git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/btree_key_cache.c

   1
   2 #include "bcachefs.h"
   3 #include "btree_cache.h"
   4 #include "btree_iter.h"
   5 #include "btree_key_cache.h"
   6 #include "btree_locking.h"
   7 #include "btree_update.h"
   8 #include "error.h"
   9 #include "journal.h"
  10 #include "journal_reclaim.h"
  11
  12 #include <linux/sched/mm.h>
  13 #include <trace/events/bcachefs.h>
  14
  15 static struct kmem_cache *bch2_key_cache;
  16
  17 static int bch2_btree_key_cache_cmp_fn(struct rhashtable_compare_arg *arg,
  18                                        const void *obj)
  19 {
  20         const struct bkey_cached *ck = obj;
  21         const struct bkey_cached_key *key = arg->key;
  22
  23         return cmp_int(ck->key.btree_id, key->btree_id) ?:
  24                 bpos_cmp(ck->key.pos, key->pos);
  25 }
  26
  27 static const struct rhashtable_params bch2_btree_key_cache_params = {
  28         .head_offset    = offsetof(struct bkey_cached, hash),
  29         .key_offset     = offsetof(struct bkey_cached, key),
  30         .key_len        = sizeof(struct bkey_cached_key),
  31         .obj_cmpfn      = bch2_btree_key_cache_cmp_fn,
  32 };
  33
  34 __flatten
  35 inline struct bkey_cached *
  36 bch2_btree_key_cache_find(struct bch_fs *c, enum btree_id btree_id, struct bpos pos)
  37 {
  38         struct bkey_cached_key key = {
  39                 .btree_id       = btree_id,
  40                 .pos            = pos,
  41         };
  42
  43         return rhashtable_lookup_fast(&c->btree_key_cache.table, &key,
  44                                       bch2_btree_key_cache_params);
  45 }
  46
  47 static bool bkey_cached_lock_for_evict(struct bkey_cached *ck)
  48 {
  49         if (!six_trylock_intent(&ck->c.lock))
  50                 return false;
  51
  52         if (!six_trylock_write(&ck->c.lock)) {
  53                 six_unlock_intent(&ck->c.lock);
  54                 return false;
  55         }
  56
  57         if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
  58                 six_unlock_write(&ck->c.lock);
  59                 six_unlock_intent(&ck->c.lock);
  60                 return false;
  61         }
  62
  63         return true;
  64 }
  65
  66 static void bkey_cached_evict(struct btree_key_cache *c,
  67                               struct bkey_cached *ck)
  68 {
  69         BUG_ON(rhashtable_remove_fast(&c->table, &ck->hash,
  70                                       bch2_btree_key_cache_params));
  71         memset(&ck->key, ~0, sizeof(ck->key));
  72
  73         atomic_long_dec(&c->nr_keys);
  74 }
  75
  76 static void bkey_cached_free(struct btree_key_cache *bc,
  77                              struct bkey_cached *ck)
  78 {
  79         struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
  80
  81         BUG_ON(test_bit(BKEY_CACHED_DIRTY, &ck->flags));
  82
  83         ck->btree_trans_barrier_seq =
  84                 start_poll_synchronize_srcu(&c->btree_trans_barrier);
  85
  86         list_move_tail(&ck->list, &bc->freed);
  87         bc->nr_freed++;
  88
  89         kfree(ck->k);
  90         ck->k           = NULL;
  91         ck->u64s        = 0;
  92
  93         six_unlock_write(&ck->c.lock);
  94         six_unlock_intent(&ck->c.lock);
  95 }
  96
  97 static struct bkey_cached *
  98 bkey_cached_alloc(struct btree_key_cache *c)
  99 {
 100         struct bkey_cached *ck;
 101
 102         ck = kmem_cache_alloc(bch2_key_cache, GFP_NOFS|__GFP_ZERO);
 103         if (likely(ck)) {
 104                 INIT_LIST_HEAD(&ck->list);
 105                 six_lock_init(&ck->c.lock);
 106                 BUG_ON(!six_trylock_intent(&ck->c.lock));
 107                 BUG_ON(!six_trylock_write(&ck->c.lock));
 108                 return ck;
 109         }
 110
 111         return NULL;
 112 }
 113
 114 static struct bkey_cached *
 115 bkey_cached_reuse(struct btree_key_cache *c)
 116 {
