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-disk.h"
   9 #include "dm-space-map-metadata.h"
  10 #include "dm-persistent-data-internal.h"
  11
  12 #include <linux/export.h>
  13 #include <linux/slab.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 DM_HASH_SIZE 256
  29 #define DM_HASH_MASK (DM_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[DM_HASH_SIZE];
  40 };
  41
  42 /*----------------------------------------------------------------*/
  43
  44 static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b)
  45 {
  46         int r = 0;
  47         unsigned bucket = dm_hash_block(b, DM_HASH_MASK);
  48         struct shadow_info *si;
  49
  50         spin_lock(&tm->lock);
  51         hlist_for_each_entry(si, tm->buckets + bucket, hlist)
  52                 if (si->where == b) {
  53                         r = 1;
  54                         break;
  55                 }
  56         spin_unlock(&tm->lock);
  57
  58         return r;
  59 }
  60
  61 /*
  62  * This can silently fail if there's no memory.  We're ok with this since
  63  * creating redundant shadows causes no harm.
  64  */
  65 static void insert_shadow(struct dm_transaction_manager *tm, dm_block_t b)
  66 {
  67         unsigned bucket;
  68         struct shadow_info *si;
  69
  70         si = kmalloc(sizeof(*si), GFP_NOIO);
  71         if (si) {
  72                 si->where = b;
  73                 bucket = dm_hash_block(b, DM_HASH_MASK);
  74                 spin_lock(&tm->lock);
  75                 hlist_add_head(&si->hlist, tm->buckets + bucket);
  76                 spin_unlock(&tm->lock);
  77         }
  78 }
  79
  80 static void wipe_shadow_table(struct dm_transaction_manager *tm)
  81 {
  82         struct shadow_info *si;
  83         struct hlist_node *tmp;
  84         struct hlist_head *bucket;
  85         int i;
  86
  87         spin_lock(&tm->lock);
  88         for (i = 0; i < DM_HASH_SIZE; i++) {
  89                 bucket = tm->buckets + i;
  90                 hlist_for_each_entry_safe(si, tmp, bucket, hlist)
  91                         kfree(si);
  92
  93                 INIT_HLIST_HEAD(bucket);
  94         }
  95
  96         spin_unlock(&tm->lock);
  97 }
  98
  99 /*----------------------------------------------------------------*/
 100
 101 static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
 102                                                    struct dm_space_map *sm)
 103 {
 104         int i;
 105         struct dm_transaction_manager *tm;
 106
 107         tm = kmalloc(sizeof(*tm), GFP_KERNEL);
 108         if (!tm)
 109                 return ERR_PTR(-ENOMEM);
 110
 111         tm->is_clone = 0;
 112         tm->real = NULL;
 113         tm->bm = bm;
 114         tm->sm = sm;
 115
 116         spin_lock_init(&tm->lock);
 117         for (i = 0; i < DM_HASH_SIZE; i++)
 118                 INIT_HLIST_HEAD(tm->buckets + i);
 119
 120         return tm;
 121 }
 122
 123 struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real)
 124 {
 125         struct dm_transaction_manager *tm;
 126
 127         tm = kmalloc(sizeof(*tm), GFP_KERNEL);
 128         if (tm) {
 129                 tm->is_clone = 1;
 130                 tm->real = real;
 131         }
 132
 133         return tm;
 134 }
 135 EXPORT_SYMBOL_GPL(dm_tm_create_non_blocking_clone);
 136
 137 void dm_tm_destroy(struct dm_transaction_manager *tm)
 138 {
 139         if (!tm->is_clone)
 140                 wipe_shadow_table(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 dm_bm_flush(tm->bm);
 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         dm_bm_unlock(root);
 168
 169         return dm_bm_flush(tm->bm);
 170 }
 171 EXPORT_SYMBOL_GPL(dm_tm_commit);
 172
 173 int dm_tm_new_block(struct dm_transaction_manager *tm,
 174                     struct dm_block_validator *v,
 175                     struct dm_block **result)
 176 {
 177         int r;
 178         dm_block_t new_block;
 179
 180         if (tm->is_clone)
 181                 return -EWOULDBLOCK;
 182
 183         r = dm_sm_new_block(tm->sm, &new_block);
 184         if (r < 0)
 185                 return r;
 186
 187         r = dm_bm_write_lock_zero(tm->bm, new_block, v, result);
 188         if (r < 0) {
 189                 dm_sm_dec_block(tm->sm, new_block);
 190                 return r;
 191         }
 192
 193         /*
 194          * New blocks count as shadows in that they don't need to be
 195          * shadowed again.
 196          */
 197         insert_shadow(tm, new_block);
 198
 199         return 0;
 200 }
 201
 202 static int __shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 203                           struct dm_block_validator *v,
 204                           struct dm_block **result)
 205 {
 206         int r;
 207         dm_block_t new;
 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_sm_dec_block(tm->sm, orig);
 215         if (r < 0)
 216                 return r;
 217
 218         r = dm_bm_read_lock(tm->bm, orig, v, &orig_block);
 219         if (r < 0)
 220                 return r;
 221
 222         /*
 223          * It would be tempting to use dm_bm_unlock_move here, but some
 224          * code, such as the space maps, keeps using the old data structures
 225          * secure in the knowledge they won't be changed until the next
 226          * transaction.  Using unlock_move would force a synchronous read
 227          * since the old block would no longer be in the cache.
