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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.
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26 * Copyright (c) 2012, 2015, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
31 * libcfs/include/libcfs/libcfs_hash.h
37 #ifndef __LIBCFS_HASH_H__
38 #define __LIBCFS_HASH_H__
40 #include <linux/spinlock.h>
41 #include <linux/workqueue.h>
42 #include <libcfs/linux/linux-hash.h>
45 #define CFS_HASH_DEBUG_NONE 0
46 /** record hash depth and output to console when it's too deep,
47 * computing overhead is low but consume more memory */
48 #define CFS_HASH_DEBUG_1 1
49 /** expensive, check key validation */
50 #define CFS_HASH_DEBUG_2 2
52 #define CFS_HASH_DEBUG_LEVEL CFS_HASH_DEBUG_NONE
55 struct cfs_hash_lock_ops;
56 struct cfs_hash_hlist_ops;
59 rwlock_t rw; /**< rwlock */
60 spinlock_t spin; /**< spinlock */
61 struct rw_semaphore rw_sem; /**< rwsem */
65 * cfs_hash_bucket is a container of:
67 * - array of hash-head starting from hsb_head[0], hash-head can be one of
68 * . struct cfs_hash_head
69 * . struct cfs_hash_head_dep
70 * . struct cfs_hash_dhead
71 * . struct cfs_hash_dhead_dep
72 * which depends on requirement of user
73 * - some extra bytes (caller can require it while creating hash)
75 struct cfs_hash_bucket {
76 union cfs_hash_lock hsb_lock; /**< bucket lock */
77 __u32 hsb_count; /**< current entries */
78 __u32 hsb_version; /**< change version */
79 unsigned int hsb_index; /**< index of bucket */
80 int hsb_depmax; /**< max depth on bucket */
81 long hsb_head[0]; /**< hash-head array */
85 * cfs_hash bucket descriptor, it's normally in stack of caller
88 /**< address of bucket */
89 struct cfs_hash_bucket *bd_bucket;
90 /**< offset in bucket */
91 unsigned int bd_offset;
94 #define CFS_HASH_NAME_LEN 16 /**< default name length */
95 #define CFS_HASH_BIGNAME_LEN 64 /**< bigname for param tree */
97 #define CFS_HASH_BKT_BITS 3 /**< default bits of bucket */
98 #define CFS_HASH_BITS_MAX 30 /**< max bits of bucket */
99 #define CFS_HASH_BITS_MIN CFS_HASH_BKT_BITS
102 * common hash attributes.
106 * don't need any lock, caller will protect operations with it's
107 * own lock. With this flag:
108 * . CFS_HASH_NO_BKTLOCK, CFS_HASH_RW_BKTLOCK, CFS_HASH_SPIN_BKTLOCK
110 * . Some functions will be disabled with this flag, i.e:
111 * cfs_hash_for_each_empty, cfs_hash_rehash
113 CFS_HASH_NO_LOCK = BIT(0),
114 /** no bucket lock, use one spinlock to protect the whole hash */
115 CFS_HASH_NO_BKTLOCK = BIT(1),
116 /** rwlock to protect bucket */
117 CFS_HASH_RW_BKTLOCK = BIT(2),
118 /** spinlock to protect bucket */
119 CFS_HASH_SPIN_BKTLOCK = BIT(3),
120 /** always add new item to tail */
121 CFS_HASH_ADD_TAIL = BIT(4),
122 /** hash-table doesn't have refcount on item */
123 CFS_HASH_NO_ITEMREF = BIT(5),
124 /** big name for param-tree */
125 CFS_HASH_BIGNAME = BIT(6),
126 /** track global count */
127 CFS_HASH_COUNTER = BIT(7),
128 /** rehash item by new key */
129 CFS_HASH_REHASH_KEY = BIT(8),
130 /** Enable dynamic hash resizing */
131 CFS_HASH_REHASH = BIT(9),
132 /** can shrink hash-size */
133 CFS_HASH_SHRINK = BIT(10),
134 /** assert hash is empty on exit */
135 CFS_HASH_ASSERT_EMPTY = BIT(11),
136 /** record hlist depth */
