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         unregister_shrinker(&bc->shrink);
 450
 451         /* vfree() can allocate memory: */
 452         flags = memalloc_nofs_save();
 453         mutex_lock(&bc->lock);
 454
 455         if (c->verify_data)
 456                 list_move(&c->verify_data->list, &bc->live);
 457
 458         kvpfree(c->verify_ondisk, btree_bytes(c));
 459
 460         for (i = 0; i < BTREE_ID_NR; i++)
 461                 if (c->btree_roots[i].b)
 462                         list_add(&c->btree_roots[i].b->list, &bc->live);
 463
 464         list_splice(&bc->freeable, &bc->live);
 465
 466         while (!list_empty(&bc->live)) {
 467                 b = list_first_entry(&bc->live, struct btree, list);
 468
 469                 BUG_ON(btree_node_read_in_flight(b) ||
 470                        btree_node_write_in_flight(b));
 471
 472                 if (btree_node_dirty(b))
 473                         bch2_btree_complete_write(c, b, btree_current_write(b));
 474                 clear_btree_node_dirty_acct(c, b);
 475
 476                 btree_node_data_free(c, b);
 477         }
 478
 479         BUG_ON(atomic_read(&c->btree_cache.dirty));
 480
 481         list_splice(&bc->freed_pcpu, &bc->freed_nonpcpu);
 482
 483         while (!list_empty(&bc->freed_nonpcpu)) {
 484                 b = list_first_entry(&bc->freed_nonpcpu, struct btree, list);
 485                 list_del(&b->list);
 486                 six_lock_exit(&b->c.lock);
 487                 kfree(b);
 488         }
 489
 490         mutex_unlock(&bc->lock);
 491         memalloc_nofs_restore(flags);
 492
 493         if (bc->table_init_done)
 494                 rhashtable_destroy(&bc->table);
 495 }
 496
 497 int bch2_fs_btree_cache_init(struct bch_fs *c)
 498 {
 499         struct btree_cache *bc = &c->btree_cache;
 500         unsigned i;
 501         int ret = 0;
 502
 503         pr_verbose_init(c->opts, "");
 504
 505         ret = rhashtable_init(&bc->table, &bch_btree_cache_params);
 506         if (ret)
 507                 goto out;
 508
 509         bc->table_init_done = true;
 510
 511         bch2_recalc_btree_reserve(c);
 512
 513         for (i = 0; i < bc->reserve; i++)
 514                 if (!__bch2_btree_node_mem_alloc(c)) {
 515                         ret = -BCH_ERR_ENOMEM_fs_btree_cache_init;
 516                         goto out;
 517                 }
 518
 519         list_splice_init(&bc->live, &bc->freeable);
 520
 521         mutex_init(&c->verify_lock);
 522
 523         bc->shrink.count_objects        = bch2_btree_cache_count;
 524         bc->shrink.scan_objects         = bch2_btree_cache_scan;
 525         bc->shrink.to_text              = bch2_btree_cache_shrinker_to_text;
 526         bc->shrink.seeks                = 4;
 527         ret = register_shrinker(&bc->shrink, "%s/btree_cache", c->name);
 528 out:
 529         pr_verbose_init(c->opts, "ret %i", ret);
 530         return ret;
 531 }
 532
 533 void bch2_fs_btree_cache_init_early(struct btree_cache *bc)
 534 {
 535         mutex_init(&bc->lock);
 536         INIT_LIST_HEAD(&bc->live);
 537         INIT_LIST_HEAD(&bc->freeable);
 538         INIT_LIST_HEAD(&bc->freed_pcpu);
 539         INIT_LIST_HEAD(&bc->freed_nonpcpu);
 540 }
 541
 542 /*
 543  * We can only have one thread cannibalizing other cached btree nodes at a time,
 544  * or we'll deadlock. We use an open coded mutex to ensure that, which a
 545  * cannibalize_bucket() will take. This means every time we unlock the root of
 546  * the btree, we need to release this lock if we have it held.
