1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef BTREE_H |
3 | #define BTREE_H |
4 | |
5 | #include <linux/kernel.h> |
6 | #include <linux/mempool.h> |
7 | |
8 | /** |
9 | * DOC: B+Tree basics |
10 | * |
11 | * A B+Tree is a data structure for looking up arbitrary (currently allowing |
12 | * unsigned long, u32, u64 and 2 * u64) keys into pointers. The data structure |
13 | * is described at https://en.wikipedia.org/wiki/B-tree, we currently do not |
14 | * use binary search to find the key on lookups. |
15 | * |
16 | * Each B+Tree consists of a head, that contains bookkeeping information and |
17 | * a variable number (starting with zero) nodes. Each node contains the keys |
18 | * and pointers to sub-nodes, or, for leaf nodes, the keys and values for the |
19 | * tree entries. |
20 | * |
21 | * Each node in this implementation has the following layout: |
22 | * [key1, key2, ..., keyN] [val1, val2, ..., valN] |
23 | * |
24 | * Each key here is an array of unsigned longs, geo->no_longs in total. The |
25 | * number of keys and values (N) is geo->no_pairs. |
26 | */ |
27 | |
28 | /** |
29 | * struct btree_head - btree head |
30 | * |
31 | * @node: the first node in the tree |
32 | * @mempool: mempool used for node allocations |
33 | * @height: current of the tree |
34 | */ |
35 | struct btree_head { |
36 | unsigned long *node; |
37 | mempool_t *mempool; |
38 | int height; |
39 | }; |
40 | |
41 | /* btree geometry */ |
42 | struct btree_geo; |
43 | |
44 | /** |
45 | * btree_alloc - allocate function for the mempool |
46 | * @gfp_mask: gfp mask for the allocation |
47 | * @pool_data: unused |
48 | */ |
49 | void *btree_alloc(gfp_t gfp_mask, void *pool_data); |
50 | |
51 | /** |
52 | * btree_free - free function for the mempool |
53 | * @element: the element to free |
54 | * @pool_data: unused |
55 | */ |
56 | void btree_free(void *element, void *pool_data); |
57 | |
58 | /** |
59 | * btree_init_mempool - initialise a btree with given mempool |
60 | * |
61 | * @head: the btree head to initialise |
62 | * @mempool: the mempool to use |
63 | * |
64 | * When this function is used, there is no need to destroy |
65 | * the mempool. |
66 | */ |
67 | void btree_init_mempool(struct btree_head *head, mempool_t *mempool); |
68 | |
69 | /** |
70 | * btree_init - initialise a btree |
71 | * |
72 | * @head: the btree head to initialise |
73 | * |
74 | * This function allocates the memory pool that the |
75 | * btree needs. Returns zero or a negative error code |
76 | * (-%ENOMEM) when memory allocation fails. |
77 | * |
78 | */ |
79 | int __must_check btree_init(struct btree_head *head); |
80 | |
81 | /** |
82 | * btree_destroy - destroy mempool |
83 | * |
84 | * @head: the btree head to destroy |
85 | * |
86 | * This function destroys the internal memory pool, use only |
87 | * when using btree_init(), not with btree_init_mempool(). |
88 | */ |
89 | void btree_destroy(struct btree_head *head); |
90 | |
91 | /** |
92 | * btree_lookup - look up a key in the btree |
93 | * |
94 | * @head: the btree to look in |
95 | * @geo: the btree geometry |
96 | * @key: the key to look up |
97 | * |
98 | * This function returns the value for the given key, or %NULL. |
99 | */ |
100 | void *btree_lookup(struct btree_head *head, struct btree_geo *geo, |
101 | unsigned long *key); |
102 | |
103 | /** |
104 | * btree_insert - insert an entry into the btree |
105 | * |
106 | * @head: the btree to add to |
107 | * @geo: the btree geometry |
108 | * @key: the key to add (must not already be present) |
109 | * @val: the value to add (must not be %NULL) |
110 | * @gfp: allocation flags for node allocations |
111 | * |
112 | * This function returns 0 if the item could be added, or an |
113 | * error code if it failed (may fail due to memory pressure). |
114 | */ |
115 | int __must_check btree_insert(struct btree_head *head, struct btree_geo *geo, |
116 | unsigned long *key, void *val, gfp_t gfp); |
117 | /** |
118 | * btree_update - update an entry in the btree |
119 | * |
120 | * @head: the btree to update |
121 | * @geo: the btree geometry |
122 | * @key: the key to update |
123 | * @val: the value to change it to (must not be %NULL) |
124 | * |
125 | * This function returns 0 if the update was successful, or |
