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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "bkey_buf.h"
   5 #include "btree_cache.h"
   6 #include "btree_io.h"
   7 #include "btree_iter.h"
   8 #include "btree_locking.h"
   9 #include "debug.h"
  10 #include "errcode.h"
  11 #include "error.h"
  12 #include "trace.h"
  13
  14 #include <linux/prefetch.h>
  15 #include <linux/sched/mm.h>
  16 #include <linux/seq_buf.h>
  17
  18 #define BTREE_CACHE_NOT_FREED_INCREMENT(counter) \
  19 do {                                             \
  20         if (shrinker_counter)                    \
  21                 bc->not_freed_##counter++;       \
  22 } while (0)
  23
  24 const char * const bch2_btree_node_flags[] = {
  25 #define x(f)    #f,
  26         BTREE_FLAGS()
  27 #undef x
  28         NULL
  29 };
  30
  31 void bch2_recalc_btree_reserve(struct bch_fs *c)
  32 {
  33         unsigned i, reserve = 16;
  34
  35         if (!c->btree_roots_known[0].b)
  36                 reserve += 8;
  37
  38         for (i = 0; i < btree_id_nr_alive(c); i++) {
  39                 struct btree_root *r = bch2_btree_id_root(c, i);
  40
  41                 if (r->b)
  42                         reserve += min_t(unsigned, 1, r->b->c.level) * 8;
  43         }
  44
  45         c->btree_cache.reserve = reserve;
  46 }
  47
  48 static inline unsigned btree_cache_can_free(struct btree_cache *bc)
  49 {
  50         return max_t(int, 0, bc->used - bc->reserve);
  51 }
  52
  53 static void btree_node_to_freedlist(struct btree_cache *bc, struct btree *b)
  54 {
  55         if (b->c.lock.readers)
  56                 list_move(&b->list, &bc->freed_pcpu);
  57         else
  58                 list_move(&b->list, &bc->freed_nonpcpu);
  59 }
  60
  61 static void btree_node_data_free(struct bch_fs *c, struct btree *b)
  62 {
  63         struct btree_cache *bc = &c->btree_cache;
  64
  65         EBUG_ON(btree_node_write_in_flight(b));
  66
  67         clear_btree_node_just_written(b);
  68
  69         kvpfree(b->data, btree_bytes(c));
  70         b->data = NULL;
  71 #ifdef __KERNEL__
  72         kvfree(b->aux_data);
  73 #else
  74         munmap(b->aux_data, btree_aux_data_bytes(b));
  75 #endif
  76         b->aux_data = NULL;
  77
  78         bc->used--;
  79
  80         btree_node_to_freedlist(bc, b);
  81 }
  82
  83 static int bch2_btree_cache_cmp_fn(struct rhashtable_compare_arg *arg,
  84                                    const void *obj)
  85 {
  86         const struct btree *b = obj;
  87         const u64 *v = arg->key;
  88
  89         return b->hash_val == *v ? 0 : 1;
  90 }
  91
  92 static const struct rhashtable_params bch_btree_cache_params = {
  93         .head_offset    = offsetof(struct btree, hash),
  94         .key_offset     = offsetof(struct btree, hash_val),
  95         .key_len        = sizeof(u64),
  96         .obj_cmpfn      = bch2_btree_cache_cmp_fn,
  97 };
  98
  99 static int btree_node_data_alloc(struct bch_fs *c, struct btree *b, gfp_t gfp)
 100 {
 101         BUG_ON(b->data || b->aux_data);
 102
 103         b->data = kvpmalloc(btree_bytes(c), gfp);
 104         if (!b->data)
 105                 return -BCH_ERR_ENOMEM_btree_node_mem_alloc;
 106 #ifdef __KERNEL__
 107         b->aux_data = kvmalloc(btree_aux_data_bytes(b), gfp);
 108 #else
 109         b->aux_data = mmap(NULL, btree_aux_data_bytes(b),
 110                            PROT_READ|PROT_WRITE|PROT_EXEC,
 111                            MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
 112         if (b->aux_data == MAP_FAILED)
 113                 b->aux_data = NULL;
 114 #endif
 115         if (!b->aux_data) {
 116                 kvpfree(b->data, btree_bytes(c));
 117                 b->data = NULL;
 118                 return -BCH_ERR_ENOMEM_btree_node_mem_alloc;
 119         }
 120
 121         return 0;
 122 }
 123
 124 static struct btree *__btree_node_mem_alloc(struct bch_fs *c, gfp_t gfp)
 125 {
 126         struct btree *b;
 127
 128         b = kzalloc(sizeof(struct btree), gfp);
 129         if (!b)
 130                 return NULL;
 131
 132         bkey_btree_ptr_init(&b->key);
 133         INIT_LIST_HEAD(&b->list);
 134         INIT_LIST_HEAD(&b->write_blocked);
 135         b->byte_order = ilog2(btree_bytes(c));
 136         return b;
 137 }
 138
 139 struct btree *__bch2_btree_node_mem_alloc(struct bch_fs *c)
 140 {
 141         struct btree_cache *bc = &c->btree_cache;
 142         struct btree *b;
 143
 144         b = __btree_node_mem_alloc(c, GFP_KERNEL);
 145         if (!b)
 146                 return NULL;
 147
 148         if (btree_node_data_alloc(c, b, GFP_KERNEL)) {
 149                 kfree(b);
 150                 return NULL;
 151         }
 152
 153         bch2_btree_lock_init(&b->c, 0);
 154
 155         bc->used++;
 156         list_add(&b->list, &bc->freeable);
 157         return b;
 158 }
 159
 160 /* Btree in memory cache - hash table */
 161
 162 void bch2_btree_node_hash_remove(struct btree_cache *bc, struct btree *b)
 163 {
 164         int ret = rhashtable_remove_fast(&bc->table, &b->hash, bch_btree_cache_params);
 165
 166         BUG_ON(ret);
 167
 168         /* Cause future lookups for this node to fail: */
 169         b->hash_val = 0;
 170 }
 171
 172 int __bch2_btree_node_hash_insert(struct btree_cache *bc, struct btree *b)
 173 {
 174         BUG_ON(b->hash_val);
 175         b->hash_val = btree_ptr_hash_val(&b->key);
 176
 177         return rhashtable_lookup_insert_fast(&bc->table, &b->hash,
 178                                              bch_btree_cache_params);
 179 }
 180
