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
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
|
/*
* extent.c --- ext2 extent abstraction
*
* This abstraction is used to provide a compact way of representing a
* translation table, for moving multiple contiguous ranges (extents)
* of blocks or inodes.
*
* Copyright (C) 1997 Theodore Ts'o
*
* %Begin-Header%
* All rights reserved.
* %End-Header%
*/
#include "resize2fs.h"
struct ext2_extent_entry {
__u32 old_loc, new_loc;
int size;
};
struct _ext2_extent {
struct ext2_extent_entry *list;
int cursor;
int size;
int num;
int sorted;
};
/*
* Create an extent table
*/
errcode_t ext2fs_create_extent_table(ext2_extent *ret_extent, int size)
{
ext2_extent extent;
errcode_t retval;
retval = ext2fs_get_mem(sizeof(struct _ext2_extent),
(void **) &extent);
if (retval)
return retval;
memset(extent, 0, sizeof(struct _ext2_extent));
extent->size = size ? size : 50;
extent->cursor = 0;
extent->num = 0;
extent->sorted = 1;
retval = ext2fs_get_mem(sizeof(struct ext2_extent_entry) *
extent->size, (void **) &extent->list);
if (retval) {
free(extent);
return retval;
}
memset(extent->list, 0,
sizeof(struct ext2_extent_entry) * extent->size);
*ret_extent = extent;
return 0;
}
/*
* Free an extent table
*/
void ext2fs_free_extent_table(ext2_extent extent)
{
if (extent->list)
ext2fs_free_mem((void **) &extent->list);
extent->list = 0;
extent->size = 0;
extent->num = 0;
ext2fs_free_mem((void **) &extent);
}
/*
* Add an entry to the extent table
*/
errcode_t ext2fs_add_extent_entry(ext2_extent extent, __u32 old_loc, __u32 new_loc)
{
struct ext2_extent_entry *ent;
errcode_t retval;
int newsize;
int curr;
if (extent->num >= extent->size) {
newsize = extent->size + 100;
retval = ext2fs_resize_mem(sizeof(struct ext2_extent_entry) *
newsize, (void **) &extent->list);
if (retval)
return retval;
extent->size = newsize;
}
curr = extent->num;
ent = extent->list + curr;
if (curr) {
/*
* Check to see if this can be coalesced with the last
* extent
*/
ent--;
if ((ent->old_loc + ent->size == old_loc) &&
(ent->new_loc + ent->size == new_loc)) {
ent->size++;
return 0;
}
/*
* Now see if we're going to ruin the sorting
*/
if (ent->old_loc + ent->size > old_loc)
extent->sorted = 0;
ent++;
}
ent->old_loc = old_loc;
ent->new_loc = new_loc;
ent->size = 1;
extent->num++;
return 0;
}
/*
* Helper function for qsort
*/
static int extent_cmp(const void *a, const void *b)
{
const struct ext2_extent_entry *db_a;
const struct ext2_extent_entry *db_b;
db_a = (struct ext2_extent_entry *) a;
db_b = (struct ext2_extent_entry *) b;
return (db_a->old_loc - db_b->old_loc);
}
/*
* Given an inode map and inode number, look up the old inode number
* and return the new inode number.
*/
__u32 ext2fs_extent_translate(ext2_extent extent, __u32 old_loc)
{
int low, high, mid;
ino_t lowval, highval;
float range;
if (!extent->sorted) {
qsort(extent->list, extent->num,
sizeof(struct ext2_extent_entry), extent_cmp);
extent->sorted = 1;
}
low = 0;
high = extent->num-1;
while (low <= high) {
#if 0
mid = (low+high)/2;
#else
if (low == high)
mid = low;
else {
/* Interpolate for efficiency */
lowval = extent->list[low].old_loc;
highval = extent->list[high].old_loc;
if (old_loc < lowval)
range = 0;
else if (old_loc > highval)
range = 1;
else
range = ((float) (old_loc - lowval)) /
(highval - lowval);
mid = low + ((int) (range * (high-low)));
}
#endif
if ((old_loc >= extent->list[mid].old_loc) &&
(old_loc < extent->list[mid].old_loc + extent->list[mid].size))
return (extent->list[mid].new_loc +
(old_loc - extent->list[mid].old_loc));
if (old_loc < extent->list[mid].old_loc)
high = mid-1;
else
low = mid+1;
}
return 0;
}
/*
* For debugging only
*/
void ext2fs_extent_dump(ext2_extent extent, FILE *out)
{
int i;
struct ext2_extent_entry *ent;
fputs("# Extent dump:\n", out);
fprintf(out, "#\tNum=%d, Size=%d, Cursor=%d, Sorted=%d\n",
extent->num, extent->size, extent->cursor, extent->sorted);
for (i=0, ent=extent->list; i < extent->num; i++, ent++) {
fprintf(out, "#\t\t %u -> %u (%d)\n", ent->old_loc,
ent->new_loc, ent->size);
}
}
/*
* Iterate over the contents of the extent table
*/
errcode_t ext2fs_iterate_extent(ext2_extent extent, __u32 *old_loc,
__u32 *new_loc, int *size)
{
struct ext2_extent_entry *ent;
if (!old_loc) {
extent->cursor = 0;
return 0;
}
if (extent->cursor >= extent->num) {
*old_loc = 0;
*new_loc = 0;
*size = 0;
return 0;
}
ent = extent->list + extent->cursor++;
*old_loc = ent->old_loc;
*new_loc = ent->new_loc;
*size = ent->size;
return 0;
}
|
