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
  35 static int node_check(struct dm_block_validator *v,
  36                       struct dm_block *b,
  37                       size_t block_size)
  38 {
  39         struct btree_node *n = dm_block_data(b);
  40         struct node_header *h = &n->header;
  41         size_t value_size;
  42         __le32 csum_disk;
  43         uint32_t flags;
  44
  45         if (dm_block_location(b) != le64_to_cpu(h->blocknr)) {
  46                 DMERR_LIMIT("node_check failed: blocknr %llu != wanted %llu",
  47                             le64_to_cpu(h->blocknr), dm_block_location(b));
  48                 return -ENOTBLK;
  49         }
  50
  51         csum_disk = cpu_to_le32(dm_bm_checksum(&h->flags,
  52                                                block_size - sizeof(__le32),
  53                                                BTREE_CSUM_XOR));
  54         if (csum_disk != h->csum) {
  55                 DMERR_LIMIT("node_check failed: csum %u != wanted %u",
  56                             le32_to_cpu(csum_disk), le32_to_cpu(h->csum));
  57                 return -EILSEQ;
  58         }
  59
  60         value_size = le32_to_cpu(h->value_size);
  61
  62         if (sizeof(struct node_header) +
  63             (sizeof(__le64) + value_size) * le32_to_cpu(h->max_entries) > block_size) {
  64                 DMERR_LIMIT("node_check failed: max_entries too large");
  65                 return -EILSEQ;
  66         }
  67
  68         if (le32_to_cpu(h->nr_entries) > le32_to_cpu(h->max_entries)) {
  69                 DMERR_LIMIT("node_check failed: too many entries");
  70                 return -EILSEQ;
  71         }
  72
  73         /*
  74          * The node must be either INTERNAL or LEAF.
  75          */
  76         flags = le32_to_cpu(h->flags);
  77         if (!(flags & INTERNAL_NODE) && !(flags & LEAF_NODE)) {
  78                 DMERR_LIMIT("node_check failed: node is neither INTERNAL or LEAF");
  79                 return -EILSEQ;
  80         }
  81
  82         return 0;
  83 }
  84
  85 struct dm_block_validator btree_node_validator = {
  86         .name = "btree_node",
  87         .prepare_for_write = node_prepare_for_write,
  88         .check = node_check
  89 };
  90
  91 /*----------------------------------------------------------------*/
  92
  93 int bn_read_lock(struct dm_btree_info *info, dm_block_t b,
  94                  struct dm_block **result)
  95 {
  96         return dm_tm_read_lock(info->tm, b, &btree_node_validator, result);
  97 }
  98
  99 static int bn_shadow(struct dm_btree_info *info, dm_block_t orig,
 100               struct dm_btree_value_type *vt,
 101               struct dm_block **result)
 102 {
 103         int r, inc;
 104
 105         r = dm_tm_shadow_block(info->tm, orig, &btree_node_validator,
 106                                result, &inc);
 107         if (!r && inc)
 108                 inc_children(info->tm, dm_block_data(*result), vt);
 109
 110         return r;
 111 }
 112
 113 int new_block(struct dm_btree_info *info, struct dm_block **result)
 114 {
 115         return dm_tm_new_block(info->tm, &btree_node_validator, result);
 116 }
 117
 118 void unlock_block(struct dm_btree_info *info, struct dm_block *b)
 119 {
 120         dm_tm_unlock(info->tm, b);
 121 }
 122
 123 /*----------------------------------------------------------------*/
 124
 125 void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info)
 126 {
 127         s->info = info;
 128         s->count = 0;
 129         s->nodes[0] = NULL;
 130         s->nodes[1] = NULL;
 131 }
 132
 133 void exit_ro_spine(struct ro_spine *s)
 134 {
 135         int i;
 136
