Root/drivers/md/persistent-data/dm-btree-spine.c

1/*
2 * Copyright (C) 2011 Red Hat, Inc.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm-btree-internal.h"
8#include "dm-transaction-manager.h"
9
10#include <linux/device-mapper.h>
11
12#define DM_MSG_PREFIX "btree spine"
13
14/*----------------------------------------------------------------*/
15
16#define BTREE_CSUM_XOR 121107
17
18static int node_check(struct dm_block_validator *v,
19              struct dm_block *b,
20              size_t block_size);
21
22static void node_prepare_for_write(struct dm_block_validator *v,
23                   struct dm_block *b,
24                   size_t block_size)
25{
26    struct node *n = dm_block_data(b);
27    struct node_header *h = &n->header;
28
29    h->blocknr = cpu_to_le64(dm_block_location(b));
30    h->csum = cpu_to_le32(dm_bm_checksum(&h->flags,
31                         block_size - sizeof(__le32),
32                         BTREE_CSUM_XOR));
33
34    BUG_ON(node_check(v, b, 4096));
35}
36
37static int node_check(struct dm_block_validator *v,
38              struct dm_block *b,
39              size_t block_size)
40{
41    struct node *n = dm_block_data(b);
42    struct node_header *h = &n->header;
43    size_t value_size;
44    __le32 csum_disk;
45    uint32_t flags;
46
47    if (dm_block_location(b) != le64_to_cpu(h->blocknr)) {
48        DMERR("node_check failed blocknr %llu wanted %llu",
49              le64_to_cpu(h->blocknr), dm_block_location(b));
50        return -ENOTBLK;
51    }
52
53    csum_disk = cpu_to_le32(dm_bm_checksum(&h->flags,
54                           block_size - sizeof(__le32),
55                           BTREE_CSUM_XOR));
56    if (csum_disk != h->csum) {
57        DMERR("node_check failed csum %u wanted %u",
58              le32_to_cpu(csum_disk), le32_to_cpu(h->csum));
59        return -EILSEQ;
60    }
61
62    value_size = le32_to_cpu(h->value_size);
63
64    if (sizeof(struct node_header) +
65        (sizeof(__le64) + value_size) * le32_to_cpu(h->max_entries) > block_size) {
66        DMERR("node_check failed: max_entries too large");
67        return -EILSEQ;
68    }
69
70    if (le32_to_cpu(h->nr_entries) > le32_to_cpu(h->max_entries)) {
71        DMERR("node_check failed, too many entries");
72        return -EILSEQ;
73    }
74
75    /*
76     * The node must be either INTERNAL or LEAF.
77     */
78    flags = le32_to_cpu(h->flags);
79    if (!(flags & INTERNAL_NODE) && !(flags & LEAF_NODE)) {
80        DMERR("node_check failed, node is neither INTERNAL or LEAF");
81        return -EILSEQ;
82    }
83
84    return 0;
85}
86
87struct dm_block_validator btree_node_validator = {
88    .name = "btree_node",
89    .prepare_for_write = node_prepare_for_write,
90    .check = node_check
91};
92
93/*----------------------------------------------------------------*/
94
95static int bn_read_lock(struct dm_btree_info *info, dm_block_t b,
96         struct dm_block **result)
97{
98    return dm_tm_read_lock(info->tm, b, &btree_node_validator, result);
99}
100
101static int bn_shadow(struct dm_btree_info *info, dm_block_t orig,
102          struct dm_btree_value_type *vt,
103          struct dm_block **result)
104{
105    int r, inc;
106
107    r = dm_tm_shadow_block(info->tm, orig, &btree_node_validator,
108                   result, &inc);
109    if (!r && inc)
110        inc_children(info->tm, dm_block_data(*result), vt);
111
112    return r;
113}
114
115int new_block(struct dm_btree_info *info, struct dm_block **result)
116{
117    return dm_tm_new_block(info->tm, &btree_node_validator, result);
118}
119
120int unlock_block(struct dm_btree_info *info, struct dm_block *b)
121{
122    return dm_tm_unlock(info->tm, b);
123}
124
125/*----------------------------------------------------------------*/
126
127void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info)
128{
129    s->info = info;
130    s->count = 0;
131    s->nodes[0] = NULL;
132    s->nodes[1] = NULL;
133}
134
135int exit_ro_spine(struct ro_spine *s)
136{
137    int r = 0, i;
138
139    for (i = 0; i < s->count; i++) {
140        int r2 = unlock_block(s->info, s->nodes[i]);
141        if (r2 < 0)
142            r = r2;
143    }
144
145    return r;
146}
147
148int ro_step(struct ro_spine *s, dm_block_t new_child)
149{
150    int r;
151
152    if (s->count == 2) {
153        r = unlock_block(s->info, s->nodes[0]);
154        if (r < 0)
155            return r;
156        s->nodes[0] = s->nodes[1];
157        s->count--;
158    }
159
160    r = bn_read_lock(s->info, new_child, s->nodes + s->count);
161    if (!r)
162        s->count++;
163
164    return r;
165}
166
167struct node *ro_node(struct ro_spine *s)
168{
169    struct dm_block *block;
170
171    BUG_ON(!s->count);
172    block = s->nodes[s->count - 1];
173
174    return dm_block_data(block);
175}
176
177/*----------------------------------------------------------------*/
178
179void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info)
180{
181    s->info = info;
182    s->count = 0;
183}
184
185int exit_shadow_spine(struct shadow_spine *s)
186{
187    int r = 0, i;
188
189    for (i = 0; i < s->count; i++) {
190        int r2 = unlock_block(s->info, s->nodes[i]);
191        if (r2 < 0)
192            r = r2;
193    }
194
195    return r;
196}
197
198int shadow_step(struct shadow_spine *s, dm_block_t b,
199        struct dm_btree_value_type *vt)
200{
201    int r;
202
203    if (s->count == 2) {
204        r = unlock_block(s->info, s->nodes[0]);
205        if (r < 0)
206            return r;
207        s->nodes[0] = s->nodes[1];
208        s->count--;
209    }
210
211    r = bn_shadow(s->info, b, vt, s->nodes + s->count);
212    if (!r) {
213        if (!s->count)
214            s->root = dm_block_location(s->nodes[0]);
215
216        s->count++;
217    }
218
219    return r;
220}
221
222struct dm_block *shadow_current(struct shadow_spine *s)
223{
224    BUG_ON(!s->count);
225
226    return s->nodes[s->count - 1];
227}
228
229struct dm_block *shadow_parent(struct shadow_spine *s)
230{
231    BUG_ON(s->count != 2);
232
233    return s->count == 2 ? s->nodes[0] : NULL;
234}
235
236int shadow_has_parent(struct shadow_spine *s)
237{
238    return s->count >= 2;
239}
240
241int shadow_root(struct shadow_spine *s)
242{
243    return s->root;
244}
245

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