137 CFS_HASH_DEPTH = BIT(12),
139 * rehash is always scheduled in a different thread, so current
140 * change on hash table is non-blocking
142 CFS_HASH_NBLK_CHANGE = BIT(13),
143 /** rw semaphore lock to protect bucket */
144 CFS_HASH_RW_SEM_BKTLOCK = BIT(14),
145 /** NB, we typed hs_flags as __u16, please change it
146 * if you need to extend >=16 flags
150 /** most used attributes */
151 #define CFS_HASH_DEFAULT (CFS_HASH_RW_BKTLOCK | \
152 CFS_HASH_COUNTER | CFS_HASH_REHASH)
155 * cfs_hash is a hash-table implementation for general purpose, it can support:
156 * . two refcount modes
157 * hash-table with & without refcount
159 * nolock, one-spinlock, rw-bucket-lock, spin-bucket-lock
160 * . general operations
161 * lookup, add(add_tail or add_head), delete
165 * locked iteration and unlocked iteration
167 * support long name hash
169 * trace max searching depth
172 * When the htable grows or shrinks, a separate task (cfs_hash_rehash_worker)
173 * is spawned to handle the rehash in the background, it's possible that other
174 * processes can concurrently perform additions, deletions, and lookups
175 * without being blocked on rehash completion, because rehash will release
176 * the global wrlock for each bucket.
178 * rehash and iteration can't run at the same time because it's too tricky
179 * to keep both of them safe and correct.
180 * As they are relatively rare operations, so:
181 * . if iteration is in progress while we try to launch rehash, then
182 * it just giveup, iterator will launch rehash at the end.
183 * . if rehash is in progress while we try to iterate the hash table,
184 * then we just wait (shouldn't be very long time), anyway, nobody
185 * should expect iteration of whole hash-table to be non-blocking.
187 * During rehashing, a (key,object) pair may be in one of two buckets,
188 * depending on whether the worker task has yet to transfer the object
189 * to its new location in the table. Lookups and deletions need to search both
190 * locations; additions must take care to only insert into the new bucket.
194 /** serialize with rehash, or serialize all operations if
195 * the hash-table has CFS_HASH_NO_BKTLOCK */
196 union cfs_hash_lock hs_lock;
197 /** hash operations */
198 struct cfs_hash_ops *hs_ops;
199 /** hash lock operations */
200 struct cfs_hash_lock_ops *hs_lops;
201 /** hash list operations */
202 struct cfs_hash_hlist_ops *hs_hops;
203 /** hash buckets-table */
204 struct cfs_hash_bucket **hs_buckets;
205 /** total number of items on this hash-table */
207 /** hash flags, see cfs_hash_tag for detail */
209 /** # of extra-bytes for bucket, for user saving extended attributes */
210 __u16 hs_extra_bytes;
211 /** wants to iterate */
213 /** hash-table is dying */
215 /** current hash bits */
221 /** bits for rehash */
223 /** bits for each bucket */
225 /** resize min threshold */
227 /** resize max threshold */
230 __u32 hs_rehash_count;
231 /** # of iterators (caller of cfs_hash_for_each_*) */
233 /** rehash workitem */
234 struct work_struct hs_rehash_work;
235 /** refcount on this hash table */
236 struct kref hs_refcount;
237 /** rehash buckets-table */
238 struct cfs_hash_bucket **hs_rehash_buckets;
239 #if CFS_HASH_DEBUG_LEVEL >= CFS_HASH_DEBUG_1
