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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "bkey_methods.h"
   5 #include "bkey_buf.h"
   6 #include "btree_cache.h"
   7 #include "btree_iter.h"
   8 #include "btree_journal_iter.h"
   9 #include "btree_key_cache.h"
  10 #include "btree_locking.h"
  11 #include "btree_update.h"
  12 #include "debug.h"
  13 #include "error.h"
  14 #include "extents.h"
  15 #include "journal.h"
  16 #include "journal_io.h"
  17 #include "replicas.h"
  18 #include "snapshot.h"
  19 #include "trace.h"
  20
  21 #include <linux/random.h>
  22 #include <linux/prefetch.h>
  23
  24 static inline void btree_path_list_remove(struct btree_trans *, struct btree_path *);
  25 static inline void btree_path_list_add(struct btree_trans *,
  26                         btree_path_idx_t, btree_path_idx_t);
  27
  28 static inline unsigned long btree_iter_ip_allocated(struct btree_iter *iter)
  29 {
  30 #ifdef TRACK_PATH_ALLOCATED
  31         return iter->ip_allocated;
  32 #else
  33         return 0;
  34 #endif
  35 }
  36
  37 static btree_path_idx_t btree_path_alloc(struct btree_trans *, btree_path_idx_t);
  38 static void bch2_trans_srcu_lock(struct btree_trans *);
  39
  40 static inline int __btree_path_cmp(const struct btree_path *l,
  41                                    enum btree_id        r_btree_id,
  42                                    bool                 r_cached,
  43                                    struct bpos          r_pos,
  44                                    unsigned             r_level)
  45 {
  46         /*
  47          * Must match lock ordering as defined by __bch2_btree_node_lock:
  48          */
  49         return   cmp_int(l->btree_id,   r_btree_id) ?:
  50                  cmp_int((int) l->cached,       (int) r_cached) ?:
  51                  bpos_cmp(l->pos,       r_pos) ?:
  52                 -cmp_int(l->level,      r_level);
  53 }
  54
  55 static inline int btree_path_cmp(const struct btree_path *l,
  56                                  const struct btree_path *r)
  57 {
  58         return __btree_path_cmp(l, r->btree_id, r->cached, r->pos, r->level);
  59 }
  60
  61 static inline struct bpos bkey_successor(struct btree_iter *iter, struct bpos p)
  62 {
  63         /* Are we iterating over keys in all snapshots? */
  64         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  65                 p = bpos_successor(p);
  66         } else {
  67                 p = bpos_nosnap_successor(p);
  68                 p.snapshot = iter->snapshot;
  69         }
  70
  71         return p;
  72 }
  73
  74 static inline struct bpos bkey_predecessor(struct btree_iter *iter, struct bpos p)
  75 {
  76         /* Are we iterating over keys in all snapshots? */
  77         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  78                 p = bpos_predecessor(p);
  79         } else {
  80                 p = bpos_nosnap_predecessor(p);
  81                 p.snapshot = iter->snapshot;
  82         }
  83
  84         return p;
  85 }
  86
  87 static inline struct bpos btree_iter_search_key(struct btree_iter *iter)
  88 {
  89         struct bpos pos = iter->pos;
  90
  91         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
  92             !bkey_eq(pos, POS_MAX))
  93                 pos = bkey_successor(iter, pos);
  94         return pos;
  95 }
  96
  97 static inline bool btree_path_pos_before_node(struct btree_path *path,
  98                                               struct btree *b)
  99 {
 100         return bpos_lt(path->pos, b->data->min_key);
 101 }
 102
 103 static inline bool btree_path_pos_after_node(struct btree_path *path,
 104                                              struct btree *b)
 105 {
 106         return bpos_gt(path->pos, b->key.k.p);
 107 }
 108
 109 static inline bool btree_path_pos_in_node(struct btree_path *path,
 110                                           struct btree *b)
 111 {
 112         return path->btree_id == b->c.btree_id &&
 113                 !btree_path_pos_before_node(path, b) &&
 114                 !btree_path_pos_after_node(path, b);
 115 }
 116
 117 /* Btree iterator: */
 118
 119 #ifdef CONFIG_BCACHEFS_DEBUG
 120
 121 static void bch2_btree_path_verify_cached(struct btree_trans *trans,
 122                                           struct btree_path *path)
 123 {
 124         struct bkey_cached *ck;
 125         bool locked = btree_node_locked(path, 0);
 126
 127         if (!bch2_btree_node_relock(trans, path, 0))
 128                 return;
 129
 130         ck = (void *) path->l[0].b;
 131         BUG_ON(ck->key.btree_id != path->btree_id ||
 132                !bkey_eq(ck->key.pos, path->pos));
 133
 134         if (!locked)
 135                 btree_node_unlock(trans, path, 0);
 136 }
 137
 138 static void bch2_btree_path_verify_level(struct btree_trans *trans,
 139                                 struct btree_path *path, unsigned level)
 140 {
 141         struct btree_path_level *l;
 142         struct btree_node_iter tmp;
 143         bool locked;
 144         struct bkey_packed *p, *k;
 145         struct printbuf buf1 = PRINTBUF;
