkt_bits);
561 cfs_hash_bd_index_set(struct cfs_hash *hs, unsigned index,
562 struct cfs_hash_bd *bd)
564 bd->bd_bucket = hs->hs_buckets[index >> hs->hs_bkt_bits];
565 bd->bd_offset = index & (CFS_HASH_BKT_NHLIST(hs) - 1U);
569 cfs_hash_bd_extra_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
571 return (void *)bd->bd_bucket +
572 cfs_hash_bkt_size(hs) - hs->hs_extra_bytes;
576 cfs_hash_bd_version_get(struct cfs_hash_bd *bd)
578 /* need hold cfs_hash_bd_lock */
579 return bd->bd_bucket->hsb_version;
583 cfs_hash_bd_count_get(struct cfs_hash_bd *bd)
585 /* need hold cfs_hash_bd_lock */
586 return bd->bd_bucket->hsb_count;
590 cfs_hash_bd_depmax_get(struct cfs_hash_bd *bd)
592 return bd->bd_bucket->hsb_depmax;
596 cfs_hash_bd_compare(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
598 if (bd1->bd_bucket->hsb_index != bd2->bd_bucket->hsb_index)
599 return bd1->bd_bucket->hsb_index - bd2->bd_bucket->hsb_index;
601 if (bd1->bd_offset != bd2->bd_offset)
602 return bd1->bd_offset - bd2->bd_offset;
607 void cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
608 struct hlist_node *hnode);
609 void cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
610 struct hlist_node *hnode);
611 void cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
612 struct cfs_hash_bd *bd_new,
613 struct hlist_node *hnode);
616 cfs_hash_bd_dec_and_lock(struct cfs_hash *hs, struct cfs_hash_bd *bd,
619 LASSERT(cfs_hash_with_spin_bktlock(hs));
620 return atomic_dec_and_lock(condition, &bd->bd_bucket->hsb_lock.spin);
623 static inline struct hlist_head *
624 cfs_hash_bd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
626 return hs->hs_hops->hop_hhead(hs, bd);
630 cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
633 cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
636 cfs_hash_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
637 const void *key, struct hlist_node *hnode,
640 cfs_hash_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
641 const void *key, struct hlist_node *hnode);
644 * operations on cfs_hash bucket (bd: bucket descriptor),
645 * they are safe for hash-table with rehash
647 void cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key,
648 struct cfs_hash_bd *bds);
649 void cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
651 void cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
655 cfs_hash_dual_bd_get_and_lock(struct cfs_hash *hs, const void *key,
656 struct cfs_hash_bd *bds, int excl)
658 cfs_hash_dual_bd_get(hs, key, bds);
659 cfs_hash_dual_bd_lock(hs, bds, excl);
663 cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
666 cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
667 const void *key, struct hlist_node *hnode,
670 cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
671 const void *key, struct hlist_node *hnode);
673 /* Hash init/cleanup functions */
675 cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits,
676 unsigned bkt_bits, unsigned extra_bytes,
677 unsigned min_theta, unsigned max_theta,
678 struct cfs_hash_ops *ops, unsigned flags);
680 struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs);
681 void cfs_hash_putref(struct cfs_hash *hs);
683 /* Hash addition functions */
684 void cfs_hash_add(struct cfs_hash *hs, const void *key,
685 struct hlist_node *hnode);
686 int cfs_hash_add_unique(struct cfs_hash *hs, const void *key,
687 struct hlist_node *hnode);
688 void *cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
689 struct hlist_node *hnode);
691 /* Hash deletion functions */
692 void *cfs_hash_del(struct cfs_hash *hs, const void *key,
693 struct hlist_node *hnode);
694 void *cfs_hash_del_key(struct cfs_hash *hs, const void *key);
696 /* Hash lookup/for_each functions */
697 #define CFS_HASH_LOOP_HOG 1024
699 typedef int (*cfs_hash_for_each_cb_t)(struct cfs_hash *hs,
700 struct cfs_hash_bd *bd,
701 struct hlist_node *node,
704 cfs_hash_lookup(struct cfs_hash *hs, const void *key);
706 cfs_hash_for_each(struct cfs_hash *hs, cfs_hash_for_each_cb_t, void *data);
708 cfs_hash_for_each_safe(struct cfs_hash *hs, cfs_hash_for_each_cb_t, void *data);
710 cfs_hash_for_each_nolock(struct cfs_hash *hs, cfs_hash_for_each_cb_t,
711 void *data, int start);
713 cfs_hash_for_each_empty(struct cfs_hash *hs, cfs_hash_for_each_cb_t,
716 cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
717 cfs_hash_for_each_cb_t, void *data);
718 typedef int (*cfs_hash_cond_opt_cb_t)(void *obj, void *data);
720 cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t, void *data);
723 cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned hindex,
724 cfs_hash_for_each_cb_t, void *data);
725 int cfs_hash_is_empty(struct cfs_hash *hs);
726 __u64 cfs_hash_size_get(struct cfs_hash *hs);
729 * Rehash - Theta is calculated to be the average chained
730 * hash depth assuming a perfectly uniform hash function.
