drivers/md/persistent-data/dm-transaction-manager.c

   1 /*
   2  * Copyright (C) 2011 Red Hat, Inc.
   3  *
   4  * This file is released under the GPL.
   5  */
   6 #include "dm-transaction-manager.h"
   7 #include "dm-space-map.h"
   8 #include "dm-space-map-checker.h"
   9 #include "dm-space-map-disk.h"
  10 #include "dm-space-map-metadata.h"
  11 #include "dm-persistent-data-internal.h"
  12
  13 #include <linux/export.h>
  14 #include <linux/slab.h>
  15 #include <linux/device-mapper.h>
  16
  17 #define DM_MSG_PREFIX "transaction manager"
  18
  19 /*----------------------------------------------------------------*/
  20
  21 struct shadow_info {
  22         struct hlist_node hlist;
  23         dm_block_t where;
  24 };
  25
  26 /*
  27  * It would be nice if we scaled with the size of transaction.
  28  */
  29 #define HASH_SIZE 256
  30 #define HASH_MASK (HASH_SIZE - 1)
  31
  32 struct dm_transaction_manager {
  33         int is_clone;
  34         struct dm_transaction_manager *real;
  35
  36         struct dm_block_manager *bm;
  37         struct dm_space_map *sm;
  38
  39         spinlock_t lock;
  40         struct hlist_head buckets[HASH_SIZE];
  41 };
  42
  43 /*----------------------------------------------------------------*/
  44
  45 static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b)
  46 {
  47         int r = 0;
  48         unsigned bucket = dm_hash_block(b, HASH_MASK);
  49         struct shadow_info *si;
  50         struct hlist_node *n;
  51
  52         spin_lock(&tm->lock);
  53         hlist_for_each_entry(si, n, tm->buckets + bucket, hlist)
  54                 if (si->where == b) {
  55                         r = 1;
  56                         break;
  57                 }
  58         spin_unlock(&tm->lock);
  59
  60         return r;
  61 }
  62
  63 /*
  64  * This can silently fail if there's no memory.  We're ok with this since
  65  * creating redundant shadows causes no harm.
  66  */
  67 static void insert_shadow(struct dm_transaction_manager *tm, dm_block_t b)
  68 {
  69         unsigned bucket;
  70         struct shadow_info *si;
  71
  72         si = kmalloc(sizeof(*si), GFP_NOIO);
  73         if (si) {
  74                 si->where = b;
  75                 bucket = dm_hash_block(b, HASH_MASK);
  76                 spin_lock(&tm->lock);
  77                 hlist_add_head(&si->hlist, tm->buckets + bucket);
  78                 spin_unlock(&tm->lock);
  79         }
  80 }
  81
  82 static void wipe_shadow_table(struct dm_transaction_manager *tm)
  83 {
  84         struct shadow_info *si;
  85         struct hlist_node *n, *tmp;
  86         struct hlist_head *bucket;
  87         int i;
  88
  89         spin_lock(&tm->lock);
  90         for (i = 0; i < HASH_SIZE; i++) {
  91                 bucket = tm->buckets + i;
  92                 hlist_for_each_entry_safe(si, n, tmp, bucket, hlist)
  93                         kfree(si);
  94
  95                 INIT_HLIST_HEAD(bucket);
  96         }
  97
  98         spin_unlock(&tm->lock);
  99 }
 100
 101 /*----------------------------------------------------------------*/
 102
 103 static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
 104                                                    struct dm_space_map *sm)
 105 {
 106         int i;
 107         struct dm_transaction_manager *tm;
 108
 109         tm = kmalloc(sizeof(*tm), GFP_KERNEL);
 110         if (!tm)
 111                 return ERR_PTR(-ENOMEM);
 112
 113         tm->is_clone = 0;
 114         tm->real = NULL;
 115         tm->bm = bm;
 116         tm->sm = sm;
 117
 118         spin_lock_init(&tm->lock);
 119         for (i = 0; i < HASH_SIZE; i++)
 120                 INIT_HLIST_HEAD(tm->buckets + i);
 121
 122         return tm;
 123 }
 124
 125 struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real)
 126 {
 127         struct dm_transaction_manager *tm;
 128
 129         tm = kmalloc(sizeof(*tm), GFP_KERNEL);
 130         if (tm) {
 131                 tm->is_clone = 1;
 132                 tm->real = real;
 133         }
 134
 135         return tm;
