1 /* 2 * Copyright (C) 2012 Red Hat, Inc. 3 * 4 * This file is released under the GPL. 5 */ 6 7 #include "dm.h" 8 #include "dm-bio-prison-v1.h" 9 #include "dm-bio-prison-v2.h" 10 11 #include <linux/spinlock.h> 12 #include <linux/mempool.h> 13 #include <linux/module.h> 14 #include <linux/slab.h> 15 16 /*----------------------------------------------------------------*/ 17 18 #define MIN_CELLS 1024 19 20 struct dm_bio_prison { 21 spinlock_t lock; 22 struct rb_root cells; 23 mempool_t cell_pool; 24 }; 25 26 static struct kmem_cache *_cell_cache; 27 28 /*----------------------------------------------------------------*/ 29 30 /* 31 * @nr_cells should be the number of cells you want in use _concurrently_. 32 * Don't confuse it with the number of distinct keys. 33 */ 34 struct dm_bio_prison *dm_bio_prison_create(void) 35 { 36 struct dm_bio_prison *prison = kzalloc(sizeof(*prison), GFP_KERNEL); 37 int ret; 38 39 if (!prison) 40 return NULL; 41 42 spin_lock_init(&prison->lock); 43 44 ret = mempool_init_slab_pool(&prison->cell_pool, MIN_CELLS, _cell_cache); 45 if (ret) { 46 kfree(prison); 47 return NULL; 48 } 49 50 prison->cells = RB_ROOT; 51 52 return prison; 53 } 54 EXPORT_SYMBOL_GPL(dm_bio_prison_create); 55 56 void dm_bio_prison_destroy(struct dm_bio_prison *prison) 57 { 58 mempool_exit(&prison->cell_pool); 59 kfree(prison); 60 } 61 EXPORT_SYMBOL_GPL(dm_bio_prison_destroy); 62 63 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp) 64 { 65 return mempool_alloc(&prison->cell_pool, gfp); 66 } 67 EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell); 68 69 void dm_bio_prison_free_cell(struct dm_bio_prison *prison, 70 struct dm_bio_prison_cell *cell) 71 { 72 mempool_free(cell, &prison->cell_pool); 73 } 74 EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell); 75 76 static void __setup_new_cell(struct dm_cell_key *key, 77 struct bio *holder, 78 struct dm_bio_prison_cell *cell) 79 { 80 memcpy(&cell->key, key, sizeof(cell->key)); 81 cell->holder = holder; 82 bio_list_init(&cell->bios); 83 } 84 85 static int cmp_keys(struct dm_cell_key *lhs, 86 struct dm_cell_key *rhs) 87 { 88 if (lhs->virtual < rhs->virtual) 89 return -1; 90 91 if (lhs->virtual > rhs->virtual) 92 return 1; 93 94 if (lhs->dev < rhs->dev) 95 return -1; 96 97 if (lhs->dev > rhs->dev) 98 return 1; 99 100 if (lhs->block_end <= rhs->block_begin) 101 return -1; 102 103 if (lhs->block_begin >= rhs->block_end) 104 return 1; 105 106 return 0; 107 } 108 109 static int __bio_detain(struct dm_bio_prison *prison, 110 struct dm_cell_key *key, 111 struct bio *inmate, 112 struct dm_bio_prison_cell *cell_prealloc, 113 struct dm_bio_prison_cell **cell_result) 114 { 115 int r; 116 struct rb_node **new = &prison->cells.rb_node, *parent = NULL; 117 118 while (*new) { 119 struct dm_bio_prison_cell *cell = 120 rb_entry(*new, struct dm_bio_prison_cell, node); 121 122 r = cmp_keys(key, &cell->key); 123 124 parent = *new; 125 if (r < 0) 126 new = &((*new)->rb_left); 127 else if (r > 0) 128 new = &((*new)->rb_right); 129 else { 130 if (inmate) 131 bio_list_add(&cell->bios, inmate); 132 *cell_result = cell; 133 return 1; 134 } 135 } 136 137 __setup_new_cell(key, inmate, cell_prealloc); 138 *cell_result = cell_prealloc; 139 140 rb_link_node(&cell_prealloc->node, parent, new); 141 rb_insert_color(&cell_prealloc->node, &prison->cells); 142 143 return 0; 144 } 145 146 static int bio_detain(struct dm_bio_prison *prison, 147 struct dm_cell_key *key, 148 struct bio *inmate, 149 struct dm_bio_prison_cell *cell_prealloc, 150 struct dm_bio_prison_cell **cell_result) 151 { 152 int r; 153 154 spin_lock_irq(&prison->lock); 155 r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result); 156 spin_unlock_irq(&prison->lock); 157 158 return r; 159 } 160 161 int