 181 int bch2_btree_node_hash_insert(struct btree_cache *bc, struct btree *b,
 182                                 unsigned level, enum btree_id id)
 183 {
 184         int ret;
 185
 186         b->c.level      = level;
 187         b->c.btree_id   = id;
 188
 189         mutex_lock(&bc->lock);
 190         ret = __bch2_btree_node_hash_insert(bc, b);
 191         if (!ret)
 192                 list_add_tail(&b->list, &bc->live);
 193         mutex_unlock(&bc->lock);
 194
 195         return ret;
 196 }
 197
 198 __flatten
 199 static inline struct btree *btree_cache_find(struct btree_cache *bc,
 200                                      const struct bkey_i *k)
 201 {
 202         u64 v = btree_ptr_hash_val(k);
 203
 204         return rhashtable_lookup_fast(&bc->table, &v, bch_btree_cache_params);
 205 }
 206
 207 /*
 208  * this version is for btree nodes that have already been freed (we're not
 209  * reaping a real btree node)
 210  */
 211 static int __btree_node_reclaim(struct bch_fs *c, struct btree *b, bool flush, bool shrinker_counter)
 212 {
 213         struct btree_cache *bc = &c->btree_cache;
 214         int ret = 0;
 215
 216         lockdep_assert_held(&bc->lock);
 217 wait_on_io:
 218         if (b->flags & ((1U << BTREE_NODE_dirty)|
 219                         (1U << BTREE_NODE_read_in_flight)|
 220                         (1U << BTREE_NODE_write_in_flight))) {
 221                 if (!flush) {
 222                         if (btree_node_dirty(b))
 223                                 BTREE_CACHE_NOT_FREED_INCREMENT(dirty);
 224                         else if (btree_node_read_in_flight(b))
 225                                 BTREE_CACHE_NOT_FREED_INCREMENT(read_in_flight);
 226                         else if (btree_node_write_in_flight(b))
 227                                 BTREE_CACHE_NOT_FREED_INCREMENT(write_in_flight);
 228                         return -BCH_ERR_ENOMEM_btree_node_reclaim;
 229                 }
 230
 231                 /* XXX: waiting on IO with btree cache lock held */
 232                 bch2_btree_node_wait_on_read(b);
 233                 bch2_btree_node_wait_on_write(b);
 234         }
 235
 236         if (!six_trylock_intent(&b->c.lock)) {
 237                 BTREE_CACHE_NOT_FREED_INCREMENT(lock_intent);
 238                 return -BCH_ERR_ENOMEM_btree_node_reclaim;
 239         }
 240
 241         if (!six_trylock_write(&b->c.lock)) {
 242                 BTREE_CACHE_NOT_FREED_INCREMENT(lock_write);
 243                 goto out_unlock_intent;
 244         }
 245
 246         /* recheck under lock */
 247         if (b->flags & ((1U << BTREE_NODE_read_in_flight)|
 248                         (1U << BTREE_NODE_write_in_flight))) {
 249                 if (!flush) {
 250                         if (btree_node_read_in_flight(b))
 251                                 BTREE_CACHE_NOT_FREED_INCREMENT(read_in_flight);
 252                         else if (btree_node_write_in_flight(b))
 253                                 BTREE_CACHE_NOT_FREED_INCREMENT(write_in_flight);
 254                         goto out_unlock;
 255                 }
 256                 six_unlock_write(&b->c.lock);
 257                 six_unlock_intent(&b->c.lock);
 258                 goto wait_on_io;
 259         }
 260
 261         if (btree_node_noevict(b)) {
 262                 BTREE_CACHE_NOT_FREED_INCREMENT(noevict);
 263                 goto out_unlock;
 264         }
 265         if (btree_node_write_blocked(b)) {
 266                 BTREE_CACHE_NOT_FREED_INCREMENT(write_blocked);
 267                 goto out_unlock;
 268         }
 269         if (btree_node_will_make_reachable(b)) {
 270                 BTREE_CACHE_NOT_FREED_INCREMENT(will_make_reachable);
 271                 goto out_unlock;
 272         }
 273
 274         if (btree_node_dirty(b)) {
 275                 if (!flush) {
 276                         BTREE_CACHE_NOT_FREED_INCREMENT(dirty);
 277                         goto out_unlock;
 278                 }
 279                 /*
 280                  * Using the underscore version because we don't want to compact
 281                  * bsets after the write, since this node is about to be evicted
 282                  * - unless btree verify mode is enabled, since it runs out of
 283                  * the post write cleanup:
 284                  */
 285                 if (bch2_verify_btree_ondisk)
 286                         bch2_btree_node_write(c, b, SIX_LOCK_intent,
 287                                               BTREE_WRITE_cache_reclaim);
 288                 else
 289                         __bch2_btree_node_write(c, b,
 290                                                 BTREE_WRITE_cache_reclaim);
 291
 292                 six_unlock_write(&b->c.lock);
 293                 six_unlock_intent(&b->c.lock);
 294                 goto wait_on_io;
 295         }
 296 out:
 297         if (b->hash_val && !ret)
 298                 trace_and_count(c, btree_cache_reap, c, b);
 299         return ret;
 300 out_unlock:
 301         six_unlock_write(&b->c.lock);
 302 out_unlock_intent:
 303         six_unlock_intent(&b->c.lock);
 304         ret = -BCH_ERR_ENOMEM_btree_node_reclaim;
 305         goto out;
 306 }
 307
 308 static int btree_node_reclaim(struct bch_fs *c, struct btree *b, bool shrinker_counter)
 309 {
 310         return __btree_node_reclaim(c, b, false, shrinker_counter);
 311 }
 312
 313 static int btree_node_write_and_reclaim(struct bch_fs *c, struct btree *b)
 314 {
 315         return __btree_node_reclaim(c, b, true, false);
 316 }
 317
 318 static unsigned long bch2_btree_cache_scan(struct shrinker *shrink,