 136 }
 137 EXPORT_SYMBOL_GPL(dm_tm_create_non_blocking_clone);
 138
 139 void dm_tm_destroy(struct dm_transaction_manager *tm)
 140 {
 141         if (!tm->is_clone)
 142                 wipe_shadow_table(tm);
 143
 144         kfree(tm);
 145 }
 146 EXPORT_SYMBOL_GPL(dm_tm_destroy);
 147
 148 int dm_tm_pre_commit(struct dm_transaction_manager *tm)
 149 {
 150         int r;
 151
 152         if (tm->is_clone)
 153                 return -EWOULDBLOCK;
 154
 155         r = dm_sm_commit(tm->sm);
 156         if (r < 0)
 157                 return r;
 158
 159         return 0;
 160 }
 161 EXPORT_SYMBOL_GPL(dm_tm_pre_commit);
 162
 163 int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *root)
 164 {
 165         if (tm->is_clone)
 166                 return -EWOULDBLOCK;
 167
 168         wipe_shadow_table(tm);
 169
 170         return dm_bm_flush_and_unlock(tm->bm, root);
 171 }
 172 EXPORT_SYMBOL_GPL(dm_tm_commit);
 173
 174 int dm_tm_new_block(struct dm_transaction_manager *tm,
 175                     struct dm_block_validator *v,
 176                     struct dm_block **result)
 177 {
 178         int r;
 179         dm_block_t new_block;
 180
 181         if (tm->is_clone)
 182                 return -EWOULDBLOCK;
 183
 184         r = dm_sm_new_block(tm->sm, &new_block);
 185         if (r < 0)
 186                 return r;
 187
 188         r = dm_bm_write_lock_zero(tm->bm, new_block, v, result);
 189         if (r < 0) {
 190                 dm_sm_dec_block(tm->sm, new_block);
 191                 return r;
 192         }
 193
 194         /*
 195          * New blocks count as shadows in that they don't need to be
 196          * shadowed again.
 197          */
 198         insert_shadow(tm, new_block);
 199
 200         return 0;
 201 }
 202
 203 static int __shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 204                           struct dm_block_validator *v,
 205                           struct dm_block **result)
 206 {
 207         int r;
 208         dm_block_t new;
 209         struct dm_block *orig_block;
 210
 211         r = dm_sm_new_block(tm->sm, &new);
 212         if (r < 0)
 213                 return r;
 214
 215         r = dm_sm_dec_block(tm->sm, orig);
 216         if (r < 0)
 217                 return r;
 218
 219         r = dm_bm_read_lock(tm->bm, orig, v, &orig_block);
 220         if (r < 0)
 221                 return r;
 222
 223         r = dm_bm_unlock_move(orig_block, new);
 224         if (r < 0) {
 225                 dm_bm_unlock(orig_block);
 226                 return r;
 227         }
 228
 229         return dm_bm_write_lock(tm->bm, new, v, result);
 230 }
 231
 232 int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 233                        struct dm_block_validator *v, struct dm_block **result,
 234                        int *inc_children)
 235 {
 236         int r;
 237
 238         if (tm->is_clone)
 239                 return -EWOULDBLOCK;
 240
 241         r = dm_sm_count_is_more_than_one(tm->sm, orig, inc_children);
 242         if (r < 0)
 243                 return r;
 244
 245         if (is_shadow(tm, orig) && !*inc_children)
 246                 return dm_bm_write_lock(tm->bm, orig, v, result);
 247
 248         r = __shadow_block(tm, orig, v, result);
 249         if (r < 0)
 250                 return r;
 251         insert_shadow(tm, dm_block_location(*result));
 252
 253         return r;
 254 }
 255
 256 int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
 257                     struct dm_block_validator *v,
 258                     struct dm_block **blk)
 259 {
 260         if (tm->is_clone)
 261                 return dm_bm_read_try_lock(tm->real->bm, b, v, blk);
 262
 263         return dm_bm_read_lock(tm->bm, b, v, blk);
 264 }
 265
 266 int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b)
 267 {
 268         return dm_bm_unlock(b);
 269 }
 270 EXPORT_SYMBOL_GPL(dm_tm_unlock);
 271
 272 void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b)
 273 {
 274         /*
 275          * The non-blocking clone doesn't support this.