dm_bio_detain(struct dm_bio_prison *prison, 162 struct dm_cell_key *key, 163 struct bio *inmate, 164 struct dm_bio_prison_cell *cell_prealloc, 165 struct dm_bio_prison_cell **cell_result) 166 { 167 return bio_detain(prison, key, inmate, cell_prealloc, cell_result); 168 } 169 EXPORT_SYMBOL_GPL(dm_bio_detain); 170 171 int dm_get_cell(struct dm_bio_prison *prison, 172 struct dm_cell_key *key, 173 struct dm_bio_prison_cell *cell_prealloc, 174 struct dm_bio_prison_cell **cell_result) 175 { 176 return bio_detain(prison, key, NULL, cell_prealloc, cell_result); 177 } 178 EXPORT_SYMBOL_GPL(dm_get_cell); 179 180 /* 181 * @inmates must have been initialised prior to this call 182 */ 183 static void __cell_release(struct dm_bio_prison *prison, 184 struct dm_bio_prison_cell *cell, 185 struct bio_list *inmates) 186 { 187 rb_erase(&cell->node, &prison->cells); 188 189 if (inmates) { 190 if (cell->holder) 191 bio_list_add(inmates, cell->holder); 192 bio_list_merge(inmates, &cell->bios); 193 } 194 } 195 196 void dm_cell_release(struct dm_bio_prison *prison, 197 struct dm_bio_prison_cell *cell, 198 struct bio_list *bios) 199 { 200 spin_lock_irq(&prison->lock); 201 __cell_release(prison, cell, bios); 202 spin_unlock_irq(&prison->lock); 203 } 204 EXPORT_SYMBOL_GPL(dm_cell_release); 205 206 /* 207 * Sometimes we don't want the holder, just the additional bios. 208 */ 209 static void __cell_release_no_holder(struct dm_bio_prison *prison, 210 struct dm_bio_prison_cell *cell, 211 struct bio_list *inmates) 212 { 213 rb_erase(&cell->node, &prison->cells); 214 bio_list_merge(inmates, &cell->bios); 215 } 216 217 void dm_cell_release_no_holder(struct dm_bio_prison *prison, 218 struct dm_bio_prison_cell *cell, 219 struct bio_list *inmates) 220 { 221 unsigned long flags; 222 223 spin_lock_irqsave(&prison->lock, flags); 224 __cell_release_no_holder(prison, cell, inmates); 225 spin_unlock_irqrestore(&prison->lock, flags); 226 } 227 EXPORT_SYMBOL_GPL(dm_cell_release_no_holder); 228 229 void dm_cell_error(struct dm_bio_prison *prison, 230 struct dm_bio_prison_cell *cell, blk_status_t error) 231 { 232 struct bio_list bios; 233 struct bio *bio; 234 235 bio_list_init(&bios); 236 dm_cell_release(prison, cell, &bios); 237 238 while ((bio = bio_list_pop(&bios))) { 239 bio->bi_status = error; 240 bio_endio(bio); 241 } 242 } 243 EXPORT_SYMBOL_GPL(dm_cell_error); 244 245 void dm_cell_visit_release(struct dm_bio_prison *prison, 246 void (*visit_fn)(void *, struct dm_bio_prison_cell *), 247 void *context, 248 struct dm_bio_prison_cell *cell) 249 { 250 spin_lock_irq(&prison->lock); 251 visit_fn(context, cell); 252 rb_erase(&cell->node, &prison->cells); 253 spin_unlock_irq(&prison->lock); 254 } 255 EXPORT_SYMBOL_GPL(dm_cell_visit_release); 256 257 static int __promote_or_release(struct dm_bio_prison *prison, 258 struct dm_bio_prison_cell *cell) 259 { 260 if (bio_list_empty(&cell->bios)) { 261 rb_erase(&cell->node, &prison->cells); 262 return 1; 263 } 264 265 cell->holder = bio_list_pop(&cell->bios); 266 return 0; 267 } 268 269 int dm_cell_promote_or_release(struct dm_bio_prison *prison, 270 struct dm_bio_prison_cell *cell) 271 { 272 int r; 273 274 spin_lock_irq(&prison->lock); 275 r = __promote_or_release(prison, cell); 276 spin_unlock_irq(&prison->lock); 277 278 return r; 279 } 280 EXPORT_SYMBOL_GPL(dm_cell_promote_or_release); 281 282 /*----------------------------------------------------------------*/ 283 284 #define DEFERRED_SET_SIZE 64 285 286 struct dm_deferred_entry { 287 struct dm_deferred_set *ds; 288 unsigned count; 289 struct list_head work_items; 290 }; 291 292 struct dm_deferred_set { 293 spinlock_t lock; 294 unsigned current_entry; 295 unsigned sweeper; 296 struct dm_deferred_entry entries[DEFERRED_SET_SIZE]; 297 }; 298 299 struct