 547  */
 548 void bch2_btree_cache_cannibalize_unlock(struct bch_fs *c)
 549 {
 550         struct btree_cache *bc = &c->btree_cache;
 551
 552         if (bc->alloc_lock == current) {
 553                 trace_and_count(c, btree_cache_cannibalize_unlock, c);
 554                 bc->alloc_lock = NULL;
 555                 closure_wake_up(&bc->alloc_wait);
 556         }
 557 }
 558
 559 int bch2_btree_cache_cannibalize_lock(struct bch_fs *c, struct closure *cl)
 560 {
 561         struct btree_cache *bc = &c->btree_cache;
 562         struct task_struct *old;
 563
 564         old = cmpxchg(&bc->alloc_lock, NULL, current);
 565         if (old == NULL || old == current)
 566                 goto success;
 567
 568         if (!cl) {
 569                 trace_and_count(c, btree_cache_cannibalize_lock_fail, c);
 570                 return -BCH_ERR_ENOMEM_btree_cache_cannibalize_lock;
 571         }
 572
 573         closure_wait(&bc->alloc_wait, cl);
 574
 575         /* Try again, after adding ourselves to waitlist */
 576         old = cmpxchg(&bc->alloc_lock, NULL, current);
 577         if (old == NULL || old == current) {
 578                 /* We raced */
 579                 closure_wake_up(&bc->alloc_wait);
 580                 goto success;
 581         }
 582
 583         trace_and_count(c, btree_cache_cannibalize_lock_fail, c);
 584         return -BCH_ERR_btree_cache_cannibalize_lock_blocked;
 585
 586 success:
 587         trace_and_count(c, btree_cache_cannibalize_lock, c);
 588         return 0;
 589 }
 590
 591 static struct btree *btree_node_cannibalize(struct bch_fs *c)
 592 {
 593         struct btree_cache *bc = &c->btree_cache;
 594         struct btree *b;
 595
 596         list_for_each_entry_reverse(b, &bc->live, list)
 597                 if (!btree_node_reclaim(c, b, false))
 598                         return b;
 599
 600         while (1) {
 601                 list_for_each_entry_reverse(b, &bc->live, list)
 602                         if (!btree_node_write_and_reclaim(c, b))
 603                                 return b;
 604
 605                 /*
 606                  * Rare case: all nodes were intent-locked.
 607                  * Just busy-wait.
 608                  */
 609                 WARN_ONCE(1, "btree cache cannibalize failed\n");
 610                 cond_resched();
 611         }
 612 }
 613
 614 struct btree *bch2_btree_node_mem_alloc(struct btree_trans *trans, bool pcpu_read_locks)
 615 {
 616         struct bch_fs *c = trans->c;
 617         struct btree_cache *bc = &c->btree_cache;
 618         struct list_head *freed = pcpu_read_locks
 619                 ? &bc->freed_pcpu
 620                 : &bc->freed_nonpcpu;
 621         struct btree *b, *b2;
 622         u64 start_time = local_clock();
 623         unsigned flags;
 624
 625         flags = memalloc_nofs_save();
 626         mutex_lock(&bc->lock);
 627
 628         /*
 629          * We never free struct btree itself, just the memory that holds the on
 630          * disk node. Check the freed list before allocating a new one:
 631          */
 632         list_for_each_entry(b, freed, list)
 633                 if (!btree_node_reclaim(c, b, false)) {
 634                         list_del_init(&b->list);
 635                         goto got_node;
 636                 }
 637
 638         b = __btree_node_mem_alloc(c, GFP_NOWAIT|__GFP_NOWARN);
 639         if (!b) {
 640                 mutex_unlock(&bc->lock);
 641                 bch2_trans_unlock(trans);
 642                 b = __btree_node_mem_alloc(c, GFP_KERNEL);
 643                 if (!b)
 644                         goto err;
 645                 mutex_lock(&bc->lock);
 646         }
 647
 648         bch2_btree_lock_init(&b->c, pcpu_read_locks ? SIX_LOCK_INIT_PCPU : 0);
 649
 650         BUG_ON(!six_trylock_intent(&b->c.lock));
 651         BUG_ON(!six_trylock_write(&b->c.lock));
 652 got_node:
 653
 654         /*
 655          * btree_free() doesn't free memory; it sticks the node on the end of
 656          * the list. Check if there's any freed nodes there:
