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463 lines
13 KiB
463 lines
13 KiB
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* erofs-utils/include/erofs/hashtable.h
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*
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* Original code taken from 'linux/include/linux/hash{,table}.h'
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*/
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#ifndef __EROFS_HASHTABLE_H
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#define __EROFS_HASHTABLE_H
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/*
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* Fast hashing routine for ints, longs and pointers.
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* (C) 2002 Nadia Yvette Chambers, IBM
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*/
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/*
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* Statically sized hash table implementation
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* (C) 2012 Sasha Levin <levinsasha928@gmail.com>
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*/
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#include "defs.h"
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/*
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* The "GOLDEN_RATIO_PRIME" is used in ifs/btrfs/brtfs_inode.h and
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* fs/inode.c. It's not actually prime any more (the previous primes
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* were actively bad for hashing), but the name remains.
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*/
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#if BITS_PER_LONG == 32
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#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_32
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#define hash_long(val, bits) hash_32(val, bits)
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#elif BITS_PER_LONG == 64
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#define hash_long(val, bits) hash_64(val, bits)
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#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_64
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#else
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#error Wordsize not 32 or 64
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#endif
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/*
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* This hash multiplies the input by a large odd number and takes the
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* high bits. Since multiplication propagates changes to the most
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* significant end only, it is essential that the high bits of the
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* product be used for the hash value.
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*
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* Chuck Lever verified the effectiveness of this technique:
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* http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
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*
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* Although a random odd number will do, it turns out that the golden
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* ratio phi = (sqrt(5)-1)/2, or its negative, has particularly nice
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* properties. (See Knuth vol 3, section 6.4, exercise 9.)
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*
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* These are the negative, (1 - phi) = phi**2 = (3 - sqrt(5))/2,
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* which is very slightly easier to multiply by and makes no
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* difference to the hash distribution.
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*/
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#define GOLDEN_RATIO_32 0x61C88647
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#define GOLDEN_RATIO_64 0x61C8864680B583EBull
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struct hlist_head {
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struct hlist_node *first;
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};
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struct hlist_node {
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struct hlist_node *next, **pprev;
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};
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/*
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* Architectures might want to move the poison pointer offset
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* into some well-recognized area such as 0xdead000000000000,
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* that is also not mappable by user-space exploits:
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*/
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#ifdef CONFIG_ILLEGAL_POINTER_VALUE
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# define POISON_POINTER_DELTA _AC(CONFIG_ILLEGAL_POINTER_VALUE, UL)
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#else
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# define POISON_POINTER_DELTA 0
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#endif
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/*
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* These are non-NULL pointers that will result in page faults
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* under normal circumstances, used to verify that nobody uses
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* non-initialized list entries.
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*/
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#define LIST_POISON1 ((void *) 0x00100100 + POISON_POINTER_DELTA)
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#define LIST_POISON2 ((void *) 0x00200200 + POISON_POINTER_DELTA)
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/*
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* Double linked lists with a single pointer list head.
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* Mostly useful for hash tables where the two pointer list head is
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* too wasteful.
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* You lose the ability to access the tail in O(1).
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*/
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#define HLIST_HEAD_INIT { .first = NULL }
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#define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
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#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
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static inline void INIT_HLIST_NODE(struct hlist_node *h)
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{
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h->next = NULL;
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h->pprev = NULL;
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}
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static inline int hlist_unhashed(const struct hlist_node *h)
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{
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return !h->pprev;
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}
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static inline int hlist_empty(const struct hlist_head *h)
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{
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return !h->first;
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}
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static inline void __hlist_del(struct hlist_node *n)
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{
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struct hlist_node *next = n->next;
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struct hlist_node **pprev = n->pprev;
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*pprev = next;
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if (next)
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next->pprev = pprev;
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}
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static inline void hlist_del(struct hlist_node *n)
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{
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__hlist_del(n);
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n->next = LIST_POISON1;
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n->pprev = LIST_POISON2;
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}
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static inline void hlist_del_init(struct hlist_node *n)
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{
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if (!hlist_unhashed(n)) {
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__hlist_del(n);
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INIT_HLIST_NODE(n);
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}
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}
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static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
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{
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struct hlist_node *first = h->first;
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n->next = first;
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if (first)
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first->pprev = &n->next;
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h->first = n;
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n->pprev = &h->first;
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}
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/* next must be != NULL */
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static inline void hlist_add_before(struct hlist_node *n,
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struct hlist_node *next)
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{
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n->pprev = next->pprev;
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n->next = next;
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next->pprev = &n->next;
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*(n->pprev) = n;
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}
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static inline void hlist_add_behind(struct hlist_node *n,
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struct hlist_node *prev)
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{
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n->next = prev->next;
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prev->next = n;
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n->pprev = &prev->next;
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if (n->next)
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n->next->pprev = &n->next;
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}
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/* after that we'll appear to be on some hlist and hlist_del will work */
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static inline void hlist_add_fake(struct hlist_node *n)
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{
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n->pprev = &n->next;
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}
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/*
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* Move a list from one list head to another. Fixup the pprev
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* reference of the first entry if it exists.