 276          */
 277         BUG_ON(tm->is_clone);
 278
 279         dm_sm_inc_block(tm->sm, b);
 280 }
 281 EXPORT_SYMBOL_GPL(dm_tm_inc);
 282
 283 void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b)
 284 {
 285         /*
 286          * The non-blocking clone doesn't support this.
 287          */
 288         BUG_ON(tm->is_clone);
 289
 290         dm_sm_dec_block(tm->sm, b);
 291 }
 292 EXPORT_SYMBOL_GPL(dm_tm_dec);
 293
 294 int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
 295               uint32_t *result)
 296 {
 297         if (tm->is_clone)
 298                 return -EWOULDBLOCK;
 299
 300         return dm_sm_get_count(tm->sm, b, result);
 301 }
 302
 303 struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm)
 304 {
 305         return tm->bm;
 306 }
 307
 308 /*----------------------------------------------------------------*/
 309
 310 static int dm_tm_create_internal(struct dm_block_manager *bm,
 311                                  dm_block_t sb_location,
 312                                  struct dm_block_validator *sb_validator,
 313                                  size_t root_offset, size_t root_max_len,
 314                                  struct dm_transaction_manager **tm,
 315                                  struct dm_space_map **sm,
 316                                  struct dm_block **sblock,
 317                                  int create)
 318 {
 319         int r;
 320         struct dm_space_map *inner;
 321
 322         inner = dm_sm_metadata_init();
 323         if (IS_ERR(inner))
 324                 return PTR_ERR(inner);
 325
 326         *tm = dm_tm_create(bm, inner);
 327         if (IS_ERR(*tm)) {
 328                 dm_sm_destroy(inner);
 329                 return PTR_ERR(*tm);
 330         }
 331
 332         if (create) {
 333                 r = dm_bm_write_lock_zero(dm_tm_get_bm(*tm), sb_location,
 334                                           sb_validator, sblock);
 335                 if (r < 0) {
 336                         DMERR("couldn't lock superblock");
 337                         goto bad1;
 338                 }
 339
 340                 r = dm_sm_metadata_create(inner, *tm, dm_bm_nr_blocks(bm),
 341                                           sb_location);
 342                 if (r) {
 343                         DMERR("couldn't create metadata space map");
 344                         goto bad2;
 345                 }
 346
 347                 *sm = dm_sm_checker_create(inner);
 348                 if (IS_ERR(*sm)) {
 349                         r = PTR_ERR(*sm);
 350                         goto bad2;
 351                 }
 352
 353         } else {
 354                 r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
 355                                      sb_validator, sblock);
 356                 if (r < 0) {
 357                         DMERR("couldn't lock superblock");
 358                         goto bad1;
 359                 }
 360
 361                 r = dm_sm_metadata_open(inner, *tm,
 362                                         dm_block_data(*sblock) + root_offset,
 363                                         root_max_len);
 364                 if (r) {
 365                         DMERR("couldn't open metadata space map");
 366                         goto bad2;
 367                 }
 368
 369                 *sm = dm_sm_checker_create(inner);
 370                 if (IS_ERR(*sm)) {
 371                         r = PTR_ERR(*sm);
 372                         goto bad2;
 373                 }
 374         }
 375
 376         return 0;
 377
 378 bad2:
 379         dm_tm_unlock(*tm, *sblock);
 380 bad1:
 381         dm_tm_destroy(*tm);
 382         dm_sm_destroy(inner);
 383         return r;
 384 }
 385
 386 int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
 387                          struct dm_block_validator *sb_validator,
 388                          struct dm_transaction_manager **tm,
 389                          struct dm_space_map **sm, struct dm_block **sblock)
 390 {
 391         return dm_tm_create_internal(bm, sb_location, sb_validator,
 392                                      0, 0, tm, sm, sblock, 1);
 393 }
 394 EXPORT_SYMBOL_GPL(dm_tm_create_with_sm);
 395
 396 int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
 397                        struct dm_block_validator *sb_validator,
 398                        size_t root_offset, size_t root_max_len,
 399                        struct dm_transaction_manager **tm,
 400                        struct dm_space_map **sm, struct dm_block **sblock)
 401 {
 402         return dm_tm_create_internal(bm, sb_location, sb_validator, root_offset,
 403                                      root_max_len, tm, sm, sblock, 0);
 404 }
 405 EXPORT_SYMBOL_GPL(dm_tm_open_with_sm);
 406
 407 /*----------------------------------------------------------------*/