 146         struct printbuf buf2 = PRINTBUF;
 147         struct printbuf buf3 = PRINTBUF;
 148         const char *msg;
 149
 150         if (!bch2_debug_check_iterators)
 151                 return;
 152
 153         l       = &path->l[level];
 154         tmp     = l->iter;
 155         locked  = btree_node_locked(path, level);
 156
 157         if (path->cached) {
 158                 if (!level)
 159                         bch2_btree_path_verify_cached(trans, path);
 160                 return;
 161         }
 162
 163         if (!btree_path_node(path, level))
 164                 return;
 165
 166         if (!bch2_btree_node_relock_notrace(trans, path, level))
 167                 return;
 168
 169         BUG_ON(!btree_path_pos_in_node(path, l->b));
 170
 171         bch2_btree_node_iter_verify(&l->iter, l->b);
 172
 173         /*
 174          * For interior nodes, the iterator will have skipped past deleted keys:
 175          */
 176         p = level
 177                 ? bch2_btree_node_iter_prev(&tmp, l->b)
 178                 : bch2_btree_node_iter_prev_all(&tmp, l->b);
 179         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 180
 181         if (p && bkey_iter_pos_cmp(l->b, p, &path->pos) >= 0) {
 182                 msg = "before";
 183                 goto err;
 184         }
 185
 186         if (k && bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 187                 msg = "after";
 188                 goto err;
 189         }
 190
 191         if (!locked)
 192                 btree_node_unlock(trans, path, level);
 193         return;
 194 err:
 195         bch2_bpos_to_text(&buf1, path->pos);
 196
 197         if (p) {
 198                 struct bkey uk = bkey_unpack_key(l->b, p);
 199
 200                 bch2_bkey_to_text(&buf2, &uk);
 201         } else {
 202                 prt_printf(&buf2, "(none)");
 203         }
 204
 205         if (k) {
 206                 struct bkey uk = bkey_unpack_key(l->b, k);
 207
 208                 bch2_bkey_to_text(&buf3, &uk);
 209         } else {
 210                 prt_printf(&buf3, "(none)");
 211         }
 212
 213         panic("path should be %s key at level %u:\n"
 214               "path pos %s\n"
 215               "prev key %s\n"
 216               "cur  key %s\n",
 217               msg, level, buf1.buf, buf2.buf, buf3.buf);
 218 }
 219
 220 static void bch2_btree_path_verify(struct btree_trans *trans,
 221                                    struct btree_path *path)
 222 {
 223         struct bch_fs *c = trans->c;
 224         unsigned i;
 225
 226         EBUG_ON(path->btree_id >= BTREE_ID_NR);
 227
 228         for (i = 0; i < (!path->cached ? BTREE_MAX_DEPTH : 1); i++) {
 229                 if (!path->l[i].b) {
 230                         BUG_ON(!path->cached &&
 231                                bch2_btree_id_root(c, path->btree_id)->b->c.level > i);
 232                         break;
 233                 }
 234
 235                 bch2_btree_path_verify_level(trans, path, i);
 236         }
 237
 238         bch2_btree_path_verify_locks(path);
 239 }
 240
 241 void bch2_trans_verify_paths(struct btree_trans *trans)
 242 {
 243         struct btree_path *path;
 244         unsigned iter;
 245
 246         trans_for_each_path(trans, path, iter)
 247                 bch2_btree_path_verify(trans, path);
 248 }
 249
 250 static void bch2_btree_iter_verify(struct btree_iter *iter)
 251 {
 252         struct btree_trans *trans = iter->trans;
 253
 254         BUG_ON(iter->btree_id >= BTREE_ID_NR);
 255
 256         BUG_ON(!!(iter->flags & BTREE_ITER_CACHED) != btree_iter_path(trans, iter)->cached);
 257
 258         BUG_ON((iter->flags & BTREE_ITER_IS_EXTENTS) &&
 259                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
 260
 261         BUG_ON(!(iter->flags & __BTREE_ITER_ALL_SNAPSHOTS) &&
 262                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 263                !btree_type_has_snapshot_field(iter->btree_id));
 264
 265         if (iter->update_path)
 266                 bch2_btree_path_verify(trans, &trans->paths[iter->update_path]);
 267         bch2_btree_path_verify(trans, btree_iter_path(trans, iter));
 268 }
 269
 270 static void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter)
 271 {
 272         BUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
 273                !iter->pos.snapshot);
 274
 275         BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 276                iter->pos.snapshot != iter->snapshot);
 277
 278         BUG_ON(bkey_lt(iter->pos, bkey_start_pos(&iter->k)) ||
 279                bkey_gt(iter->pos, iter->k.p));
 280 }
 281
 282 static int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k)
 283 {
 284         struct btree_trans *trans = iter->trans;
 285         struct btree_iter copy;
 286         struct bkey_s_c prev;
 287         int ret = 0;
 288
 289         if (!bch2_debug_check_iterators)
 290                 return 0;
 291
 292         if (!(iter->flags & BTREE_ITER_FILTER_SNAPSHOTS))
 293                 return 0;
 294
 295         if (bkey_err(k) || !k.k)
 296                 return 0;
 297
 298         BUG_ON(!bch2_snapshot_is_ancestor(trans->c,