 117         struct bucket_table *tbl;
 118         struct rhash_head *pos;
 119         struct bkey_cached *ck;
 120         unsigned i;
 121
 122         mutex_lock(&c->lock);
 123         list_for_each_entry_reverse(ck, &c->freed, list)
 124                 if (bkey_cached_lock_for_evict(ck)) {
 125                         c->nr_freed--;
 126                         list_del(&ck->list);
 127                         mutex_unlock(&c->lock);
 128                         return ck;
 129                 }
 130         mutex_unlock(&c->lock);
 131
 132         rcu_read_lock();
 133         tbl = rht_dereference_rcu(c->table.tbl, &c->table);
 134         for (i = 0; i < tbl->size; i++)
 135                 rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
 136                         if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags) &&
 137                             bkey_cached_lock_for_evict(ck)) {
 138                                 bkey_cached_evict(c, ck);
 139                                 rcu_read_unlock();
 140                                 return ck;
 141                         }
 142                 }
 143         rcu_read_unlock();
 144
 145         return NULL;
 146 }
 147
 148 static struct bkey_cached *
 149 btree_key_cache_create(struct btree_key_cache *c,
 150                        enum btree_id btree_id,
 151                        struct bpos pos)
 152 {
 153         struct bkey_cached *ck;
 154         bool was_new = true;
 155
 156         ck = bkey_cached_alloc(c);
 157
 158         if (unlikely(!ck)) {
 159                 ck = bkey_cached_reuse(c);
 160                 if (unlikely(!ck))
 161                         return ERR_PTR(-ENOMEM);
 162
 163                 was_new = false;
 164         }
 165
 166         ck->c.level             = 0;
 167         ck->c.btree_id          = btree_id;
 168         ck->key.btree_id        = btree_id;
 169         ck->key.pos             = pos;
 170         ck->valid               = false;
 171         ck->flags               = 1U << BKEY_CACHED_ACCESSED;
 172
 173         if (unlikely(rhashtable_lookup_insert_fast(&c->table,
 174                                           &ck->hash,
 175                                           bch2_btree_key_cache_params))) {
 176                 /* We raced with another fill: */
 177
 178                 if (likely(was_new)) {
 179                         six_unlock_write(&ck->c.lock);
 180                         six_unlock_intent(&ck->c.lock);
 181                         kfree(ck);
 182                 } else {
 183                         mutex_lock(&c->lock);
 184                         bkey_cached_free(c, ck);
 185                         mutex_unlock(&c->lock);
 186                 }
 187
 188                 return NULL;
 189         }
 190
 191         atomic_long_inc(&c->nr_keys);
 192
 193         six_unlock_write(&ck->c.lock);
 194
 195         return ck;
 196 }
 197
 198 static int btree_key_cache_fill(struct btree_trans *trans,
 199                                 struct btree_iter *ck_iter,
 200                                 struct bkey_cached *ck)
 201 {
 202         struct btree_iter *iter;
 203         struct bkey_s_c k;
 204         unsigned new_u64s = 0;
 205         struct bkey_i *new_k = NULL;
 206         int ret;
 207
 208         iter = bch2_trans_get_iter(trans, ck->key.btree_id,
 209                                    ck->key.pos, BTREE_ITER_SLOTS);
 210         k = bch2_btree_iter_peek_slot(iter);
 211         ret = bkey_err(k);
 212         if (ret)
 213                 goto err;
 214
 215         if (!bch2_btree_node_relock(ck_iter, 0)) {
 216                 trace_transaction_restart_ip(trans->ip, _THIS_IP_);
 217                 ret = btree_trans_restart(trans);
 218                 goto err;
 219         }
 220
 221         /*
 222          * bch2_varint_decode can read past the end of the buffer by at
 223          * most 7 bytes (it won't be used):
 224          */
