1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2011 Red Hat, Inc.
4 *
5 * This file is released under the GPL.
6 */
7
8 #ifndef DM_BTREE_INTERNAL_H
9 #define DM_BTREE_INTERNAL_H
10
11 #include "dm-btree.h"
12
13 /*----------------------------------------------------------------*/
14
15 /*
16 * We'll need 2 accessor functions for n->csum and n->blocknr
17 * to support dm-btree-spine.c in that case.
18 */
19
20 enum node_flags {
21 INTERNAL_NODE = 1,
22 LEAF_NODE = 1 << 1
23 };
24
25 /*
26 * Every btree node begins with this structure. Make sure it's a multiple
27 * of 8-bytes in size, otherwise the 64bit keys will be mis-aligned.
28 */
29 struct node_header {
30 __le32 csum;
31 __le32 flags;
32 __le64 blocknr; /* Block this node is supposed to live in. */
33
34 __le32 nr_entries;
35 __le32 max_entries;
36 __le32 value_size;
37 __le32 padding;
38 } __packed __aligned(8);
39
40 struct btree_node {
41 struct node_header header;
42 __le64 keys[];
43 } __packed __aligned(8);
44
45
46 /*
47 * Locks a block using the btree node validator.
48 */
49 int bn_read_lock(struct dm_btree_info *info, dm_block_t b,
50 struct dm_block **result);
51
52 void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
53 struct dm_btree_value_type *vt);
54
55 int new_block(struct dm_btree_info *info, struct dm_block **result);
56 void unlock_block(struct dm_btree_info *info, struct dm_block *b);
57
58 /*
59 * Spines keep track of the rolling locks. There are 2 variants, read-only
60 * and one that uses shadowing. These are separate structs to allow the
61 * type checker to spot misuse, for example accidentally calling read_lock
62 * on a shadow spine.
63 */
64 struct ro_spine {
65 struct dm_btree_info *info;
66
67 int count;
68 struct dm_block *nodes[2];
69 };
70
71 void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info);
72 void exit_ro_spine(struct ro_spine *s);
73 int ro_step(struct ro_spine *s, dm_block_t new_child);
74 void ro_pop(struct ro_spine *s);
75 struct btree_node *ro_node(struct ro_spine *s);
76
77 struct shadow_spine {
78 struct dm_btree_info *info;
79
80 int count;
81 struct dm_block *nodes[2];
82
83 dm_block_t root;
84 };
85
86 void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info);
87 void exit_shadow_spine(struct shadow_spine *s);
88
89 int shadow_step(struct shadow_spine *s, dm_block_t b,
90 struct dm_btree_value_type *vt);
91
92 /*
93 * The spine must have at least one entry before calling this.
94 */
95 struct dm_block *shadow_current(struct shadow_spine *s);
96
97 /*
98 * The spine must have at least two entries before calling this.
99 */
100 struct dm_block *shadow_parent(struct shadow_spine *s);
101
102 int shadow_has_parent(struct shadow_spine *s);
103
104 dm_block_t shadow_root(struct shadow_spine *s);
105
106 /*
107 * Some inlines.
108 */
key_ptr(struct btree_node * n,uint32_t index)109 static inline __le64 *key_ptr(struct btree_node *n, uint32_t index)
110 {
111 return n->keys + index;
112 }
113
value_base(struct btree_node * n)114 static inline void *value_base(struct btree_node *n)
115 {
116 return &n->keys[le32_to_cpu(n->header.max_entries)];
117 }
118
value_ptr(struct btree_node * n,uint32_t index)119 static inline void *value_ptr(struct btree_node *n, uint32_t index)
120 {
121 uint32_t value_size = le32_to_cpu(n->header.value_size);
122
123 return value_base(n) + (value_size * index);
124 }
125
126 /*
127 * Assumes the values are suitably-aligned and converts to core format.
128 */
value64(struct btree_node * n,uint32_t index)129 static inline uint64_t value64(struct btree_node *n, uint32_t index)
130 {
131 __le64 *values_le = value_base(n);
132
133 return le64_to_cpu(values_le[index]);
134 }
135
136 /*
137 * Searching for a key within a single node.
138 */
139 int lower_bound(struct btree_node *n, uint64_t key);
140
141 extern const struct dm_block_validator btree_node_validator;
142
143 /*
144 * Value type for upper levels of multi-level btrees.
145 */
146 extern void init_le64_type(struct dm_transaction_manager *tm,
147 struct dm_btree_value_type *vt);
148
149 /*
150 * This returns a shadowed btree leaf that you may modify. In practise
151 * this means overwrites only, since an insert could cause a node to
152 * be split. Useful if you need access to the old value to calculate the
153 * new one.
154 *
155 * This only works with single level btrees. The given key must be present in
156 * the tree, otherwise -EINVAL will be returned.
157 */
158 int btree_get_overwrite_leaf(struct dm_btree_info *info, dm_block_t root,
159 uint64_t key, int *index,
160 dm_block_t *new_root, struct dm_block **leaf);
161
162 #endif /* DM_BTREE_INTERNAL_H */
163