fs/bcachefs/btree_key_cache.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "btree_cache.h"
   5 #include "btree_iter.h"
   6 #include "btree_key_cache.h"
   7 #include "btree_locking.h"
   8 #include "btree_update.h"
   9 #include "errcode.h"
  10 #include "error.h"
  11 #include "journal.h"
  12 #include "journal_reclaim.h"
  13 #include "trace.h"
  14
  15 #include <linux/sched/mm.h>
  16
  17 static inline bool btree_uses_pcpu_readers(enum btree_id id)
  18 {
  19         return id == BTREE_ID_subvolumes;
  20 }
  21
  22 static struct kmem_cache *bch2_key_cache;
  23
  24 static int bch2_btree_key_cache_cmp_fn(struct rhashtable_compare_arg *arg,
  25                                        const void *obj)
  26 {
  27         const struct bkey_cached *ck = obj;
  28         const struct bkey_cached_key *key = arg->key;
  29
  30         return ck->key.btree_id != key->btree_id ||
  31                 !bpos_eq(ck->key.pos, key->pos);
  32 }
  33
  34 static const struct rhashtable_params bch2_btree_key_cache_params = {
  35         .head_offset    = offsetof(struct bkey_cached, hash),
  36         .key_offset     = offsetof(struct bkey_cached, key),
  37         .key_len        = sizeof(struct bkey_cached_key),
  38         .obj_cmpfn      = bch2_btree_key_cache_cmp_fn,
  39 };
  40
  41 __flatten
  42 inline struct bkey_cached *
  43 bch2_btree_key_cache_find(struct bch_fs *c, enum btree_id btree_id, struct bpos pos)
  44 {
  45         struct bkey_cached_key key = {
  46                 .btree_id       = btree_id,
  47                 .pos            = pos,
  48         };
  49
  50         return rhashtable_lookup_fast(&c->btree_key_cache.table, &key,
  51                                       bch2_btree_key_cache_params);
  52 }
  53
  54 static bool bkey_cached_lock_for_evict(struct bkey_cached *ck)
  55 {
  56         if (!six_trylock_intent(&ck->c.lock))
  57                 return false;
  58
  59         if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
  60                 six_unlock_intent(&ck->c.lock);
  61                 return false;
  62         }
  63
  64         if (!six_trylock_write(&ck->c.lock)) {
  65                 six_unlock_intent(&ck->c.lock);
  66                 return false;
  67         }
  68
  69         return true;
  70 }
  71
  72 static void bkey_cached_evict(struct btree_key_cache *c,
  73                               struct bkey_cached *ck)
  74 {
  75         BUG_ON(rhashtable_remove_fast(&c->table, &ck->hash,
  76                                       bch2_btree_key_cache_params));
  77         memset(&ck->key, ~0, sizeof(ck->key));
  78
  79         atomic_long_dec(&c->nr_keys);
  80 }
  81
  82 static void bkey_cached_free(struct btree_key_cache *bc,
  83                              struct bkey_cached *ck)
  84 {
  85         struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
  86
  87         BUG_ON(test_bit(BKEY_CACHED_DIRTY, &ck->flags));
  88
  89         ck->btree_trans_barrier_seq =
  90                 start_poll_synchronize_srcu(&c->btree_trans_barrier);
  91
  92         if (ck->c.lock.readers) {
  93                 list_move_tail(&ck->list, &bc->freed_pcpu);
  94                 bc->nr_freed_pcpu++;
  95         } else {
  96                 list_move_tail(&ck->list, &bc->freed_nonpcpu);
  97                 bc->nr_freed_nonpcpu++;
  98         }
  99         atomic_long_inc(&bc->nr_freed);
 100
 101         kfree(ck->k);
 102         ck->k           = NULL;
 103         ck->u64s        = 0;
 104
 105         six_unlock_write(&ck->c.lock);
 106         six_unlock_intent(&ck->c.lock);
 107 }
 108
 109 #ifdef __KERNEL__
 110 static void __bkey_cached_move_to_freelist_ordered(struct btree_key_cache *bc,
 111                                                    struct bkey_cached *ck)
 112 {
 113         struct bkey_cached *pos;
 114
 115         bc->nr_freed_nonpcpu++;
 116
 117         list_for_each_entry_reverse(pos, &bc->freed_nonpcpu, list) {
 118                 if (ULONG_CMP_GE(ck->btree_trans_barrier_seq,
 119                                  pos->btree_trans_barrier_seq)) {
 120                         list_move(&ck->list, &pos->list);
 121                         return;
 122                 }
 123         }
 124
 125         list_move(&ck->list, &bc->freed_nonpcpu);
 126 }
 127 #endif
 128
 129 static void bkey_cached_move_to_freelist(struct btree_key_cache *bc,
 130                                          struct bkey_cached *ck)
 131 {
 132         BUG_ON(test_bit(BKEY_CACHED_DIRTY, &ck->flags));
 133
 134         if (!ck->c.lock.readers) {
 135 #ifdef __KERNEL__
 136                 struct btree_key_cache_freelist *f;
 137                 bool freed = false;
 138
 139                 preempt_disable();
 140                 f = this_cpu_ptr(bc->pcpu_freed);
 141
 142                 if (f->nr < ARRAY_SIZE(f->objs)) {
 143                         f->objs[f->nr++] = ck;
 144                         freed = true;
 145                 }
 146                 preempt_enable();
 147
 148                 if (!freed) {
 149                         mutex_lock(&bc->lock);
 150                         preempt_disable();
 151                         f = this_cpu_ptr(bc->pcpu_freed);
 152