 299                                           iter->snapshot,
 300                                           k.k->p.snapshot));
 301
 302         bch2_trans_iter_init(trans, &copy, iter->btree_id, iter->pos,
 303                              BTREE_ITER_NOPRESERVE|
 304                              BTREE_ITER_ALL_SNAPSHOTS);
 305         prev = bch2_btree_iter_prev(&copy);
 306         if (!prev.k)
 307                 goto out;
 308
 309         ret = bkey_err(prev);
 310         if (ret)
 311                 goto out;
 312
 313         if (bkey_eq(prev.k->p, k.k->p) &&
 314             bch2_snapshot_is_ancestor(trans->c, iter->snapshot,
 315                                       prev.k->p.snapshot) > 0) {
 316                 struct printbuf buf1 = PRINTBUF, buf2 = PRINTBUF;
 317
 318                 bch2_bkey_to_text(&buf1, k.k);
 319                 bch2_bkey_to_text(&buf2, prev.k);
 320
 321                 panic("iter snap %u\n"
 322                       "k    %s\n"
 323                       "prev %s\n",
 324                       iter->snapshot,
 325                       buf1.buf, buf2.buf);
 326         }
 327 out:
 328         bch2_trans_iter_exit(trans, &copy);
 329         return ret;
 330 }
 331
 332 void bch2_assert_pos_locked(struct btree_trans *trans, enum btree_id id,
 333                             struct bpos pos, bool key_cache)
 334 {
 335         struct btree_path *path;
 336         struct trans_for_each_path_inorder_iter iter;
 337         struct printbuf buf = PRINTBUF;
 338
 339         btree_trans_sort_paths(trans);
 340
 341         trans_for_each_path_inorder(trans, path, iter) {
 342                 int cmp = cmp_int(path->btree_id, id) ?:
 343                         cmp_int(path->cached, key_cache);
 344
 345                 if (cmp > 0)
 346                         break;
 347                 if (cmp < 0)
 348                         continue;
 349
 350                 if (!btree_node_locked(path, 0) ||
 351                     !path->should_be_locked)
 352                         continue;
 353
 354                 if (!key_cache) {
 355                         if (bkey_ge(pos, path->l[0].b->data->min_key) &&
 356                             bkey_le(pos, path->l[0].b->key.k.p))
 357                                 return;
 358                 } else {
 359                         if (bkey_eq(pos, path->pos))
 360                                 return;
 361                 }
 362         }
 363
 364         bch2_dump_trans_paths_updates(trans);
 365         bch2_bpos_to_text(&buf, pos);
 366
 367         panic("not locked: %s %s%s\n",
 368               bch2_btree_id_str(id), buf.buf,
 369               key_cache ? " cached" : "");
 370 }
 371
 372 #else
 373
 374 static inline void bch2_btree_path_verify_level(struct btree_trans *trans,
 375                                                 struct btree_path *path, unsigned l) {}
 376 static inline void bch2_btree_path_verify(struct btree_trans *trans,
 377                                           struct btree_path *path) {}
 378 static inline void bch2_btree_iter_verify(struct btree_iter *iter) {}
 379 static inline void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter) {}
 380 static inline int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k) { return 0; }
 381
 382 #endif
 383
 384 /* Btree path: fixups after btree updates */
 385
 386 static void btree_node_iter_set_set_pos(struct btree_node_iter *iter,
 387                                         struct btree *b,
 388                                         struct bset_tree *t,
 389                                         struct bkey_packed *k)
 390 {
 391         struct btree_node_iter_set *set;
 392
 393         btree_node_iter_for_each(iter, set)
 394                 if (set->end == t->end_offset) {
 395                         set->k = __btree_node_key_to_offset(b, k);
 396                         bch2_btree_node_iter_sort(iter, b);
 397                         return;
 398                 }
 399
 400         bch2_btree_node_iter_push(iter, b, k, btree_bkey_last(b, t));
 401 }
 402
 403 static void __bch2_btree_path_fix_key_modified(struct btree_path *path,
 404                                                struct btree *b,
 405                                                struct bkey_packed *where)
 406 {
 407         struct btree_path_level *l = &path->l[b->c.level];
 408
 409         if (where != bch2_btree_node_iter_peek_all(&l->iter, l->b))
 410                 return;
 411
 412         if (bkey_iter_pos_cmp(l->b, where, &path->pos) < 0)
 413                 bch2_btree_node_iter_advance(&l->iter, l->b);
 414 }
 415
 416 void bch2_btree_path_fix_key_modified(struct btree_trans *trans,
 417                                       struct btree *b,
 418                                       struct bkey_packed *where)
 419 {
 420         struct btree_path *path;
 421         unsigned i;
 422
 423         trans_for_each_path_with_node(trans, b, path, i) {
 424                 __bch2_btree_path_fix_key_modified(path, b, where);
 425                 bch2_btree_path_verify_level(trans, path, b->c.level);
 426         }
 427 }