240 /** serialize debug members */
241 spinlock_t hs_dep_lock;
243 unsigned int hs_dep_max;
244 /** id of the deepest bucket */
245 unsigned int hs_dep_bkt;
246 /** offset in the deepest bucket */
247 unsigned int hs_dep_off;
248 /** bits when we found the max depth */
249 unsigned int hs_dep_bits;
250 /** workitem to output max depth */
251 struct work_struct hs_dep_work;
253 /** name of htable */
257 struct cfs_hash_lock_ops {
258 /** lock the hash table */
259 void (*hs_lock)(union cfs_hash_lock *lock, int exclusive);
260 /** unlock the hash table */
261 void (*hs_unlock)(union cfs_hash_lock *lock, int exclusive);
262 /** lock the hash bucket */
263 void (*hs_bkt_lock)(union cfs_hash_lock *lock, int exclusive);
264 /** unlock the hash bucket */
265 void (*hs_bkt_unlock)(union cfs_hash_lock *lock, int exclusive);
268 struct cfs_hash_hlist_ops {
269 /** return hlist_head of hash-head of @bd */
270 struct hlist_head *(*hop_hhead)(struct cfs_hash *hs, struct cfs_hash_bd *bd);
271 /** return hash-head size */
272 int (*hop_hhead_size)(struct cfs_hash *hs);
273 /** add @hnode to hash-head of @bd */
274 int (*hop_hnode_add)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
275 struct hlist_node *hnode);
276 /** remove @hnode from hash-head of @bd */
277 int (*hop_hnode_del)(struct cfs_hash *hs, struct cfs_hash_bd *bd,
278 struct hlist_node *hnode);
281 struct cfs_hash_ops {
282 /** return hashed value from @key */
283 unsigned int (*hs_hash)(struct cfs_hash *hs, const void *key,
284 const unsigned int bits);
285 /** return key address of @hnode */
286 void * (*hs_key)(struct hlist_node *hnode);
287 /** copy key from @hnode to @key */
288 void (*hs_keycpy)(struct hlist_node *hnode, void *key);
290 * compare @key with key of @hnode
291 * returns 1 on a match
293 int (*hs_keycmp)(const void *key, struct hlist_node *hnode);
294 /** return object address of @hnode, i.e: container_of(...hnode) */
295 void * (*hs_object)(struct hlist_node *hnode);
296 /** get refcount of item, always called with holding bucket-lock */
297 void (*hs_get)(struct cfs_hash *hs, struct hlist_node *hnode);
298 /** release refcount of item */
299 void (*hs_put)(struct cfs_hash *hs, struct hlist_node *hnode);
300 /** release refcount of item, always called with holding bucket-lock */
301 void (*hs_put_locked)(struct cfs_hash *hs, struct hlist_node *hnode);
302 /** it's called before removing of @hnode */
303 void (*hs_exit)(struct cfs_hash *hs, struct hlist_node *hnode);
306 /** total number of buckets in @hs */
307 #define CFS_HASH_NBKT(hs) \
308 (1U << ((hs)->hs_cur_bits - (hs)->hs_bkt_bits))
310 /** total number of buckets in @hs while rehashing */
311 #define CFS_HASH_RH_NBKT(hs) \
312 (1U << ((hs)->hs_rehash_bits - (hs)->hs_bkt_bits))
314 /** number of hlist for in bucket */
315 #define CFS_HASH_BKT_NHLIST(hs) (1U << (hs)->hs_bkt_bits)
317 /** total number of hlist in @hs */
318 #define CFS_HASH_NHLIST(hs) (1U << (hs)->hs_cur_bits)
320 /** total number of hlist in @hs while rehashing */
321 #define CFS_HASH_RH_NHLIST(hs) (1U << (hs)->hs_rehash_bits)
324 cfs_hash_with_no_lock(struct cfs_hash *hs)
326 /* caller will serialize all operations for this hash-table */
327 return (hs->hs_flags & CFS_HASH_NO_LOCK) != 0;