 153                         while (f->nr > ARRAY_SIZE(f->objs) / 2) {
 154                                 struct bkey_cached *ck2 = f->objs[--f->nr];
 155
 156                                 __bkey_cached_move_to_freelist_ordered(bc, ck2);
 157                         }
 158                         preempt_enable();
 159
 160                         __bkey_cached_move_to_freelist_ordered(bc, ck);
 161                         mutex_unlock(&bc->lock);
 162                 }
 163 #else
 164                 mutex_lock(&bc->lock);
 165                 list_move_tail(&ck->list, &bc->freed_nonpcpu);
 166                 bc->nr_freed_nonpcpu++;
 167                 mutex_unlock(&bc->lock);
 168 #endif
 169         } else {
 170                 mutex_lock(&bc->lock);
 171                 list_move_tail(&ck->list, &bc->freed_pcpu);
 172                 bc->nr_freed_pcpu++;
 173                 mutex_unlock(&bc->lock);
 174         }
 175 }
 176
 177 static void bkey_cached_free_fast(struct btree_key_cache *bc,
 178                                   struct bkey_cached *ck)
 179 {
 180         struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
 181
 182         ck->btree_trans_barrier_seq =
 183                 start_poll_synchronize_srcu(&c->btree_trans_barrier);
 184
 185         list_del_init(&ck->list);
 186         atomic_long_inc(&bc->nr_freed);
 187
 188         kfree(ck->k);
 189         ck->k           = NULL;
 190         ck->u64s        = 0;
 191
 192         bkey_cached_move_to_freelist(bc, ck);
 193
 194         six_unlock_write(&ck->c.lock);
 195         six_unlock_intent(&ck->c.lock);
 196 }
 197
 198 static struct bkey_cached *
 199 bkey_cached_alloc(struct btree_trans *trans, struct btree_path *path,
 200                   bool *was_new)
 201 {
 202         struct bch_fs *c = trans->c;
 203         struct btree_key_cache *bc = &c->btree_key_cache;
 204         struct bkey_cached *ck = NULL;
 205         bool pcpu_readers = btree_uses_pcpu_readers(path->btree_id);
 206         int ret;
 207
 208         if (!pcpu_readers) {
 209 #ifdef __KERNEL__
 210                 struct btree_key_cache_freelist *f;
 211
 212                 preempt_disable();
 213                 f = this_cpu_ptr(bc->pcpu_freed);
 214                 if (f->nr)
 215                         ck = f->objs[--f->nr];
 216                 preempt_enable();
 217
 218                 if (!ck) {
 219                         mutex_lock(&bc->lock);
 220                         preempt_disable();
 221                         f = this_cpu_ptr(bc->pcpu_freed);
 222
 223                         while (!list_empty(&bc->freed_nonpcpu) &&
 224                                f->nr < ARRAY_SIZE(f->objs) / 2) {
 225                                 ck = list_last_entry(&bc->freed_nonpcpu, struct bkey_cached, list);
 226                                 list_del_init(&ck->list);
 227                                 bc->nr_freed_nonpcpu--;
 228                                 f->objs[f->nr++] = ck;
 229                         }
 230
 231                         ck = f->nr ? f->objs[--f->nr] : NULL;
 232                         preempt_enable();
 233                         mutex_unlock(&bc->lock);
 234                 }
 235 #else
 236                 mutex_lock(&bc->lock);
 237                 if (!list_empty(&bc->freed_nonpcpu)) {
 238                         ck = list_last_entry(&bc->freed_nonpcpu, struct bkey_cached, list);
 239                         list_del_init(&ck->list);
 240                         bc->nr_freed_nonpcpu--;
 241                 }
 242                 mutex_unlock(&bc->lock);
 243 #endif
 244         } else {
 245                 mutex_lock(&bc->lock);
 246                 if (!list_empty(&bc->freed_pcpu)) {
 247                         ck = list_last_entry(&bc->freed_pcpu, struct bkey_cached, list);
 248                         list_del_init(&ck->list);
 249                         bc->nr_freed_pcpu--;
 250                 }
 251                 mutex_unlock(&bc->lock);
 252         }
 253
 254         if (ck) {
 255                 ret = btree_node_lock_nopath(trans, &ck->c, SIX_LOCK_intent, _THIS_IP_);
 256                 if (unlikely(ret)) {
 257                         bkey_cached_move_to_freelist(bc, ck);
 258                         return ERR_PTR(ret);
 259                 }
 260
 261                 path->l[0].b = (void *) ck;
 262                 path->l[0].lock_seq = six_lock_seq(&ck->c.lock);
 263                 mark_btree_node_locked(trans, path, 0, BTREE_NODE_INTENT_LOCKED);
 264
 265                 ret = bch2_btree_node_lock_write(trans, path, &ck->c);
 266                 if (unlikely(ret)) {
 267                         btree_node_unlock(trans, path, 0);
 268                         bkey_cached_move_to_freelist(bc, ck);
 269                         return ERR_PTR(ret);
 270                 }
 271
 272                 return ck;
 273         }
 274
 275         ck = allocate_dropping_locks(trans, ret,
 276                         kmem_cache_zalloc(bch2_key_cache, _gfp));
 277         if (ret) {
 278                 kmem_cache_free(bch2_key_cache, ck);
 279                 return ERR_PTR(ret);
 280         }
 281
 282         if (!ck)
 283                 return NULL;
