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

   1 /*
   2  * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
   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-disk.h"
   9 #include "dm-space-map-metadata.h"
  10 #include "dm-persistent-data-internal.h"
  11
  12 #include <linux/slab.h>
  13 #include <linux/export.h>
  14 #include <linux/device-mapper.h>
  15
  16 #define DM_MSG_PREFIX "transaction manager"
  17
  18 /*----------------------------------------------------------------*/
  19
  20 struct shadow_info {
  21         struct hlist_node hlist;
  22         dm_block_t where;
  23 };
  24
  25 /*
  26  * It would be nice if we scaled with the size of transaction.
  27  */
  28 #define HASH_SIZE 256
  29 #define HASH_MASK (HASH_SIZE - 1)
  30
  31 struct dm_transaction_manager {
  32         int is_clone;
  33         struct dm_transaction_manager *real;
  34
  35         struct dm_block_manager *bm;
  36         struct dm_space_map *sm;
  37
  38         spinlock_t lock;
  39         struct hlist_head buckets[HASH_SIZE];
  40 };
  41
  42 /*----------------------------------------------------------------*/
  43
  44 static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b)
  45 {
  46         unsigned bucket = dm_hash_block(b, HASH_MASK);
  47         struct shadow_info *si;
  48         struct hlist_node *n;
  49         int r = 0;
  50
  51         spin_lock(&tm->lock);
  52
  53         hlist_for_each_entry(si, n, tm->buckets + bucket, hlist)
  54                 if (si->where == b) {
  55                         r = 1;
  56                         break;
  57                 }
  58
  59         spin_unlock(&tm->lock);
  60
  61         return r;
  62 }
  63
  64 /*
  65  * This can silently fail if there's no memory.  We're ok with this since
  66  * creating redundant shadows causes no harm.
  67  */
  68 static void insert_shadow(struct dm_transaction_manager *tm, dm_block_t b)
  69 {
  70         unsigned bucket;
  71         struct shadow_info *si;
  72
  73         si = kmalloc(sizeof(*si), GFP_NOIO);
  74         if (si) {
  75                 si->where = b;
  76                 bucket = dm_hash_block(b, HASH_MASK);
  77
  78                 spin_lock(&tm->lock);
  79                 hlist_add_head(&si->hlist, tm->buckets + bucket);
  80                 spin_unlock(&tm->lock);
  81         }
  82 }
  83
  84 static void wipe_shadow_table(struct dm_transaction_manager *tm)
  85 {
  86         struct shadow_info *si;
  87         struct hlist_node *n, *tmp;
  88         struct hlist_head *bucket;
  89         int i;
  90
  91         spin_lock(&tm->lock);
  92         for (i = 0; i < HASH_SIZE; i++) {
  93                 bucket = tm->buckets + i;
  94                 hlist_for_each_entry_safe(si, n, tmp, bucket, hlist)
  95                         kfree(si);
  96
  97                 INIT_HLIST_HEAD(bucket);
  98         }
  99         spin_unlock(&tm->lock);
 100 }
 101
 102 /*----------------------------------------------------------------*/
 103
 104 static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
 105                                                    struct dm_space_map *sm)
 106 {
 107         int i;
 108         struct dm_transaction_manager *tm;
 109
 110         tm = kmalloc(sizeof(*tm), GFP_KERNEL);
 111         if (!tm)
 112                 return ERR_PTR(-ENOMEM);
 113
 114         tm->is_clone = 0;
 115         tm->real = NULL;
 116         tm->bm = bm;
 117         tm->sm = sm;
 118
 119         spin_lock_init(&tm->lock);
 120         for (i = 0; i < HASH_SIZE; i++)
 121                 INIT_HLIST_HEAD(tm->buckets + i);
 122
 123         return tm;
 124 }
 125
 126 struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real)
 127 {
 128         struct dm_transaction_manager *tm;
 129
 130         tm = kmalloc(sizeof(*tm), GFP_KERNEL);
 131         if (tm) {
 132                 tm->is_clone = 1;
 133                 tm->real = real;
 134         }
 135
 136         return tm;
 137 }
 138 EXPORT_SYMBOL_GPL(dm_tm_create_non_blocking_clone);
 139
 140 void dm_tm_destroy(struct dm_transaction_manager *tm)
 141 {
 142         kfree(tm);
 143 }
 144 EXPORT_SYMBOL_GPL(dm_tm_destroy);
 145
 146 int dm_tm_pre_commit(struct dm_transaction_manager *tm)
 147 {
 148         int r;
 149
 150         if (tm->is_clone)
 151                 return -EWOULDBLOCK;
