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 
18 static int node_check(struct dm_block_validator *v,
19 		      struct dm_block *b,
20 		      size_t block_size);
21 
22 static void node_prepare_for_write(struct dm_block_validator *v,
23 				   struct dm_block *b,
24 				   size_t block_size)
25 {
26 	struct btree_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 
37 static int node_check(struct dm_block_validator *v,
38 		      struct dm_block *b,
39 		      size_t block_size)
40 {
41 	struct btree_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_LIMIT("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_LIMIT("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_LIMIT("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_LIMIT("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_LIMIT("node_check failed: node is neither INTERNAL or LEAF");
81 		return -EILSEQ;
82 	}
83 
84 	return 0;
85 }
86 
87 struct 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 
95 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 
101 static 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 
115 int 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 
120 void unlock_block(struct dm_btree_info *info, struct dm_block *b)
121 {
122 	dm_tm_unlock(info->tm, b);
123 }
124 
125 /*----------------------------------------------------------------*/
126 
127 void 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 
135 void exit_ro_spine(struct ro_spine *s)
136 {
137 	int i;
138 
139 	for (i = 0; i < s->count; i++) {
140 		unlock_block(s->info, s->nodes[i]);
141 	}
142 }
143 
144 int ro_step(struct ro_spine *s, dm_block_t new_child)
145 {
146 	int r;
147 
148 	if (s->count == 2) {
149 		unlock_block(s->info, s->nodes[0]);
150 		s->nodes[0] = s->nodes[1];
151 		s->count--;
152 	}
153 
154 	r = bn_read_lock(s->info, new_child, s->nodes + s->count);
155 	if (!r)
156 		s->count++;
157 
158 	return r;
159 }
160 
161 void ro_pop(struct ro_spine *s)
162 {
163 	BUG_ON(!s->count);
164 	--s->count;
165 	unlock_block(s->info, s->nodes[s->count]);
166 }
167 
168 struct btree_node *ro_node(struct ro_spine *s)
169 {
170 	struct dm_block *block;
171 
172 	BUG_ON(!s->count);
173 	block = s->nodes[s->count - 1];
174 
175 	return dm_block_data(block);
176 }
177 
178 /*----------------------------------------------------------------*/
179 
180 void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info)
181 {
182 	s->info = info;
183 	s->count = 0;
184 }
185 
186 int exit_shadow_spine(struct shadow_spine *s)
187 {
188 	int r = 0, i;
189 
190 	for (i = 0; i < s->count; i++) {
191 		unlock_block(s->info, s->nodes[i]);
192 	}
193 
194 	return r;
195 }
196 
197 int shadow_step(struct shadow_spine *s, dm_block_t b,
198 		struct dm_btree_value_type *vt)
199 {
200 	int r;
201 
202 	if (s->count == 2) {
203 		unlock_block(s->info, s->nodes[0]);
204 		s->nodes[0] = s->nodes[1];
205 		s->count--;
206 	}
207 
208 	r = bn_shadow(s->info, b, vt, s->nodes + s->count);
209 	if (!r) {
210 		if (!s->count)
211 			s->root = dm_block_location(s->nodes[0]);
212 
213 		s->count++;
214 	}
215 
216 	return r;
217 }
218 
219 struct dm_block *shadow_current(struct shadow_spine *s)
220 {
221 	BUG_ON(!s->count);
222 
223 	return s->nodes[s->count - 1];
224 }
225 
226 struct dm_block *shadow_parent(struct shadow_spine *s)
227 {
228 	BUG_ON(s->count != 2);
229 
230 	return s->count == 2 ? s->nodes[0] : NULL;
231 }
232 
233 int shadow_has_parent(struct shadow_spine *s)
234 {
235 	return s->count >= 2;
236 }
237 
238 dm_block_t shadow_root(struct shadow_spine *s)
239 {
240 	return s->root;
241 }
242 
243 static void le64_inc(void *context, const void *value_le)
244 {
245 	struct dm_transaction_manager *tm = context;
246 	__le64 v_le;
247 
248 	memcpy(&v_le, value_le, sizeof(v_le));
249 	dm_tm_inc(tm, le64_to_cpu(v_le));
250 }
251 
252 static void le64_dec(void *context, const void *value_le)
253 {
254 	struct dm_transaction_manager *tm = context;
255 	__le64 v_le;
256 
257 	memcpy(&v_le, value_le, sizeof(v_le));
258 	dm_tm_dec(tm, le64_to_cpu(v_le));
259 }
260 
261 static int le64_equal(void *context, const void *value1_le, const void *value2_le)
262 {
263 	__le64 v1_le, v2_le;
264 
265 	memcpy(&v1_le, value1_le, sizeof(v1_le));
266 	memcpy(&v2_le, value2_le, sizeof(v2_le));
267 	return v1_le == v2_le;
268 }
269 
270 void init_le64_type(struct dm_transaction_manager *tm,
271 		    struct dm_btree_value_type *vt)
272 {
273 	vt->context = tm;
274 	vt->size = sizeof(__le64);
275 	vt->inc = le64_inc;
276 	vt->dec = le64_dec;
277 	vt->equal = le64_equal;
278 }
279