 284
 285         INIT_LIST_HEAD(&ck->list);
 286         bch2_btree_lock_init(&ck->c, pcpu_readers ? SIX_LOCK_INIT_PCPU : 0);
 287
 288         ck->c.cached = true;
 289         BUG_ON(!six_trylock_intent(&ck->c.lock));
 290         BUG_ON(!six_trylock_write(&ck->c.lock));
 291         *was_new = true;
 292         return ck;
 293 }
 294
 295 static struct bkey_cached *
 296 bkey_cached_reuse(struct btree_key_cache *c)
 297 {
 298         struct bucket_table *tbl;
 299         struct rhash_head *pos;
 300         struct bkey_cached *ck;
 301         unsigned i;
 302
 303         mutex_lock(&c->lock);
 304         rcu_read_lock();
 305         tbl = rht_dereference_rcu(c->table.tbl, &c->table);
 306         for (i = 0; i < tbl->size; i++)
 307                 rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
 308                         if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags) &&
 309                             bkey_cached_lock_for_evict(ck)) {
 310                                 bkey_cached_evict(c, ck);
 311                                 goto out;
 312                         }
 313                 }
 314         ck = NULL;
 315 out:
 316         rcu_read_unlock();
 317         mutex_unlock(&c->lock);
 318         return ck;
 319 }
 320
 321 static struct bkey_cached *
 322 btree_key_cache_create(struct btree_trans *trans, struct btree_path *path)
 323 {
 324         struct bch_fs *c = trans->c;
 325         struct btree_key_cache *bc = &c->btree_key_cache;
 326         struct bkey_cached *ck;
 327         bool was_new = false;
 328
 329         ck = bkey_cached_alloc(trans, path, &was_new);
 330         if (IS_ERR(ck))
 331                 return ck;
 332
 333         if (unlikely(!ck)) {
 334                 ck = bkey_cached_reuse(bc);
 335                 if (unlikely(!ck)) {
 336                         bch_err(c, "error allocating memory for key cache item, btree %s",
 337                                 bch2_btree_id_str(path->btree_id));
 338                         return ERR_PTR(-BCH_ERR_ENOMEM_btree_key_cache_create);
 339                 }
 340
 341                 mark_btree_node_locked(trans, path, 0, BTREE_NODE_INTENT_LOCKED);
 342         }
 343
 344         ck->c.level             = 0;
 345         ck->c.btree_id          = path->btree_id;
 346         ck->key.btree_id        = path->btree_id;
 347         ck->key.pos             = path->pos;
 348         ck->valid               = false;
 349         ck->flags               = 1U << BKEY_CACHED_ACCESSED;
 350
 351         if (unlikely(rhashtable_lookup_insert_fast(&bc->table,
 352                                           &ck->hash,
 353                                           bch2_btree_key_cache_params))) {
 354                 /* We raced with another fill: */
 355
 356                 if (likely(was_new)) {
 357                         six_unlock_write(&ck->c.lock);
 358                         six_unlock_intent(&ck->c.lock);
 359                         kfree(ck);
 360                 } else {
 361                         bkey_cached_free_fast(bc, ck);
 362                 }
 363
 364                 mark_btree_node_locked(trans, path, 0, BTREE_NODE_UNLOCKED);
 365                 return NULL;
 366         }
 367
 368         atomic_long_inc(&bc->nr_keys);
 369
 370         six_unlock_write(&ck->c.lock);
 371
 372         return ck;
 373 }
 374
 375 static int btree_key_cache_fill(struct btree_trans *trans,
 376                                 struct btree_path *ck_path,
 377                                 struct bkey_cached *ck)
 378 {
 379         struct btree_iter iter;
 380         struct bkey_s_c k;
 381         unsigned new_u64s = 0;
 382         struct bkey_i *new_k = NULL;
 383         int ret;
 384
 385         bch2_trans_iter_init(trans, &iter, ck->key.btree_id, ck->key.pos,
 386                              BTREE_ITER_KEY_CACHE_FILL|
 387                              BTREE_ITER_CACHED_NOFILL);
 388         iter.flags &= ~BTREE_ITER_WITH_JOURNAL;
 389         k = bch2_btree_iter_peek_slot(&iter);
 390         ret = bkey_err(k);
 391         if (ret)
 392                 goto err;
 393
 394         if (!bch2_btree_node_relock(trans, ck_path, 0)) {
 395                 trace_and_count(trans->c, trans_restart_relock_key_cache_fill, trans, _THIS_IP_, ck_path);
 396                 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_fill);
 397                 goto err;
 398         }
 399
 400         /*
 401          * bch2_varint_decode can read past the end of the buffer by at
 402          * most 7 bytes (it won't be used):
 403          */
 404         new_u64s = k.k->u64s + 1;
 405
 406         /*
 407          * Allocate some extra space so that the transaction commit path is less
 408          * likely to have to reallocate, since that requires a transaction
 409          * restart:
 410          */
 411         new_u64s = min(256U, (new_u64s * 3) / 2);
 412
 413         if (new_u64s > ck->u64s) {
 414                 new_u64s = roundup_pow_of_two(new_u64s);
 415                 new_k = kmalloc(new_u64s * sizeof(u64), GFP_NOWAIT|__GFP_NOWARN);
 416                 if (!new_k) {
 417                         bch2_trans_unlock(trans);
 418