331 cfs_hash_with_no_bktlock(struct cfs_hash *hs)
333 /* no bucket lock, one single lock to protect the hash-table */
334 return (hs->hs_flags & CFS_HASH_NO_BKTLOCK) != 0;
338 cfs_hash_with_rw_bktlock(struct cfs_hash *hs)
340 /* rwlock to protect hash bucket */
341 return (hs->hs_flags & CFS_HASH_RW_BKTLOCK) != 0;
345 cfs_hash_with_spin_bktlock(struct cfs_hash *hs)
347 /* spinlock to protect hash bucket */
348 return (hs->hs_flags & CFS_HASH_SPIN_BKTLOCK) != 0;
352 cfs_hash_with_rw_sem_bktlock(struct cfs_hash *hs)
354 /* rw sem lock to protect hash bucket */
355 return (hs->hs_flags & CFS_HASH_RW_SEM_BKTLOCK) != 0;
359 cfs_hash_with_add_tail(struct cfs_hash *hs)
361 return (hs->hs_flags & CFS_HASH_ADD_TAIL) != 0;
365 cfs_hash_with_no_itemref(struct cfs_hash *hs)
367 /* hash-table doesn't keep refcount on item,
368 * item can't be removed from hash unless it's
370 return (hs->hs_flags & CFS_HASH_NO_ITEMREF) != 0;
374 cfs_hash_with_bigname(struct cfs_hash *hs)
376 return (hs->hs_flags & CFS_HASH_BIGNAME) != 0;
380 cfs_hash_with_counter(struct cfs_hash *hs)
382 return (hs->hs_flags & CFS_HASH_COUNTER) != 0;
386 cfs_hash_with_rehash(struct cfs_hash *hs)
388 return (hs->hs_flags & CFS_HASH_REHASH) != 0;
392 cfs_hash_with_rehash_key(struct cfs_hash *hs)
394 return (hs->hs_flags & CFS_HASH_REHASH_KEY) != 0;
398 cfs_hash_with_shrink(struct cfs_hash *hs)
400 return (hs->hs_flags & CFS_HASH_SHRINK) != 0;
404 cfs_hash_with_assert_empty(struct cfs_hash *hs)
406 return (hs->hs_flags & CFS_HASH_ASSERT_EMPTY) != 0;
410 cfs_hash_with_depth(struct cfs_hash *hs)
412 return (hs->hs_flags & CFS_HASH_DEPTH) != 0;
416 cfs_hash_with_nblk_change(struct cfs_hash *hs)
418 return (hs->hs_flags & CFS_HASH_NBLK_CHANGE) != 0;
422 cfs_hash_is_exiting(struct cfs_hash *hs)
423 { /* cfs_hash_destroy is called */
424 return hs->hs_exiting;
428 cfs_hash_is_rehashing(struct cfs_hash *hs)
429 { /* rehash is launched */
430 return hs->hs_rehash_bits != 0;
434 cfs_hash_is_iterating(struct cfs_hash *hs)
435 { /* someone is calling cfs_hash_for_each_* */
436 return hs->hs_iterating || hs->hs_iterators != 0;
440 cfs_hash_bkt_size(struct cfs_hash *hs)
442 return offsetof(struct cfs_hash_bucket, hsb_head[0]) +
443 hs->hs_hops->hop_hhead_size(hs) * CFS_HASH_BKT_NHLIST(hs) +
447 static inline unsigned int
448 cfs_hash_id(struct cfs_hash *hs, const void *key, const unsigned int bits)
450 return hs->hs_ops->hs_hash(hs, key, bits);
454 cfs_hash_key(struct cfs_hash *hs, struct hlist_node *hnode)
456 return hs->hs_ops->hs_key(hnode);
460 cfs_hash_keycpy(struct cfs_hash *hs, struct hlist_node *hnode, void *key)
462 if (hs->hs_ops->hs_keycpy != NULL)
463 hs->hs_ops->hs_keycpy(hnode, key);
467 * Returns 1 on a match,
470 cfs_hash_keycmp(struct cfs_hash *hs, const void *key, struct hlist_node *hnode)
472 return hs->hs_ops->hs_keycmp(key, hnode);
476 cfs_hash_object(struct cfs_hash *hs, struct hlist_node *hnode)
478 return hs->hs_ops->hs_object(hnode);
482 cfs_hash_get(struct cfs_hash *hs, struct hlist_node *hnode)
484 return hs->hs_ops->hs_get(hs, hnode);
488 cfs_hash_put_locked(struct cfs_hash *hs, struct hlist_node *hnode)
490 return hs->hs_ops->hs_put_locked(hs, hnode);
494 cfs_hash_put(struct cfs_hash *hs, struct hlist_node *hnode)
