1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
#ifndef __CTREE__
#define __CTREE__
#include "list.h"
#define CTREE_BLOCKSIZE 1024
/*
* the key defines the order in the tree, and so it also defines (optimal)
* block layout. objectid corresonds to the inode number. The flags
* tells us things about the object, and is a kind of stream selector.
* so for a given inode, keys with flags of 1 might refer to the inode
* data, flags of 2 may point to file data in the btree and flags == 3
* may point to extents.
*
* offset is the starting byte offset for this key in the stream.
*/
struct key {
u64 objectid;
u32 flags;
u64 offset;
} __attribute__ ((__packed__));
/*
* every tree block (leaf or node) starts with this header.
*/
struct header {
u64 fsid[2]; /* FS specific uuid */
u64 blocknr; /* which block this node is supposed to live in */
u64 parentid; /* objectid of the tree root */
u32 csum;
u32 ham;
u16 nritems;
u16 flags;
/* generation flags to be added */
} __attribute__ ((__packed__));
#define NODEPTRS_PER_BLOCK ((CTREE_BLOCKSIZE - sizeof(struct header)) / \
(sizeof(struct key) + sizeof(u64)))
#define MAX_LEVEL 8
#define node_level(f) ((f) & (MAX_LEVEL-1))
#define is_leaf(f) (node_level(f) == 0)
struct tree_buffer;
/*
* in ram representation of the tree. extent_root is used for all allocations
* and for the extent tree extent_root root. current_insert is used
* only for the extent tree.
*/
struct ctree_root {
struct tree_buffer *node;
struct ctree_root *extent_root;
struct key current_insert;
int fp;
struct radix_tree_root cache_radix;
struct list_head trans;
struct list_head cache;
int cache_size;
};
/*
* describes a tree on disk
*/
struct ctree_root_info {
u64 fsid[2]; /* FS specific uuid */
u64 blocknr; /* blocknr of this block */
u64 objectid; /* inode number of this root */
u64 tree_root; /* the tree root block */
u32 csum;
u32 ham;
u64 snapuuid[2]; /* root specific uuid */
} __attribute__ ((__packed__));
/*
* the super block basically lists the main trees of the FS
* it currently lacks any block count etc etc
*/
struct ctree_super_block {
struct ctree_root_info root_info;
struct ctree_root_info extent_info;
} __attribute__ ((__packed__));
/*
* A leaf is full of items. The exact type of item is defined by
* the key flags parameter. offset and size tell us where to find
* the item in the leaf (relative to the start of the data area)
*/
struct item {
struct key key;
u16 offset;
u16 size;
} __attribute__ ((__packed__));
/*
* leaves have an item area and a data area:
* [item0, item1....itemN] [free space] [dataN...data1, data0]
*
* The data is separate from the items to get the keys closer together
* during searches.
*/
#define LEAF_DATA_SIZE (CTREE_BLOCKSIZE - sizeof(struct header))
struct leaf {
struct header header;
union {
struct item items[LEAF_DATA_SIZE/sizeof(struct item)];
u8 data[CTREE_BLOCKSIZE-sizeof(struct header)];
};
} __attribute__ ((__packed__));
/*
* all non-leaf blocks are nodes, they hold only keys and pointers to
* other blocks
*/
struct node {
struct header header;
struct key keys[NODEPTRS_PER_BLOCK];
u64 blockptrs[NODEPTRS_PER_BLOCK];
} __attribute__ ((__packed__));
/*
* items in the extent btree are used to record the objectid of the
* owner of the block and the number of references
*/
struct extent_item {
u32 refs;
u64 owner;
} __attribute__ ((__packed__));
/*
* ctree_paths remember the path taken from the root down to the leaf.
* level 0 is always the leaf, and nodes[1...MAX_LEVEL] will point
* to any other levels that are present.
*
* The slots array records the index of the item or block pointer
* used while walking the tree.
*/
struct ctree_path {
struct tree_buffer *nodes[MAX_LEVEL];
int slots[MAX_LEVEL];
};
struct tree_buffer *alloc_free_block(struct ctree_root *root);
int free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks);
int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p, int ins_len);
void release_path(struct ctree_root *root, struct ctree_path *p);
void init_path(struct ctree_path *p);
int del_item(struct ctree_root *root, struct ctree_path *path);
int insert_item(struct ctree_root *root, struct key *key, void *data, int data_size);
int next_leaf(struct ctree_root *root, struct ctree_path *path);
int leaf_free_space(struct leaf *leaf);
#endif
|
