drivers/md/dm-bio-prison-v1.c

   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");