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 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 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
  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 struct 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
 179 void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info)
 180 {
 181         s->info = info;
 182         s->count = 0;
 183 }
 184
 185 int 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
 198 int 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
 222 struct dm_block *shadow_current(struct shadow_spine *s)
 223 {
 224         BUG_ON(!s->count);
 225
 226         return s->nodes[s->count - 1];
 227 }
 228
 229 struct 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
 236 int shadow_has_parent(struct shadow_spine *s)
 237 {
 238         return s->count >= 2;
 239 }
 240
 241 int shadow_root(struct shadow_spine *s)
 242 {
 243         return s->root;
 244 }