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
  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 int 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 }