dm_deferred_set *dm_deferred_set_create(void) 300 { 301 int i; 302 struct dm_deferred_set *ds; 303 304 ds = kmalloc(sizeof(*ds), GFP_KERNEL); 305 if (!ds) 306 return NULL; 307 308 spin_lock_init(&ds->lock); 309 ds->current_entry = 0; 310 ds->sweeper = 0; 311 for (i = 0; i < DEFERRED_SET_SIZE; i++) { 312 ds->entries[i].ds = ds; 313 ds->entries[i].count = 0; 314 INIT_LIST_HEAD(&ds->entries[i].work_items); 315 } 316 317 return ds; 318 } 319 EXPORT_SYMBOL_GPL(dm_deferred_set_create); 320 321 void dm_deferred_set_destroy(struct dm_deferred_set *ds) 322 { 323 kfree(ds); 324 } 325 EXPORT_SYMBOL_GPL(dm_deferred_set_destroy); 326 327 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds) 328 { 329 unsigned long flags; 330 struct dm_deferred_entry *entry; 331 332 spin_lock_irqsave(&ds->lock, flags); 333 entry = ds->entries + ds->current_entry; 334 entry->count++; 335 spin_unlock_irqrestore(&ds->lock, flags); 336 337 return entry; 338 } 339 EXPORT_SYMBOL_GPL(dm_deferred_entry_inc); 340 341 static unsigned ds_next(unsigned index) 342 { 343 return (index + 1) % DEFERRED_SET_SIZE; 344 } 345 346 static void __sweep(struct dm_deferred_set *ds, struct list_head *head) 347 { 348 while ((ds->sweeper != ds->current_entry) && 349 !ds->entries[ds->sweeper].count) { 350 list_splice_init(&ds->entries[ds->sweeper].work_items, head); 351 ds->sweeper = ds_next(ds->sweeper); 352 } 353 354 if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count) 355 list_splice_init(&ds->entries[ds->sweeper].work_items, head); 356 } 357 358 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head) 359 { 360 unsigned long flags; 361 362 spin_lock_irqsave(&entry->ds->lock, flags); 363 BUG_ON(!entry->count); 364 --entry->count; 365 __sweep(entry->ds, head); 366 spin_unlock_irqrestore(&entry->ds->lock, flags); 367 } 368 EXPORT_SYMBOL_GPL(dm_deferred_entry_dec); 369 370 /* 371 * Returns 1 if deferred or 0 if no pending items to delay job. 372 */ 373 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work) 374 { 375 int r = 1; 376 unsigned next_entry; 377 378 spin_lock_irq(&ds->lock); 379 if ((ds->sweeper == ds->current_entry) && 380 !ds->entries[ds->current_entry].count) 381 r = 0; 382 else { 383 list_add(work, &ds->entries[ds->current_entry].work_items); 384 next_entry = ds_next(ds->current_entry); 385 if (!ds->entries[next_entry].count) 386 ds->current_entry = next_entry; 387 } 388 spin_unlock_irq(&ds->lock); 389 390 return r; 391 } 392 EXPORT_SYMBOL_GPL(dm_deferred_set_add_work); 393 394 /*----------------------------------------------------------------*/ 395 396 static int __init dm_bio_prison_init_v1(void) 397 { 398 _cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0); 399 if (!_cell_cache) 400 return -ENOMEM; 401 402 return 0; 403 } 404 405 static void dm_bio_prison_exit_v1(void) 406 { 407 kmem_cache_destroy(_cell_cache); 408 _cell_cache = NULL; 409 } 410 411 static int (*_inits[])(void) __initdata = { 412 dm_bio_prison_init_v1, 413 dm_bio_prison_init_v2, 414 }; 415 416 static void (*_exits[])(void) = { 417 dm_bio_prison_exit_v1, 418 dm_bio_prison_exit_v2, 419 }; 420 421 static int __init dm_bio_prison_init(void) 422 { 423 const int count = ARRAY_SIZE(_inits); 424 425 int r, i; 426 427 for (i = 0; i < count; i++) { 428 r = _inits[i](); 429 if (r) 430 goto bad; 431 } 432 433 return 0; 434 435 bad: 436 while (i--) 437 _exits[i](); 438 439 return r; 440 } 441 442 static void __exit dm_bio_prison_exit(void) 443 { 444 int i = ARRAY_SIZE(_exits); 445 446 while (i--) 447 _exits[i](); 448 } 449 450 /* 451 * module hooks 452 */ 453 module_init(dm_bio_prison_init); 454 module_exit(dm_bio_prison_exit); 455 456 MODULE_DESCRIPTION(DM_NAME " bio prison"); 457 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); 458 MODULE_LICENSE("GPL"); 459