126 | * -%ENOENT if the key could not be found. |
127 | */ |
128 | int btree_update(struct btree_head *head, struct btree_geo *geo, |
129 | unsigned long *key, void *val); |
130 | /** |
131 | * btree_remove - remove an entry from the btree |
132 | * |
133 | * @head: the btree to update |
134 | * @geo: the btree geometry |
135 | * @key: the key to remove |
136 | * |
137 | * This function returns the removed entry, or %NULL if the key |
138 | * could not be found. |
139 | */ |
140 | void *btree_remove(struct btree_head *head, struct btree_geo *geo, |
141 | unsigned long *key); |
142 | |
143 | /** |
144 | * btree_merge - merge two btrees |
145 | * |
146 | * @target: the tree that gets all the entries |
147 | * @victim: the tree that gets merged into @target |
148 | * @geo: the btree geometry |
149 | * @gfp: allocation flags |
150 | * |
151 | * The two trees @target and @victim may not contain the same keys, |
152 | * that is a bug and triggers a BUG(). This function returns zero |
153 | * if the trees were merged successfully, and may return a failure |
154 | * when memory allocation fails, in which case both trees might have |
155 | * been partially merged, i.e. some entries have been moved from |
156 | * @victim to @target. |
157 | */ |
158 | int btree_merge(struct btree_head *target, struct btree_head *victim, |
159 | struct btree_geo *geo, gfp_t gfp); |
160 | |
161 | /** |
162 | * btree_last - get last entry in btree |
163 | * |
164 | * @head: btree head |
165 | * @geo: btree geometry |
166 | * @key: last key |
167 | * |
168 | * Returns the last entry in the btree, and sets @key to the key |
169 | * of that entry; returns NULL if the tree is empty, in that case |
170 | * key is not changed. |
171 | */ |
172 | void *btree_last(struct btree_head *head, struct btree_geo *geo, |
173 | unsigned long *key); |
174 | |
175 | /** |
176 | * btree_get_prev - get previous entry |
177 | * |
178 | * @head: btree head |
179 | * @geo: btree geometry |
180 | * @key: pointer to key |
181 | * |
182 | * The function returns the next item right before the value pointed to by |
183 | * @key, and updates @key with its key, or returns %NULL when there is no |
184 | * entry with a key smaller than the given key. |
185 | */ |
186 | void *btree_get_prev(struct btree_head *head, struct btree_geo *geo, |
187 | unsigned long *key); |
188 | |
189 | |
190 | /* internal use, use btree_visitor{l,32,64,128} */ |
191 | size_t btree_visitor(struct btree_head *head, struct btree_geo *geo, |
192 | unsigned long opaque, |
193 | void (*func)(void *elem, unsigned long opaque, |
194 | unsigned long *key, size_t index, |
195 | void *func2), |
196 | void *func2); |
197 | |
198 | /* internal use, use btree_grim_visitor{l,32,64,128} */ |
199 | size_t btree_grim_visitor(struct btree_head *head, struct btree_geo *geo, |
200 | unsigned long opaque, |
201 | void (*func)(void *elem, unsigned long opaque, |
202 | unsigned long *key, |
203 | size_t index, void *func2), |
204 | void *func2); |
205 | |
206 | |
207 | #include <linux/btree-128.h> |
208 | |
209 | extern struct btree_geo btree_geo32; |
210 | #define BTREE_TYPE_SUFFIX l |
211 | #define BTREE_TYPE_BITS BITS_PER_LONG |
212 | #define BTREE_TYPE_GEO &btree_geo32 |
213 | #define BTREE_KEYTYPE unsigned long |
214 | #include <linux/btree-type.h> |
215 | |
216 | #define btree_for_each_safel(head, key, val) \ |
217 | for (val = btree_lastl(head, &key); \ |
218 | val; \ |
219 | val = btree_get_prevl(head, &key)) |
220 | |
221 | #define BTREE_TYPE_SUFFIX 32 |
222 | #define BTREE_TYPE_BITS 32 |
223 | #define BTREE_TYPE_GEO &btree_geo32 |
224 | #define BTREE_KEYTYPE u32 |
225 | #include <linux/btree-type.h> |
226 | |
227 | #define btree_for_each_safe32(head, key, val) \ |
228 | for (val = btree_last32(head, &key); \ |
229 | val; \ |
230 | val = btree_get_prev32(head, &key)) |
231 | |
232 | extern struct btree_geo btree_geo64; |
233 | #define BTREE_TYPE_SUFFIX 64 |
234 | #define BTREE_TYPE_BITS 64 |
235 | #define BTREE_TYPE_GEO &btree_geo64 |
236 | #define BTREE_KEYTYPE u64 |
237 | #include <linux/btree-type.h> |
238 | |
239 | #define btree_for_each_safe64(head, key, val) \ |
240 | for (val = btree_last64(head, &key); \ |
241 | val; \ |
242 | val = btree_get_prev64(head, &key)) |
243 | |
244 | #endif |
245 | |