496 return hs->hs_ops->hs_put(hs, hnode);
500 cfs_hash_exit(struct cfs_hash *hs, struct hlist_node *hnode)
502 if (hs->hs_ops->hs_exit)
503 hs->hs_ops->hs_exit(hs, hnode);
506 static inline void cfs_hash_lock(struct cfs_hash *hs, int excl)
508 hs->hs_lops->hs_lock(&hs->hs_lock, excl);
511 static inline void cfs_hash_unlock(struct cfs_hash *hs, int excl)
513 hs->hs_lops->hs_unlock(&hs->hs_lock, excl);
516 static inline int cfs_hash_dec_and_lock(struct cfs_hash *hs,
519 LASSERT(cfs_hash_with_no_bktlock(hs));
520 return atomic_dec_and_lock(condition, &hs->hs_lock.spin);
523 static inline void cfs_hash_bd_lock(struct cfs_hash *hs,
524 struct cfs_hash_bd *bd, int excl)
526 hs->hs_lops->hs_bkt_lock(&bd->bd_bucket->hsb_lock, excl);
529 static inline void cfs_hash_bd_unlock(struct cfs_hash *hs,
530 struct cfs_hash_bd *bd, int excl)
532 hs->hs_lops->hs_bkt_unlock(&bd->bd_bucket->hsb_lock, excl);
536 * operations on cfs_hash bucket (bd: bucket descriptor),
537 * they are normally for hash-table without rehash
539 void cfs_hash_bd_get(struct cfs_hash *hs, const void *key,
540 struct cfs_hash_bd *bd);
543 cfs_hash_bd_get_and_lock(struct cfs_hash *hs, const void *key,
544 struct cfs_hash_bd *bd, int excl)
546 cfs_hash_bd_get(hs, key, bd);
547 cfs_hash_bd_lock(hs, bd, excl);
550 static inline unsigned
551 cfs_hash_bd_index_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
553 return bd->bd_offset | (bd->bd_bucket->hsb_index << hs->hs_bkt_bits);
557 cfs_hash_bd_index_set(struct cfs_hash *hs, unsigned index,
558 struct cfs_hash_bd *bd)
560 bd->bd_bucket = hs->hs_buckets[index >> hs->hs_bkt_bits];
561 bd->bd_offset = index & (CFS_HASH_BKT_NHLIST(hs) - 1U);
565 cfs_hash_bd_extra_get(struct cfs_hash *hs, struct cfs_hash_bd *bd)
567 return (void *)bd->bd_bucket +
568 cfs_hash_bkt_size(hs) - hs->hs_extra_bytes;
572 cfs_hash_bd_version_get(struct cfs_hash_bd *bd)
574 /* need hold cfs_hash_bd_lock */
575 return bd->bd_bucket->hsb_version;
579 cfs_hash_bd_count_get(struct cfs_hash_bd *bd)
581 /* need hold cfs_hash_bd_lock */
582 return bd->bd_bucket->hsb_count;
586 cfs_hash_bd_depmax_get(struct cfs_hash_bd *bd)
588 return bd->bd_bucket->hsb_depmax;
592 cfs_hash_bd_compare(struct cfs_hash_bd *bd1, struct cfs_hash_bd *bd2)
594 if (bd1->bd_bucket->hsb_index != bd2->bd_bucket->hsb_index)
595 return bd1->bd_bucket->hsb_index - bd2->bd_bucket->hsb_index;
597 if (bd1->bd_offset != bd2->bd_offset)
598 return bd1->bd_offset - bd2->bd_offset;
603 void cfs_hash_bd_add_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
604 struct hlist_node *hnode);
605 void cfs_hash_bd_del_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
606 struct hlist_node *hnode);
607 void cfs_hash_bd_move_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd_old,
608 struct cfs_hash_bd *bd_new,
609 struct hlist_node *hnode);
612 cfs_hash_bd_dec_and_lock(struct cfs_hash *hs, struct cfs_hash_bd *bd,
615 LASSERT(cfs_hash_with_spin_bktlock(hs));
616 return atomic_dec_and_lock(condition, &bd->bd_bucket->hsb_lock.spin);
619 static inline struct hlist_head *
620 cfs_hash_bd_hhead(struct cfs_hash *hs, struct cfs_hash_bd *bd)
622 return hs->hs_hops->hop_hhead(hs, bd);
626 cfs_hash_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