 225         new_u64s = k.k->u64s + 1;
 226
 227         if (new_u64s > ck->u64s) {
 228                 new_u64s = roundup_pow_of_two(new_u64s);
 229                 new_k = kmalloc(new_u64s * sizeof(u64), GFP_NOFS);
 230                 if (!new_k) {
 231                         ret = -ENOMEM;
 232                         goto err;
 233                 }
 234         }
 235
 236         /*
 237          * XXX: not allowed to be holding read locks when we take a write lock,
 238          * currently
 239          */
 240         bch2_btree_node_lock_write(ck_iter->l[0].b, ck_iter);
 241         if (new_k) {
 242                 kfree(ck->k);
 243                 ck->u64s = new_u64s;
 244                 ck->k = new_k;
 245         }
 246
 247         bkey_reassemble(ck->k, k);
 248         ck->valid = true;
 249         bch2_btree_node_unlock_write(ck_iter->l[0].b, ck_iter);
 250
 251         /* We're not likely to need this iterator again: */
 252         set_btree_iter_dontneed(trans, iter);
 253 err:
 254         bch2_trans_iter_put(trans, iter);
 255         return ret;
 256 }
 257
 258 static int bkey_cached_check_fn(struct six_lock *lock, void *p)
 259 {
 260         struct bkey_cached *ck = container_of(lock, struct bkey_cached, c.lock);
 261         const struct btree_iter *iter = p;
 262
 263         return ck->key.btree_id == iter->btree_id &&
 264                 !bpos_cmp(ck->key.pos, iter->pos) ? 0 : -1;
 265 }
 266
 267 __flatten
 268 int bch2_btree_iter_traverse_cached(struct btree_iter *iter)
 269 {
 270         struct btree_trans *trans = iter->trans;
 271         struct bch_fs *c = trans->c;
 272         struct bkey_cached *ck;
 273         int ret = 0;
 274
 275         BUG_ON(iter->level);
 276
 277         iter->l[1].b = NULL;
 278
 279         if (bch2_btree_node_relock(iter, 0)) {
 280                 ck = (void *) iter->l[0].b;
 281                 goto fill;
 282         }
 283 retry:
 284         ck = bch2_btree_key_cache_find(c, iter->btree_id, iter->pos);
 285         if (!ck) {
 286                 if (iter->flags & BTREE_ITER_CACHED_NOCREATE) {
 287                         iter->l[0].b = NULL;
 288                         return 0;
 289                 }
 290
 291                 ck = btree_key_cache_create(&c->btree_key_cache,
 292                                             iter->btree_id, iter->pos);
 293                 ret = PTR_ERR_OR_ZERO(ck);
 294                 if (ret)
 295                         goto err;
 296                 if (!ck)
 297                         goto retry;
 298
 299                 mark_btree_node_locked(iter, 0, SIX_LOCK_intent);
 300                 iter->locks_want = 1;
 301         } else {
 302                 enum six_lock_type lock_want = __btree_lock_want(iter, 0);
 303
 304                 if (!btree_node_lock((void *) ck, iter->pos, 0, iter, lock_want,
 305                                      bkey_cached_check_fn, iter, _THIS_IP_)) {
 306                         if (!trans->restarted)
 307                                 goto retry;
 308
 309                         trace_transaction_restart_ip(trans->ip, _THIS_IP_);
 310                         ret = -EINTR;
 311                         goto err;
 312                 }
 313
 314                 if (ck->key.btree_id != iter->btree_id ||
 315                     bpos_cmp(ck->key.pos, iter->pos)) {
 316                         six_unlock_type(&ck->c.lock, lock_want);
 317                         goto retry;
 318                 }
 319
 320                 mark_btree_node_locked(iter, 0, lock_want);
 321         }
 322
 323         iter->l[0].lock_seq     = ck->c.lock.state.seq;
 324         iter->l[0].b            = (void *) ck;
 325 fill:
 326         if (!ck->valid && !(iter->flags & BTREE_ITER_CACHED_NOFILL)) {
 327                 if (!iter->locks_want &&
 328                     !!__bch2_btree_iter_upgrade(iter, 1)) {
 329                         trace_transaction_restart_ip(trans->ip, _THIS_IP_);
