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 /*----------------------------------------------------------------*/ 383