 419                         new_k = kmalloc(new_u64s * sizeof(u64), GFP_KERNEL);
 420                         if (!new_k) {
 421                                 bch_err(trans->c, "error allocating memory for key cache key, btree %s u64s %u",
 422                                         bch2_btree_id_str(ck->key.btree_id), new_u64s);
 423                                 ret = -BCH_ERR_ENOMEM_btree_key_cache_fill;
 424                                 goto err;
 425                         }
 426
 427                         if (!bch2_btree_node_relock(trans, ck_path, 0)) {
 428                                 kfree(new_k);
 429                                 trace_and_count(trans->c, trans_restart_relock_key_cache_fill, trans, _THIS_IP_, ck_path);
 430                                 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_fill);
 431                                 goto err;
 432                         }
 433
 434                         ret = bch2_trans_relock(trans);
 435                         if (ret) {
 436                                 kfree(new_k);
 437                                 goto err;
 438                         }
 439                 }
 440         }
 441
 442         ret = bch2_btree_node_lock_write(trans, ck_path, &ck_path->l[0].b->c);
 443         if (ret) {
 444                 kfree(new_k);
 445                 goto err;
 446         }
 447
 448         if (new_k) {
 449                 kfree(ck->k);
 450                 ck->u64s = new_u64s;
 451                 ck->k = new_k;
 452         }
 453
 454         bkey_reassemble(ck->k, k);
 455         ck->valid = true;
 456         bch2_btree_node_unlock_write(trans, ck_path, ck_path->l[0].b);
 457
 458         /* We're not likely to need this iterator again: */
 459         set_btree_iter_dontneed(&iter);
 460 err:
 461         bch2_trans_iter_exit(trans, &iter);
 462         return ret;
 463 }
 464
 465 static noinline int
 466 bch2_btree_path_traverse_cached_slowpath(struct btree_trans *trans, struct btree_path *path,
 467                                          unsigned flags)
 468 {
 469         struct bch_fs *c = trans->c;
 470         struct bkey_cached *ck;
 471         int ret = 0;
 472
 473         BUG_ON(path->level);
 474
 475         path->l[1].b = NULL;
 476
 477         if (bch2_btree_node_relock_notrace(trans, path, 0)) {
 478                 ck = (void *) path->l[0].b;
 479                 goto fill;
 480         }
 481 retry:
 482         ck = bch2_btree_key_cache_find(c, path->btree_id, path->pos);
 483         if (!ck) {
 484                 ck = btree_key_cache_create(trans, path);
 485                 ret = PTR_ERR_OR_ZERO(ck);
 486                 if (ret)
 487                         goto err;
 488                 if (!ck)
 489                         goto retry;
 490
 491                 mark_btree_node_locked(trans, path, 0, BTREE_NODE_INTENT_LOCKED);
 492                 path->locks_want = 1;
 493         } else {
 494                 enum six_lock_type lock_want = __btree_lock_want(path, 0);
 495
 496                 ret = btree_node_lock(trans, path, (void *) ck, 0,
 497                                       lock_want, _THIS_IP_);
 498                 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 499                         goto err;
 500
 501                 BUG_ON(ret);
 502
 503                 if (ck->key.btree_id != path->btree_id ||
 504                     !bpos_eq(ck->key.pos, path->pos)) {
 505                         six_unlock_type(&ck->c.lock, lock_want);
 506                         goto retry;
 507                 }
 508
 509                 mark_btree_node_locked(trans, path, 0,
 510                                        (enum btree_node_locked_type) lock_want);
 511         }
 512
 513         path->l[0].lock_seq     = six_lock_seq(&ck->c.lock);
 514         path->l[0].b            = (void *) ck;
 515 fill:
 516         path->uptodate = BTREE_ITER_UPTODATE;
 517
 518         if (!ck->valid && !(flags & BTREE_ITER_CACHED_NOFILL)) {
 519                 /*
 520                  * Using the underscore version because we haven't set
 521                  * path->uptodate yet:
 522                  */
 523                 if (!path->locks_want &&
 524                     !__bch2_btree_path_upgrade(trans, path, 1, NULL)) {
 525                         trace_and_count(trans->c, trans_restart_key_cache_upgrade, trans, _THIS_IP_);
 526                         ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_upgrade);
 527                         goto err;
 528                 }
 529
 530                 ret = btree_key_cache_fill(trans, path, ck);
 531                 if (ret)
 532                         goto err;
 533
 534                 ret = bch2_btree_path_relock(trans, path, _THIS_IP_);
 535                 if (ret)
 536                         goto err;
 537
 538                 path->uptodate = BTREE_ITER_UPTODATE;
 539         }
 540
 541         if (!test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
 542                 set_bit(BKEY_CACHED_ACCESSED, &ck->flags);
 543
 544         BUG_ON(btree_node_locked_type(path, 0) != btree_lock_want(path, 0));
 545         BUG_ON(path->uptodate);
 546
 547         return ret;
 548 err:
 549         path->uptodate = BTREE_ITER_NEED_TRAVERSE;
 550         if (!bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
 551                 btree_node_unlock(trans, path, 0);
 552                 path->l[0].b = ERR_PTR(ret);
 553         }
 554         return ret;
 555 }
 556
 557 int bch2_btree_path_traverse_cached(struct btree_trans *trans, struct btree_path *path,
 558                                     unsigned flags)
 559 {
 560         struct bch_fs *c = trans->c;
 561         struct bkey_cached *ck;
 562         int ret = 0;
 563
 564         EBUG_ON(path->level);
 565
 566         path->l[1].b = NULL;
 567
 568         if (bch2_btree_node_relock_notrace(trans, path, 0)) {
 569                 ck = (void *) path->l[0].b;
 570                 goto fill;
 571         }
 572 retry:
 573         ck = bch2_btree_key_cache_find(c, path->btree_id, path->pos);
 574         if (!ck) {
 575                 return bch2_btree_path_traverse_cached_slowpath(trans, path, flags);
 576         } else {
 577                 enum six_lock_type lock_want = __btree_lock_want(path, 0);
 578
 579                 ret = btree_node_lock(trans, path, (void *) ck, 0,
 580                                       lock_want, _THIS_IP_);
 581                 EBUG_ON(ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart));
 582
 583                 if (ret)
 584                         return ret;
 585
 586                 if (ck->key.btree_id != path->btree_id ||
 587                     !bpos_eq(ck->key.pos, path->pos)) {
 588                         six_unlock_type(&ck->c.lock, lock_want);
 589                         goto retry;
 590                 }
 591
 592                 mark_btree_node_locked(trans, path, 0,
 593                                        (enum btree_node_locked_type) lock_want);
 594         }
 595
 596         path->l[0].lock_seq     = six_lock_seq(&ck->c.lock);
 597         path->l[0].b            = (void *) ck;
 598 fill:
 599         if (!ck->valid)
 600                 return bch2_btree_path_traverse_cached_slowpath(trans, path, flags);
 601
 602         if (!test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
 603                 set_bit(BKEY_CACHED_ACCESSED, &ck->flags);
 604
 605         path->uptodate = BTREE_ITER_UPTODATE;
 606         EBUG_ON(!ck->valid);
 607         EBUG_ON(btree_node_locked_type(path, 0) != btree_lock_want(path, 0));
 608
 609         return ret;
 610 }
 611
 612 static int btree_key_cache_flush_pos(struct btree_trans *trans,
 613                                      struct bkey_cached_key key,
 614                                      u64 journal_seq,
 615                                      unsigned commit_flags,
 616                                      bool evict)
 617 {
 618         struct bch_fs *c = trans->c;
 619         struct journal *j = &c->journal;
 620         struct btree_iter c_iter, b_iter;
 621         struct bkey_cached *ck = NULL;
 622         int ret;
 623
 624         bch2_trans_iter_init(trans, &b_iter, key.btree_id, key.pos,
 625                              BTREE_ITER_SLOTS|
 626                              BTREE_ITER_INTENT|
 627                              BTREE_ITER_ALL_SNAPSHOTS);
 628         bch2_trans_iter_init(trans, &c_iter, key.btree_id, key.pos,
 629                              BTREE_ITER_CACHED|
 630                              BTREE_ITER_INTENT);
 631         b_iter.flags &= ~BTREE_ITER_WITH_KEY_CACHE;
 632
 633         ret = bch2_btree_iter_traverse(&c_iter);
 634         if (ret)
 635                 goto out;
 636
 637         ck = (void *) btree_iter_path(trans, &c_iter)->l[0].b;
 638         if (!ck)
 639                 goto out;
 640
 641         if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 642                 if (evict)
 643                         goto evict;
 644                 goto out;
 645         }
 646
 647         BUG_ON(!ck->valid);
 648
 649         if (journal_seq && ck->journal.seq != journal_seq)
 650                 goto out;
 651
 652         trans->journal_res.seq = ck->journal.seq;
 653
 654         /*
 655          * If we're at the end of the journal, we really want to free up space
 656          * in the journal right away - we don't want to pin that old journal
 657          * sequence number with a new btree node write, we want to re-journal
 658          * the update
 659          */
 660         if (ck->journal.seq == journal_last_seq(j))
 661                 commit_flags |= BCH_WATERMARK_reclaim;
 662
 663         if (ck->journal.seq != journal_last_seq(j) ||
 664             !test_bit(JOURNAL_SPACE_LOW, &c->journal.flags))
 665                 commit_flags |= BCH_TRANS_COMMIT_no_journal_res;
 666
 667         ret   = bch2_btree_iter_traverse(&b_iter) ?:
 668                 bch2_trans_update(trans, &b_iter, ck->k,
 669                                   BTREE_UPDATE_KEY_CACHE_RECLAIM|
 670                                   BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
 671                                   BTREE_TRIGGER_NORUN) ?:
 672                 bch2_trans_commit(trans, NULL, NULL,
 673                                   BCH_TRANS_COMMIT_no_check_rw|
 674                                   BCH_TRANS_COMMIT_no_enospc|
