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1.1 root 1: /*
2: * QEMU Enhanced Disk Format Consistency Check
3: *
4: * Copyright IBM, Corp. 2010
5: *
6: * Authors:
7: * Stefan Hajnoczi <[email protected]>
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 "qed.h"
15:
16: typedef struct {
17: BDRVQEDState *s;
18: BdrvCheckResult *result;
19: bool fix; /* whether to fix invalid offsets */
20:
1.1.1.2 ! root 21: uint64_t nclusters;
1.1 root 22: uint32_t *used_clusters; /* referenced cluster bitmap */
23:
24: QEDRequest request;
25: } QEDCheck;
26:
27: static bool qed_test_bit(uint32_t *bitmap, uint64_t n) {
28: return !!(bitmap[n / 32] & (1 << (n % 32)));
29: }
30:
31: static void qed_set_bit(uint32_t *bitmap, uint64_t n) {
32: bitmap[n / 32] |= 1 << (n % 32);
33: }
34:
35: /**
36: * Set bitmap bits for clusters
37: *
38: * @check: Check structure
39: * @offset: Starting offset in bytes
40: * @n: Number of clusters
41: */
42: static bool qed_set_used_clusters(QEDCheck *check, uint64_t offset,
43: unsigned int n)
44: {
45: uint64_t cluster = qed_bytes_to_clusters(check->s, offset);
46: unsigned int corruptions = 0;
47:
48: while (n-- != 0) {
49: /* Clusters should only be referenced once */
50: if (qed_test_bit(check->used_clusters, cluster)) {
51: corruptions++;
52: }
53:
54: qed_set_bit(check->used_clusters, cluster);
55: cluster++;
56: }
57:
58: check->result->corruptions += corruptions;
59: return corruptions == 0;
60: }
61:
62: /**
63: * Check an L2 table
64: *
65: * @ret: Number of invalid cluster offsets
66: */
67: static unsigned int qed_check_l2_table(QEDCheck *check, QEDTable *table)
68: {
69: BDRVQEDState *s = check->s;
70: unsigned int i, num_invalid = 0;
71:
72: for (i = 0; i < s->table_nelems; i++) {
73: uint64_t offset = table->offsets[i];
74:
75: if (!offset) {
76: continue;
77: }
78:
79: /* Detect invalid cluster offset */
80: if (!qed_check_cluster_offset(s, offset)) {
81: if (check->fix) {
82: table->offsets[i] = 0;
83: } else {
84: check->result->corruptions++;
85: }
86:
87: num_invalid++;
88: continue;
89: }
90:
91: qed_set_used_clusters(check, offset, 1);
92: }
93:
94: return num_invalid;
95: }
96:
97: /**
98: * Descend tables and check each cluster is referenced once only
99: */
100: static int qed_check_l1_table(QEDCheck *check, QEDTable *table)
101: {
102: BDRVQEDState *s = check->s;
103: unsigned int i, num_invalid_l1 = 0;
104: int ret, last_error = 0;
105:
106: /* Mark L1 table clusters used */
107: qed_set_used_clusters(check, s->header.l1_table_offset,
108: s->header.table_size);
109:
110: for (i = 0; i < s->table_nelems; i++) {
111: unsigned int num_invalid_l2;
112: uint64_t offset = table->offsets[i];
113:
114: if (!offset) {
115: continue;
116: }
117:
118: /* Detect invalid L2 offset */
119: if (!qed_check_table_offset(s, offset)) {
120: /* Clear invalid offset */
121: if (check->fix) {
122: table->offsets[i] = 0;
123: } else {
124: check->result->corruptions++;
125: }
126:
127: num_invalid_l1++;
128: continue;
129: }
130:
131: if (!qed_set_used_clusters(check, offset, s->header.table_size)) {
132: continue; /* skip an invalid table */
133: }
134:
135: ret = qed_read_l2_table_sync(s, &check->request, offset);
136: if (ret) {
137: check->result->check_errors++;
138: last_error = ret;
139: continue;
140: }
141:
142: num_invalid_l2 = qed_check_l2_table(check,
143: check->request.l2_table->table);
144:
145: /* Write out fixed L2 table */
146: if (num_invalid_l2 > 0 && check->fix) {
147: ret = qed_write_l2_table_sync(s, &check->request, 0,
148: s->table_nelems, false);
149: if (ret) {
150: check->result->check_errors++;
151: last_error = ret;
152: continue;
153: }
154: }
155: }
156:
157: /* Drop reference to final table */
158: qed_unref_l2_cache_entry(check->request.l2_table);
159: check->request.l2_table = NULL;
160:
161: /* Write out fixed L1 table */
162: if (num_invalid_l1 > 0 && check->fix) {
163: ret = qed_write_l1_table_sync(s, 0, s->table_nelems);
164: if (ret) {
165: check->result->check_errors++;
166: last_error = ret;
167: }
168: }
169:
170: return last_error;
171: }
172:
173: /**
174: * Check for unreferenced (leaked) clusters
175: */
176: static void qed_check_for_leaks(QEDCheck *check)
177: {
178: BDRVQEDState *s = check->s;
1.1.1.2 ! root 179: uint64_t i;
1.1 root 180:
181: for (i = s->header.header_size; i < check->nclusters; i++) {
182: if (!qed_test_bit(check->used_clusters, i)) {
183: check->result->leaks++;
184: }
185: }
186: }
187:
188: int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix)
189: {
190: QEDCheck check = {
191: .s = s,
192: .result = result,
193: .nclusters = qed_bytes_to_clusters(s, s->file_size),
194: .request = { .l2_table = NULL },
195: .fix = fix,
196: };
197: int ret;
198:
199: check.used_clusters = qemu_mallocz(((check.nclusters + 31) / 32) *
200: sizeof(check.used_clusters[0]));
201:
202: ret = qed_check_l1_table(&check, s->l1_table);
203: if (ret == 0) {
204: /* Only check for leaks if entire image was scanned successfully */
205: qed_check_for_leaks(&check);
206: }
207:
208: qemu_free(check.used_clusters);
209: return ret;
210: }
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