1 /*
2 * QEMU Enhanced Disk Format Consistency Check
3 *
4 * Copyright IBM, Corp. 2010
5 *
6 * Authors:
7 * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
8 *
9 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
10 * See the COPYING.LIB file in the top-level directory.
11 *
12 */
13
14 #include "qemu/osdep.h"
15 #include "block/block-io.h"
16 #include "qed.h"
17
18 typedef struct {
19 BDRVQEDState *s;
20 BdrvCheckResult *result;
21 bool fix; /* whether to fix invalid offsets */
22
23 uint64_t nclusters;
24 uint32_t *used_clusters; /* referenced cluster bitmap */
25
26 QEDRequest request;
27 } QEDCheck;
28
qed_test_bit(uint32_t * bitmap,uint64_t n)29 static bool qed_test_bit(uint32_t *bitmap, uint64_t n) {
30 return !!(bitmap[n / 32] & (1 << (n % 32)));
31 }
32
qed_set_bit(uint32_t * bitmap,uint64_t n)33 static void qed_set_bit(uint32_t *bitmap, uint64_t n) {
34 bitmap[n / 32] |= 1 << (n % 32);
35 }
36
37 /**
38 * Set bitmap bits for clusters
39 *
40 * @check: Check structure
41 * @offset: Starting offset in bytes
42 * @n: Number of clusters
43 */
qed_set_used_clusters(QEDCheck * check,uint64_t offset,unsigned int n)44 static bool qed_set_used_clusters(QEDCheck *check, uint64_t offset,
45 unsigned int n)
46 {
47 uint64_t cluster = qed_bytes_to_clusters(check->s, offset);
48 unsigned int corruptions = 0;
49
50 while (n-- != 0) {
51 /* Clusters should only be referenced once */
52 if (qed_test_bit(check->used_clusters, cluster)) {
53 corruptions++;
54 }
55
56 qed_set_bit(check->used_clusters, cluster);
57 cluster++;
58 }
59
60 check->result->corruptions += corruptions;
61 return corruptions == 0;
62 }
63
64 /**
65 * Check an L2 table
66 *
67 * @ret: Number of invalid cluster offsets
68 */
qed_check_l2_table(QEDCheck * check,QEDTable * table)69 static unsigned int qed_check_l2_table(QEDCheck *check, QEDTable *table)
70 {
71 BDRVQEDState *s = check->s;
72 unsigned int i, num_invalid = 0;
73 uint64_t last_offset = 0;
74
75 for (i = 0; i < s->table_nelems; i++) {
76 uint64_t offset = table->offsets[i];
77
78 if (qed_offset_is_unalloc_cluster(offset) ||
79 qed_offset_is_zero_cluster(offset)) {
80 continue;
81 }
82 check->result->bfi.allocated_clusters++;
83 if (last_offset && (last_offset + s->header.cluster_size != offset)) {
84 check->result->bfi.fragmented_clusters++;
85 }
86 last_offset = offset;
87
88 /* Detect invalid cluster offset */
89 if (!qed_check_cluster_offset(s, offset)) {
90 if (check->fix) {
91 table->offsets[i] = 0;
92 check->result->corruptions_fixed++;
93 } else {
94 check->result->corruptions++;
95 }
96
97 num_invalid++;
98 continue;
99 }
100
101 qed_set_used_clusters(check, offset, 1);
102 }
103
104 return num_invalid;
105 }
106
107 /**
108 * Descend tables and check each cluster is referenced once only
109 */
110 static int coroutine_fn GRAPH_RDLOCK
qed_check_l1_table(QEDCheck * check,QEDTable * table)111 qed_check_l1_table(QEDCheck *check, QEDTable *table)
112 {
113 BDRVQEDState *s = check->s;
114 unsigned int i, num_invalid_l1 = 0;
115 int ret, last_error = 0;
116
117 /* Mark L1 table clusters used */
118 qed_set_used_clusters(check, s->header.l1_table_offset,
119 s->header.table_size);
120
121 for (i = 0; i < s->table_nelems; i++) {
122 unsigned int num_invalid_l2;
123 uint64_t offset = table->offsets[i];
124
125 if (qed_offset_is_unalloc_cluster(offset)) {
126 continue;
127 }
128