 152
 153         r = dm_sm_commit(tm->sm);
 154         if (r < 0)
 155                 return r;
 156
 157         return 0;
 158 }
 159 EXPORT_SYMBOL_GPL(dm_tm_pre_commit);
 160
 161 int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *root)
 162 {
 163         if (tm->is_clone)
 164                 return -EWOULDBLOCK;
 165
 166         wipe_shadow_table(tm);
 167
 168         return dm_bm_flush_and_unlock(tm->bm, root);
 169 }
 170 EXPORT_SYMBOL_GPL(dm_tm_commit);
 171
 172 int dm_tm_new_block(struct dm_transaction_manager *tm,
 173                     struct dm_block_validator *v,
 174                     struct dm_block **result)
 175 {
 176         int r;
 177         dm_block_t new_block;
 178
 179         if (tm->is_clone)
 180                 return -EWOULDBLOCK;
 181
 182         r = dm_sm_new_block(tm->sm, &new_block);
 183         if (r < 0)
 184                 return r;
 185
 186         r = dm_bm_write_lock_zero(tm->bm, new_block, v, result);
 187         if (r < 0) {
 188                 dm_sm_dec_block(tm->sm, new_block);
 189                 return r;
 190         }
 191
 192         /*
 193          * New blocks count as shadows in that they don't need to be
 194          * shadowed again.
 195          */
 196         insert_shadow(tm, new_block);
 197
 198         return 0;
 199 }
 200
 201 static int __shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 202                           struct dm_block_validator *v,
 203                           struct dm_block **result, int *inc_children)
 204 {
 205         int r;
 206         dm_block_t new;
 207         uint32_t count;
 208         struct dm_block *orig_block;
 209
 210         r = dm_sm_new_block(tm->sm, &new);
 211         if (r < 0)
 212                 return r;
 213
 214         r = dm_bm_write_lock_zero(tm->bm, new, v, result);
 215         if (r < 0)
 216                 goto bad_dec_block;
 217
 218         r = dm_bm_read_lock(tm->bm, orig, v, &orig_block);
 219         if (r < 0)
 220                 goto bad_dec_block;
 221
 222         memcpy(dm_block_data(*result), dm_block_data(orig_block),
 223                dm_bm_block_size(tm->bm));
 224
 225         r = dm_bm_unlock(orig_block);
 226         if (r < 0)
 227                 goto bad_dec_block;
 228
 229         r = dm_sm_get_count(tm->sm, orig, &count);
 230         if (r < 0)
 231                 goto bad;
 232
 233         r = dm_sm_dec_block(tm->sm, orig);
 234         if (r < 0)
 235                 goto bad;
 236
 237         *inc_children = count > 1;
 238
 239         return 0;
 240
 241 bad:
 242         dm_bm_unlock(*result);
 243 bad_dec_block:
 244         dm_sm_dec_block(tm->sm, new);
 245
 246         return r;
 247 }
 248
 249 int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 250                        struct dm_block_validator *v, struct dm_block **result,
 251                        int *inc_children)
 252 {
 253         int r, more_than_one;
 254
 255         if (tm->is_clone)
 256                 return -EWOULDBLOCK;
 257
 258         if (is_shadow(tm, orig)) {
 259                 r = dm_sm_count_is_more_than_one(tm->sm, orig, &more_than_one);
 260                 if (r < 0)
 261                         return r;
 262
 263                 if (!more_than_one) {
 264                         *inc_children = 0;
 265                         return dm_bm_write_lock(tm->bm, orig, v, result);
 266                 }
 267                 /* fall through */
 268         }
 269
 270         r = __shadow_block(tm, orig, v, result, inc_children);
 271         if (r < 0)
 272                 return r;
 273
 274         insert_shadow(tm, dm_block_location(*result));
 275
 276         return r;
 277 }
 278
 279 int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
 280                     struct dm_block_validator *v,
 281                     struct dm_block **blk)
 282 {
 283         if (tm->is_clone)
 284                 return dm_bm_read_try_lock(tm->real->bm, b, v, blk);
 285
 286         return dm_bm_read_lock(tm->bm, b, v, blk);
 287 }
 288
 289 int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b)
 290 {
 291         return dm_bm_unlock(b);
 292 }
 293 EXPORT_SYMBOL_GPL(dm_tm_unlock);
 294
 295 void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b)
 296 {
 297         /*
 298          * The non-blocking clone doesn't support this.