 319                                            struct shrink_control *sc)
 320 {
 321         struct bch_fs *c = container_of(shrink, struct bch_fs,
 322                                         btree_cache.shrink);
 323         struct btree_cache *bc = &c->btree_cache;
 324         struct btree *b, *t;
 325         unsigned long nr = sc->nr_to_scan;
 326         unsigned long can_free = 0;
 327         unsigned long freed = 0;
 328         unsigned long touched = 0;
 329         unsigned i, flags;
 330         unsigned long ret = SHRINK_STOP;
 331         bool trigger_writes = atomic_read(&bc->dirty) + nr >=
 332                 bc->used * 3 / 4;
 333
 334         if (bch2_btree_shrinker_disabled)
 335                 return SHRINK_STOP;
 336
 337         mutex_lock(&bc->lock);
 338         flags = memalloc_nofs_save();
 339
 340         /*
 341          * It's _really_ critical that we don't free too many btree nodes - we
 342          * have to always leave ourselves a reserve. The reserve is how we
 343          * guarantee that allocating memory for a new btree node can always
 344          * succeed, so that inserting keys into the btree can always succeed and
 345          * IO can always make forward progress:
 346          */
 347         can_free = btree_cache_can_free(bc);
 348         nr = min_t(unsigned long, nr, can_free);
 349
 350         i = 0;
 351         list_for_each_entry_safe(b, t, &bc->freeable, list) {
 352                 /*
 353                  * Leave a few nodes on the freeable list, so that a btree split
 354                  * won't have to hit the system allocator:
 355                  */
 356                 if (++i <= 3)
 357                         continue;
 358
 359                 touched++;
 360
 361                 if (touched >= nr)
 362                         goto out;
 363
 364                 if (!btree_node_reclaim(c, b, true)) {
 365                         btree_node_data_free(c, b);
 366                         six_unlock_write(&b->c.lock);
 367                         six_unlock_intent(&b->c.lock);
 368                         freed++;
 369                         bc->freed++;
 370                 }
 371         }
 372 restart:
 373         list_for_each_entry_safe(b, t, &bc->live, list) {
 374                 touched++;
 375
 376                 if (btree_node_accessed(b)) {
 377                         clear_btree_node_accessed(b);
 378                         bc->not_freed_access_bit++;
 379                 } else if (!btree_node_reclaim(c, b, true)) {
 380                         freed++;
 381                         btree_node_data_free(c, b);
 382                         bc->freed++;
 383
 384                         bch2_btree_node_hash_remove(bc, b);
 385                         six_unlock_write(&b->c.lock);
 386                         six_unlock_intent(&b->c.lock);
 387
 388                         if (freed == nr)
 389                                 goto out_rotate;
 390                 } else if (trigger_writes &&
 391                            btree_node_dirty(b) &&
 392                            !btree_node_will_make_reachable(b) &&
 393                            !btree_node_write_blocked(b) &&
 394                            six_trylock_read(&b->c.lock)) {
 395                         list_move(&bc->live, &b->list);
 396                         mutex_unlock(&bc->lock);
 397                         __bch2_btree_node_write(c, b, BTREE_WRITE_cache_reclaim);
 398                         six_unlock_read(&b->c.lock);
 399                         if (touched >= nr)
 400                                 goto out_nounlock;
 401                         mutex_lock(&bc->lock);
 402                         goto restart;
 403                 }
 404
 405                 if (touched >= nr)
 406                         break;
 407         }
 408 out_rotate:
 409         if (&t->list != &bc->live)
 410                 list_move_tail(&bc->live, &t->list);
 411 out:
 412         mutex_unlock(&bc->lock);
 413 out_nounlock:
 414         ret = freed;
 415         memalloc_nofs_restore(flags);
 416         trace_and_count(c, btree_cache_scan, sc->nr_to_scan, can_free, ret);
 417         return ret;
 418 }
 419
 420 static unsigned long bch2_btree_cache_count(struct shrinker *shrink,
 421                                             struct shrink_control *sc)
 422 {
 423         struct bch_fs *c = container_of(shrink, struct bch_fs,
 424                                         btree_cache.shrink);
 425         struct btree_cache *bc = &c->btree_cache;
 426
 427         if (bch2_btree_shrinker_disabled)
 428                 return 0;
 429
 430         return btree_cache_can_free(bc);
 431 }
 432
 433 static void bch2_btree_cache_shrinker_to_text(struct seq_buf *s, struct shrinker *shrink)
 434 {
 435         struct bch_fs *c = container_of(shrink, struct bch_fs,
 436                                         btree_cache.shrink);
 437         char *cbuf;
 438         size_t buflen = seq_buf_get_buf(s, &cbuf);
 439         struct printbuf out = PRINTBUF_EXTERN(cbuf, buflen);
 440
 441         bch2_btree_cache_to_text(&out, &c->btree_cache);
 442         seq_buf_commit(s, out.pos);
 443 }
 444
 445 void bch2_fs_btree_cache_exit(struct bch_fs *c)
 446 {
 447         struct btree_cache *bc = &c->btree_cache;
 448         struct btree *b;
 449         unsigned i, flags;
 450
 451         unregister_shrinker(&bc->shrink);
 452
 453         /* vfree() can allocate memory: */
 454         flags = memalloc_nofs_save();
 455         mutex_lock(&bc->lock);
 456
 457         if (c->verify_data)