 657          */
 658         list_for_each_entry(b2, &bc->freeable, list)
 659                 if (!btree_node_reclaim(c, b2, false)) {
 660                         swap(b->data, b2->data);
 661                         swap(b->aux_data, b2->aux_data);
 662                         btree_node_to_freedlist(bc, b2);
 663                         six_unlock_write(&b2->c.lock);
 664                         six_unlock_intent(&b2->c.lock);
 665                         goto got_mem;
 666                 }
 667
 668         mutex_unlock(&bc->lock);
 669
 670         if (btree_node_data_alloc(c, b, GFP_NOWAIT|__GFP_NOWARN)) {
 671                 bch2_trans_unlock(trans);
 672                 if (btree_node_data_alloc(c, b, GFP_KERNEL|__GFP_NOWARN))
 673                         goto err;
 674         }
 675
 676         mutex_lock(&bc->lock);
 677         bc->used++;
 678 got_mem:
 679         mutex_unlock(&bc->lock);
 680
 681         BUG_ON(btree_node_hashed(b));
 682         BUG_ON(btree_node_dirty(b));
 683         BUG_ON(btree_node_write_in_flight(b));
 684 out:
 685         b->flags                = 0;
 686         b->written              = 0;
 687         b->nsets                = 0;
 688         b->sib_u64s[0]          = 0;
 689         b->sib_u64s[1]          = 0;
 690         b->whiteout_u64s        = 0;
 691         bch2_btree_keys_init(b);
 692         set_btree_node_accessed(b);
 693
 694         bch2_time_stats_update(&c->times[BCH_TIME_btree_node_mem_alloc],
 695                                start_time);
 696
 697         memalloc_nofs_restore(flags);
 698         return b;
 699 err:
 700         mutex_lock(&bc->lock);
 701
 702         /* Try to cannibalize another cached btree node: */
 703         if (bc->alloc_lock == current) {
 704                 b2 = btree_node_cannibalize(c);
 705                 clear_btree_node_just_written(b2);
 706                 bch2_btree_node_hash_remove(bc, b2);
 707
 708                 if (b) {
 709                         swap(b->data, b2->data);
 710                         swap(b->aux_data, b2->aux_data);
 711                         btree_node_to_freedlist(bc, b2);
 712                         six_unlock_write(&b2->c.lock);
 713                         six_unlock_intent(&b2->c.lock);
 714                 } else {
 715                         b = b2;
 716                         list_del_init(&b->list);
 717                 }
 718
 719                 mutex_unlock(&bc->lock);
 720
 721                 trace_and_count(c, btree_cache_cannibalize, c);
 722                 goto out;
 723         }
 724
 725         mutex_unlock(&bc->lock);
 726         memalloc_nofs_restore(flags);
 727         return ERR_PTR(-BCH_ERR_ENOMEM_btree_node_mem_alloc);
 728 }
 729
 730 /* Slowpath, don't want it inlined into btree_iter_traverse() */
 731 static noinline struct btree *bch2_btree_node_fill(struct btree_trans *trans,
 732                                 struct btree_path *path,
 733                                 const struct bkey_i *k,
 734                                 enum btree_id btree_id,
 735                                 unsigned level,
 736                                 enum six_lock_type lock_type,
 737                                 bool sync)
 738 {
 739         struct bch_fs *c = trans->c;
 740         struct btree_cache *bc = &c->btree_cache;
 741         struct btree *b;
 742         u32 seq;
 743
 744         BUG_ON(level + 1 >= BTREE_MAX_DEPTH);
 745         /*
 746          * Parent node must be locked, else we could read in a btree node that's
 747          * been freed:
 748          */
 749         if (path && !bch2_btree_node_relock(trans, path, level + 1)) {
 750                 trace_and_count(c, trans_restart_relock_parent_for_fill, trans, _THIS_IP_, path);
 751                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_fill_relock));
 752         }
 753
 754         b = bch2_btree_node_mem_alloc(trans, level != 0);
 755
 756         if (bch2_err_matches(PTR_ERR_OR_ZERO(b), ENOMEM)) {
 757                 trans->memory_allocation_failure = true;