629 cfs_hash_bd_peek_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
632 cfs_hash_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
633 const void *key, struct hlist_node *hnode,
636 cfs_hash_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bd,
637 const void *key, struct hlist_node *hnode);
640 * operations on cfs_hash bucket (bd: bucket descriptor),
641 * they are safe for hash-table with rehash
643 void cfs_hash_dual_bd_get(struct cfs_hash *hs, const void *key,
644 struct cfs_hash_bd *bds);
645 void cfs_hash_dual_bd_lock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
647 void cfs_hash_dual_bd_unlock(struct cfs_hash *hs, struct cfs_hash_bd *bds,
651 cfs_hash_dual_bd_get_and_lock(struct cfs_hash *hs, const void *key,
652 struct cfs_hash_bd *bds, int excl)
654 cfs_hash_dual_bd_get(hs, key, bds);
655 cfs_hash_dual_bd_lock(hs, bds, excl);
659 cfs_hash_dual_bd_lookup_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
662 cfs_hash_dual_bd_findadd_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
663 const void *key, struct hlist_node *hnode,
666 cfs_hash_dual_bd_finddel_locked(struct cfs_hash *hs, struct cfs_hash_bd *bds,
667 const void *key, struct hlist_node *hnode);
669 /* Hash init/cleanup functions */
671 cfs_hash_create(char *name, unsigned cur_bits, unsigned max_bits,
672 unsigned bkt_bits, unsigned extra_bytes,
673 unsigned min_theta, unsigned max_theta,
674 struct cfs_hash_ops *ops, unsigned flags);
676 struct cfs_hash *cfs_hash_getref(struct cfs_hash *hs);
677 void cfs_hash_putref(struct cfs_hash *hs);
679 /* Hash addition functions */
680 void cfs_hash_add(struct cfs_hash *hs, const void *key,
681 struct hlist_node *hnode);
682 int cfs_hash_add_unique(struct cfs_hash *hs, const void *key,
683 struct hlist_node *hnode);
684 void *cfs_hash_findadd_unique(struct cfs_hash *hs, const void *key,
685 struct hlist_node *hnode);
687 /* Hash deletion functions */
688 void *cfs_hash_del(struct cfs_hash *hs, const void *key,
689 struct hlist_node *hnode);
690 void *cfs_hash_del_key(struct cfs_hash *hs, const void *key);
692 /* Hash lookup/for_each functions */
693 #define CFS_HASH_LOOP_HOG 1024
695 typedef int (*cfs_hash_for_each_cb_t)(struct cfs_hash *hs,
696 struct cfs_hash_bd *bd,
697 struct hlist_node *node,
700 cfs_hash_lookup(struct cfs_hash *hs, const void *key);
702 cfs_hash_for_each(struct cfs_hash *hs, cfs_hash_for_each_cb_t, void *data);
704 cfs_hash_for_each_safe(struct cfs_hash *hs, cfs_hash_for_each_cb_t, void *data);
706 cfs_hash_for_each_nolock(struct cfs_hash *hs, cfs_hash_for_each_cb_t,
707 void *data, int start);
709 cfs_hash_for_each_empty(struct cfs_hash *hs, cfs_hash_for_each_cb_t,
712 cfs_hash_for_each_key(struct cfs_hash *hs, const void *key,
713 cfs_hash_for_each_cb_t, void *data);
714 typedef int (*cfs_hash_cond_opt_cb_t)(void *obj, void *data);
716 cfs_hash_cond_del(struct cfs_hash *hs, cfs_hash_cond_opt_cb_t, void *data);
719 cfs_hash_hlist_for_each(struct cfs_hash *hs, unsigned hindex,
720 cfs_hash_for_each_cb_t, void *data);
721 int cfs_hash_is_empty(struct cfs_hash *hs);
722 __u64 cfs_hash_size_get(struct cfs_hash *hs);
725 * Rehash - Theta is calculated to be the average chained
726 * hash depth assuming a perfectly uniform hash function.
