xref: /openbmc/qemu/block/qed-check.c (revision ddbb0d09) 
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 "qed.h"
15 
16 typedef struct {
17     BDRVQEDState *s;
18     BdrvCheckResult *result;
19     bool fix;                           /* whether to fix invalid offsets */
20 
21     uint64_t nclusters;
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     uint64_t last_offset = 0;
72 
73     for (i = 0; i < s->table_nelems; i++) {
74         uint64_t offset = table->offsets[i];
75 
76         if (qed_offset_is_unalloc_cluster(offset) ||
77             qed_offset_is_zero_cluster(offset)) {
78             continue;
79         }
80         check->result->bfi.allocated_clusters++;
81         if (last_offset && (last_offset + s->header.cluster_size != offset)) {
82             check->result->bfi.fragmented_clusters++;
83         }
84         last_offset = offset;
85 
86         /* Detect invalid cluster offset */
87         if (!qed_check_cluster_offset(s, offset)) {
88             if (check->fix) {
89                 table->offsets[i] = 0;
90                 check->result->corruptions_fixed++;
91             } else {
92                 check->result->corruptions++;
93             }
94 
95             num_invalid++;
96             continue;
97         }
98 
99         qed_set_used_clusters(check, offset, 1);
100     }
101 
102     return num_invalid;
103 }
104 
105 /**
106  * Descend tables and check each cluster is referenced once only
107  */
108 static int qed_check_l1_table(QEDCheck *check, QEDTable *table)
109 {
110     BDRVQEDState *s = check->s;
111     unsigned int i, num_invalid_l1 = 0;
112     int ret, last_error = 0;
113 
114     /* Mark L1 table clusters used */
115     qed_set_used_clusters(check, s->header.l1_table_offset,
116                           s->header.table_size);
117 
118     for (i = 0; i < s->table_nelems; i++) {
119         unsigned int num_invalid_l2;
120         uint64_t offset = table->offsets[i];
121 
122         if (qed_offset_is_unalloc_cluster(offset)) {
123             continue;
124         }
125 
126         /* Detect invalid L2 offset */
127         if (!qed_check_table_offset(s, offset)) {
128             /* Clear invalid offset */
129             if (check->fix) {
130                 table->offsets[i] = 0;
131                 check->result->corruptions_fixed++;
132             } else {
133                 check->result->corruptions++;
134             }
135 
136             num_invalid_l1++;
137             continue;
138         }
139 
140         if (!qed_set_used_clusters(check, offset, s->header.table_size)) {
141             continue; /* skip an invalid table */
142         }
143 
144         ret = qed_read_l2_table_sync(s, &check->request, offset);
145         if (ret) {
146             check->result->check_errors++;
147             last_error = ret;
148             continue;
149         }
150 
151         num_invalid_l2 = qed_check_l2_table(check,
152                                             check->request.l2_table->table);
153 
154         /* Write out fixed L2 table */
155         if (num_invalid_l2 > 0 && check->fix) {
156             ret = qed_write_l2_table_sync(s, &check->request, 0,
157                                           s->table_nelems, false);
158             if (ret) {
159                 check->result->check_errors++;
160                 last_error = ret;
161                 continue;
162             }
163         }
164     }
165 
166     /* Drop reference to final table */
167     qed_unref_l2_cache_entry(check->request.l2_table);
168     check->request.l2_table = NULL;
169 
170     /* Write out fixed L1 table */
171     if (num_invalid_l1 > 0 && check->fix) {
172         ret = qed_write_l1_table_sync(s, 0, s->table_nelems);
173         if (ret) {
174             check->result->check_errors++;
175             last_error = ret;
176         }
177     }
178 
179     return last_error;
180 }
181 
182 /**
183  * Check for unreferenced (leaked) clusters
184  */
185 static void qed_check_for_leaks(QEDCheck *check)
186 {
187     BDRVQEDState *s = check->s;
188     uint64_t i;
189 
190     for (i = s->header.header_size; i < check->nclusters; i++) {
191         if (!qed_test_bit(check->used_clusters, i)) {
192             check->result->leaks++;
193         }
194     }
195 }
196 
197 /**
198  * Mark an image clean once it passes check or has been repaired
199  */
200 static void qed_check_mark_clean(BDRVQEDState *s, BdrvCheckResult *result)
201 {
202     /* Skip if there were unfixable corruptions or I/O errors */
203     if (result->corruptions > 0 || result->check_errors > 0) {
204         return;
205     }
206 
207     /* Skip if image is already marked clean */
208     if (!(s->header.features & QED_F_NEED_CHECK)) {
209         return;
210     }
211 
212     /* Ensure fixes reach storage before clearing check bit */
213     bdrv_flush(s->bs);
214 
215     s->header.features &= ~QED_F_NEED_CHECK;
216     qed_write_header_sync(s);
217 }
218 
219 int qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix)
220 {
221     QEDCheck check = {
222         .s = s,
223         .result = result,
224         .nclusters = qed_bytes_to_clusters(s, s->file_size),
225         .request = { .l2_table = NULL },
226         .fix = fix,
227     };
228     int ret;
229 
230     check.used_clusters = g_try_new0(uint32_t, (check.nclusters + 31) / 32);
231     if (check.nclusters && check.used_clusters == NULL) {
232         return -ENOMEM;
233     }
234 
235     check.result->bfi.total_clusters =
236         (s->header.image_size + s->header.cluster_size - 1) /
237             s->header.cluster_size;
238     ret = qed_check_l1_table(&check, s->l1_table);
239     if (ret == 0) {
240         /* Only check for leaks if entire image was scanned successfully */
241         qed_check_for_leaks(&check);
242 
243         if (fix) {
244             qed_check_mark_clean(s, result);
245         }
246     }
247 
248     g_free(check.used_clusters);
249     return ret;
250 }
251