 758                 trace_and_count(c, trans_restart_memory_allocation_failure, trans, _THIS_IP_, path);
 759                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_fill_mem_alloc_fail));
 760         }
 761
 762         if (IS_ERR(b))
 763                 return b;
 764
 765         /*
 766          * Btree nodes read in from disk should not have the accessed bit set
 767          * initially, so that linear scans don't thrash the cache:
 768          */
 769         clear_btree_node_accessed(b);
 770
 771         bkey_copy(&b->key, k);
 772         if (bch2_btree_node_hash_insert(bc, b, level, btree_id)) {
 773                 /* raced with another fill: */
 774
 775                 /* mark as unhashed... */
 776                 b->hash_val = 0;
 777
 778                 mutex_lock(&bc->lock);
 779                 list_add(&b->list, &bc->freeable);
 780                 mutex_unlock(&bc->lock);
 781
 782                 six_unlock_write(&b->c.lock);
 783                 six_unlock_intent(&b->c.lock);
 784                 return NULL;
 785         }
 786
 787         set_btree_node_read_in_flight(b);
 788
 789         six_unlock_write(&b->c.lock);
 790         seq = six_lock_seq(&b->c.lock);
 791         six_unlock_intent(&b->c.lock);
 792
 793         /* Unlock before doing IO: */
 794         if (trans && sync)
 795                 bch2_trans_unlock_noassert(trans);
 796
 797         bch2_btree_node_read(c, b, sync);
 798
 799         if (!sync)
 800                 return NULL;
 801
 802         if (path) {
 803                 int ret = bch2_trans_relock(trans) ?:
 804                         bch2_btree_path_relock_intent(trans, path);
 805                 if (ret) {
 806                         BUG_ON(!trans->restarted);
 807                         return ERR_PTR(ret);
 808                 }
 809         }
 810
 811         if (!six_relock_type(&b->c.lock, lock_type, seq)) {
 812                 if (path)
 813                         trace_and_count(c, trans_restart_relock_after_fill, trans, _THIS_IP_, path);
 814                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_relock_after_fill));
 815         }
 816
 817         return b;
 818 }
 819
 820 static noinline void btree_bad_header(struct bch_fs *c, struct btree *b)
 821 {
 822         struct printbuf buf = PRINTBUF;
 823
 824         if (!test_bit(BCH_FS_INITIAL_GC_DONE, &c->flags))
 825                 return;
 826
 827         prt_printf(&buf,
 828                "btree node header doesn't match ptr\n"
 829                "btree %s level %u\n"
 830                "ptr: ",
 831                bch2_btree_ids[b->c.btree_id], b->c.level);
 832         bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
 833
 834         prt_printf(&buf, "\nheader: btree %s level %llu\n"
 835                "min ",
 836                bch2_btree_ids[BTREE_NODE_ID(b->data)],
 837                BTREE_NODE_LEVEL(b->data));
 838         bch2_bpos_to_text(&buf, b->data->min_key);
 839
 840         prt_printf(&buf, "\nmax ");
 841         bch2_bpos_to_text(&buf, b->data->max_key);
 842
 843         bch2_fs_inconsistent(c, "%s", buf.buf);
 844         printbuf_exit(&buf);
 845 }
 846
 847 static inline void btree_check_header(struct bch_fs *c, struct btree *b)
 848 {
 849         if (b->c.btree_id != BTREE_NODE_ID(b->data) ||
 850             b->c.level != BTREE_NODE_LEVEL(b->data) ||
 851             !bpos_eq(b->data->max_key, b->key.k.p) ||
 852             (b->key.k.type == KEY_TYPE_btree_ptr_v2 &&
 853              !bpos_eq(b->data->min_key,
 854                       bkey_i_to_btree_ptr_v2(&b->key)->v.min_key)))
 855                 btree_bad_header(c, b);
 856 }
 857
 858 static struct btree *__bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
 859                                            const struct bkey_i *k, unsigned level,
 860                                            enum six_lock_type lock_type,
 861                                            unsigned long trace_ip)
 862 {
 863         struct bch_fs *c = trans->c;
