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
|
/*
* QEMU Enhanced Disk Format Consistency Check
*
* Copyright IBM, Corp. 2010
*
* Authors:
* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qed.h"
typedef struct {
BDRVQEDState *s;
BdrvCheckResult *result;
bool fix; /* whether to fix invalid offsets */
uint64_t nclusters;
uint32_t *used_clusters; /* referenced cluster bitmap */
QEDRequest request;
} QEDCheck;
static bool qed_test_bit(uint32_t *bitmap, uint64_t n) {
return !!(bitmap[n / 32] & (1 << (n % 32)));
}
static void qed_set_bit(uint32_t *bitmap, uint64_t n) {
bitmap[n / 32] |= 1 << (n % 32);
}
/**
* Set bitmap bits for clusters
*
* @check: Check structure
* @offset: Starting offset in bytes
* @n: Number of clusters
*/
static bool qed_set_used_clusters(QEDCheck *check, uint64_t offset,
unsigned int n)
{
uint64_t cluster = qed_bytes_to_clusters(check->s, offset);
unsigned int corruptions = 0;
while (n-- != 0) {
/* Clusters should only be referenced once */
if (qed_test_bit(check->used_clusters, cluster)) {
corruptions++;
}
qed_set_bit(check->used_clusters, cluster);
cluster++;
}
check->result->corruptions += corruptions;
return corruptions == 0;
}
/**
* Check an L2 table
*
* @ret: Number of invalid cluster offsets
*/
static unsigned int qed_check_l2_table(QEDCheck *check, QEDTable *table)
{
BDRVQEDState *s = check->s;
unsigned int i, num_invalid = 0;
for (i = 0; i < s->table_nelems; i++) {
uint64_t offset = table->offsets[i];
if (qed_offset_is_unalloc_cluster(offset) ||
qed_offset_is_zero_cluster(offset)) {
continue;
}
/* Detect invalid cluster offset */
if (!qed_check_cluster_offset(s, offset)) {
if (check->fix) {
table->offsets[i] = 0;
} else {
check->result->corruptions++;
}
num_invalid++;
continue;
}
qed_set_used_clusters(check, offset, 1);
}
return num_invalid;
}
/**
* Descend tables and check each cluster is referenced once only
*/
static int qed_check_l1_table(QEDCheck *check, QEDTable *table)
{
BDRVQEDState *s = check->s;
unsigned int i, num_invalid_l1 = 0;
int ret, last_error = 0;
/* Mark L1 table clusters used */
qed_set_used_clusters(check, s->header.l1_table_offset,
s->header.table_size);
for (i = 0; i < s->table_nelems; i++) {
unsigned int num_invalid_l2;
uint64_t offset = table->offsets[i];
if (qed_offset_is_unalloc_cluster(offset)) {
continue;
}
/* Detect invalid L2 offset */
if (!qed_check_table_offset(s, offset)) {
/* Clear invalid offset */
if (check->fix) {
table->offsets[i] = 0;
} else {
check->result->corruptions++;
}
num_invalid_l1++;
continue;
}
if (!qed_set_used_clusters(check, offset, s->header.table_size)) {
continue; /* skip an invalid table */
}
ret = qed_read_l2_table_sync(s, &check->request, offset);
if (ret) {
check->result->check_errors++;
last_error = ret;
continue;
}
num_invalid_l2 = qed_check_l2_table(check,
check->request.l2_table->table);
/* Write out fixed L2 table */
if (num_invalid_l2 > 0 && check->fix) {
ret = qed_write_l2_table_sync(s, &check->request, 0,
s->table_nelems, false);
if (ret) {
check->result->check_errors++;
last_error = ret;
continue;
}
}
}
/* Drop reference to final table */
qed_unref_l2_cache_entry(check->request.l2_table);
check->request.l2_table = NULL;
/* Write out fixed L1 table */
if (num_invalid_l1 > 0 && check->fix) {
ret = qed_write_l1_table_sync(s, 0, s->table_nelems);
if (ret) {
check->result->check_errors++;
last_error = ret;
}
}
return last_error;
}
/**
* Check for unreferenced (leaked) clusters
*/
static void qed_check_for_leaks(QEDCheck *check)
{
BDRVQEDState *s = check->s;
uint64_t i;
for (i = s->header.header_size; i < check->nclusters; i++) {
if (!qed_test_bit(check->used_clusters, i)) {
check->result->leaks++;
}
}
}
int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix)
{
QEDCheck check = {
.s = s,
.result = result,
.nclusters = qed_bytes_to_clusters(s, s->file_size),
.request = { .l2_table = NULL },
.fix = fix,
};
int ret;
check.used_clusters = qemu_mallocz(((check.nclusters + 31) / 32) *
sizeof(check.used_clusters[0]));
ret = qed_check_l1_table(&check, s->l1_table);
if (ret == 0) {
/* Only check for leaks if entire image was scanned successfully */
qed_check_for_leaks(&check);
}
qemu_free(check.used_clusters);
return ret;
}
|
