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 void node_prepare_for_write(struct dm_block_validator *v,
 19				   struct dm_block *b,
 20				   size_t block_size)
 21{
 22	struct btree_node *n = dm_block_data(b);
 23	struct node_header *h = &n->header;
 24
 25	h->blocknr = cpu_to_le64(dm_block_location(b));
 26	h->csum = cpu_to_le32(dm_bm_checksum(&h->flags,
 27					     block_size - sizeof(__le32),
 28					     BTREE_CSUM_XOR));
 29}
 30
 31static int node_check(struct dm_block_validator *v,
 32		      struct dm_block *b,
 33		      size_t block_size)
 34{
 35	struct btree_node *n = dm_block_data(b);
 36	struct node_header *h = &n->header;
 37	size_t value_size;
 38	__le32 csum_disk;
 39	uint32_t flags, nr_entries, max_entries;
 40
 41	if (dm_block_location(b) != le64_to_cpu(h->blocknr)) {
 42		DMERR_LIMIT("node_check failed: blocknr %llu != wanted %llu",
 43			    le64_to_cpu(h->blocknr), dm_block_location(b));
 44		return -ENOTBLK;
 45	}
 46
 47	csum_disk = cpu_to_le32(dm_bm_checksum(&h->flags,
 48					       block_size - sizeof(__le32),
 49					       BTREE_CSUM_XOR));
 50	if (csum_disk != h->csum) {
 51		DMERR_LIMIT("node_check failed: csum %u != wanted %u",
 52			    le32_to_cpu(csum_disk), le32_to_cpu(h->csum));
 53		return -EILSEQ;
 54	}
 55
 56	nr_entries = le32_to_cpu(h->nr_entries);
 57	max_entries = le32_to_cpu(h->max_entries);
 58	value_size = le32_to_cpu(h->value_size);
 59
 60	if (sizeof(struct node_header) +
 61	    (sizeof(__le64) + value_size) * max_entries > block_size) {
 62		DMERR_LIMIT("node_check failed: max_entries too large");
 63		return -EILSEQ;
 64	}
 65
 66	if (nr_entries > max_entries) {
 67		DMERR_LIMIT("node_check failed: too many entries");
 68		return -EILSEQ;
 69	}
 70
 71	/*
 72	 * The node must be either INTERNAL or LEAF.
 73	 */
 74	flags = le32_to_cpu(h->flags);
 75	if (!(flags & INTERNAL_NODE) && !(flags & LEAF_NODE)) {
 76		DMERR_LIMIT("node_check failed: node is neither INTERNAL or LEAF");
 77		return -EILSEQ;
 78	}
 79
 80	return 0;
 81}
 82
 83struct dm_block_validator btree_node_validator = {
 84	.name = "btree_node",
 85	.prepare_for_write = node_prepare_for_write,
 86	.check = node_check
 87};
 88
 89/*----------------------------------------------------------------*/
 90
 91int bn_read_lock(struct dm_btree_info *info, dm_block_t b,
 92		 struct dm_block **result)
 93{
 94	return dm_tm_read_lock(info->tm, b, &btree_node_validator, result);
 95}
 96
 97static int bn_shadow(struct dm_btree_info *info, dm_block_t orig,
 98	      struct dm_btree_value_type *vt,
 99	      struct dm_block **result)
100{
101	int r, inc;
102
103	r = dm_tm_shadow_block(info->tm, orig, &btree_node_validator,
104			       result, &inc);
105	if (!r && inc)
106		inc_children(info->tm, dm_block_data(*result), vt);
107
108	return r;
109}
110
111int new_block(struct dm_btree_info *info, struct dm_block **result)
112{
113	return dm_tm_new_block(info->tm, &btree_node_validator, result);
114}
115
116void unlock_block(struct dm_btree_info *info, struct dm_block *b)
117{
118	dm_tm_unlock(info->tm, b);
119}
120
121/*----------------------------------------------------------------*/
122
123void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info)
124{
125	s->info = info;
126	s->count = 0;
127	s->nodes[0] = NULL;
128	s->nodes[1] = NULL;
129}
130
131void exit_ro_spine(struct ro_spine *s)
132{
133	int i;
134
135	for (i = 0; i < s->count; i++) {
136		unlock_block(s->info, s->nodes[i]);
137	}
138}
139
140int ro_step(struct ro_spine *s, dm_block_t new_child)
141{
142	int r;
143
144	if (s->count == 2) {
145		unlock_block(s->info, s->nodes[0]);
146		s->nodes[0] = s->nodes[1];
147		s->count--;
148	}
149
150	r = bn_read_lock(s->info, new_child, s->nodes + s->count);
151	if (!r)
152		s->count++;
153
154	return r;
155}
156
157void ro_pop(struct ro_spine *s)
158{
159	BUG_ON(!s->count);
160	--s->count;
161	unlock_block(s->info, s->nodes[s->count]);
162}
163
164struct btree_node *ro_node(struct ro_spine *s)
165{
166	struct dm_block *block;
167
168	BUG_ON(!s->count);
169	block = s->nodes[s->count - 1];
170
171	return dm_block_data(block);
172}
173
174/*----------------------------------------------------------------*/
175
176void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info)
177{
178	s->info = info;
179	s->count = 0;
180}
181
182void exit_shadow_spine(struct shadow_spine *s)
183{
184	int i;
185
186	for (i = 0; i < s->count; i++) {
187		unlock_block(s->info, s->nodes[i]);
188	}
189}
190
191int shadow_step(struct shadow_spine *s, dm_block_t b,
192		struct dm_btree_value_type *vt)
193{
194	int r;
195
196	if (s->count == 2) {
197		unlock_block(s->info, s->nodes[0]);
198		s->nodes[0] = s->nodes[1];
199		s->count--;
200	}
201
202	r = bn_shadow(s->info, b, vt, s->nodes + s->count);
203	if (!r) {
204		if (!s->count)
205			s->root = dm_block_location(s->nodes[0]);
206
207		s->count++;
208	}
209
210	return r;
211}
212
213struct dm_block *shadow_current(struct shadow_spine *s)
214{
215	BUG_ON(!s->count);
216
217	return s->nodes[s->count - 1];
218}
219
220struct dm_block *shadow_parent(struct shadow_spine *s)
221{
222	BUG_ON(s->count != 2);
223
224	return s->count == 2 ? s->nodes[0] : NULL;
225}
226
227int shadow_has_parent(struct shadow_spine *s)
228{
229	return s->count >= 2;
230}
231
232dm_block_t shadow_root(struct shadow_spine *s)
233{
234	return s->root;
235}
236
237static void le64_inc(void *context, const void *value_le, unsigned count)
238{
239	dm_tm_with_runs(context, value_le, count, dm_tm_inc_range);
240}
241
242static void le64_dec(void *context, const void *value_le, unsigned count)
243{
244	dm_tm_with_runs(context, value_le, count, dm_tm_dec_range);
245}
246
247static int le64_equal(void *context, const void *value1_le, const void *value2_le)
248{
249	__le64 v1_le, v2_le;
250
251	memcpy(&v1_le, value1_le, sizeof(v1_le));
252	memcpy(&v2_le, value2_le, sizeof(v2_le));
253	return v1_le == v2_le;
254}
255
256void init_le64_type(struct dm_transaction_manager *tm,
257		    struct dm_btree_value_type *vt)
258{
259	vt->context = tm;
260	vt->size = sizeof(__le64);
261	vt->inc = le64_inc;
262	vt->dec = le64_dec;
263	vt->equal = le64_equal;
264}