 137         for (i = 0; i < s->count; i++) {
 138                 unlock_block(s->info, s->nodes[i]);
 139         }
 140 }
 141
 142 int ro_step(struct ro_spine *s, dm_block_t new_child)
 143 {
 144         int r;
 145
 146         if (s->count == 2) {
 147                 unlock_block(s->info, s->nodes[0]);
 148                 s->nodes[0] = s->nodes[1];
 149                 s->count--;
 150         }
 151
 152         r = bn_read_lock(s->info, new_child, s->nodes + s->count);
 153         if (!r)
 154                 s->count++;
 155
 156         return r;
 157 }
 158
 159 void ro_pop(struct ro_spine *s)
 160 {
 161         BUG_ON(!s->count);
 162         --s->count;
 163         unlock_block(s->info, s->nodes[s->count]);
 164 }
 165
 166 struct btree_node *ro_node(struct ro_spine *s)
 167 {
 168         struct dm_block *block;
 169
 170         BUG_ON(!s->count);
 171         block = s->nodes[s->count - 1];
 172
 173         return dm_block_data(block);
 174 }
 175
 176 /*----------------------------------------------------------------*/
 177
 178 void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info)
 179 {
 180         s->info = info;
 181         s->count = 0;
 182 }
 183
 184 void exit_shadow_spine(struct shadow_spine *s)
 185 {
 186         int i;
 187
 188         for (i = 0; i < s->count; i++) {
 189                 unlock_block(s->info, s->nodes[i]);
 190         }
 191 }
 192
 193 int shadow_step(struct shadow_spine *s, dm_block_t b,
 194                 struct dm_btree_value_type *vt)
 195 {
 196         int r;
 197
 198         if (s->count == 2) {
 199                 unlock_block(s->info, s->nodes[0]);
 200                 s->nodes[0] = s->nodes[1];
 201                 s->count--;
 202         }
 203
 204         r = bn_shadow(s->info, b, vt, s->nodes + s->count);
 205         if (!r) {
 206                 if (!s->count)
 207                         s->root = dm_block_location(s->nodes[0]);
 208
 209                 s->count++;
 210         }
 211
 212         return r;
 213 }
 214
 215 struct dm_block *shadow_current(struct shadow_spine *s)
 216 {
 217         BUG_ON(!s->count);
 218
 219         return s->nodes[s->count - 1];
 220 }
 221
 222 struct dm_block *shadow_parent(struct shadow_spine *s)
 223 {
 224         BUG_ON(s->count != 2);
 225
 226         return s->count == 2 ? s->nodes[0] : NULL;
 227 }
 228
 229 int shadow_has_parent(struct shadow_spine *s)
 230 {
 231         return s->count >= 2;
 232 }
 233
 234 dm_block_t shadow_root(struct shadow_spine *s)
 235 {
 236         return s->root;
 237 }
 238
 239 static void le64_inc(void *context, const void *value_le)
 240 {
 241         struct dm_transaction_manager *tm = context;
 242         __le64 v_le;
 243
 244         memcpy(&v_le, value_le, sizeof(v_le));
 245         dm_tm_inc(tm, le64_to_cpu(v_le));
 246 }
 247
 248 static void le64_dec(void *context, const void *value_le)
 249 {
 250         struct dm_transaction_manager *tm = context;
 251         __le64 v_le;
 252
 253         memcpy(&v_le, value_le, sizeof(v_le));
 254         dm_tm_dec(tm, le64_to_cpu(v_le));
 255 }
 256
 257 static int le64_equal(void *context, const void *value1_le, const void *value2_le)
 258 {
 259         __le64 v1_le, v2_le;
 260
 261         memcpy(&v1_le, value1_le, sizeof(v1_le));
 262         memcpy(&v2_le, value2_le, sizeof(v2_le));
 263         return v1_le == v2_le;
 264 }
 265
 266 void init_le64_type(struct dm_transaction_manager *tm,
 267                     struct dm_btree_value_type *vt)
 268 {
 269         vt->context = tm;
 270         vt->size = sizeof(__le64);
 271         vt->inc = le64_inc;
 272         vt->dec = le64_dec;
 273         vt->equal = le64_equal;
 274 }