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