 458                 list_move(&c->verify_data->list, &bc->live);
 459
 460         kvpfree(c->verify_ondisk, btree_bytes(c));
 461
 462         for (i = 0; i < btree_id_nr_alive(c); i++) {
 463                 struct btree_root *r = bch2_btree_id_root(c, i);
 464
 465                 if (r->b)
 466                         list_add(&r->b->list, &bc->live);
 467         }
 468
 469         list_splice(&bc->freeable, &bc->live);
 470
 471         while (!list_empty(&bc->live)) {
 472                 b = list_first_entry(&bc->live, struct btree, list);
 473
 474                 BUG_ON(btree_node_read_in_flight(b) ||
 475                        btree_node_write_in_flight(b));
 476
 477                 if (btree_node_dirty(b))
 478                         bch2_btree_complete_write(c, b, btree_current_write(b));
 479                 clear_btree_node_dirty_acct(c, b);
 480
 481                 btree_node_data_free(c, b);
 482         }
 483
 484         BUG_ON(atomic_read(&c->btree_cache.dirty));
 485
 486         list_splice(&bc->freed_pcpu, &bc->freed_nonpcpu);
 487
 488         while (!list_empty(&bc->freed_nonpcpu)) {
 489                 b = list_first_entry(&bc->freed_nonpcpu, struct btree, list);
 490                 list_del(&b->list);
 491                 six_lock_exit(&b->c.lock);
 492                 kfree(b);
 493         }
 494
 495         mutex_unlock(&bc->lock);
 496         memalloc_nofs_restore(flags);
 497
 498         if (bc->table_init_done)
 499                 rhashtable_destroy(&bc->table);
 500 }
 501
 502 int bch2_fs_btree_cache_init(struct bch_fs *c)
 503 {
 504         struct btree_cache *bc = &c->btree_cache;
 505         unsigned i;
 506         int ret = 0;
 507
 508         pr_verbose_init(c->opts, "");
 509
 510         ret = rhashtable_init(&bc->table, &bch_btree_cache_params);
 511         if (ret)
 512                 goto out;
 513
 514         bc->table_init_done = true;
 515
 516         bch2_recalc_btree_reserve(c);
 517
 518         for (i = 0; i < bc->reserve; i++)
 519                 if (!__bch2_btree_node_mem_alloc(c)) {
 520                         ret = -BCH_ERR_ENOMEM_fs_btree_cache_init;
 521                         goto out;
 522                 }
 523
 524         list_splice_init(&bc->live, &bc->freeable);
 525
 526         mutex_init(&c->verify_lock);
 527
 528         bc->shrink.count_objects        = bch2_btree_cache_count;
 529         bc->shrink.scan_objects         = bch2_btree_cache_scan;
 530         bc->shrink.to_text              = bch2_btree_cache_shrinker_to_text;
 531         bc->shrink.seeks                = 4;
 532         ret = register_shrinker(&bc->shrink, "%s/btree_cache", c->name);
 533 out:
 534         pr_verbose_init(c->opts, "ret %i", ret);
 535         return ret;
 536 }
 537
 538 void bch2_fs_btree_cache_init_early(struct btree_cache *bc)
 539 {
 540         mutex_init(&bc->lock);
 541         INIT_LIST_HEAD(&bc->live);
 542         INIT_LIST_HEAD(&bc->freeable);
 543         INIT_LIST_HEAD(&bc->freed_pcpu);
 544         INIT_LIST_HEAD(&bc->freed_nonpcpu);
 545 }
 546
 547 /*
 548  * We can only have one thread cannibalizing other cached btree nodes at a time,
 549  * or we'll deadlock. We use an open coded mutex to ensure that, which a
 550  * cannibalize_bucket() will take. This means every time we unlock the root of
 551  * the btree, we need to release this lock if we have it held.
 552  */
 553 void bch2_btree_cache_cannibalize_unlock(struct bch_fs *c)
 554 {
 555         struct btree_cache *bc = &c->btree_cache;
 556
 557         if (bc->alloc_lock == current) {
 558                 trace_and_count(c, btree_cache_cannibalize_unlock, c);
 559                 bc->alloc_lock = NULL;
 560                 closure_wake_up(&bc->alloc_wait);
 561         }
 562 }
 563
 564 int bch2_btree_cache_cannibalize_lock(struct bch_fs *c, struct closure *cl)
 565 {
 566         struct btree_cache *bc = &c->btree_cache;
 567         struct task_struct *old;
 568
 569         old = cmpxchg(&bc->alloc_lock, NULL, current);
 570         if (old == NULL || old == current)
 571                 goto success;
 572
 573         if (!cl) {
 574                 trace_and_count(c, btree_cache_cannibalize_lock_fail, c);
 575                 return -BCH_ERR_ENOMEM_btree_cache_cannibalize_lock;
 576         }
 577
 578         closure_wait(&bc->alloc_wait, cl);
 579
 580         /* Try again, after adding ourselves to waitlist */
 581         old = cmpxchg(&bc->alloc_lock, NULL, current);
 582         if (old == NULL || old == current) {
 583                 /* We raced */
 584                 closure_wake_up(&bc->alloc_wait);
 585                 goto success;
 586         }
 587
 588         trace_and_count(c, btree_cache_cannibalize_lock_fail, c);
 589         return -BCH_ERR_btree_cache_cannibalize_lock_blocked;
 590
 591 success:
 592         trace_and_count(c, btree_cache_cannibalize_lock, c);
 593         return 0;
 594 }
 595
 596 static struct btree *btree_node_cannibalize(struct bch_fs *c)
 597 {
 598         struct btree_cache *bc = &c->btree_cache;
 599         struct btree *b;
 600
 601         list_for_each_entry_reverse(b, &bc->live, list)
 602                 if (!btree_node_reclaim(c, b, false))
 603                         return b;
 604
 605         while (1) {
 606                 list_for_each_entry_reverse(b, &bc->live, list)
 607                         if (!btree_node_write_and_reclaim(c, b))
 608                                 return b;
 609
 610                 /*
 611                  * Rare case: all nodes were intent-locked.
 612                  * Just busy-wait.