 330                         BUG_ON(!trans->restarted);
 331                         ret = -EINTR;
 332                         goto err;
 333                 }
 334
 335                 ret = btree_key_cache_fill(trans, iter, ck);
 336                 if (ret)
 337                         goto err;
 338         }
 339
 340         if (!test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
 341                 set_bit(BKEY_CACHED_ACCESSED, &ck->flags);
 342
 343         iter->uptodate = BTREE_ITER_NEED_PEEK;
 344
 345         if ((iter->flags & BTREE_ITER_INTENT) &&
 346             !bch2_btree_iter_upgrade(iter, 1)) {
 347                 BUG_ON(!trans->restarted);
 348                 ret = -EINTR;
 349         }
 350
 351         BUG_ON(!ret && !btree_node_locked(iter, 0));
 352
 353         return ret;
 354 err:
 355         if (ret != -EINTR) {
 356                 btree_node_unlock(iter, 0);
 357                 iter->flags |= BTREE_ITER_ERROR;
 358                 iter->l[0].b = BTREE_ITER_NO_NODE_ERROR;
 359         }
 360         return ret;
 361 }
 362
 363 static int btree_key_cache_flush_pos(struct btree_trans *trans,
 364                                      struct bkey_cached_key key,
 365                                      u64 journal_seq,
 366                                      unsigned commit_flags,
 367                                      bool evict)
 368 {
 369         struct bch_fs *c = trans->c;
 370         struct journal *j = &c->journal;
 371         struct btree_iter *c_iter = NULL, *b_iter = NULL;
 372         struct bkey_cached *ck = NULL;
 373         int ret;
 374
 375         b_iter = bch2_trans_get_iter(trans, key.btree_id, key.pos,
 376                                      BTREE_ITER_SLOTS|
 377                                      BTREE_ITER_INTENT);
 378         c_iter = bch2_trans_get_iter(trans, key.btree_id, key.pos,
 379                                      BTREE_ITER_CACHED|
 380                                      BTREE_ITER_CACHED_NOFILL|
 381                                      BTREE_ITER_CACHED_NOCREATE|
 382                                      BTREE_ITER_INTENT);
 383         ret = bch2_btree_iter_traverse(c_iter);
 384         if (ret)
 385                 goto out;
 386
 387         ck = (void *) c_iter->l[0].b;
 388         if (!ck ||
 389             (journal_seq && ck->journal.seq != journal_seq))
 390                 goto out;
 391
 392         if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 393                 if (!evict)
 394                         goto out;
 395                 goto evict;
 396         }
 397
 398         /*
 399          * Since journal reclaim depends on us making progress here, and the
 400          * allocator/copygc depend on journal reclaim making progress, we need
 401          * to be using alloc reserves:
 402          * */
 403         ret   = bch2_btree_iter_traverse(b_iter) ?:
 404                 bch2_trans_update(trans, b_iter, ck->k,
 405                                   BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
 406                                   BTREE_TRIGGER_NORUN) ?:
 407                 bch2_trans_commit(trans, NULL, NULL,
 408                                   BTREE_INSERT_NOCHECK_RW|
 409                                   BTREE_INSERT_NOFAIL|
 410                                   BTREE_INSERT_USE_RESERVE|
 411                                   (ck->journal.seq == journal_last_seq(j)
 412                                    ? BTREE_INSERT_JOURNAL_RESERVED
 413                                    : 0)|
 414                                   commit_flags);
 415         if (ret) {
 416                 bch2_fs_fatal_err_on(ret != -EINTR &&
 417                                      ret != -EAGAIN &&
 418                                      !bch2_journal_error(j), c,
 419                         "error flushing key cache: %i", ret);
 420                 goto out;
 421         }
 422
