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