732 void cfs_hash_rehash_cancel_locked(struct cfs_hash *hs);
733 void cfs_hash_rehash_cancel(struct cfs_hash *hs);
734 void cfs_hash_rehash(struct cfs_hash *hs, int do_rehash);
735 void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
736 void *new_key, struct hlist_node *hnode);
738 #if CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1
739 /* Validate hnode references the correct key */
741 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
742 struct hlist_node *hnode)
744 LASSERT(cfs_hash_keycmp(hs, key, hnode));
747 /* Validate hnode is in the correct bucket */
749 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
750 struct hlist_node *hnode)
752 struct cfs_hash_bd bds[2];
754 cfs_hash_dual_bd_get(hs, cfs_hash_key(hs, hnode), bds);
755 LASSERT(bds[0].bd_bucket == bd->bd_bucket ||
756 bds[1].bd_bucket == bd->bd_bucket);
759 #else /* CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1 */
762 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
763 struct hlist_node *hnode) {}
766 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
767 struct hlist_node *hnode) {}
769 #endif /* CFS_HASH_DEBUG_LEVEL */
771 #define CFS_HASH_THETA_BITS 10
772 #define CFS_HASH_MIN_THETA (1U << (CFS_HASH_THETA_BITS - 1))
773 #define CFS_HASH_MAX_THETA (1U << (CFS_HASH_THETA_BITS + 1))
775 /* Return integer component of theta */
776 static inline int __cfs_hash_theta_int(int theta)
778 return (theta >> CFS_HASH_THETA_BITS);
781 /* Return a fractional value between 0 and 999 */
782 static inline int __cfs_hash_theta_frac(int theta)
784 return ((theta * 1000) >> CFS_HASH_THETA_BITS) -
785 (__cfs_hash_theta_int(theta) * 1000);
788 static inline int __cfs_hash_theta(struct cfs_hash *hs)
790 return (atomic_read(&hs->hs_count) <<
791 CFS_HASH_THETA_BITS) >> hs->hs_cur_bits;
795 __cfs_hash_set_theta(struct cfs_hash *hs, int min, int max)
798 hs->hs_min_theta = (__u16)min;
799 hs->hs_max_theta = (__u16)max;
802 /* Generic debug formatting routines mainly for proc handler */
804 void cfs_hash_debug_header(struct seq_file *m);
805 void cfs_hash_debug_str(struct cfs_hash *hs, struct seq_file *m);
808 * Generic djb2 hash algorithm for character arrays.
810 static inline unsigned
811 cfs_hash_djb2_hash(const void *key, size_t size, unsigned mask)
813 unsigned i, hash = 5381;
815 LASSERT(key != NULL);
817 for (i = 0; i < size; i++)
818 hash = hash * 33 + ((char *)key)[i];
820 return (hash & mask);
824 * Generic u32 hash algorithm.
826 static inline unsigned
827 cfs_hash_u32_hash(const __u32 key, unsigned mask)
829 return ((key * CFS_GOLDEN_RATIO_PRIME_32) & mask);
833 * Generic u64 hash algorithm.
835 static inline unsigned
836 cfs_hash_u64_hash(const __u64 key, unsigned mask)
838 return ((unsigned)(key * CFS_GOLDEN_RATIO_PRIME_64) & mask);
841 /** iterate over all buckets in @bds (array of struct cfs_hash_bd) */
842 #define cfs_hash_for_each_bd(bds, n, i) \
843 for (i = 0; i < n && (bds)[i].bd_bucket != NULL; i++)
845 /** iterate over all buckets of @hs */
846 #define cfs_hash_for_each_bucket(hs, bd, pos) \
848 pos < CFS_HASH_NBKT(hs) && \
849 ((bd)->bd_bucket = (hs)->hs_buckets[pos]) != NULL; pos++)
851 /** iterate over all hlist of bucket @bd */
852 #define cfs_hash_bd_for_each_hlist(hs, bd, hlist) \
853 for ((bd)->bd_offset = 0; \
854 (bd)->bd_offset < CFS_HASH_BKT_NHLIST(hs) && \
855 (hlist = cfs_hash_bd_hhead(hs, bd)) != NULL; \
858 /* !__LIBCFS__HASH_H__ */