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         kfree(tm);
 142 }
 143 EXPORT_SYMBOL_GPL(dm_tm_destroy);
 144
 145 int dm_tm_pre_commit(struct dm_transaction_manager *tm)
 146 {
 147         int r;
 148
 149         if (tm->is_clone)
 150                 return -EWOULDBLOCK;
 151
 152         r = dm_sm_commit(tm->sm);
 153         if (r < 0)
 154                 return r;
 155
 156         return 0;
 157 }
 158 EXPORT_SYMBOL_GPL(dm_tm_pre_commit);
 159
 160 int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *root)
 161 {
 162         if (tm->is_clone)
 163                 return -EWOULDBLOCK;
 164
 165         wipe_shadow_table(tm);
 166
 167         return dm_bm_flush_and_unlock(tm->bm, root);
 168 }
 169 EXPORT_SYMBOL_GPL(dm_tm_commit);
 170
 171 int dm_tm_new_block(struct dm_transaction_manager *tm,
 172                     struct dm_block_validator *v,
 173                     struct dm_block **result)
 174 {
 175         int r;
 176         dm_block_t new_block;
 177
 178         if (tm->is_clone)
 179                 return -EWOULDBLOCK;
 180
 181         r = dm_sm_new_block(tm->sm, &new_block);
 182         if (r < 0)
 183                 return r;
 184
 185         r = dm_bm_write_lock_zero(tm->bm, new_block, v, result);
 186         if (r < 0) {
 187                 dm_sm_dec_block(tm->sm, new_block);
 188                 return r;
 189         }
 190
 191         /*
 192          * New blocks count as shadows in that they don't need to be
 193          * shadowed again.
 194          */
 195         insert_shadow(tm, new_block);
 196
 197         return 0;
 198 }
 199
 200 static int __shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 201                           struct dm_block_validator *v,
 202                           struct dm_block **result)
 203 {
 204         int r;
 205         dm_block_t new;
 206         struct dm_block *orig_block;
 207
 208         r = dm_sm_new_block(tm->sm, &new);
 209         if (r < 0)
 210                 return r;
 211
 212         r = dm_sm_dec_block(tm->sm, orig);
 213         if (r < 0)
 214                 return r;
 215
 216         r = dm_bm_read_lock(tm->bm, orig, v, &orig_block);
 217         if (r < 0)
 218                 return r;
 219
 220         r = dm_bm_unlock_move(orig_block, new);
 221         if (r < 0) {
 222                 dm_bm_unlock(orig_block);
 223                 return r;
 224         }
 225
 226         return dm_bm_write_lock(tm->bm, new, v, result);
 227 }
 228
 229 int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 230                        struct dm_block_validator *v, struct dm_block **result,
 231                        int *inc_children)
 232 {
 233         int r;
 234
 235         if (tm->is_clone)
 236                 return -EWOULDBLOCK;
 237
 238         r = dm_sm_count_is_more_than_one(tm->sm, orig, inc_children);
 239         if (r < 0)
 240                 return r;
 241
 242         if (is_shadow(tm, orig) && !*inc_children)
 243                 return dm_bm_write_lock(tm->bm, orig, v, result);
 244
 245         r = __shadow_block(tm, orig, v, result);
 246         if (r < 0)
 247                 return r;
 248         insert_shadow(tm, dm_block_location(*result));
 249
 250         return r;
 251 }
 252
 253 int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
 254                     struct dm_block_validator *v,
 255                     struct dm_block **blk)
 256 {
 257         if (tm->is_clone)
 258                 return dm_bm_read_try_lock(tm->real->bm, b, v, blk);
 259
 260         return dm_bm_read_lock(tm->bm, b, v, blk);
 261 }
 262
 263 int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b)
 264 {
 265         return dm_bm_unlock(b);
 266 }
 267 EXPORT_SYMBOL_GPL(dm_tm_unlock);
 268
 269 void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b)
 270 {
 271         /*
 272          * The non-blocking clone doesn't support this.
 273          */
 274         BUG_ON(tm->is_clone);
 275
 276         dm_sm_inc_block(tm->sm, b);
 277 }
 278 EXPORT_SYMBOL_GPL(dm_tm_inc);
 279
 280 void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b)
 281 {
 282         /*
 283          * The non-blocking clone doesn't support this.