 299          */
 300         BUG_ON(tm->is_clone);
 301
 302         dm_sm_inc_block(tm->sm, b);
 303 }
 304 EXPORT_SYMBOL_GPL(dm_tm_inc);
 305
 306 void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b)
 307 {
 308         /*
 309          * The non-blocking clone doesn't support this.
 310          */
 311         BUG_ON(tm->is_clone);
 312
 313         dm_sm_dec_block(tm->sm, b);
 314 }
 315
 316 int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
 317               uint32_t *result)
 318 {
 319         if (tm->is_clone)
 320                 return -EWOULDBLOCK;
 321
 322         return dm_sm_get_count(tm->sm, b, result);
 323 }
 324
 325 struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm)
 326 {
 327         return tm->bm;
 328 }
 329
 330 /*----------------------------------------------------------------*/
 331
 332 static int dm_tm_create_internal(struct dm_block_manager *bm,
 333                                  dm_block_t sb_location,
 334                                  struct dm_block_validator *sb_validator,
 335                                  size_t root_offset, size_t root_max_len,
 336                                  struct dm_transaction_manager **tm,
 337                                  struct dm_space_map **sm,
 338                                  struct dm_block **sblock,
 339                                  int create)
 340 {
 341         int r;
 342
 343         *sm = dm_sm_metadata_init();
 344         if (IS_ERR(*sm))
 345                 return PTR_ERR(*sm);
 346
 347         *tm = dm_tm_create(bm, *sm);
 348         if (IS_ERR(*tm)) {
 349                 dm_sm_destroy(*sm);
 350                 return PTR_ERR(*tm);
 351         }
 352
 353         if (create) {
 354                 r = dm_bm_write_lock_zero(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_create(*sm, *tm, dm_bm_nr_blocks(bm),
 362                                           sb_location);
 363                 if (r) {
 364                         DMERR("couldn't create metadata space map");
 365                         goto bad2;
 366                 }
 367
 368         } else {
 369                 r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
 370                                      sb_validator, sblock);
 371                 if (r < 0) {
 372                         DMERR("couldn't lock superblock");
 373                         goto bad1;
 374                 }
 375
 376                 r = dm_sm_metadata_open(*sm, *tm,
 377                                         dm_block_data(*sblock) + root_offset,
 378                                         root_max_len);
 379                 if (IS_ERR(*sm)) {
 380                         DMERR("couldn't open metadata space map");
 381                         goto bad2;
 382                 }
 383         }
 384
 385         return 0;
 386
 387 bad2:
 388         dm_tm_unlock(*tm, *sblock);
 389 bad1:
 390         dm_tm_destroy(*tm);
 391         dm_sm_destroy(*sm);
 392         return r;
 393 }
 394
 395 int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
 396                          struct dm_block_validator *sb_validator,
 397                          struct dm_transaction_manager **tm,
 398                          struct dm_space_map **sm, struct dm_block **sblock)
 399 {
 400         return dm_tm_create_internal(bm, sb_location, sb_validator,
 401                                      0, 0, tm, sm, sblock, 1);
 402 }
 403 EXPORT_SYMBOL_GPL(dm_tm_create_with_sm);
 404
 405 int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
 406                        struct dm_block_validator *sb_validator,
 407                        size_t root_offset, size_t root_max_len,
 408                        struct dm_transaction_manager **tm,
 409                        struct dm_space_map **sm, struct dm_block **sblock)
 410 {
 411         return dm_tm_create_internal(bm, sb_location, sb_validator, root_offset,
 412                                      root_max_len, tm, sm, sblock, 0);
 413 }
 414 EXPORT_SYMBOL_GPL(dm_tm_open_with_sm);