 675                                   commit_flags);
 676
 677         bch2_fs_fatal_err_on(ret &&
 678                              !bch2_err_matches(ret, BCH_ERR_transaction_restart) &&
 679                              !bch2_err_matches(ret, BCH_ERR_journal_reclaim_would_deadlock) &&
 680                              !bch2_journal_error(j), c,
 681                              "flushing key cache: %s", bch2_err_str(ret));
 682         if (ret)
 683                 goto out;
 684
 685         bch2_journal_pin_drop(j, &ck->journal);
 686
 687         struct btree_path *path = btree_iter_path(trans, &c_iter);
 688         BUG_ON(!btree_node_locked(path, 0));
 689
 690         if (!evict) {
 691                 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 692                         clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
 693                         atomic_long_dec(&c->btree_key_cache.nr_dirty);
 694                 }
 695         } else {
 696                 struct btree_path *path2;
 697                 unsigned i;
 698 evict:
 699                 trans_for_each_path(trans, path2, i)
 700                         if (path2 != path)
 701                                 __bch2_btree_path_unlock(trans, path2);
 702
 703                 bch2_btree_node_lock_write_nofail(trans, path, &ck->c);
 704
 705                 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 706                         clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
 707                         atomic_long_dec(&c->btree_key_cache.nr_dirty);
 708                 }
 709
 710                 mark_btree_node_locked_noreset(path, 0, BTREE_NODE_UNLOCKED);
 711                 bkey_cached_evict(&c->btree_key_cache, ck);
 712                 bkey_cached_free_fast(&c->btree_key_cache, ck);
 713         }
 714 out:
 715         bch2_trans_iter_exit(trans, &b_iter);
 716         bch2_trans_iter_exit(trans, &c_iter);
 717         return ret;
 718 }
 719
 720 int bch2_btree_key_cache_journal_flush(struct journal *j,
 721                                 struct journal_entry_pin *pin, u64 seq)
 722 {
 723         struct bch_fs *c = container_of(j, struct bch_fs, journal);
 724         struct bkey_cached *ck =
 725                 container_of(pin, struct bkey_cached, journal);
 726         struct bkey_cached_key key;
 727         struct btree_trans *trans = bch2_trans_get(c);
 728         int srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
 729         int ret = 0;
 730
 731         btree_node_lock_nopath_nofail(trans, &ck->c, SIX_LOCK_read);
 732         key = ck->key;
 733
 734         if (ck->journal.seq != seq ||
 735             !test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 736                 six_unlock_read(&ck->c.lock);
 737                 goto unlock;
 738         }
 739
 740         if (ck->seq != seq) {
 741                 bch2_journal_pin_update(&c->journal, ck->seq, &ck->journal,
 742                                         bch2_btree_key_cache_journal_flush);
 743                 six_unlock_read(&ck->c.lock);
 744                 goto unlock;
 745         }
 746         six_unlock_read(&ck->c.lock);
 747
 748         ret = lockrestart_do(trans,
 749                 btree_key_cache_flush_pos(trans, key, seq,
 750                                 BCH_TRANS_COMMIT_journal_reclaim, false));
 751 unlock:
 752         srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
 753
 754         bch2_trans_put(trans);
 755         return ret;
 756 }
 757
 758 bool bch2_btree_insert_key_cached(struct btree_trans *trans,
 759                                   unsigned flags,
 760                                   struct btree_insert_entry *insert_entry)
 761 {
 762         struct bch_fs *c = trans->c;
 763         struct bkey_cached *ck = (void *) (trans->paths + insert_entry->path)->l[0].b;
 764         struct bkey_i *insert = insert_entry->k;
 765         bool kick_reclaim = false;
 766
 767         BUG_ON(insert->k.u64s > ck->u64s);
 768
 769         bkey_copy(ck->k, insert);
 770         ck->valid = true;
 771
 772         if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 773                 EBUG_ON(test_bit(BCH_FS_clean_shutdown, &c->flags));
 774                 set_bit(BKEY_CACHED_DIRTY, &ck->flags);
 775                 atomic_long_inc(&c->btree_key_cache.nr_dirty);
 776
 777                 if (bch2_nr_btree_keys_need_flush(c))
 778                         kick_reclaim = true;
 779         }
 780
 781         /*
 782          * To minimize lock contention, we only add the journal pin here and
 783          * defer pin updates to the flush callback via ->seq. Be careful not to
 784          * update ->seq on nojournal commits because we don't want to update the
 785          * pin to a seq that doesn't include journal updates on disk. Otherwise
 786          * we risk losing the update after a crash.
 787          *
 788          * The only exception is if the pin is not active in the first place. We
 789          * have to add the pin because journal reclaim drives key cache
 790          * flushing. The flush callback will not proceed unless ->seq matches
 791          * the latest pin, so make sure it starts with a consistent value.