 864         struct btree_cache *bc = &c->btree_cache;
 865         struct btree *b;
 866         struct bset_tree *t;
 867         bool need_relock = false;
 868         int ret;
 869
 870         EBUG_ON(level >= BTREE_MAX_DEPTH);
 871 retry:
 872         b = btree_cache_find(bc, k);
 873         if (unlikely(!b)) {
 874                 /*
 875                  * We must have the parent locked to call bch2_btree_node_fill(),
 876                  * else we could read in a btree node from disk that's been
 877                  * freed:
 878                  */
 879                 b = bch2_btree_node_fill(trans, path, k, path->btree_id,
 880                                          level, lock_type, true);
 881                 need_relock = true;
 882
 883                 /* We raced and found the btree node in the cache */
 884                 if (!b)
 885                         goto retry;
 886
 887                 if (IS_ERR(b))
 888                         return b;
 889         } else {
 890                 if (btree_node_read_locked(path, level + 1))
 891                         btree_node_unlock(trans, path, level + 1);
 892
 893                 ret = btree_node_lock(trans, path, &b->c, level, lock_type, trace_ip);
 894                 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 895                         return ERR_PTR(ret);
 896
 897                 BUG_ON(ret);
 898
 899                 if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
 900                              b->c.level != level ||
 901                              race_fault())) {
 902                         six_unlock_type(&b->c.lock, lock_type);
 903                         if (bch2_btree_node_relock(trans, path, level + 1))
 904                                 goto retry;
 905
 906                         trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
 907                         return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_lock_node_reused));
 908                 }
 909
 910                 /* avoid atomic set bit if it's not needed: */
 911                 if (!btree_node_accessed(b))
 912                         set_btree_node_accessed(b);
 913         }
 914
 915         if (unlikely(btree_node_read_in_flight(b))) {
 916                 u32 seq = six_lock_seq(&b->c.lock);
 917
 918                 six_unlock_type(&b->c.lock, lock_type);
 919                 bch2_trans_unlock(trans);
 920                 need_relock = true;
 921
 922                 bch2_btree_node_wait_on_read(b);
 923
 924                 /*
 925                  * should_be_locked is not set on this path yet, so we need to
 926                  * relock it specifically:
 927                  */
 928                 if (!six_relock_type(&b->c.lock, lock_type, seq))
 929                         goto retry;
 930         }
 931
 932         if (unlikely(need_relock)) {
 933                 int ret = bch2_trans_relock(trans) ?:
 934                         bch2_btree_path_relock_intent(trans, path);
 935                 if (ret) {
 936                         six_unlock_type(&b->c.lock, lock_type);
 937                         return ERR_PTR(ret);
 938                 }
 939         }
 940
 941         prefetch(b->aux_data);
 942
 943         for_each_bset(b, t) {
 944                 void *p = (u64 *) b->aux_data + t->aux_data_offset;
 945
 946                 prefetch(p + L1_CACHE_BYTES * 0);
 947                 prefetch(p + L1_CACHE_BYTES * 1);
 948                 prefetch(p + L1_CACHE_BYTES * 2);
 949         }
 950
 951         if (unlikely(btree_node_read_error(b))) {
 952                 six_unlock_type(&b->c.lock, lock_type);
 953                 return ERR_PTR(-EIO);
 954         }
 955
 956         EBUG_ON(b->c.btree_id != path->btree_id);
 957         EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
 958         btree_check_header(c, b);
 959
 960         return b;
 961 }
 962
 963 /**
 964  * bch_btree_node_get - find a btree node in the cache and lock it, reading it
 965  * in from disk if necessary.