 613                  */
 614                 WARN_ONCE(1, "btree cache cannibalize failed\n");
 615                 cond_resched();
 616         }
 617 }
 618
 619 struct btree *bch2_btree_node_mem_alloc(struct btree_trans *trans, bool pcpu_read_locks)
 620 {
 621         struct bch_fs *c = trans->c;
 622         struct btree_cache *bc = &c->btree_cache;
 623         struct list_head *freed = pcpu_read_locks
 624                 ? &bc->freed_pcpu
 625                 : &bc->freed_nonpcpu;
 626         struct btree *b, *b2;
 627         u64 start_time = local_clock();
 628         unsigned flags;
 629
 630         flags = memalloc_nofs_save();
 631         mutex_lock(&bc->lock);
 632
 633         /*
 634          * We never free struct btree itself, just the memory that holds the on
 635          * disk node. Check the freed list before allocating a new one:
 636          */
 637         list_for_each_entry(b, freed, list)
 638                 if (!btree_node_reclaim(c, b, false)) {
 639                         list_del_init(&b->list);
 640                         goto got_node;
 641                 }
 642
 643         b = __btree_node_mem_alloc(c, GFP_NOWAIT|__GFP_NOWARN);
 644         if (!b) {
 645                 mutex_unlock(&bc->lock);
 646                 bch2_trans_unlock(trans);
 647                 b = __btree_node_mem_alloc(c, GFP_KERNEL);
 648                 if (!b)
 649                         goto err;
 650                 mutex_lock(&bc->lock);
 651         }
 652
 653         bch2_btree_lock_init(&b->c, pcpu_read_locks ? SIX_LOCK_INIT_PCPU : 0);
 654
 655         BUG_ON(!six_trylock_intent(&b->c.lock));
 656         BUG_ON(!six_trylock_write(&b->c.lock));
 657 got_node:
 658
 659         /*
 660          * btree_free() doesn't free memory; it sticks the node on the end of
 661          * the list. Check if there's any freed nodes there:
 662          */
 663         list_for_each_entry(b2, &bc->freeable, list)
 664                 if (!btree_node_reclaim(c, b2, false)) {
 665                         swap(b->data, b2->data);
 666                         swap(b->aux_data, b2->aux_data);
 667                         btree_node_to_freedlist(bc, b2);
 668                         six_unlock_write(&b2->c.lock);
 669                         six_unlock_intent(&b2->c.lock);
 670                         goto got_mem;
 671                 }
 672
 673         mutex_unlock(&bc->lock);
 674
 675         if (btree_node_data_alloc(c, b, GFP_NOWAIT|__GFP_NOWARN)) {
 676                 bch2_trans_unlock(trans);
 677                 if (btree_node_data_alloc(c, b, GFP_KERNEL|__GFP_NOWARN))
 678                         goto err;
 679         }
 680
 681         mutex_lock(&bc->lock);
 682         bc->used++;
 683 got_mem:
 684         mutex_unlock(&bc->lock);
 685
 686         BUG_ON(btree_node_hashed(b));
 687         BUG_ON(btree_node_dirty(b));
 688         BUG_ON(btree_node_write_in_flight(b));
 689 out:
 690         b->flags                = 0;
 691         b->written              = 0;
 692         b->nsets                = 0;
 693         b->sib_u64s[0]          = 0;
 694         b->sib_u64s[1]          = 0;
 695         b->whiteout_u64s        = 0;
 696         bch2_btree_keys_init(b);
 697         set_btree_node_accessed(b);
 698
 699         bch2_time_stats_update(&c->times[BCH_TIME_btree_node_mem_alloc],
 700                                start_time);
 701
 702         memalloc_nofs_restore(flags);
 703         return b;
 704 err:
 705         mutex_lock(&bc->lock);
 706
 707         /* Try to cannibalize another cached btree node: */
 708         if (bc->alloc_lock == current) {
 709                 b2 = btree_node_cannibalize(c);
 710                 clear_btree_node_just_written(b2);
 711                 bch2_btree_node_hash_remove(bc, b2);
 712
 713                 if (b) {
 714                         swap(b->data, b2->data);
 715                         swap(b->aux_data, b2->aux_data);
 716                         btree_node_to_freedlist(bc, b2);
 717                         six_unlock_write(&b2->c.lock);
 718                         six_unlock_intent(&b2->c.lock);
 719                 } else {
 720                         b = b2;
 721                         list_del_init(&b->list);
 722                 }
 723
 724                 mutex_unlock(&bc->lock);
 725
 726                 trace_and_count(c, btree_cache_cannibalize, c);
 727                 goto out;
 728         }
 729
 730         mutex_unlock(&bc->lock);
 731         memalloc_nofs_restore(flags);
 732         return ERR_PTR(-BCH_ERR_ENOMEM_btree_node_mem_alloc);
 733 }
 734
 735 /* Slowpath, don't want it inlined into btree_iter_traverse() */
 736 static noinline struct btree *bch2_btree_node_fill(struct btree_trans *trans,
 737                                 struct btree_path *path,
 738                                 const struct bkey_i *k,
 739                                 enum btree_id btree_id,
 740                                 unsigned level,
 741                                 enum six_lock_type lock_type,
 742                                 bool sync)
 743 {
 744         struct bch_fs *c = trans->c;
 745         struct btree_cache *bc = &c->btree_cache;
 746         struct btree *b;
 747         u32 seq;
 748
 749         BUG_ON(level + 1 >= BTREE_MAX_DEPTH);
 750         /*
 751          * Parent node must be locked, else we could read in a btree node that's
 752          * been freed:
 753          */
 754         if (path && !bch2_btree_node_relock(trans, path, level + 1)) {
 755                 trace_and_count(c, trans_restart_relock_parent_for_fill, trans, _THIS_IP_, path);
 756                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_fill_relock));
 757         }
 758
 759         b = bch2_btree_node_mem_alloc(trans, level != 0);
 760
 761         if (bch2_err_matches(PTR_ERR_OR_ZERO(b), ENOMEM)) {
 762                 trans->memory_allocation_failure = true;
 763                 trace_and_count(c, trans_restart_memory_allocation_failure, trans, _THIS_IP_, path);
 764                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_fill_mem_alloc_fail));
 765         }
 766
 767         if (IS_ERR(b))
 768                 return b;
 769
 770         /*
 771          * Btree nodes read in from disk should not have the accessed bit set
 772          * initially, so that linear scans don't thrash the cache:
 773          */
 774         clear_btree_node_accessed(b);
 775
 776         bkey_copy(&b->key, k);
 777         if (bch2_btree_node_hash_insert(bc, b, level, btree_id)) {
 778                 /* raced with another fill: */
 779
 780                 /* mark as unhashed... */
 781                 b->hash_val = 0;
 782
 783                 mutex_lock(&bc->lock);
 784                 list_add(&b->list, &bc->freeable);
 785                 mutex_unlock(&bc->lock);
 786
 787                 six_unlock_write(&b->c.lock);
 788                 six_unlock_intent(&b->c.lock);
 789                 return NULL;
 790         }
 791