 428
 429 static void __bch2_btree_node_iter_fix(struct btree_path *path,
 430                                        struct btree *b,
 431                                        struct btree_node_iter *node_iter,
 432                                        struct bset_tree *t,
 433                                        struct bkey_packed *where,
 434                                        unsigned clobber_u64s,
 435                                        unsigned new_u64s)
 436 {
 437         const struct bkey_packed *end = btree_bkey_last(b, t);
 438         struct btree_node_iter_set *set;
 439         unsigned offset = __btree_node_key_to_offset(b, where);
 440         int shift = new_u64s - clobber_u64s;
 441         unsigned old_end = t->end_offset - shift;
 442         unsigned orig_iter_pos = node_iter->data[0].k;
 443         bool iter_current_key_modified =
 444                 orig_iter_pos >= offset &&
 445                 orig_iter_pos <= offset + clobber_u64s;
 446
 447         btree_node_iter_for_each(node_iter, set)
 448                 if (set->end == old_end)
 449                         goto found;
 450
 451         /* didn't find the bset in the iterator - might have to readd it: */
 452         if (new_u64s &&
 453             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 454                 bch2_btree_node_iter_push(node_iter, b, where, end);
 455                 goto fixup_done;
 456         } else {
 457                 /* Iterator is after key that changed */
 458                 return;
 459         }
 460 found:
 461         set->end = t->end_offset;
 462
 463         /* Iterator hasn't gotten to the key that changed yet: */
 464         if (set->k < offset)
 465                 return;
 466
 467         if (new_u64s &&
 468             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 469                 set->k = offset;
 470         } else if (set->k < offset + clobber_u64s) {
 471                 set->k = offset + new_u64s;
 472                 if (set->k == set->end)
 473                         bch2_btree_node_iter_set_drop(node_iter, set);
 474         } else {
 475                 /* Iterator is after key that changed */
 476                 set->k = (int) set->k + shift;
 477                 return;
 478         }
 479
 480         bch2_btree_node_iter_sort(node_iter, b);
 481 fixup_done:
 482         if (node_iter->data[0].k != orig_iter_pos)
 483                 iter_current_key_modified = true;
 484
 485         /*
 486          * When a new key is added, and the node iterator now points to that
 487          * key, the iterator might have skipped past deleted keys that should
 488          * come after the key the iterator now points to. We have to rewind to
 489          * before those deleted keys - otherwise
 490          * bch2_btree_node_iter_prev_all() breaks:
 491          */
 492         if (!bch2_btree_node_iter_end(node_iter) &&
 493             iter_current_key_modified &&
 494             b->c.level) {
 495                 struct bkey_packed *k, *k2, *p;
 496
 497                 k = bch2_btree_node_iter_peek_all(node_iter, b);
 498
 499                 for_each_bset(b, t) {
 500                         bool set_pos = false;
 501
 502                         if (node_iter->data[0].end == t->end_offset)
 503                                 continue;
 504
 505                         k2 = bch2_btree_node_iter_bset_pos(node_iter, b, t);
 506
 507                         while ((p = bch2_bkey_prev_all(b, t, k2)) &&
 508                                bkey_iter_cmp(b, k, p) < 0) {
 509                                 k2 = p;
 510                                 set_pos = true;
 511                         }
 512
 513                         if (set_pos)
 514                                 btree_node_iter_set_set_pos(node_iter,
 515                                                             b, t, k2);
 516                 }
 517         }
 518 }
 519
 520 void bch2_btree_node_iter_fix(struct btree_trans *trans,
 521                               struct btree_path *path,
 522                               struct btree *b,
 523                               struct btree_node_iter *node_iter,
 524                               struct bkey_packed *where,
 525                               unsigned clobber_u64s,
 526                               unsigned new_u64s)
 527 {
 528         struct bset_tree *t = bch2_bkey_to_bset_inlined(b, where);
 529         struct btree_path *linked;
 530         unsigned i;
 531
 532         if (node_iter != &path->l[b->c.level].iter) {
 533                 __bch2_btree_node_iter_fix(path, b, node_iter, t,
 534                                            where, clobber_u64s, new_u64s);
 535
 536                 if (bch2_debug_check_iterators)
 537                         bch2_btree_node_iter_verify(node_iter, b);
 538         }
 539
 540         trans_for_each_path_with_node(trans, b, linked, i) {
 541                 __bch2_btree_node_iter_fix(linked, b,
 542                                            &linked->l[b->c.level].iter, t,
 543                                            where, clobber_u64s, new_u64s);