 792          */
 793         if (!(insert_entry->flags & BTREE_UPDATE_NOJOURNAL) ||
 794             !journal_pin_active(&ck->journal)) {
 795                 ck->seq = trans->journal_res.seq;
 796         }
 797         bch2_journal_pin_add(&c->journal, trans->journal_res.seq,
 798                              &ck->journal, bch2_btree_key_cache_journal_flush);
 799
 800         if (kick_reclaim)
 801                 journal_reclaim_kick(&c->journal);
 802         return true;
 803 }
 804
 805 void bch2_btree_key_cache_drop(struct btree_trans *trans,
 806                                struct btree_path *path)
 807 {
 808         struct bch_fs *c = trans->c;
 809         struct bkey_cached *ck = (void *) path->l[0].b;
 810
 811         BUG_ON(!ck->valid);
 812
 813         /*
 814          * We just did an update to the btree, bypassing the key cache: the key
 815          * cache key is now stale and must be dropped, even if dirty:
 816          */
 817         if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
 818                 clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
 819                 atomic_long_dec(&c->btree_key_cache.nr_dirty);
 820                 bch2_journal_pin_drop(&c->journal, &ck->journal);
 821         }
 822
 823         ck->valid = false;
 824 }
 825
 826 static unsigned long bch2_btree_key_cache_scan(struct shrinker *shrink,
 827                                            struct shrink_control *sc)
 828 {
 829         struct bch_fs *c = shrink->private_data;
 830         struct btree_key_cache *bc = &c->btree_key_cache;
 831         struct bucket_table *tbl;
 832         struct bkey_cached *ck, *t;
 833         size_t scanned = 0, freed = 0, nr = sc->nr_to_scan;
 834         unsigned start, flags;
 835         int srcu_idx;
 836
 837         mutex_lock(&bc->lock);
 838         srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
 839         flags = memalloc_nofs_save();
 840
 841         /*
 842          * Newest freed entries are at the end of the list - once we hit one
 843          * that's too new to be freed, we can bail out:
 844          */
 845         scanned += bc->nr_freed_nonpcpu;
 846
 847         list_for_each_entry_safe(ck, t, &bc->freed_nonpcpu, list) {
 848                 if (!poll_state_synchronize_srcu(&c->btree_trans_barrier,
 849                                                  ck->btree_trans_barrier_seq))
 850                         break;
 851
 852                 list_del(&ck->list);
 853                 six_lock_exit(&ck->c.lock);
 854                 kmem_cache_free(bch2_key_cache, ck);
 855                 atomic_long_dec(&bc->nr_freed);
 856                 freed++;
 857                 bc->nr_freed_nonpcpu--;
 858         }
 859
 860         if (scanned >= nr)
 861                 goto out;
 862
 863         scanned += bc->nr_freed_pcpu;
 864
 865         list_for_each_entry_safe(ck, t, &bc->freed_pcpu, list) {
 866                 if (!poll_state_synchronize_srcu(&c->btree_trans_barrier,
 867                                                  ck->btree_trans_barrier_seq))
 868                         break;
 869
 870                 list_del(&ck->list);
 871                 six_lock_exit(&ck->c.lock);
 872                 kmem_cache_free(bch2_key_cache, ck);
 873                 atomic_long_dec(&bc->nr_freed);
 874                 freed++;
 875                 bc->nr_freed_pcpu--;
 876         }
 877
 878         if (scanned >= nr)
 879                 goto out;
 880
 881         rcu_read_lock();
 882         tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
 883         if (bc->shrink_iter >= tbl->size)
 884                 bc->shrink_iter = 0;
 885         start = bc->shrink_iter;
 886
 887         do {
 888                 struct rhash_head *pos, *next;
 889
 890                 pos = rht_ptr_rcu(rht_bucket(tbl, bc->shrink_iter));
 891
 892                 while (!rht_is_a_nulls(pos)) {
 893                         next = rht_dereference_bucket_rcu(pos->next, tbl, bc->shrink_iter);
 894                         ck = container_of(pos, struct bkey_cached, hash);
 895
 896                         if (test_bit(BKEY_CACHED_DIRTY, &ck->flags))
 897                                 goto next;
 898
 899                         if (test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
 900                                 clear_bit(BKEY_CACHED_ACCESSED, &ck->flags);
 901                         else if (bkey_cached_lock_for_evict(ck)) {
 902                                 bkey_cached_evict(bc, ck);
 903                                 bkey_cached_free(bc, ck);
 904                         }
 905
 906                         scanned++;
 907                         if (scanned >= nr)
 908                                 break;
 909 next:
 910                         pos = next;
 911                 }
 912
 913                 bc->shrink_iter++;
 914                 if (bc->shrink_iter >= tbl->size)
 915                         bc->shrink_iter = 0;
 916         } while (scanned < nr && bc->shrink_iter != start);
 917
 918         rcu_read_unlock();
 919 out:
 920         memalloc_nofs_restore(flags);
 921         srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
 922         mutex_unlock(&bc->lock);
 923
 924         return freed;
 925 }
 926
 927 static unsigned long bch2_btree_key_cache_count(struct shrinker *shrink,
