xref: /qemu/block/qed-check.c (revision 8b7b9c5c) 
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 
29 static bool qed_test_bit(uint32_t *bitmap, uint64_t n) {
30     return !!(bitmap[n / 32] & (1 << (n % 32)));
31 }
32 
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  */
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  */
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
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  */
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
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.  */
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