 544                 bch2_btree_path_verify_level(trans, linked, b->c.level);
 545         }
 546 }
 547
 548 /* Btree path level: pointer to a particular btree node and node iter */
 549
 550 static inline struct bkey_s_c __btree_iter_unpack(struct bch_fs *c,
 551                                                   struct btree_path_level *l,
 552                                                   struct bkey *u,
 553                                                   struct bkey_packed *k)
 554 {
 555         if (unlikely(!k)) {
 556                 /*
 557                  * signal to bch2_btree_iter_peek_slot() that we're currently at
 558                  * a hole
 559                  */
 560                 u->type = KEY_TYPE_deleted;
 561                 return bkey_s_c_null;
 562         }
 563
 564         return bkey_disassemble(l->b, k, u);
 565 }
 566
 567 static inline struct bkey_s_c btree_path_level_peek_all(struct bch_fs *c,
 568                                                         struct btree_path_level *l,
 569                                                         struct bkey *u)
 570 {
 571         return __btree_iter_unpack(c, l, u,
 572                         bch2_btree_node_iter_peek_all(&l->iter, l->b));
 573 }
 574
 575 static inline struct bkey_s_c btree_path_level_peek(struct btree_trans *trans,
 576                                                     struct btree_path *path,
 577                                                     struct btree_path_level *l,
 578                                                     struct bkey *u)
 579 {
 580         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 581                         bch2_btree_node_iter_peek(&l->iter, l->b));
 582
 583         path->pos = k.k ? k.k->p : l->b->key.k.p;
 584         trans->paths_sorted = false;
 585         bch2_btree_path_verify_level(trans, path, l - path->l);
 586         return k;
 587 }
 588
 589 static inline struct bkey_s_c btree_path_level_prev(struct btree_trans *trans,
 590                                                     struct btree_path *path,
 591                                                     struct btree_path_level *l,
 592                                                     struct bkey *u)
 593 {
 594         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 595                         bch2_btree_node_iter_prev(&l->iter, l->b));
 596
 597         path->pos = k.k ? k.k->p : l->b->data->min_key;
 598         trans->paths_sorted = false;
 599         bch2_btree_path_verify_level(trans, path, l - path->l);
 600         return k;
 601 }
 602
 603 static inline bool btree_path_advance_to_pos(struct btree_path *path,
 604                                              struct btree_path_level *l,
 605                                              int max_advance)
 606 {
 607         struct bkey_packed *k;
 608         int nr_advanced = 0;
 609
 610         while ((k = bch2_btree_node_iter_peek_all(&l->iter, l->b)) &&
 611                bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 612                 if (max_advance > 0 && nr_advanced >= max_advance)
 613                         return false;
 614
 615                 bch2_btree_node_iter_advance(&l->iter, l->b);
 616                 nr_advanced++;
 617         }
 618
 619         return true;
 620 }
 621
 622 static inline void __btree_path_level_init(struct btree_path *path,
 623                                            unsigned level)
 624 {
 625         struct btree_path_level *l = &path->l[level];
 626
 627         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
 628
 629         /*
 630          * Iterators to interior nodes should always be pointed at the first non
 631          * whiteout:
 632          */
 633         if (level)
 634                 bch2_btree_node_iter_peek(&l->iter, l->b);
 635 }
 636
 637 void bch2_btree_path_level_init(struct btree_trans *trans,
 638                                 struct btree_path *path,
 639                                 struct btree *b)
 640 {
 641         BUG_ON(path->cached);
 642
 643         EBUG_ON(!btree_path_pos_in_node(path, b));
 644
 645         path->l[b->c.level].lock_seq = six_lock_seq(&b->c.lock);
 646         path->l[b->c.level].b = b;
 647         __btree_path_level_init(path, b->c.level);
 648 }
 649
 650 /* Btree path: fixups after btree node updates: */
 651
 652 static void bch2_trans_revalidate_updates_in_node(struct btree_trans *trans, struct btree *b)
 653 {
 654         struct bch_fs *c = trans->c;
 655         struct btree_insert_entry *i;
 656
 657         trans_for_each_update(trans, i)
 658                 if (!i->cached &&
 659                     i->level    == b->c.level &&
 660                     i->btree_id == b->c.btree_id &&
 661                     bpos_cmp(i->k->k.p, b->data->min_key) >= 0 &&
 662                     bpos_cmp(i->k->k.p, b->data->max_key) <= 0) {
 663                         i->old_v = bch2_btree_path_peek_slot(trans->paths + i->path, &i->old_k).v;
 664
 665                         if (unlikely(trans->journal_replay_not_finished)) {
 666                                 struct bkey_i *j_k =