728 void cfs_hash_rehash_cancel_locked(struct cfs_hash *hs);
729 void cfs_hash_rehash_cancel(struct cfs_hash *hs);
730 void cfs_hash_rehash(struct cfs_hash *hs, int do_rehash);
731 void cfs_hash_rehash_key(struct cfs_hash *hs, const void *old_key,
732 void *new_key, struct hlist_node *hnode);
734 #if CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1
735 /* Validate hnode references the correct key */
737 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
738 struct hlist_node *hnode)
740 LASSERT(cfs_hash_keycmp(hs, key, hnode));
743 /* Validate hnode is in the correct bucket */
745 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
746 struct hlist_node *hnode)
748 struct cfs_hash_bd bds[2];
750 cfs_hash_dual_bd_get(hs, cfs_hash_key(hs, hnode), bds);
751 LASSERT(bds[0].bd_bucket == bd->bd_bucket ||
752 bds[1].bd_bucket == bd->bd_bucket);
755 #else /* CFS_HASH_DEBUG_LEVEL > CFS_HASH_DEBUG_1 */
758 cfs_hash_key_validate(struct cfs_hash *hs, const void *key,
759 struct hlist_node *hnode) {}
762 cfs_hash_bucket_validate(struct cfs_hash *hs, struct cfs_hash_bd *bd,
763 struct hlist_node *hnode) {}
765 #endif /* CFS_HASH_DEBUG_LEVEL */
767 #define CFS_HASH_THETA_BITS 10
768 #define CFS_HASH_MIN_THETA (1U << (CFS_HASH_THETA_BITS - 1))
769 #define CFS_HASH_MAX_THETA (1U << (CFS_HASH_THETA_BITS + 1))
771 /* Return integer component of theta */
772 static inline int __cfs_hash_theta_int(int theta)
774 return (theta >> CFS_HASH_THETA_BITS);
777 /* Return a fractional value between 0 and 999 */
778 static inline int __cfs_hash_theta_frac(int theta)
780 return ((theta * 1000) >> CFS_HASH_THETA_BITS) -
781 (__cfs_hash_theta_int(theta) * 1000);
784 static inline int __cfs_hash_theta(struct cfs_hash *hs)
786 return (atomic_read(&hs->hs_count) <<
787 CFS_HASH_THETA_BITS) >> hs->hs_cur_bits;
791 __cfs_hash_set_theta(struct cfs_hash *hs, int min, int max)
794 hs->hs_min_theta = (__u16)min;
795 hs->hs_max_theta = (__u16)max;
798 /* Generic debug formatting routines mainly for proc handler */
800 void cfs_hash_debug_header(struct seq_file *m);
801 void cfs_hash_debug_str(struct cfs_hash *hs, struct seq_file *m);
804 * Generic djb2 hash algorithm for character arrays.
806 static inline unsigned
807 cfs_hash_djb2_hash(const void *key, size_t size, const unsigned int bits)
809 unsigned int i, hash = 5381;
811 LASSERT(key != NULL);
813 for (i = 0; i < size; i++)
814 hash = hash * 33 + ((char *)key)[i];
816 return (hash & ((1U << bits) - 1));
819 /** iterate over all buckets in @bds (array of struct cfs_hash_bd) */
820 #define cfs_hash_for_each_bd(bds, n, i) \
821 for (i = 0; i < n && (bds)[i].bd_bucket != NULL; i++)
823 /** iterate over all buckets of @hs */
824 #define cfs_hash_for_each_bucket(hs, bd, pos) \
826 pos < CFS_HASH_NBKT(hs) && \
827 ((bd)->bd_bucket = (hs)->hs_buckets[pos]) != NULL; pos++)
829 /** iterate over all hlist of bucket @bd */
830 #define cfs_hash_bd_for_each_hlist(hs, bd, hlist) \
831 for ((bd)->bd_offset = 0; \
832 (bd)->bd_offset < CFS_HASH_BKT_NHLIST(hs) && \
833 (hlist = cfs_hash_bd_hhead(hs, bd)) != NULL; \
836 /* !__LIBCFS__HASH_H__ */