 792         set_btree_node_read_in_flight(b);
 793
 794         six_unlock_write(&b->c.lock);
 795         seq = six_lock_seq(&b->c.lock);
 796         six_unlock_intent(&b->c.lock);
 797
 798         /* Unlock before doing IO: */
 799         if (trans && sync)
 800                 bch2_trans_unlock_noassert(trans);
 801
 802         bch2_btree_node_read(c, b, sync);
 803
 804         if (!sync)
 805                 return NULL;
 806
 807         if (path) {
 808                 int ret = bch2_trans_relock(trans) ?:
 809                         bch2_btree_path_relock_intent(trans, path);
 810                 if (ret) {
 811                         BUG_ON(!trans->restarted);
 812                         return ERR_PTR(ret);
 813                 }
 814         }
 815
 816         if (!six_relock_type(&b->c.lock, lock_type, seq)) {
 817                 if (path)
 818                         trace_and_count(c, trans_restart_relock_after_fill, trans, _THIS_IP_, path);
 819                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_relock_after_fill));
 820         }
 821
 822         return b;
 823 }
 824
 825 static noinline void btree_bad_header(struct bch_fs *c, struct btree *b)
 826 {
 827         struct printbuf buf = PRINTBUF;
 828
 829         if (!test_bit(BCH_FS_INITIAL_GC_DONE, &c->flags))
 830                 return;
 831
 832         prt_printf(&buf,
 833                "btree node header doesn't match ptr\n"
 834                "btree %s level %u\n"
 835                "ptr: ",
 836                bch2_btree_ids[b->c.btree_id], b->c.level);
 837         bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
 838
 839         prt_printf(&buf, "\nheader: btree %s level %llu\n"
 840                "min ",
 841                bch2_btree_ids[BTREE_NODE_ID(b->data)],
 842                BTREE_NODE_LEVEL(b->data));
 843         bch2_bpos_to_text(&buf, b->data->min_key);
 844
 845         prt_printf(&buf, "\nmax ");
 846         bch2_bpos_to_text(&buf, b->data->max_key);
 847
 848         bch2_fs_inconsistent(c, "%s", buf.buf);
 849         printbuf_exit(&buf);
 850 }
 851
 852 static inline void btree_check_header(struct bch_fs *c, struct btree *b)
 853 {
 854         if (b->c.btree_id != BTREE_NODE_ID(b->data) ||
 855             b->c.level != BTREE_NODE_LEVEL(b->data) ||
 856             !bpos_eq(b->data->max_key, b->key.k.p) ||
 857             (b->key.k.type == KEY_TYPE_btree_ptr_v2 &&
 858              !bpos_eq(b->data->min_key,
 859                       bkey_i_to_btree_ptr_v2(&b->key)->v.min_key)))
 860                 btree_bad_header(c, b);
 861 }
 862
 863 static struct btree *__bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
 864                                            const struct bkey_i *k, unsigned level,
 865                                            enum six_lock_type lock_type,
 866                                            unsigned long trace_ip)
 867 {
 868         struct bch_fs *c = trans->c;
 869         struct btree_cache *bc = &c->btree_cache;
 870         struct btree *b;
 871         struct bset_tree *t;
 872         bool need_relock = false;
 873         int ret;
 874
 875         EBUG_ON(level >= BTREE_MAX_DEPTH);
 876 retry:
 877         b = btree_cache_find(bc, k);
 878         if (unlikely(!b)) {
 879                 /*
 880                  * We must have the parent locked to call bch2_btree_node_fill(),
 881                  * else we could read in a btree node from disk that's been
 882                  * freed:
 883                  */
 884                 b = bch2_btree_node_fill(trans, path, k, path->btree_id,
 885                                          level, lock_type, true);
 886                 need_relock = true;
 887
 888                 /* We raced and found the btree node in the cache */
 889                 if (!b)
 890                         goto retry;
 891
 892                 if (IS_ERR(b))
 893                         return b;
 894         } else {
 895                 if (btree_node_read_locked(path, level + 1))
 896                         btree_node_unlock(trans, path, level + 1);
 897
 898                 ret = btree_node_lock(trans, path, &b->c, level, lock_type, trace_ip);
 899                 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 900                         return ERR_PTR(ret);
 901
 902                 BUG_ON(ret);
 903
 904                 if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
 905                              b->c.level != level ||
 906                              race_fault())) {
 907                         six_unlock_type(&b->c.lock, lock_type);
 908                         if (bch2_btree_node_relock(trans, path, level + 1))
 909                                 goto retry;
 910
 911                         trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
 912                         return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_lock_node_reused));
 913                 }
 914
 915                 /* avoid atomic set bit if it's not needed: */
 916                 if (!btree_node_accessed(b))
 917                         set_btree_node_accessed(b);
 918         }
 919
 920         if (unlikely(btree_node_read_in_flight(b))) {
 921                 u32 seq = six_lock_seq(&b->c.lock);
 922
 923                 six_unlock_type(&b->c.lock, lock_type);
 924                 bch2_trans_unlock(trans);
 925                 need_relock = true;
 926
 927                 bch2_btree_node_wait_on_read(b);
 928
 929                 /*
 930                  * should_be_locked is not set on this path yet, so we need to
 931                  * relock it specifically:
 932                  */
 933                 if (!six_relock_type(&b->c.lock, lock_type, seq))
 934                         goto retry;
 935         }
 936
 937         if (unlikely(need_relock)) {
 938                 int ret = bch2_trans_relock(trans) ?:
 939                         bch2_btree_path_relock_intent(trans, path);
 940                 if (ret) {
 941                         six_unlock_type(&b->c.lock, lock_type);
 942                         return ERR_PTR(ret);
 943                 }
 944         }
 945
 946         prefetch(b->aux_data);
 947
 948         for_each_bset(b, t) {
 949                 void *p = (u64 *) b->aux_data + t->aux_data_offset;
 950
 951                 prefetch(p + L1_CACHE_BYTES * 0);
 952                 prefetch(p + L1_CACHE_BYTES * 1);
 953                 prefetch(p + L1_CACHE_BYTES * 2);
 954         }
 955
 956         if (unlikely(btree_node_read_error(b))) {
 957                 six_unlock_type(&b->c.lock, lock_type);
 958                 return ERR_PTR(-EIO);
 959         }
 960
 961         EBUG_ON(b->c.btree_id != path->btree_id);
 962         EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
 963         btree_check_header(c, b);
 964
 965         return b;
 966 }
 967
 968 /**
 969  * bch_btree_node_get - find a btree node in the cache and lock it, reading it
 970  * in from disk if necessary.