 423         bch2_journal_pin_drop(j, &ck->journal);
 424         bch2_journal_preres_put(j, &ck->res);
 425
 426         BUG_ON(!btree_node_locked(c_iter, 0));
 427
 428         if (!evict) {
 429                 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 430                         clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
 431                         atomic_long_dec(&c->btree_key_cache.nr_dirty);
 432                 }
 433         } else {
 434 evict:
 435                 BUG_ON(!btree_node_intent_locked(c_iter, 0));
 436
 437                 mark_btree_node_unlocked(c_iter, 0);
 438                 c_iter->l[0].b = NULL;
 439
 440                 six_lock_write(&ck->c.lock, NULL, NULL);
 441
 442                 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 443                         clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
 444                         atomic_long_dec(&c->btree_key_cache.nr_dirty);
 445                 }
 446
 447                 bkey_cached_evict(&c->btree_key_cache, ck);
 448
 449                 mutex_lock(&c->btree_key_cache.lock);
 450                 bkey_cached_free(&c->btree_key_cache, ck);
 451                 mutex_unlock(&c->btree_key_cache.lock);
 452         }
 453 out:
 454         bch2_trans_iter_put(trans, b_iter);
 455         bch2_trans_iter_put(trans, c_iter);
 456         return ret;
 457 }
 458
 459 int bch2_btree_key_cache_journal_flush(struct journal *j,
 460                                 struct journal_entry_pin *pin, u64 seq)
 461 {
 462         struct bch_fs *c = container_of(j, struct bch_fs, journal);
 463         struct bkey_cached *ck =
 464                 container_of(pin, struct bkey_cached, journal);
 465         struct bkey_cached_key key;
 466         int ret = 0;
 467
 468         int srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
 469
 470         six_lock_read(&ck->c.lock, NULL, NULL);
 471         key = ck->key;
 472
 473         if (ck->journal.seq != seq ||
 474             !test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 475                 six_unlock_read(&ck->c.lock);
 476                 goto unlock;
 477         }
 478         six_unlock_read(&ck->c.lock);
 479
 480         ret = bch2_trans_do(c, NULL, NULL, 0,
 481                 btree_key_cache_flush_pos(&trans, key, seq,
 482                                 BTREE_INSERT_JOURNAL_RECLAIM, false));
 483 unlock:
 484         srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
 485
 486         return ret;
 487 }
 488
 489 /*
 490  * Flush and evict a key from the key cache:
 491  */
 492 int bch2_btree_key_cache_flush(struct btree_trans *trans,
 493                                enum btree_id id, struct bpos pos)
 494 {
 495         struct bch_fs *c = trans->c;
 496         struct bkey_cached_key key = { id, pos };
 497
 498         /* Fastpath - assume it won't be found: */
 499         if (!bch2_btree_key_cache_find(c, id, pos))
 500                 return 0;
 501
 502         return btree_key_cache_flush_pos(trans, key, 0, 0, true);
 503 }
 504
 505 bool bch2_btree_insert_key_cached(struct btree_trans *trans,
 506                                   struct btree_iter *iter,
 507                                   struct bkey_i *insert)
 508 {
 509         struct bch_fs *c = trans->c;
 510         struct bkey_cached *ck = (void *) iter->l[0].b;
 511         bool kick_reclaim = false;
 512
 513         BUG_ON(insert->u64s > ck->u64s);
 514
 515         if (likely(!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY))) {
 516                 int difference;
 517
 518                 BUG_ON(jset_u64s(insert->u64s) > trans->journal_preres.u64s);
 519
 520                 difference = jset_u64s(insert->u64s) - ck->res.u64s;
 521                 if (difference > 0) {
 522                         trans->journal_preres.u64s      -= difference;
 523                         ck->res.u64s                    += difference;
 524                 }
 525         }