 667                                         bch2_journal_keys_peek_slot(c, i->btree_id, i->level,
 668                                                                     i->k->k.p);
 669
 670                                 if (j_k) {
 671                                         i->old_k = j_k->k;
 672                                         i->old_v = &j_k->v;
 673                                 }
 674                         }
 675                 }
 676 }
 677
 678 /*
 679  * A btree node is being replaced - update the iterator to point to the new
 680  * node:
 681  */
 682 void bch2_trans_node_add(struct btree_trans *trans,
 683                          struct btree_path *path,
 684                          struct btree *b)
 685 {
 686         struct btree_path *prev;
 687
 688         BUG_ON(!btree_path_pos_in_node(path, b));
 689
 690         while ((prev = prev_btree_path(trans, path)) &&
 691                btree_path_pos_in_node(prev, b))
 692                 path = prev;
 693
 694         for (;
 695              path && btree_path_pos_in_node(path, b);
 696              path = next_btree_path(trans, path))
 697                 if (path->uptodate == BTREE_ITER_UPTODATE && !path->cached) {
 698                         enum btree_node_locked_type t =
 699                                 btree_lock_want(path, b->c.level);
 700
 701                         if (t != BTREE_NODE_UNLOCKED) {
 702                                 btree_node_unlock(trans, path, b->c.level);
 703                                 six_lock_increment(&b->c.lock, (enum six_lock_type) t);
 704                                 mark_btree_node_locked(trans, path, b->c.level, t);
 705                         }
 706
 707                         bch2_btree_path_level_init(trans, path, b);
 708                 }
 709
 710         bch2_trans_revalidate_updates_in_node(trans, b);
 711 }
 712
 713 /*
 714  * A btree node has been modified in such a way as to invalidate iterators - fix
 715  * them:
 716  */
 717 void bch2_trans_node_reinit_iter(struct btree_trans *trans, struct btree *b)
 718 {
 719         struct btree_path *path;
 720         unsigned i;
 721
 722         trans_for_each_path_with_node(trans, b, path, i)
 723                 __btree_path_level_init(path, b->c.level);
 724
 725         bch2_trans_revalidate_updates_in_node(trans, b);
 726 }
 727
 728 /* Btree path: traverse, set_pos: */
 729
 730 static inline int btree_path_lock_root(struct btree_trans *trans,
 731                                        struct btree_path *path,
 732                                        unsigned depth_want,
 733                                        unsigned long trace_ip)
 734 {
 735         struct bch_fs *c = trans->c;
 736         struct btree *b, **rootp = &bch2_btree_id_root(c, path->btree_id)->b;
 737         enum six_lock_type lock_type;
 738         unsigned i;
 739         int ret;
 740
 741         EBUG_ON(path->nodes_locked);
 742
 743         while (1) {
 744                 b = READ_ONCE(*rootp);
 745                 path->level = READ_ONCE(b->c.level);
 746
 747                 if (unlikely(path->level < depth_want)) {
 748                         /*
 749                          * the root is at a lower depth than the depth we want:
 750                          * got to the end of the btree, or we're walking nodes
 751                          * greater than some depth and there are no nodes >=
 752                          * that depth
 753                          */
 754                         path->level = depth_want;
 755                         for (i = path->level; i < BTREE_MAX_DEPTH; i++)
 756                                 path->l[i].b = NULL;
 757                         return 1;
 758                 }
 759
 760                 lock_type = __btree_lock_want(path, path->level);
 761                 ret = btree_node_lock(trans, path, &b->c,
 762                                       path->level, lock_type, trace_ip);
 763                 if (unlikely(ret)) {
 764                         if (bch2_err_matches(ret, BCH_ERR_lock_fail_root_changed))
 765                                 continue;
 766                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 767                                 return ret;
 768                         BUG();
 769                 }
 770
 771                 if (likely(b == READ_ONCE(*rootp) &&
 772                            b->c.level == path->level &&
 773                            !race_fault())) {
 774                         for (i = 0; i < path->level; i++)
 775                                 path->l[i].b = ERR_PTR(-BCH_ERR_no_btree_node_lock_root);
 776                         path->l[path->level].b = b;
 777                         for (i = path->level + 1; i < BTREE_MAX_DEPTH; i++)
 778                                 path->l[i].b = NULL;
 779
 780                         mark_btree_node_locked(trans, path, path->level,
 781                                                (enum btree_node_locked_type) lock_type);
 782                         bch2_btree_path_level_init(trans, path, b);
 783                         return 0;
 784                 }
 785
 786                 six_unlock_type(&b->c.lock, lock_type);