 966  *
 967  * The btree node will have either a read or a write lock held, depending on
 968  * the @write parameter.
 969  */
 970 struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
 971                                   const struct bkey_i *k, unsigned level,
 972                                   enum six_lock_type lock_type,
 973                                   unsigned long trace_ip)
 974 {
 975         struct bch_fs *c = trans->c;
 976         struct btree *b;
 977         struct bset_tree *t;
 978         int ret;
 979
 980         EBUG_ON(level >= BTREE_MAX_DEPTH);
 981
 982         b = btree_node_mem_ptr(k);
 983
 984         /*
 985          * Check b->hash_val _before_ calling btree_node_lock() - this might not
 986          * be the node we want anymore, and trying to lock the wrong node could
 987          * cause an unneccessary transaction restart:
 988          */
 989         if (unlikely(!c->opts.btree_node_mem_ptr_optimization ||
 990                      !b ||
 991                      b->hash_val != btree_ptr_hash_val(k)))
 992                 return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
 993
 994         if (btree_node_read_locked(path, level + 1))
 995                 btree_node_unlock(trans, path, level + 1);
 996
 997         ret = btree_node_lock(trans, path, &b->c, level, lock_type, trace_ip);
 998         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 999                 return ERR_PTR(ret);
1000
1001         BUG_ON(ret);
1002
1003         if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
1004                      b->c.level != level ||
1005                      race_fault())) {
1006                 six_unlock_type(&b->c.lock, lock_type);
1007                 if (bch2_btree_node_relock(trans, path, level + 1))
1008                         return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
1009
1010                 trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
1011                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_lock_node_reused));
1012         }
1013
1014         if (unlikely(btree_node_read_in_flight(b))) {
1015                 u32 seq = six_lock_seq(&b->c.lock);
1016
1017                 six_unlock_type(&b->c.lock, lock_type);
1018                 bch2_trans_unlock(trans);
1019
1020                 bch2_btree_node_wait_on_read(b);
1021
1022                 /*
1023                  * should_be_locked is not set on this path yet, so we need to
1024                  * relock it specifically:
1025                  */
1026                 if (trans) {
1027                         int ret = bch2_trans_relock(trans) ?:
1028                                 bch2_btree_path_relock_intent(trans, path);
1029                         if (ret) {
1030                                 BUG_ON(!trans->restarted);
1031                                 return ERR_PTR(ret);
1032                         }
1033                 }
1034
1035                 if (!six_relock_type(&b->c.lock, lock_type, seq))
1036                         return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
1037         }
1038
1039         prefetch(b->aux_data);
1040
1041         for_each_bset(b, t) {
1042                 void *p = (u64 *) b->aux_data + t->aux_data_offset;
1043
1044                 prefetch(p + L1_CACHE_BYTES * 0);
1045                 prefetch(p + L1_CACHE_BYTES * 1);
1046                 prefetch(p + L1_CACHE_BYTES * 2);
1047         }
1048
1049         /* avoid atomic set bit if it's not needed: */
1050         if (!btree_node_accessed(b))
1051                 set_btree_node_accessed(b);
1052
1053         if (unlikely(btree_node_read_error(b))) {
1054                 six_unlock_type(&b->c.lock, lock_type);
1055                 return ERR_PTR(-EIO);
1056         }
1057
1058         EBUG_ON(b->c.btree_id != path->btree_id);
1059         EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
1060         btree_check_header(c, b);
1061
1062         return b;
1063 }
1064
1065 struct btree *bch2_btree_node_get_noiter(struct btree_trans *trans,
1066                                          const struct bkey_i *k,