129 /* Detect invalid L2 offset */
130 if (!qed_check_table_offset(s, offset)) {
131 /* Clear invalid offset */
132 if (check->fix) {
133 table->offsets[i] = 0;
134 check->result->corruptions_fixed++;
135 } else {
136 check->result->corruptions++;
137 }
138
139 num_invalid_l1++;
140 continue;
141 }
142
143 if (!qed_set_used_clusters(check, offset, s->header.table_size)) {
144 continue; /* skip an invalid table */
145 }
146
147 ret = qed_read_l2_table_sync(s, &check->request, offset);
148 if (ret) {
149 check->result->check_errors++;
150 last_error = ret;
151 continue;
152 }
153
154 num_invalid_l2 = qed_check_l2_table(check,
155 check->request.l2_table->table);
156
157 /* Write out fixed L2 table */
158 if (num_invalid_l2 > 0 && check->fix) {
159 ret = qed_write_l2_table_sync(s, &check->request, 0,
160 s->table_nelems, false);
161 if (ret) {
162 check->result->check_errors++;
163 last_error = ret;
164 continue;
165 }
166 }
167 }
168
169 /* Drop reference to final table */
170 qed_unref_l2_cache_entry(check->request.l2_table);
171 check->request.l2_table = NULL;
172
173 /* Write out fixed L1 table */
174 if (num_invalid_l1 > 0 && check->fix) {
175 ret = qed_write_l1_table_sync(s, 0, s->table_nelems);
176 if (ret) {
177 check->result->check_errors++;
178 last_error = ret;
179 }
180 }
181
182 return last_error;
183 }
184
185 /**
186 * Check for unreferenced (leaked) clusters
187 */
qed_check_for_leaks(QEDCheck * check)188 static void qed_check_for_leaks(QEDCheck *check)
189 {
190 BDRVQEDState *s = check->s;
191 uint64_t i;
192
193 for (i = s->header.header_size; i < check->nclusters; i++) {
194 if (!qed_test_bit(check->used_clusters, i)) {
195 check->result->leaks++;
196 }
197 }
198 }
199
200 /**
201 * Mark an image clean once it passes check or has been repaired
202 */
203 static void coroutine_fn GRAPH_RDLOCK
qed_check_mark_clean(BDRVQEDState * s,BdrvCheckResult * result)204 qed_check_mark_clean(BDRVQEDState *s, BdrvCheckResult *result)
205 {
206 /* Skip if there were unfixable corruptions or I/O errors */
207 if (result->corruptions > 0 || result->check_errors > 0) {
208 return;
209 }
210
211 /* Skip if image is already marked clean */
212 if (!(s->header.features & QED_F_NEED_CHECK)) {
213 return;
214 }
215
216 /* Ensure fixes reach storage before clearing check bit */
217 bdrv_co_flush(s->bs);
218
219 s->header.features &= ~QED_F_NEED_CHECK;
220 qed_write_header_sync(s);
221 }
222
223 /* Called with table_lock held. */
qed_check(BDRVQEDState * s,BdrvCheckResult * result,bool fix)224 int coroutine_fn qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix)
225 {
226 QEDCheck check = {
227 .s = s,
228 .result = result,
229 .nclusters = qed_bytes_to_clusters(s, s->file_size),
230 .request = { .l2_table = NULL },
231 .fix = fix,
232 };
233 int ret;
234
235 check.used_clusters = g_try_new0(uint32_t, (check.nclusters + 31) / 32);
236 if (check.nclusters && check.used_clusters == NULL) {
237 return -ENOMEM;
238 }
239
240 check.result->bfi.total_clusters =
241 DIV_ROUND_UP(s->header.image_size, s->header.cluster_size);
242 ret = qed_check_l1_table(&check, s->l1_table);
243 if (ret == 0) {
244 /* Only check for leaks if entire image was scanned successfully */
245 qed_check_for_leaks(&check);
246
247 if (fix) {
248 qed_check_mark_clean(s, result);
249 }
250 }
251
252 g_free(check.used_clusters);
253 return ret;
254 }
255