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 static 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 int unlock_block(struct dm_btree_info *info, struct dm_block *b)
121 {
122 	return 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 int 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 
148 int 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 
167 void ro_pop(struct ro_spine *s)
168 {
169 	BUG_ON(!s->count);
170 	--s->count;
171 	unlock_block(s->info, s->nodes[s->count]);
172 }
173 
174 struct btree_node *ro_node(struct ro_spine *s)
175 {
176 	struct dm_block *block;
177 
178 	BUG_ON(!s->count);
179 	block = s->nodes[s->count - 1];
180 
181 	return dm_block_data(block);
182 }
183 
184 /*----------------------------------------------------------------*/
185 
186 void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info)
187 {
188 	s->info = info;
189 	s->count = 0;
190 }
191 
192 int exit_shadow_spine(struct shadow_spine *s)
193 {
194 	int r = 0, i;
195 
196 	for (i = 0; i < s->count; i++) {
197 		int r2 = unlock_block(s->info, s->nodes[i]);
198 		if (r2 < 0)
199 			r = r2;
200 	}
201 
202 	return r;
203 }
204 
205 int shadow_step(struct shadow_spine *s, dm_block_t b,
206 		struct dm_btree_value_type *vt)
207 {
208 	int r;
209 
210 	if (s->count == 2) {
211 		r = unlock_block(s->info, s->nodes[0]);
212 		if (r < 0)
213 			return r;
214 		s->nodes[0] = s->nodes[1];
215 		s->count--;
216 	}
217 
218 	r = bn_shadow(s->info, b, vt, s->nodes + s->count);
219 	if (!r) {
220 		if (!s->count)
221 			s->root = dm_block_location(s->nodes[0]);
222 
223 		s->count++;
224 	}
225 
226 	return r;
227 }
228 
229 struct dm_block *shadow_current(struct shadow_spine *s)
230 {
231 	BUG_ON(!s->count);
232 
233 	return s->nodes[s->count - 1];
234 }
235 
236 struct dm_block *shadow_parent(struct shadow_spine *s)
237 {
238 	BUG_ON(s->count != 2);
239 
240 	return s->count == 2 ? s->nodes[0] : NULL;
241 }
242 
243 int shadow_has_parent(struct shadow_spine *s)
244 {
245 	return s->count >= 2;
246 }
247 
248 int shadow_root(struct shadow_spine *s)
249 {
250 	return s->root;
251 }
252