 526
 527         bkey_copy(ck->k, insert);
 528         ck->valid = true;
 529
 530         if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 531                 set_bit(BKEY_CACHED_DIRTY, &ck->flags);
 532                 atomic_long_inc(&c->btree_key_cache.nr_dirty);
 533
 534                 if (bch2_nr_btree_keys_need_flush(c))
 535                         kick_reclaim = true;
 536         }
 537
 538         bch2_journal_pin_update(&c->journal, trans->journal_res.seq,
 539                                 &ck->journal, bch2_btree_key_cache_journal_flush);
 540
 541         if (kick_reclaim)
 542                 journal_reclaim_kick(&c->journal);
 543         return true;
 544 }
 545
 546 #ifdef CONFIG_BCACHEFS_DEBUG
 547 void bch2_btree_key_cache_verify_clean(struct btree_trans *trans,
 548                                enum btree_id id, struct bpos pos)
 549 {
 550         BUG_ON(bch2_btree_key_cache_find(trans->c, id, pos));
 551 }
 552 #endif
 553
 554 static unsigned long bch2_btree_key_cache_scan(struct shrinker *shrink,
 555                                            struct shrink_control *sc)
 556 {
 557         struct bch_fs *c = container_of(shrink, struct bch_fs,
 558                                         btree_key_cache.shrink);
 559         struct btree_key_cache *bc = &c->btree_key_cache;
 560         struct bucket_table *tbl;
 561         struct bkey_cached *ck, *t;
 562         size_t scanned = 0, freed = 0, nr = sc->nr_to_scan;
 563         unsigned start, flags;
 564         int srcu_idx;
 565
 566         /* Return -1 if we can't do anything right now */
 567         if (sc->gfp_mask & __GFP_FS)
 568                 mutex_lock(&bc->lock);
 569         else if (!mutex_trylock(&bc->lock))
 570                 return -1;
 571
 572         srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
 573         flags = memalloc_nofs_save();
 574
 575         /*
 576          * Newest freed entries are at the end of the list - once we hit one
 577          * that's too new to be freed, we can bail out:
 578          */
 579         list_for_each_entry_safe(ck, t, &bc->freed, list) {
 580                 if (!poll_state_synchronize_srcu(&c->btree_trans_barrier,
 581                                                  ck->btree_trans_barrier_seq))
 582                         break;
 583
 584                 list_del(&ck->list);
 585                 kmem_cache_free(bch2_key_cache, ck);
 586                 bc->nr_freed--;
 587                 scanned++;
 588                 freed++;
 589         }
 590
 591         if (scanned >= nr)
 592                 goto out;
 593
 594         rcu_read_lock();
 595         tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
 596         if (bc->shrink_iter >= tbl->size)
 597                 bc->shrink_iter = 0;
 598         start = bc->shrink_iter;
 599
 600         do {
 601                 struct rhash_head *pos, *next;
 602
 603                 pos = rht_ptr_rcu(rht_bucket(tbl, bc->shrink_iter));
 604
 605                 while (!rht_is_a_nulls(pos)) {
 606                         next = rht_dereference_bucket_rcu(pos->next, tbl, bc->shrink_iter);
 607                         ck = container_of(pos, struct bkey_cached, hash);
 608
 609                         if (test_bit(BKEY_CACHED_DIRTY, &ck->flags))
 610                                 goto next;
 611
 612                         if (test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
 613                                 clear_bit(BKEY_CACHED_ACCESSED, &ck->flags);
 614                         else if (bkey_cached_lock_for_evict(ck)) {
 615                                 bkey_cached_evict(bc, ck);
 616                                 bkey_cached_free(bc, ck);
 617                         }
 618
 619                         scanned++;
 620                         if (scanned >= nr)
 621                                 break;
 622 next:
 623                         pos = next;
 624                 }