 284          */
 285         BUG_ON(tm->is_clone);
 286
 287         dm_sm_dec_block(tm->sm, b);
 288 }
 289 EXPORT_SYMBOL_GPL(dm_tm_dec);
 290
 291 int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
 292               uint32_t *result)
 293 {
 294         if (tm->is_clone)
 295                 return -EWOULDBLOCK;
 296
 297         return dm_sm_get_count(tm->sm, b, result);
 298 }
 299
 300 struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm)
 301 {
 302         return tm->bm;
 303 }
 304
 305 /*----------------------------------------------------------------*/
 306
 307 static int dm_tm_create_internal(struct dm_block_manager *bm,
 308                                  dm_block_t sb_location,
 309                                  struct dm_block_validator *sb_validator,
 310                                  size_t root_offset, size_t root_max_len,
 311                                  struct dm_transaction_manager **tm,
 312                                  struct dm_space_map **sm,
 313                                  struct dm_block **sblock,
 314                                  int create)
 315 {
 316         int r;
 317         struct dm_space_map *inner;
 318
 319         inner = dm_sm_metadata_init();
 320         if (IS_ERR(inner))
 321                 return PTR_ERR(inner);
 322
 323         *tm = dm_tm_create(bm, inner);
 324         if (IS_ERR(*tm)) {
 325                 dm_sm_destroy(inner);
 326                 return PTR_ERR(*tm);
 327         }
 328
 329         if (create) {
 330                 r = dm_bm_write_lock_zero(dm_tm_get_bm(*tm), sb_location,
 331                                           sb_validator, sblock);
 332                 if (r < 0) {
 333                         DMERR("couldn't lock superblock");
 334                         goto bad1;
 335                 }
 336
 337                 r = dm_sm_metadata_create(inner, *tm, dm_bm_nr_blocks(bm),
 338                                           sb_location);
 339                 if (r) {
 340                         DMERR("couldn't create metadata space map");
 341                         goto bad2;
 342                 }
 343
 344                 *sm = dm_sm_checker_create(inner);
 345                 if (!*sm)
 346                         goto bad2;
 347
 348         } else {
 349                 r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
 350                                      sb_validator, sblock);
 351                 if (r < 0) {
 352                         DMERR("couldn't lock superblock");
 353                         goto bad1;
 354                 }
 355
 356                 r = dm_sm_metadata_open(inner, *tm,
 357                                         dm_block_data(*sblock) + root_offset,
 358                                         root_max_len);
 359                 if (r) {
 360                         DMERR("couldn't open metadata space map");
 361                         goto bad2;
 362                 }
 363
 364                 *sm = dm_sm_checker_create(inner);
 365                 if (!*sm)
 366                         goto bad2;
 367         }
 368
 369         return 0;
 370
 371 bad2:
 372         dm_tm_unlock(*tm, *sblock);
 373 bad1:
 374         dm_tm_destroy(*tm);
 375         dm_sm_destroy(inner);
 376         return r;
 377 }
 378
 379 int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
 380                          struct dm_block_validator *sb_validator,
 381                          struct dm_transaction_manager **tm,
 382                          struct dm_space_map **sm, struct dm_block **sblock)
 383 {
 384         return dm_tm_create_internal(bm, sb_location, sb_validator,
 385                                      0, 0, tm, sm, sblock, 1);
 386 }
 387 EXPORT_SYMBOL_GPL(dm_tm_create_with_sm);
 388
 389 int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
 390                        struct dm_block_validator *sb_validator,
 391                        size_t root_offset, size_t root_max_len,
 392                        struct dm_transaction_manager **tm,
 393                        struct dm_space_map **sm, struct dm_block **sblock)
 394 {
 395         return dm_tm_create_internal(bm, sb_location, sb_validator, root_offset,
 396                                      root_max_len, tm, sm, sblock, 0);
 397 }
 398 EXPORT_SYMBOL_GPL(dm_tm_open_with_sm);
 399
 400 /*----------------------------------------------------------------*/