1067                                          enum btree_id btree_id,
1068                                          unsigned level,
1069                                          bool nofill)
1070 {
1071         struct bch_fs *c = trans->c;
1072         struct btree_cache *bc = &c->btree_cache;
1073         struct btree *b;
1074         struct bset_tree *t;
1075         int ret;
1076
1077         EBUG_ON(level >= BTREE_MAX_DEPTH);
1078
1079         if (c->opts.btree_node_mem_ptr_optimization) {
1080                 b = btree_node_mem_ptr(k);
1081                 if (b)
1082                         goto lock_node;
1083         }
1084 retry:
1085         b = btree_cache_find(bc, k);
1086         if (unlikely(!b)) {
1087                 if (nofill)
1088                         goto out;
1089
1090                 b = bch2_btree_node_fill(trans, NULL, k, btree_id,
1091                                          level, SIX_LOCK_read, true);
1092
1093                 /* We raced and found the btree node in the cache */
1094                 if (!b)
1095                         goto retry;
1096
1097                 if (IS_ERR(b) &&
1098                     !bch2_btree_cache_cannibalize_lock(c, NULL))
1099                         goto retry;
1100
1101                 if (IS_ERR(b))
1102                         goto out;
1103         } else {
1104 lock_node:
1105                 ret = btree_node_lock_nopath(trans, &b->c, SIX_LOCK_read, _THIS_IP_);
1106                 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
1107                         return ERR_PTR(ret);
1108
1109                 BUG_ON(ret);
1110
1111                 if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
1112                              b->c.btree_id != btree_id ||
1113                              b->c.level != level)) {
1114                         six_unlock_read(&b->c.lock);
1115                         goto retry;
1116                 }
1117         }
1118
1119         /* XXX: waiting on IO with btree locks held: */
1120         __bch2_btree_node_wait_on_read(b);
1121
1122         prefetch(b->aux_data);
1123
1124         for_each_bset(b, t) {
1125                 void *p = (u64 *) b->aux_data + t->aux_data_offset;
1126
1127                 prefetch(p + L1_CACHE_BYTES * 0);
1128                 prefetch(p + L1_CACHE_BYTES * 1);
1129                 prefetch(p + L1_CACHE_BYTES * 2);
1130         }
1131
1132         /* avoid atomic set bit if it's not needed: */
1133         if (!btree_node_accessed(b))
1134                 set_btree_node_accessed(b);
1135
1136         if (unlikely(btree_node_read_error(b))) {
1137                 six_unlock_read(&b->c.lock);
1138                 b = ERR_PTR(-EIO);
1139                 goto out;
1140         }
1141
1142         EBUG_ON(b->c.btree_id != btree_id);
1143         EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
1144         btree_check_header(c, b);
1145 out:
1146         bch2_btree_cache_cannibalize_unlock(c);
1147         return b;
1148 }
1149
1150 int bch2_btree_node_prefetch(struct btree_trans *trans,
1151                              struct btree_path *path,
1152                              const struct bkey_i *k,
1153                              enum btree_id btree_id, unsigned level)
1154 {
1155         struct bch_fs *c = trans->c;
1156         struct btree_cache *bc = &c->btree_cache;
1157         struct btree *b;
1158
1159         BUG_ON(trans && !btree_node_locked(path, level + 1));
1160         BUG_ON(level >= BTREE_MAX_DEPTH);
1161
1162         b = btree_cache_find(bc, k);
1163         if (b)
1164                 return 0;
1165
1166         b = bch2_btree_node_fill(trans, path, k, btree_id,
1167                                  level, SIX_LOCK_read, false);
1168         return PTR_ERR_OR_ZERO(b);
1169 }
1170
1171 void bch2_btree_node_evict(struct btree_trans *trans, const struct bkey_i *k)
1172 {
1173         struct bch_fs *c = trans->c;
1174         struct btree_cache *bc = &c->btree_cache;
1175         struct btree *b;
1176
1177         b = btree_cache_find(bc, k);
1178         if (!b)
1179                 return;
1180 wait_on_io:
1181         /* not allowed to wait on io with btree locks held: */
1182
1183         /* XXX we're called from btree_gc which will be holding other btree
1184          * nodes locked
1185          */
1186         __bch2_btree_node_wait_on_read(b);
1187         __bch2_btree_node_wait_on_write(b);
1188
1189         btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_intent);
1190         btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_write);
1191
1192         if (btree_node_dirty(b)) {
1193                 __bch2_btree_node_write(c, b, BTREE_WRITE_cache_reclaim);
1194                 six_unlock_write(&b->c.lock);
1195                 six_unlock_intent(&b->c.lock);
1196                 goto wait_on_io;
1197         }
1198
1199         BUG_ON(btree_node_dirty(b));
1200
1201         mutex_lock(&bc->lock);
1202         btree_node_data_free(c, b);
1203         bch2_btree_node_hash_remove(bc, b);
1204         mutex_unlock(&bc->lock);
1205
1206         six_unlock_write(&b->c.lock);
1207         six_unlock_intent(&b->c.lock);
1208 }
1209
1210 void bch2_btree_node_to_text(struct printbuf *out, struct bch_fs *c,
1211                              const struct btree *b)
1212 {
1213         const struct bkey_format *f = &b->format;
1214         struct bset_stats stats;
1215
1216         memset(&stats, 0, sizeof(stats));
1217
1218         bch2_btree_keys_stats(b, &stats);
1219
1220         prt_printf(out, "l %u ", b->c.level);
1221         bch2_bpos_to_text(out, b->data->min_key);
1222         prt_printf(out, " - ");
1223         bch2_bpos_to_text(out, b->data->max_key);
1224         prt_printf(out, ":\n"
1225                "    ptrs: ");
1226         bch2_val_to_text(out, c, bkey_i_to_s_c(&b->key));
1227
1228         prt_printf(out, "\n"
1229                "    format: u64s %u fields %u %u %u %u %u\n"
1230                "    unpack fn len: %u\n"
1231                "    bytes used %zu/%zu (%zu%% full)\n"
1232                "    sib u64s: %u, %u (merge threshold %u)\n"
1233                "    nr packed keys %u\n"
1234                "    nr unpacked keys %u\n"
1235                "    floats %zu\n"
1236                "    failed unpacked %zu\n",
1237                f->key_u64s,
1238                f->bits_per_field[0],
1239                f->bits_per_field[1],
1240                f->bits_per_field[2],
1241                f->bits_per_field[3],
1242                f->bits_per_field[4],
1243                b->unpack_fn_len,
1244                b->nr.live_u64s * sizeof(u64),
1245                btree_bytes(c) - sizeof(struct btree_node),
1246                b->nr.live_u64s * 100 / btree_max_u64s(c),
1247                b->sib_u64s[0],
1248                b->sib_u64s[1],
1249                c->btree_foreground_merge_threshold,
1250                b->nr.packed_keys,
1251                b->nr.unpacked_keys,
1252                stats.floats,
1253                stats.failed);
1254 }
1255
1256 void bch2_btree_cache_to_text(struct printbuf *out, const struct btree_cache *bc)
1257 {
1258         prt_printf(out, "nr nodes:\t\t%u\n", bc->used);
1259         prt_printf(out, "nr dirty:\t\t%u\n", atomic_read(&bc->dirty));
1260         prt_printf(out, "cannibalize lock:\t%p\n", bc->alloc_lock);
1261
1262         prt_printf(out, "freed:\t\t\t\t%u\n", bc->freed);
1263         prt_printf(out, "not freed, dirty:\t\t%u\n", bc->not_freed_dirty);
1264         prt_printf(out, "not freed, write in flight:\t%u\n", bc->not_freed_write_in_flight);
1265         prt_printf(out, "not freed, read in flight:\t%u\n", bc->not_freed_read_in_flight);
1266         prt_printf(out, "not freed, lock intent failed:\t%u\n", bc->not_freed_lock_intent);
1267         prt_printf(out, "not freed, lock write failed:\t%u\n", bc->not_freed_lock_write);
1268         prt_printf(out, "not freed, access bit:\t\t%u\n", bc->not_freed_access_bit);
1269         prt_printf(out, "not freed, no evict failed:\t%u\n", bc->not_freed_noevict);
1270         prt_printf(out, "not freed, write blocked:\t%u\n", bc->not_freed_write_blocked);
1271         prt_printf(out, "not freed, will make reachable:\t%u\n", bc->not_freed_will_make_reachable);
1272
1273 }