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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
#include "disk-io.h"
static int allocated_blocks = 0;
struct ctree_header {
u64 root_block;
} __attribute__ ((__packed__));
static int get_free_block(struct ctree_root *root, u64 *block)
{
struct stat st;
int ret;
st.st_size = 0;
ret = fstat(root->fp, &st);
if (st.st_size > sizeof(struct ctree_header)) {
*block = (st.st_size -
sizeof(struct ctree_header)) / CTREE_BLOCKSIZE;
} else {
*block = 0;
}
ret = ftruncate(root->fp, sizeof(struct ctree_header) + (*block + 1) *
CTREE_BLOCKSIZE);
return ret;
}
struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)
{
struct tree_buffer *buf;
int ret;
buf = malloc(sizeof(struct tree_buffer));
if (!buf)
return buf;
allocated_blocks++;
buf->blocknr = blocknr;
buf->count = 1;
radix_tree_preload(GFP_KERNEL);
ret = radix_tree_insert(&root->cache_radix, blocknr, buf);
radix_tree_preload_end();
if (ret) {
free(buf);
return NULL;
}
return buf;
}
struct tree_buffer *alloc_free_block(struct ctree_root *root)
{
u64 free_block;
int ret;
struct tree_buffer * buf;
ret = get_free_block(root, &free_block);
if (ret) {
BUG();
return NULL;
}
buf = alloc_tree_block(root, free_block);
if (!buf)
BUG();
return buf;
}
struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
{
loff_t offset = blocknr * CTREE_BLOCKSIZE + sizeof(struct ctree_header);
struct tree_buffer *buf;
int ret;
buf = radix_tree_lookup(&root->cache_radix, blocknr);
if (buf) {
buf->count++;
if (buf->blocknr != blocknr)
BUG();
if (buf->blocknr != buf->node.header.blocknr)
BUG();
return buf;
}
buf = alloc_tree_block(root, blocknr);
if (!buf)
return NULL;
ret = pread(root->fp, &buf->node, CTREE_BLOCKSIZE, offset);
if (ret != CTREE_BLOCKSIZE) {
free(buf);
return NULL;
}
if (buf->blocknr != buf->node.header.blocknr)
BUG();
return buf;
}
int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
{
u64 blocknr = buf->blocknr;
loff_t offset = blocknr * CTREE_BLOCKSIZE + sizeof(struct ctree_header);
int ret;
if (buf->blocknr != buf->node.header.blocknr)
BUG();
ret = pwrite(root->fp, &buf->node, CTREE_BLOCKSIZE, offset);
if (ret != CTREE_BLOCKSIZE)
return ret;
if (buf == root->node)
return update_root_block(root);
return 0;
}
struct ctree_root *open_ctree(char *filename)
{
struct ctree_root *root = malloc(sizeof(struct ctree_root));
int fp;
u64 root_block;
int ret;
fp = open(filename, O_CREAT | O_RDWR);
if (fp < 0) {
free(root);
return NULL;
}
root->fp = fp;
INIT_RADIX_TREE(&root->cache_radix, GFP_KERNEL);
ret = pread(fp, &root_block, sizeof(u64), 0);
if (ret == sizeof(u64)) {
printf("reading root node at block %lu\n", root_block);
root->node = read_tree_block(root, root_block);
} else
root->node = NULL;
return root;
}
int close_ctree(struct ctree_root *root)
{
close(root->fp);
if (root->node)
tree_block_release(root, root->node);
free(root);
printf("on close %d blocks are allocated\n", allocated_blocks);
return 0;
}
int update_root_block(struct ctree_root *root)
{
int ret;
u64 root_block = root->node->blocknr;
ret = pwrite(root->fp, &root_block, sizeof(u64), 0);
if (ret != sizeof(u64))
return ret;
return 0;
}
void tree_block_release(struct ctree_root *root, struct tree_buffer *buf)
{
buf->count--;
if (buf->count == 0) {
if (!radix_tree_lookup(&root->cache_radix, buf->blocknr))
BUG();
radix_tree_delete(&root->cache_radix, buf->blocknr);
memset(buf, 0, sizeof(*buf));
free(buf);
BUG_ON(allocated_blocks == 0);
allocated_blocks--;
}
}
|
