4 #include <linux/kernel.h>
5 #include <linux/mempool.h>
10 * A B+Tree is a data structure for looking up arbitrary (currently allowing
11 * unsigned long, u32, u64 and 2 * u64) keys into pointers. The data structure
12 * is described at http://en.wikipedia.org/wiki/B-tree, we currently do not
13 * use binary search to find the key on lookups.
15 * Each B+Tree consists of a head, that contains bookkeeping information and
16 * a variable number (starting with zero) nodes. Each node contains the keys
17 * and pointers to sub-nodes, or, for leaf nodes, the keys and values for the
20 * Each node in this implementation has the following layout:
21 * [key1, key2, ..., keyN] [val1, val2, ..., valN]
23 * Each key here is an array of unsigned longs, geo->no_longs in total. The
24 * number of keys and values (N) is geo->no_pairs.
28 * struct btree_head - btree head
30 * @node: the first node in the tree
31 * @mempool: mempool used for node allocations
32 * @height: current of the tree
44 * btree_alloc - allocate function for the mempool
45 * @gfp_mask: gfp mask for the allocation
48 void *btree_alloc(gfp_t gfp_mask
, void *pool_data
);
51 * btree_free - free function for the mempool
52 * @element: the element to free
55 void btree_free(void *element
, void *pool_data
);
58 * btree_init_mempool - initialise a btree with given mempool
60 * @head: the btree head to initialise
61 * @mempool: the mempool to use
63 * When this function is used, there is no need to destroy
66 void btree_init_mempool(struct btree_head
*head
, mempool_t
*mempool
);
69 * btree_init - initialise a btree
71 * @head: the btree head to initialise
73 * This function allocates the memory pool that the
74 * btree needs. Returns zero or a negative error code
75 * (-%ENOMEM) when memory allocation fails.
78 int __must_check
btree_init(struct btree_head
*head
);
81 * btree_destroy - destroy mempool
83 * @head: the btree head to destroy
85 * This function destroys the internal memory pool, use only
86 * when using btree_init(), not with btree_init_mempool().
88 void btree_destroy(struct btree_head
*head
);
91 * btree_lookup - look up a key in the btree
93 * @head: the btree to look in
94 * @geo: the btree geometry
95 * @key: the key to look up
97 * This function returns the value for the given key, or %NULL.
99 void *btree_lookup(struct btree_head
*head
, struct btree_geo
*geo
,
103 * btree_insert - insert an entry into the btree
105 * @head: the btree to add to
106 * @geo: the btree geometry
107 * @key: the key to add (must not already be present)
108 * @val: the value to add (must not be %NULL)
109 * @gfp: allocation flags for node allocations
111 * This function returns 0 if the item could be added, or an
112 * error code if it failed (may fail due to memory pressure).
114 int __must_check
btree_insert(struct btree_head
*head
, struct btree_geo
*geo
,
115 unsigned long *key
, void *val
, gfp_t gfp
);
117 * btree_update - update an entry in the btree
119 * @head: the btree to update
120 * @geo: the btree geometry
121 * @key: the key to update
122 * @val: the value to change it to (must not be %NULL)
124 * This function returns 0 if the update was successful, or
125 * -%ENOENT if the key could not be found.
127 int btree_update(struct btree_head
*head
, struct btree_geo
*geo
,
128 unsigned long *key
, void *val
);
130 * btree_remove - remove an entry from the btree
132 * @head: the btree to update
133 * @geo: the btree geometry
134 * @key: the key to remove
136 * This function returns the removed entry, or %NULL if the key
137 * could not be found.
139 void *btree_remove(struct btree_head
*head
, struct btree_geo
*geo
,
143 * btree_merge - merge two btrees
145 * @target: the tree that gets all the entries
146 * @victim: the tree that gets merged into @target
147 * @geo: the btree geometry
148 * @gfp: allocation flags
150 * The two trees @target and @victim may not contain the same keys,
151 * that is a bug and triggers a BUG(). This function returns zero
152 * if the trees were merged successfully, and may return a failure
153 * when memory allocation fails, in which case both trees might have
154 * been partially merged, i.e. some entries have been moved from
155 * @victim to @target.
157 int btree_merge(struct btree_head
*target
, struct btree_head
*victim
,
158 struct btree_geo
*geo
, gfp_t gfp
);
161 * btree_last - get last entry in btree
164 * @geo: btree geometry
167 * Returns the last entry in the btree, and sets @key to the key
168 * of that entry; returns NULL if the tree is empty, in that case
169 * key is not changed.
171 void *btree_last(struct btree_head
*head
, struct btree_geo
*geo
,
175 * btree_get_prev - get previous entry
178 * @geo: btree geometry
179 * @key: pointer to key
181 * The function returns the next item right before the value pointed to by
182 * @key, and updates @key with its key, or returns %NULL when there is no
183 * entry with a key smaller than the given key.
185 void *btree_get_prev(struct btree_head
*head
, struct btree_geo
*geo
,
189 /* internal use, use btree_visitor{l,32,64,128} */
190 size_t btree_visitor(struct btree_head
*head
, struct btree_geo
*geo
,
191 unsigned long opaque
,
192 void (*func
)(void *elem
, unsigned long opaque
,
193 unsigned long *key
, size_t index
,
197 /* internal use, use btree_grim_visitor{l,32,64,128} */
198 size_t btree_grim_visitor(struct btree_head
*head
, struct btree_geo
*geo
,
199 unsigned long opaque
,
200 void (*func
)(void *elem
, unsigned long opaque
,
202 size_t index
, void *func2
),
206 #include <linux/btree-128.h>
208 extern struct btree_geo btree_geo32
;
209 #define BTREE_TYPE_SUFFIX l
210 #define BTREE_TYPE_BITS BITS_PER_LONG
211 #define BTREE_TYPE_GEO &btree_geo32
212 #define BTREE_KEYTYPE unsigned long
213 #include <linux/btree-type.h>
215 #define btree_for_each_safel(head, key, val) \
216 for (val = btree_lastl(head, &key); \
218 val = btree_get_prevl(head, &key))
220 #define BTREE_TYPE_SUFFIX 32
221 #define BTREE_TYPE_BITS 32
222 #define BTREE_TYPE_GEO &btree_geo32
223 #define BTREE_KEYTYPE u32
224 #include <linux/btree-type.h>
226 #define btree_for_each_safe32(head, key, val) \
227 for (val = btree_last32(head, &key); \
229 val = btree_get_prev32(head, &key))
231 extern struct btree_geo btree_geo64
;
232 #define BTREE_TYPE_SUFFIX 64
233 #define BTREE_TYPE_BITS 64
234 #define BTREE_TYPE_GEO &btree_geo64
235 #define BTREE_KEYTYPE u64
236 #include <linux/btree-type.h>
238 #define btree_for_each_safe64(head, key, val) \
239 for (val = btree_last64(head, &key); \
241 val = btree_get_prev64(head, &key))
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