 971  *
 972  * The btree node will have either a read or a write lock held, depending on
 973  * the @write parameter.
 974  */
 975 struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
 976                                   const struct bkey_i *k, unsigned level,
 977                                   enum six_lock_type lock_type,
 978                                   unsigned long trace_ip)
 979 {
 980         struct bch_fs *c = trans->c;
 981         struct btree *b;
 982         struct bset_tree *t;
 983         int ret;
 984
 985         EBUG_ON(level >= BTREE_MAX_DEPTH);
 986
 987         b = btree_node_mem_ptr(k);
 988
 989         /*
 990          * Check b->hash_val _before_ calling btree_node_lock() - this might not
 991          * be the node we want anymore, and trying to lock the wrong node could
 992          * cause an unneccessary transaction restart:
 993          */
 994         if (unlikely(!c->opts.btree_node_mem_ptr_optimization ||
 995                      !b ||
 996                      b->hash_val != btree_ptr_hash_val(k)))
 997                 return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
 998
 999         if (btree_node_read_locked(path, level + 1))
1000                 btree_node_unlock(trans, path, level + 1);
1001
1002         ret = btree_node_lock(trans, path, &b->c, level, lock_type, trace_ip);
1003         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
1004                 return ERR_PTR(ret);
1005
1006         BUG_ON(ret);
1007
1008         if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
1009                      b->c.level != level ||
1010                      race_fault())) {
1011                 six_unlock_type(&b->c.lock, lock_type);
1012                 if (bch2_btree_node_relock(trans, path, level + 1))
1013                         return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
1014
1015                 trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
1016                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_lock_node_reused));
1017         }
1018
1019         if (unlikely(btree_node_read_in_flight(b))) {
1020                 u32 seq = six_lock_seq(&b->c.lock);
1021
1022                 six_unlock_type(&b->c.lock, lock_type);
1023                 bch2_trans_unlock(trans);
1024
1025                 bch2_btree_node_wait_on_read(b);
1026
1027                 /*
1028                  * should_be_locked is not set on this path yet, so we need to
1029                  * relock it specifically:
1030                  */
1031                 if (trans) {
1032                         int ret = bch2_trans_relock(trans) ?:
1033                                 bch2_btree_path_relock_intent(trans, path);
1034                         if (ret) {
1035                                 BUG_ON(!trans->restarted);
1036                                 return ERR_PTR(ret);
1037                         }
1038                 }
1039
1040                 if (!six_relock_type(&b->c.lock, lock_type, seq))
1041                         return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
1042         }
1043
1044         prefetch(b->aux_data);
1045
1046         for_each_bset(b, t) {
1047                 void *p = (u64 *) b->aux_data + t->aux_data_offset;
1048
1049                 prefetch(p + L1_CACHE_BYTES * 0);
1050                 prefetch(p + L1_CACHE_BYTES * 1);
1051                 prefetch(p + L1_CACHE_BYTES * 2);
1052         }
1053
1054         /* avoid atomic set bit if it's not needed: */
1055         if (!btree_node_accessed(b))
1056                 set_btree_node_accessed(b);
1057
1058         if (unlikely(btree_node_read_error(b))) {
1059                 six_unlock_type(&b->c.lock, lock_type);
1060                 return ERR_PTR(-EIO);
1061         }
1062
1063         EBUG_ON(b->c.btree_id != path->btree_id);
1064         EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
1065         btree_check_header(c, b);
1066
1067         return b;
1068 }
1069
1070 struct btree *bch2_btree_node_get_noiter(struct btree_trans *trans,
1071                                          const struct bkey_i *k,
1072                                          enum btree_id btree_id,
1073                                          unsigned level,
1074                                          bool nofill)
1075 {
1076         struct bch_fs *c = trans->c;
1077         struct btree_cache *bc = &c->btree_cache;
1078         struct btree *b;
1079         struct bset_tree *t;
1080         int ret;
1081
1082         EBUG_ON(level >= BTREE_MAX_DEPTH);
1083
1084         if (c->opts.btree_node_mem_ptr_optimization) {
1085                 b = btree_node_mem_ptr(k);
1086                 if (b)
1087                         goto lock_node;
1088         }
1089 retry:
1090         b = btree_cache_find(bc, k);
1091         if (unlikely(!b)) {
1092                 if (nofill)
1093                         goto out;
1094
1095                 b = bch2_btree_node_fill(trans, NULL, k, btree_id,
1096                                          level, SIX_LOCK_read, true);
1097
1098                 /* We raced and found the btree node in the cache */
1099                 if (!b)
1100                         goto retry;
1101
1102                 if (IS_ERR(b) &&
1103                     !bch2_btree_cache_cannibalize_lock(c, NULL))
1104                         goto retry;
1105
1106                 if (IS_ERR(b))
1107                         goto out;
1108         } else {
1109 lock_node:
1110                 ret = btree_node_lock_nopath(trans, &b->c, SIX_LOCK_read, _THIS_IP_);
1111                 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
1112                         return ERR_PTR(ret);
1113
1114                 BUG_ON(ret);
1115
1116                 if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
1117                              b->c.btree_id != btree_id ||
1118                              b->c.level != level)) {
1119                         six_unlock_read(&b->c.lock);
1120                         goto retry;
1121                 }
1122         }
1123
1124         /* XXX: waiting on IO with btree locks held: */
1125         __bch2_btree_node_wait_on_read(b);