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*/
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static inline void hlist_move_list(struct hlist_head *old,
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struct hlist_head *new)
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{
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new->first = old->first;
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if (new->first)
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new->first->pprev = &new->first;
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old->first = NULL;
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}
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#define hlist_entry(ptr, type, member) container_of(ptr, type, member)
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#define hlist_for_each(pos, head) \
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for (pos = (head)->first; pos; pos = pos->next)
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#define hlist_for_each_safe(pos, n, head) \
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for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
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pos = n)
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#define hlist_entry_safe(ptr, type, member) \
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({ typeof(ptr) ____ptr = (ptr); \
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____ptr ? hlist_entry(____ptr, type, member) : NULL; \
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})
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/**
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* hlist_for_each_entry - iterate over list of given type
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* @pos:the type * to use as a loop cursor.
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* @head:the head for your list.
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* @member:the name of the hlist_node within the struct.
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*/
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#define hlist_for_each_entry(pos, head, member) \
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for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
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pos; \
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pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
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/**
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* hlist_for_each_entry_continue
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* iterate over a hlist continuing after current point
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* @pos:the type * to use as a loop cursor.
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* @member:the name of the hlist_node within the struct.
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*/
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#define hlist_for_each_entry_continue(pos, member) \
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for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
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pos; \
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pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
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/**
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* hlist_for_each_entry_from
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* iterate over a hlist continuing from current point
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* @pos: the type * to use as a loop cursor.
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* @member: the name of the hlist_node within the struct.
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*/
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#define hlist_for_each_entry_from(pos, member) \
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for (; pos; \
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pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
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/**
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* hlist_for_each_entry_safe
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* iterate over list of given type safe against removal of list entry
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* @pos:the type * to use as a loop cursor.
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* @n:another &struct hlist_node to use as temporary storage
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* @head:the head for your list.
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* @member:the name of the hlist_node within the struct.
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*/
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#define hlist_for_each_entry_safe(pos, n, head, member) \
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for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
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pos && ({ n = pos->member.next; 1; }); \
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pos = hlist_entry_safe(n, typeof(*pos), member))
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static inline u32 __hash_32(u32 val)
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{
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return val * GOLDEN_RATIO_32;
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}
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static inline u32 hash_32(u32 val, unsigned int bits)
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{
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/* High bits are more random, so use them. */
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return __hash_32(val) >> (32 - bits);
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}
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static __always_inline u32 hash_64(u64 val, unsigned int bits)
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{
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#if BITS_PER_LONG == 64
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/* 64x64-bit multiply is efficient on all 64-bit processors */
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return val * GOLDEN_RATIO_64 >> (64 - bits);
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#else
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/* Hash 64 bits using only 32x32-bit multiply. */
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return hash_32((u32)val ^ __hash_32(val >> 32), bits);
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#endif
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}
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/**
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* ilog2 - log of base 2 of 32-bit or a 64-bit unsigned value
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* @n - parameter
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*
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* constant-capable log of base 2 calculation
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* - this can be used to initialise global variables from constant data, hence
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* the massive ternary operator construction
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*
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* selects the appropriately-sized optimised version depending on sizeof(n)
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*/
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#define ilog2(n) \
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( \
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(n) & (1ULL << 63) ? 63 : \
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(n) & (1ULL << 62) ? 62 : \
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(n) & (1ULL << 61) ? 61 : \
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(n) & (1ULL << 60) ? 60 : \
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(n) & (1ULL << 59) ? 59 : \
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(n) & (1ULL << 58) ? 58 : \
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(n) & (1ULL << 57) ? 57 : \
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(n) & (1ULL << 56) ? 56 : \
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(n) & (1ULL << 55) ? 55 : \
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(n) & (1ULL << 54) ? 54 : \
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(n) & (1ULL << 53) ? 53 : \
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(n) & (1ULL << 52) ? 52 : \
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(n) & (1ULL << 51) ? 51 : \
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(n) & (1ULL << 50) ? 50 : \
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(n) & (1ULL << 49) ? 49 : \
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(n) & (1ULL << 48) ? 48 : \
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(n) & (1ULL << 47) ? 47 : \
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(n) & (1ULL << 46) ? 46 : \
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(n) & (1ULL << 45) ? 45 : \
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(n) & (1ULL << 44) ? 44 : \
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(n) & (1ULL << 43) ? 43 : \
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(n) & (1ULL << 42) ? 42 : \
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(n) & (1ULL << 41) ? 41 : \
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(n) & (1ULL << 40) ? 40 : \
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(n) & (1ULL << 39) ? 39 : \
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(n) & (1ULL << 38) ? 38 : \
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(n) & (1ULL << 37) ? 37 : \
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(n) & (1ULL << 36) ? 36 : \
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(n) & (1ULL << 35) ? 35 : \
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(n) & (1ULL << 34) ? 34 : \
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(n) & (1ULL << 33) ? 33 : \
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(n) & (1ULL << 32) ? 32 : \
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(n) & (1ULL << 31) ? 31 : \
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(n) & (1ULL << 30) ? 30 : \
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(n) & (1ULL << 29) ? 29 : \
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(n) & (1ULL << 28) ? 28 : \
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(n) & (1ULL << 27) ? 27 : \
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(n) & (1ULL << 26) ? 26 : \
