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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Red Hat, Inc.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm.h"
   9 #include "dm-bio-prison-v1.h"
  10 #include "dm-bio-prison-v2.h"
  11
  12 #include <linux/spinlock.h>
  13 #include <linux/mempool.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16
  17 /*----------------------------------------------------------------*/
  18
  19 #define MIN_CELLS 1024
  20
  21 struct prison_region {
  22         spinlock_t lock;
  23         struct rb_root cell;
  24 } ____cacheline_aligned_in_smp;
  25
  26 struct dm_bio_prison {
  27         mempool_t cell_pool;
  28         unsigned int num_locks;
  29         struct prison_region regions[] __counted_by(num_locks);
  30 };
  31
  32 static struct kmem_cache *_cell_cache;
  33
  34 /*----------------------------------------------------------------*/
  35
  36 /*
  37  * @nr_cells should be the number of cells you want in use _concurrently_.
  38  * Don't confuse it with the number of distinct keys.
  39  */
  40 struct dm_bio_prison *dm_bio_prison_create(void)
  41 {
  42         int ret;
  43         unsigned int i, num_locks;
  44         struct dm_bio_prison *prison;
  45
  46         num_locks = dm_num_hash_locks();
  47         prison = kzalloc(struct_size(prison, regions, num_locks), GFP_KERNEL);
  48         if (!prison)
  49                 return NULL;
  50         prison->num_locks = num_locks;
  51
  52         for (i = 0; i < prison->num_locks; i++) {
  53                 spin_lock_init(&prison->regions[i].lock);
  54                 prison->regions[i].cell = RB_ROOT;
  55         }
  56
  57         ret = mempool_init_slab_pool(&prison->cell_pool, MIN_CELLS, _cell_cache);
  58         if (ret) {
  59                 kfree(prison);
  60                 return NULL;
  61         }
  62
  63         return prison;
  64 }
  65 EXPORT_SYMBOL_GPL(dm_bio_prison_create);
  66
  67 void dm_bio_prison_destroy(struct dm_bio_prison *prison)
  68 {
  69         mempool_exit(&prison->cell_pool);
  70         kfree(prison);
  71 }
  72 EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
  73
  74 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
  75 {
  76         return mempool_alloc(&prison->cell_pool, gfp);
  77 }
  78 EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
  79
  80 void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
  81                              struct dm_bio_prison_cell *cell)
  82 {
  83         mempool_free(cell, &prison->cell_pool);
  84 }
  85 EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
  86
  87 static void __setup_new_cell(struct dm_cell_key *key,
  88                              struct bio *holder,
  89                              struct dm_bio_prison_cell *cell)
  90 {
  91         memcpy(&cell->key, key, sizeof(cell->key));
  92         cell->holder = holder;
  93         bio_list_init(&cell->bios);
  94 }
  95
  96 static int cmp_keys(struct dm_cell_key *lhs,
  97                     struct dm_cell_key *rhs)
  98 {
  99         if (lhs->virtual < rhs->virtual)
 100                 return -1;
 101
 102         if (lhs->virtual > rhs->virtual)
 103                 return 1;
 104
 105         if (lhs->dev < rhs->dev)
 106                 return -1;
 107
 108         if (lhs->dev > rhs->dev)
 109                 return 1;
 110
 111         if (lhs->block_end <= rhs->block_begin)
 112                 return -1;
 113
 114         if (lhs->block_begin >= rhs->block_end)
 115                 return 1;
 116
 117         return 0;
 118 }
 119
 120 static inline unsigned int lock_nr(struct dm_cell_key *key, unsigned int num_locks)
 121 {
 122         return dm_hash_locks_index((key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT),
 123                                    num_locks);
 124 }
 125
 126 bool dm_cell_key_has_valid_range(struct dm_cell_key *key)
 127 {
 128         if (WARN_ON_ONCE(key->block_end - key->block_begin > BIO_PRISON_MAX_RANGE))
 129                 return false;
 130         if (WARN_ON_ONCE((key->block_begin >> BIO_PRISON_MAX_RANGE_SHIFT) !=
 131                          (key->block_end - 1) >> BIO_PRISON_MAX_RANGE_SHIFT))
 132                 return false;
 133
 134         return true;
 135 }
 136 EXPORT_SYMBOL(dm_cell_key_has_valid_range);
 137
 138 static int __bio_detain(struct rb_root *root,
 139                         struct dm_cell_key *key,
 140                         struct bio *inmate,
 141                         struct dm_bio_prison_cell *cell_prealloc,
 142                         struct dm_bio_prison_cell **cell_result)
 143 {
 144         int r;
 145         struct rb_node **new = &root->rb_node, *parent = NULL;
 146
 147         while (*new) {
 148                 struct dm_bio_prison_cell *cell =
 149                         rb_entry(*new, struct dm_bio_prison_cell, node);
 150
 151                 r = cmp_keys(key, &cell->key);
 152
 153                 parent = *new;
 154                 if (r < 0)
 155                         new = &((*new)->rb_left);
 156                 else if (r > 0)
 157                         new = &((*new)->rb_right);
 158                 else {
 159                         if (inmate)
