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