 228          */
 229         r = dm_bm_write_lock_zero(tm->bm, new, v, result);
 230         if (r) {
 231                 dm_bm_unlock(orig_block);
 232                 return r;
 233         }
 234
 235         memcpy(dm_block_data(*result), dm_block_data(orig_block),
 236                dm_bm_block_size(tm->bm));
 237
 238         dm_bm_unlock(orig_block);
 239         return r;
 240 }
 241
 242 int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 243                        struct dm_block_validator *v, struct dm_block **result,
 244                        int *inc_children)
 245 {
 246         int r;
 247
 248         if (tm->is_clone)
 249                 return -EWOULDBLOCK;
 250
 251         r = dm_sm_count_is_more_than_one(tm->sm, orig, inc_children);
 252         if (r < 0)
 253                 return r;
 254
 255         if (is_shadow(tm, orig) && !*inc_children)
 256                 return dm_bm_write_lock(tm->bm, orig, v, result);
 257
 258         r = __shadow_block(tm, orig, v, result);
 259         if (r < 0)
 260                 return r;
 261         insert_shadow(tm, dm_block_location(*result));
 262
 263         return r;
 264 }
 265 EXPORT_SYMBOL_GPL(dm_tm_shadow_block);
 266
 267 int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
 268                     struct dm_block_validator *v,
 269                     struct dm_block **blk)
 270 {
 271         if (tm->is_clone)
 272                 return dm_bm_read_try_lock(tm->real->bm, b, v, blk);
 273
 274         return dm_bm_read_lock(tm->bm, b, v, blk);
 275 }
 276 EXPORT_SYMBOL_GPL(dm_tm_read_lock);
 277
 278 int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b)
 279 {
 280         return dm_bm_unlock(b);
 281 }
 282 EXPORT_SYMBOL_GPL(dm_tm_unlock);
 283
 284 void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b)
 285 {
 286         /*
 287          * The non-blocking clone doesn't support this.
 288          */
 289         BUG_ON(tm->is_clone);
 290
 291         dm_sm_inc_block(tm->sm, b);
 292 }
 293 EXPORT_SYMBOL_GPL(dm_tm_inc);
 294
 295 void dm_tm_dec(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_dec_block(tm->sm, b);
 303 }
 304 EXPORT_SYMBOL_GPL(dm_tm_dec);
 305
 306 int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
 307               uint32_t *result)
 308 {
 309         if (tm->is_clone)
 310                 return -EWOULDBLOCK;
 311
 312         return dm_sm_get_count(tm->sm, b, result);
 313 }
 314
 315 struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm)
 316 {
 317         return tm->bm;
 318 }
 319
 320 /*----------------------------------------------------------------*/
 321
 322 static int dm_tm_create_internal(struct dm_block_manager *bm,
 323                                  dm_block_t sb_location,
 324                                  struct dm_transaction_manager **tm,
 325                                  struct dm_space_map **sm,
 326                                  int create,
 327                                  void *sm_root, size_t sm_len)
 328 {
 329         int r;
 330
 331         *sm = dm_sm_metadata_init();
 332         if (IS_ERR(*sm))
 333                 return PTR_ERR(*sm);
 334
 335         *tm = dm_tm_create(bm, *sm);
 336         if (IS_ERR(*tm)) {
 337                 dm_sm_destroy(*sm);
 338                 return PTR_ERR(*tm);
 339         }
 340
 341         if (create) {
 342                 r = dm_sm_metadata_create(*sm, *tm, dm_bm_nr_blocks(bm),
 343                                           sb_location);
 344                 if (r) {
 345                         DMERR("couldn't create metadata space map");
 346                         goto bad;
 347                 }
 348
 349         } else {
 350                 r = dm_sm_metadata_open(*sm, *tm, sm_root, sm_len);
 351                 if (r) {
 352                         DMERR("couldn't open metadata space map");
 353                         goto bad;
 354                 }
 355         }
 356
 357         return 0;
 358
 359 bad:
 360         dm_tm_destroy(*tm);
 361         dm_sm_destroy(*sm);
 362         return r;
 363 }
 364
 365 int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
 366                          struct dm_transaction_manager **tm,
 367                          struct dm_space_map **sm)
 368 {
 369         return dm_tm_create_internal(bm, sb_location, tm, sm, 1, NULL, 0);
 370 }
 371 EXPORT_SYMBOL_GPL(dm_tm_create_with_sm);
 372
 373 int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
 374                        void *sm_root, size_t root_len,
 375                        struct dm_transaction_manager **tm,
 376                        struct dm_space_map **sm)
 377 {
 378         return dm_tm_create_internal(bm, sb_location, tm, sm, 0, sm_root, root_len);
 379 }
 380 EXPORT_SYMBOL_GPL(dm_tm_open_with_sm);
 381
 382 /*----------------------------------------------------------------*/