 787         }
 788 }
 789
 790 noinline
 791 static int btree_path_prefetch(struct btree_trans *trans, struct btree_path *path)
 792 {
 793         struct bch_fs *c = trans->c;
 794         struct btree_path_level *l = path_l(path);
 795         struct btree_node_iter node_iter = l->iter;
 796         struct bkey_packed *k;
 797         struct bkey_buf tmp;
 798         unsigned nr = test_bit(BCH_FS_started, &c->flags)
 799                 ? (path->level > 1 ? 0 :  2)
 800                 : (path->level > 1 ? 1 : 16);
 801         bool was_locked = btree_node_locked(path, path->level);
 802         int ret = 0;
 803
 804         bch2_bkey_buf_init(&tmp);
 805
 806         while (nr-- && !ret) {
 807                 if (!bch2_btree_node_relock(trans, path, path->level))
 808                         break;
 809
 810                 bch2_btree_node_iter_advance(&node_iter, l->b);
 811                 k = bch2_btree_node_iter_peek(&node_iter, l->b);
 812                 if (!k)
 813                         break;
 814
 815                 bch2_bkey_buf_unpack(&tmp, c, l->b, k);
 816                 ret = bch2_btree_node_prefetch(trans, path, tmp.k, path->btree_id,
 817                                                path->level - 1);
 818         }
 819
 820         if (!was_locked)
 821                 btree_node_unlock(trans, path, path->level);
 822
 823         bch2_bkey_buf_exit(&tmp, c);
 824         return ret;
 825 }
 826
 827 static int btree_path_prefetch_j(struct btree_trans *trans, struct btree_path *path,
 828                                  struct btree_and_journal_iter *jiter)
 829 {
 830         struct bch_fs *c = trans->c;
 831         struct bkey_s_c k;
 832         struct bkey_buf tmp;
 833         unsigned nr = test_bit(BCH_FS_started, &c->flags)
 834                 ? (path->level > 1 ? 0 :  2)
 835                 : (path->level > 1 ? 1 : 16);
 836         bool was_locked = btree_node_locked(path, path->level);
 837         int ret = 0;
 838
 839         bch2_bkey_buf_init(&tmp);
 840
 841         while (nr-- && !ret) {
 842                 if (!bch2_btree_node_relock(trans, path, path->level))
 843                         break;
 844
 845                 bch2_btree_and_journal_iter_advance(jiter);
 846                 k = bch2_btree_and_journal_iter_peek(jiter);
 847                 if (!k.k)
 848                         break;
 849
 850                 bch2_bkey_buf_reassemble(&tmp, c, k);
 851                 ret = bch2_btree_node_prefetch(trans, path, tmp.k, path->btree_id,
 852                                                path->level - 1);
 853         }
 854
 855         if (!was_locked)
 856                 btree_node_unlock(trans, path, path->level);
 857
 858         bch2_bkey_buf_exit(&tmp, c);
 859         return ret;
 860 }
 861
 862 static noinline void btree_node_mem_ptr_set(struct btree_trans *trans,
 863                                             struct btree_path *path,
 864                                             unsigned plevel, struct btree *b)
 865 {
 866         struct btree_path_level *l = &path->l[plevel];
 867         bool locked = btree_node_locked(path, plevel);
 868         struct bkey_packed *k;
 869         struct bch_btree_ptr_v2 *bp;
 870
 871         if (!bch2_btree_node_relock(trans, path, plevel))
 872                 return;
 873
 874         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 875         BUG_ON(k->type != KEY_TYPE_btree_ptr_v2);
 876
 877         bp = (void *) bkeyp_val(&l->b->format, k);
 878         bp->mem_ptr = (unsigned long)b;
 879
 880         if (!locked)
 881                 btree_node_unlock(trans, path, plevel);
 882 }
 883
 884 static noinline int btree_node_iter_and_journal_peek(struct btree_trans *trans,
 885                                                      struct btree_path *path,
 886                                                      unsigned flags,
 887                                                      struct bkey_buf *out)
 888 {
 889         struct bch_fs *c = trans->c;
 890         struct btree_path_level *l = path_l(path);
 891         struct btree_and_journal_iter jiter;
 892         struct bkey_s_c k;
 893         int ret = 0;
 894
 895         __bch2_btree_and_journal_iter_init_node_iter(&jiter, c, l->b, l->iter, path->pos);
 896
 897         k = bch2_btree_and_journal_iter_peek(&jiter);
 898
 899         bch2_bkey_buf_reassemble(out, c, k);
 900
 901         if (flags & BTREE_ITER_PREFETCH)
 902                 ret = btree_path_prefetch_j(trans, path, &jiter);
 903
 904         bch2_btree_and_journal_iter_exit(&jiter);
 905         return ret;
 906 }
 907
 908 static __always_inline int btree_path_down(struct btree_trans *trans,
 909                                            struct btree_path *path,
 910                                            unsigned flags,
 911                                            unsigned long trace_ip)
 912 {
 913         struct bch_fs *c = trans->c;
 914         struct btree_path_level *l = path_l(path);
 915         struct btree *b;
 916         unsigned level = path->level - 1;
 917         enum six_lock_type lock_type = __btree_lock_want(path, level);