 928                                             struct shrink_control *sc)
 929 {
 930         struct bch_fs *c = shrink->private_data;
 931         struct btree_key_cache *bc = &c->btree_key_cache;
 932         long nr = atomic_long_read(&bc->nr_keys) -
 933                 atomic_long_read(&bc->nr_dirty);
 934
 935         return max(0L, nr);
 936 }
 937
 938 void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
 939 {
 940         struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
 941         struct bucket_table *tbl;
 942         struct bkey_cached *ck, *n;
 943         struct rhash_head *pos;
 944         LIST_HEAD(items);
 945         unsigned i;
 946 #ifdef __KERNEL__
 947         int cpu;
 948 #endif
 949
 950         shrinker_free(bc->shrink);
 951
 952         mutex_lock(&bc->lock);
 953
 954         /*
 955          * The loop is needed to guard against racing with rehash:
 956          */
 957         while (atomic_long_read(&bc->nr_keys)) {
 958                 rcu_read_lock();
 959                 tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
 960                 if (tbl)
 961                         for (i = 0; i < tbl->size; i++)
 962                                 rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
 963                                         bkey_cached_evict(bc, ck);
 964                                         list_add(&ck->list, &items);
 965                                 }
 966                 rcu_read_unlock();
 967         }
 968
 969 #ifdef __KERNEL__
 970         for_each_possible_cpu(cpu) {
 971                 struct btree_key_cache_freelist *f =
 972                         per_cpu_ptr(bc->pcpu_freed, cpu);
 973
 974                 for (i = 0; i < f->nr; i++) {
 975                         ck = f->objs[i];
 976                         list_add(&ck->list, &items);
 977                 }
 978         }
 979 #endif
 980
 981         BUG_ON(list_count_nodes(&bc->freed_pcpu) != bc->nr_freed_pcpu);
 982         BUG_ON(list_count_nodes(&bc->freed_nonpcpu) != bc->nr_freed_nonpcpu);
 983
 984         list_splice(&bc->freed_pcpu,    &items);
 985         list_splice(&bc->freed_nonpcpu, &items);
 986
 987         mutex_unlock(&bc->lock);
 988
 989         list_for_each_entry_safe(ck, n, &items, list) {
 990                 cond_resched();
 991
 992                 list_del(&ck->list);
 993                 kfree(ck->k);
 994                 six_lock_exit(&ck->c.lock);
 995                 kmem_cache_free(bch2_key_cache, ck);
 996         }
 997
 998         if (atomic_long_read(&bc->nr_dirty) &&
 999             !bch2_journal_error(&c->journal) &&
1000             test_bit(BCH_FS_was_rw, &c->flags))
1001                 panic("btree key cache shutdown error: nr_dirty nonzero (%li)\n",
1002                       atomic_long_read(&bc->nr_dirty));
1003
1004         if (atomic_long_read(&bc->nr_keys))
1005                 panic("btree key cache shutdown error: nr_keys nonzero (%li)\n",
1006                       atomic_long_read(&bc->nr_keys));
1007
1008         if (bc->table_init_done)
1009                 rhashtable_destroy(&bc->table);
1010
1011         free_percpu(bc->pcpu_freed);
1012 }
1013
1014 void bch2_fs_btree_key_cache_init_early(struct btree_key_cache *c)
1015 {
1016         mutex_init(&c->lock);
1017         INIT_LIST_HEAD(&c->freed_pcpu);
1018         INIT_LIST_HEAD(&c->freed_nonpcpu);
1019 }
1020
1021 int bch2_fs_btree_key_cache_init(struct btree_key_cache *bc)
1022 {
1023         struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
1024         struct shrinker *shrink;
1025
1026 #ifdef __KERNEL__
1027         bc->pcpu_freed = alloc_percpu(struct btree_key_cache_freelist);
1028         if (!bc->pcpu_freed)
1029                 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
1030 #endif
1031
1032         if (rhashtable_init(&bc->table, &bch2_btree_key_cache_params))
1033                 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
1034
1035         bc->table_init_done = true;
1036
1037         shrink = shrinker_alloc(0, "%s-btree_key_cache", c->name);
1038         if (!shrink)
1039                 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
1040         bc->shrink = shrink;
1041         shrink->seeks           = 0;
1042         shrink->count_objects   = bch2_btree_key_cache_count;
1043         shrink->scan_objects    = bch2_btree_key_cache_scan;
1044         shrink->private_data    = c;
1045         shrinker_register(shrink);
1046         return 0;
1047 }
1048
1049 void bch2_btree_key_cache_to_text(struct printbuf *out, struct btree_key_cache *c)
1050 {
1051         prt_printf(out, "nr_freed:\t%lu",       atomic_long_read(&c->nr_freed));
1052         prt_newline(out);
1053         prt_printf(out, "nr_keys:\t%lu",        atomic_long_read(&c->nr_keys));
1054         prt_newline(out);
1055         prt_printf(out, "nr_dirty:\t%lu",       atomic_long_read(&c->nr_dirty));
1056         prt_newline(out);
1057 }
1058
1059 void bch2_btree_key_cache_exit(void)
1060 {
1061         kmem_cache_destroy(bch2_key_cache);
1062 }
1063
1064 int __init bch2_btree_key_cache_init(void)
1065 {
1066         bch2_key_cache = KMEM_CACHE(bkey_cached, SLAB_RECLAIM_ACCOUNT);
1067         if (!bch2_key_cache)
1068                 return -ENOMEM;
1069
1070         return 0;
1071 }