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}