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(n) & (1ULL << 25) ? 25 : \
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(n) & (1ULL << 24) ? 24 : \
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(n) & (1ULL << 23) ? 23 : \
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(n) & (1ULL << 22) ? 22 : \
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(n) & (1ULL << 21) ? 21 : \
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(n) & (1ULL << 20) ? 20 : \
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(n) & (1ULL << 19) ? 19 : \
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(n) & (1ULL << 18) ? 18 : \
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(n) & (1ULL << 17) ? 17 : \
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(n) & (1ULL << 16) ? 16 : \
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(n) & (1ULL << 15) ? 15 : \
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(n) & (1ULL << 14) ? 14 : \
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(n) & (1ULL << 13) ? 13 : \
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(n) & (1ULL << 12) ? 12 : \
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(n) & (1ULL << 11) ? 11 : \
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(n) & (1ULL << 10) ? 10 : \
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(n) & (1ULL << 9) ? 9 : \
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(n) & (1ULL << 8) ? 8 : \
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(n) & (1ULL << 7) ? 7 : \
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(n) & (1ULL << 6) ? 6 : \
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(n) & (1ULL << 5) ? 5 : \
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(n) & (1ULL << 4) ? 4 : \
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(n) & (1ULL << 3) ? 3 : \
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(n) & (1ULL << 2) ? 2 : \
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(n) & (1ULL << 1) ? 1 : 0 \
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)
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#define DEFINE_HASHTABLE(name, bits) \
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struct hlist_head name[1 << (bits)] = \
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{ [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT }
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#define DECLARE_HASHTABLE(name, bits) \
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struct hlist_head name[1 << (bits)]
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#define HASH_SIZE(name) (ARRAY_SIZE(name))
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#define HASH_BITS(name) ilog2(HASH_SIZE(name))
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/* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels*/
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#define hash_min(val, bits) \
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(sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits))
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static inline void __hash_init(struct hlist_head *ht, unsigned int sz)
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{
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unsigned int i;
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for (i = 0; i < sz; i++)
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INIT_HLIST_HEAD(&ht[i]);
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}
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/**
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* hash_init - initialize a hash table
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* @hashtable: hashtable to be initialized
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*
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* Calculates the size of the hashtable from the given parameter, otherwise
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* same as hash_init_size.
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*
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* This has to be a macro since HASH_BITS() will not work on pointers since
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* it calculates the size during preprocessing.
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*/
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#define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable))
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/**
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* hash_add - add an object to a hashtable
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* @hashtable: hashtable to add to
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* @node: the &struct hlist_node of the object to be added
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* @key: the key of the object to be added
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*/
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#define hash_add(hashtable, node, key) \
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hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
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/**
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* hash_hashed - check whether an object is in any hashtable
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* @node: the &struct hlist_node of the object to be checked
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*/
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static inline bool hash_hashed(struct hlist_node *node)
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{
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return !hlist_unhashed(node);
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}
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static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz)
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{
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unsigned int i;
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for (i = 0; i < sz; i++)
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if (!hlist_empty(&ht[i]))
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return false;
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return true;
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}
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/**
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* hash_empty - check whether a hashtable is empty
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* @hashtable: hashtable to check
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*
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* This has to be a macro since HASH_BITS() will not work on pointers since
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* it calculates the size during preprocessing.
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*/
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#define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable))
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/**
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* hash_del - remove an object from a hashtable
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* @node: &struct hlist_node of the object to remove
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*/
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static inline void hash_del(struct hlist_node *node)
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{
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hlist_del_init(node);
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}
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/**
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* hash_for_each - iterate over a hashtable
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* @name: hashtable to iterate
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* @bkt: integer to use as bucket loop cursor
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* @obj: the type * to use as a loop cursor for each entry
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* @member: the name of the hlist_node within the struct
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*/
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#define hash_for_each(name, bkt, obj, member) \
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for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
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(bkt)++)\
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hlist_for_each_entry(obj, &name[bkt], member)
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/**
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* hash_for_each_safe - iterate over a hashtable safe against removal of
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* hash entry
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* @name: hashtable to iterate
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* @bkt: integer to use as bucket loop cursor
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* @tmp: a &struct used for temporary storage
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* @obj: the type * to use as a loop cursor for each entry
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* @member: the name of the hlist_node within the struct
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*/
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#define hash_for_each_safe(name, bkt, tmp, obj, member) \
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for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
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(bkt)++)\
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hlist_for_each_entry_safe(obj, tmp, &name[bkt], member)
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/**
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* hash_for_each_possible - iterate over all possible objects hashing to the
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* same bucket
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* @name: hashtable to iterate
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* @obj: the type * to use as a loop cursor for each entry
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* @member: the name of the hlist_node within the struct
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* @key: the key of the objects to iterate over
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*/
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#define hash_for_each_possible(name, obj, member, key) \
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hlist_for_each_entry(obj, &name[hash_min(key, HASH_BITS(name))], member)
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#endif
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