 625
 626                 bc->shrink_iter++;
 627                 if (bc->shrink_iter >= tbl->size)
 628                         bc->shrink_iter = 0;
 629         } while (scanned < nr && bc->shrink_iter != start);
 630
 631         rcu_read_unlock();
 632 out:
 633         memalloc_nofs_restore(flags);
 634         srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
 635         mutex_unlock(&bc->lock);
 636
 637         return freed;
 638 }
 639
 640 static unsigned long bch2_btree_key_cache_count(struct shrinker *shrink,
 641                                             struct shrink_control *sc)
 642 {
 643         struct bch_fs *c = container_of(shrink, struct bch_fs,
 644                                         btree_key_cache.shrink);
 645         struct btree_key_cache *bc = &c->btree_key_cache;
 646         long nr = atomic_long_read(&bc->nr_keys) -
 647                 atomic_long_read(&bc->nr_dirty);
 648
 649         return max(0L, nr);
 650 }
 651
 652 void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
 653 {
 654         struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
 655         struct bucket_table *tbl;
 656         struct bkey_cached *ck, *n;
 657         struct rhash_head *pos;
 658         unsigned i;
 659
 660         if (bc->shrink.list.next)
 661                 unregister_shrinker(&bc->shrink);
 662
 663         mutex_lock(&bc->lock);
 664
 665         rcu_read_lock();
 666         tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
 667         for (i = 0; i < tbl->size; i++)
 668                 rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
 669                         bkey_cached_evict(bc, ck);
 670                         list_add(&ck->list, &bc->freed);
 671                 }
 672         rcu_read_unlock();
 673
 674         list_for_each_entry_safe(ck, n, &bc->freed, list) {
 675                 cond_resched();
 676
 677                 bch2_journal_pin_drop(&c->journal, &ck->journal);
 678                 bch2_journal_preres_put(&c->journal, &ck->res);
 679
 680                 list_del(&ck->list);
 681                 kfree(ck->k);
 682                 kmem_cache_free(bch2_key_cache, ck);
 683         }
 684
 685         BUG_ON(atomic_long_read(&bc->nr_dirty) &&
 686                !bch2_journal_error(&c->journal) &&
 687                test_bit(BCH_FS_WAS_RW, &c->flags));
 688         BUG_ON(atomic_long_read(&bc->nr_keys));
 689
 690         mutex_unlock(&bc->lock);
 691
 692         if (bc->table_init_done)
 693                 rhashtable_destroy(&bc->table);
 694 }
 695
 696 void bch2_fs_btree_key_cache_init_early(struct btree_key_cache *c)
 697 {
 698         mutex_init(&c->lock);
 699         INIT_LIST_HEAD(&c->freed);
 700 }
 701
 702 int bch2_fs_btree_key_cache_init(struct btree_key_cache *c)
 703 {
 704         int ret;
 705
 706         ret = rhashtable_init(&c->table, &bch2_btree_key_cache_params);
 707         if (ret)
 708                 return ret;
 709
 710         c->table_init_done = true;
 711
 712         c->shrink.seeks                 = 1;
 713         c->shrink.count_objects         = bch2_btree_key_cache_count;
 714         c->shrink.scan_objects          = bch2_btree_key_cache_scan;
 715         return register_shrinker(&c->shrink);
 716 }
 717
 718 void bch2_btree_key_cache_to_text(struct printbuf *out, struct btree_key_cache *c)
 719 {
 720         pr_buf(out, "nr_freed:\t%zu\n", c->nr_freed);
 721         pr_buf(out, "nr_keys:\t%zu\n",  atomic_long_read(&c->nr_keys));
 722         pr_buf(out, "nr_dirty:\t%zu\n", atomic_long_read(&c->nr_dirty));
 723 }
 724
 725 void bch2_btree_key_cache_exit(void)
 726 {
 727         if (bch2_key_cache)
 728                 kmem_cache_destroy(bch2_key_cache);
 729 }
 730
 731 int __init bch2_btree_key_cache_init(void)
 732 {
 733         bch2_key_cache = KMEM_CACHE(bkey_cached, 0);
 734         if (!bch2_key_cache)
 735                 return -ENOMEM;
 736
 737         return 0;
 738 }