1126
1127         prefetch(b->aux_data);
1128
1129         for_each_bset(b, t) {
1130                 void *p = (u64 *) b->aux_data + t->aux_data_offset;
1131
1132                 prefetch(p + L1_CACHE_BYTES * 0);
1133                 prefetch(p + L1_CACHE_BYTES * 1);
1134                 prefetch(p + L1_CACHE_BYTES * 2);
1135         }
1136
1137         /* avoid atomic set bit if it's not needed: */
1138         if (!btree_node_accessed(b))
1139                 set_btree_node_accessed(b);
1140
1141         if (unlikely(btree_node_read_error(b))) {
1142                 six_unlock_read(&b->c.lock);
1143                 b = ERR_PTR(-EIO);
1144                 goto out;
1145         }
1146
1147         EBUG_ON(b->c.btree_id != btree_id);
1148         EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
1149         btree_check_header(c, b);
1150 out:
1151         bch2_btree_cache_cannibalize_unlock(c);
1152         return b;
1153 }
1154
1155 int bch2_btree_node_prefetch(struct btree_trans *trans,
1156                              struct btree_path *path,
1157                              const struct bkey_i *k,
1158                              enum btree_id btree_id, unsigned level)
1159 {
1160         struct bch_fs *c = trans->c;
1161         struct btree_cache *bc = &c->btree_cache;
1162         struct btree *b;
1163
1164         BUG_ON(trans && !btree_node_locked(path, level + 1));
1165         BUG_ON(level >= BTREE_MAX_DEPTH);
1166
1167         b = btree_cache_find(bc, k);
1168         if (b)
1169                 return 0;
1170
1171         b = bch2_btree_node_fill(trans, path, k, btree_id,
1172                                  level, SIX_LOCK_read, false);
1173         return PTR_ERR_OR_ZERO(b);
1174 }
1175
1176 void bch2_btree_node_evict(struct btree_trans *trans, const struct bkey_i *k)
1177 {
1178         struct bch_fs *c = trans->c;
1179         struct btree_cache *bc = &c->btree_cache;
1180         struct btree *b;
1181
1182         b = btree_cache_find(bc, k);
1183         if (!b)
1184                 return;
1185 wait_on_io:
1186         /* not allowed to wait on io with btree locks held: */
1187
1188         /* XXX we're called from btree_gc which will be holding other btree
1189          * nodes locked
1190          */
1191         __bch2_btree_node_wait_on_read(b);
1192         __bch2_btree_node_wait_on_write(b);
1193
1194         btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_intent);
1195         btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_write);
1196
1197         if (btree_node_dirty(b)) {
1198                 __bch2_btree_node_write(c, b, BTREE_WRITE_cache_reclaim);
1199                 six_unlock_write(&b->c.lock);
1200                 six_unlock_intent(&b->c.lock);
1201                 goto wait_on_io;
1202         }
1203
1204         BUG_ON(btree_node_dirty(b));
1205
1206         mutex_lock(&bc->lock);
1207         btree_node_data_free(c, b);
1208         bch2_btree_node_hash_remove(bc, b);
1209         mutex_unlock(&bc->lock);
1210
1211         six_unlock_write(&b->c.lock);
1212         six_unlock_intent(&b->c.lock);
1213 }
1214
1215 void bch2_btree_node_to_text(struct printbuf *out, struct bch_fs *c,
1216                              const struct btree *b)
1217 {
1218         const struct bkey_format *f = &b->format;
1219         struct bset_stats stats;
1220
1221         memset(&stats, 0, sizeof(stats));
1222
1223         bch2_btree_keys_stats(b, &stats);
1224
1225         prt_printf(out, "l %u ", b->c.level);
1226         bch2_bpos_to_text(out, b->data->min_key);
1227         prt_printf(out, " - ");
1228         bch2_bpos_to_text(out, b->data->max_key);
1229         prt_printf(out, ":\n"
1230                "    ptrs: ");
1231         bch2_val_to_text(out, c, bkey_i_to_s_c(&b->key));
1232
1233         prt_printf(out, "\n"
1234                "    format: u64s %u fields %u %u %u %u %u\n"
1235                "    unpack fn len: %u\n"
1236                "    bytes used %zu/%zu (%zu%% full)\n"
1237                "    sib u64s: %u, %u (merge threshold %u)\n"
1238                "    nr packed keys %u\n"
1239                "    nr unpacked keys %u\n"
1240                "    floats %zu\n"
1241                "    failed unpacked %zu\n",
1242                f->key_u64s,
1243                f->bits_per_field[0],
1244                f->bits_per_field[1],
1245                f->bits_per_field[2],
1246                f->bits_per_field[3],
1247                f->bits_per_field[4],
1248                b->unpack_fn_len,
1249                b->nr.live_u64s * sizeof(u64),
1250                btree_bytes(c) - sizeof(struct btree_node),
1251                b->nr.live_u64s * 100 / btree_max_u64s(c),
1252                b->sib_u64s[0],
1253                b->sib_u64s[1],
1254                c->btree_foreground_merge_threshold,
1255                b->nr.packed_keys,
1256                b->nr.unpacked_keys,
1257                stats.floats,
1258                stats.failed);
1259 }
1260
1261 void bch2_btree_cache_to_text(struct printbuf *out, const struct btree_cache *bc)
1262 {
1263         prt_printf(out, "nr nodes:\t\t%u\n", bc->used);
1264         prt_printf(out, "nr dirty:\t\t%u\n", atomic_read(&bc->dirty));
1265         prt_printf(out, "cannibalize lock:\t%p\n", bc->alloc_lock);
1266
1267         prt_printf(out, "freed:\t\t\t\t%u\n", bc->freed);
1268         prt_printf(out, "not freed, dirty:\t\t%u\n", bc->not_freed_dirty);
1269         prt_printf(out, "not freed, write in flight:\t%u\n", bc->not_freed_write_in_flight);
1270         prt_printf(out, "not freed, read in flight:\t%u\n", bc->not_freed_read_in_flight);
1271         prt_printf(out, "not freed, lock intent failed:\t%u\n", bc->not_freed_lock_intent);
1272         prt_printf(out, "not freed, lock write failed:\t%u\n", bc->not_freed_lock_write);
1273         prt_printf(out, "not freed, access bit:\t\t%u\n", bc->not_freed_access_bit);
1274         prt_printf(out, "not freed, no evict failed:\t%u\n", bc->not_freed_noevict);
1275         prt_printf(out, "not freed, write blocked:\t%u\n", bc->not_freed_write_blocked);
1276         prt_printf(out, "not freed, will make reachable:\t%u\n", bc->not_freed_will_make_reachable);
1277
1278 }