 160                                 bio_list_add(&cell->bios, inmate);
 161                         *cell_result = cell;
 162                         return 1;
 163                 }
 164         }
 165
 166         __setup_new_cell(key, inmate, cell_prealloc);
 167         *cell_result = cell_prealloc;
 168
 169         rb_link_node(&cell_prealloc->node, parent, new);
 170         rb_insert_color(&cell_prealloc->node, root);
 171
 172         return 0;
 173 }
 174
 175 static int bio_detain(struct dm_bio_prison *prison,
 176                       struct dm_cell_key *key,
 177                       struct bio *inmate,
 178                       struct dm_bio_prison_cell *cell_prealloc,
 179                       struct dm_bio_prison_cell **cell_result)
 180 {
 181         int r;
 182         unsigned l = lock_nr(key, prison->num_locks);
 183
 184         spin_lock_irq(&prison->regions[l].lock);
 185         r = __bio_detain(&prison->regions[l].cell, key, inmate, cell_prealloc, cell_result);
 186         spin_unlock_irq(&prison->regions[l].lock);
 187
 188         return r;
 189 }
 190
 191 int dm_bio_detain(struct dm_bio_prison *prison,
 192                   struct dm_cell_key *key,
 193                   struct bio *inmate,
 194                   struct dm_bio_prison_cell *cell_prealloc,
 195                   struct dm_bio_prison_cell **cell_result)
 196 {
 197         return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
 198 }
 199 EXPORT_SYMBOL_GPL(dm_bio_detain);
 200
 201 /*
 202  * @inmates must have been initialised prior to this call
 203  */
 204 static void __cell_release(struct rb_root *root,
 205                            struct dm_bio_prison_cell *cell,
 206                            struct bio_list *inmates)
 207 {
 208         rb_erase(&cell->node, root);
 209
 210         if (inmates) {
 211                 if (cell->holder)
 212                         bio_list_add(inmates, cell->holder);
 213                 bio_list_merge(inmates, &cell->bios);
 214         }
 215 }
 216
 217 void dm_cell_release(struct dm_bio_prison *prison,
 218                      struct dm_bio_prison_cell *cell,
 219                      struct bio_list *bios)
 220 {
 221         unsigned l = lock_nr(&cell->key, prison->num_locks);
 222
 223         spin_lock_irq(&prison->regions[l].lock);
 224         __cell_release(&prison->regions[l].cell, cell, bios);
 225         spin_unlock_irq(&prison->regions[l].lock);
 226 }
 227 EXPORT_SYMBOL_GPL(dm_cell_release);
 228
 229 /*
 230  * Sometimes we don't want the holder, just the additional bios.
 231  */
 232 static void __cell_release_no_holder(struct rb_root *root,
 233                                      struct dm_bio_prison_cell *cell,
 234                                      struct bio_list *inmates)
 235 {
 236         rb_erase(&cell->node, root);
 237         bio_list_merge(inmates, &cell->bios);
 238 }
 239
 240 void dm_cell_release_no_holder(struct dm_bio_prison *prison,
 241                                struct dm_bio_prison_cell *cell,
 242                                struct bio_list *inmates)
 243 {
 244         unsigned l = lock_nr(&cell->key, prison->num_locks);
 245         unsigned long flags;
 246
 247         spin_lock_irqsave(&prison->regions[l].lock, flags);
 248         __cell_release_no_holder(&prison->regions[l].cell, cell, inmates);
 249         spin_unlock_irqrestore(&prison->regions[l].lock, flags);
 250 }
 251 EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
 252
 253 void dm_cell_error(struct dm_bio_prison *prison,
 254                    struct dm_bio_prison_cell *cell, blk_status_t error)
 255 {
 256         struct bio_list bios;
 257         struct bio *bio;
 258
 259         bio_list_init(&bios);
 260         dm_cell_release(prison, cell, &bios);
 261
 262         while ((bio = bio_list_pop(&bios))) {
 263                 bio->bi_status = error;
 264                 bio_endio(bio);
 265         }
 266 }
 267 EXPORT_SYMBOL_GPL(dm_cell_error);
 268
 269 void dm_cell_visit_release(struct dm_bio_prison *prison,
 270                            void (*visit_fn)(void *, struct dm_bio_prison_cell *),
 271                            void *context,
 272                            struct dm_bio_prison_cell *cell)
 273 {
 274         unsigned l = lock_nr(&cell->key, prison->num_locks);
 275         spin_lock_irq(&prison->regions[l].lock);
 276         visit_fn(context, cell);
 277         rb_erase(&cell->node, &prison->regions[l].cell);
 278         spin_unlock_irq(&prison->regions[l].lock);
 279 }
 280 EXPORT_SYMBOL_GPL(dm_cell_visit_release);
 281
 282 /*----------------------------------------------------------------*/
 283
 284 #define DEFERRED_SET_SIZE 64
 285
 286 struct dm_deferred_entry {
 287         struct dm_deferred_set *ds;
 288         unsigned int count;
 289         struct list_head work_items;
 290 };
 291
 292 struct dm_deferred_set {
 293         spinlock_t lock;
 294         unsigned int current_entry;
 295         unsigned int 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 int ds_next(unsigned int 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 int 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@lists.linux.dev>");
 458 MODULE_LICENSE("GPL");