 918         struct bkey_buf tmp;
 919         int ret;
 920
 921         EBUG_ON(!btree_node_locked(path, path->level));
 922
 923         bch2_bkey_buf_init(&tmp);
 924
 925         if (unlikely(trans->journal_replay_not_finished)) {
 926                 ret = btree_node_iter_and_journal_peek(trans, path, flags, &tmp);
 927                 if (ret)
 928                         goto err;
 929         } else {
 930                 bch2_bkey_buf_unpack(&tmp, c, l->b,
 931                                  bch2_btree_node_iter_peek(&l->iter, l->b));
 932
 933                 if (flags & BTREE_ITER_PREFETCH) {
 934                         ret = btree_path_prefetch(trans, path);
 935                         if (ret)
 936                                 goto err;
 937                 }
 938         }
 939
 940         b = bch2_btree_node_get(trans, path, tmp.k, level, lock_type, trace_ip);
 941         ret = PTR_ERR_OR_ZERO(b);
 942         if (unlikely(ret))
 943                 goto err;
 944
 945         if (likely(!trans->journal_replay_not_finished &&
 946                    tmp.k->k.type == KEY_TYPE_btree_ptr_v2) &&
 947             unlikely(b != btree_node_mem_ptr(tmp.k)))
 948                 btree_node_mem_ptr_set(trans, path, level + 1, b);
 949
 950         if (btree_node_read_locked(path, level + 1))
 951                 btree_node_unlock(trans, path, level + 1);
 952
 953         mark_btree_node_locked(trans, path, level,
 954                                (enum btree_node_locked_type) lock_type);
 955         path->level = level;
 956         bch2_btree_path_level_init(trans, path, b);
 957
 958         bch2_btree_path_verify_locks(path);
 959 err:
 960         bch2_bkey_buf_exit(&tmp, c);
 961         return ret;
 962 }
 963
 964
 965 static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 966 {
 967         struct bch_fs *c = trans->c;
 968         struct btree_path *path;
 969         unsigned long trace_ip = _RET_IP_;
 970         unsigned i;
 971         int ret = 0;
 972
 973         if (trans->in_traverse_all)
 974                 return -BCH_ERR_transaction_restart_in_traverse_all;
 975
 976         trans->in_traverse_all = true;
 977 retry_all:
 978         trans->restarted = 0;
 979         trans->last_restarted_ip = 0;
 980
 981         trans_for_each_path(trans, path, i)
 982                 path->should_be_locked = false;
 983
 984         btree_trans_sort_paths(trans);
 985
 986         bch2_trans_unlock(trans);
 987         cond_resched();
 988
 989         if (unlikely(trans->memory_allocation_failure)) {
 990                 struct closure cl;
 991
 992                 closure_init_stack(&cl);
 993
 994                 do {
 995                         ret = bch2_btree_cache_cannibalize_lock(trans, &cl);
 996                         closure_sync(&cl);
 997                 } while (ret);
 998         }
 999
1000         /* Now, redo traversals in correct order: */
1001         i = 0;
1002         while (i < trans->nr_sorted) {
1003                 btree_path_idx_t idx = trans->sorted[i];
1004
1005                 /*
1006                  * Traversing a path can cause another path to be added at about
1007                  * the same position:
1008                  */
1009                 if (trans->paths[idx].uptodate) {
1010                         __btree_path_get(&trans->paths[idx], false);
1011                         ret = bch2_btree_path_traverse_one(trans, idx, 0, _THIS_IP_);
1012                         __btree_path_put(&trans->paths[idx], false);
1013
1014                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) ||
1015                             bch2_err_matches(ret, ENOMEM))
1016                                 goto retry_all;
1017                         if (ret)
1018                                 goto err;
1019                 } else {
1020                         i++;
1021                 }
1022         }
1023
1024         /*
1025          * We used to assert that all paths had been traversed here
1026          * (path->uptodate < BTREE_ITER_NEED_TRAVERSE); however, since
1027          * path->should_be_locked is not set yet, we might have unlocked and
1028          * then failed to relock a path - that's fine.
1029          */
1030 err:
1031         bch2_btree_cache_cannibalize_unlock(trans);
1032
1033         trans->in_traverse_all = false;
1034
1035         trace_and_count(c, trans_traverse_all, trans, trace_ip);
1036         return ret;
1037 }
1038
1039 static inline bool btree_path_check_pos_in_node(struct btree_path *path,
1040                                                 unsigned l, int check_pos)
1041 {
1042         if (check_pos < 0 && btree_path_pos_before_node(path, path->l[l].b))
1043                 return false;
1044         if (check_pos > 0 && btree_path_pos_after_node(path, path->l[l].b))
1045                 return false;
1046         return true;
1047 }
1048
1049 static inline bool btree_path_good_node(struct btree_trans *trans,
1050                                         struct btree_path *path,
1051                                         unsigned l, int check_pos)
1052 {
1053         return is_btree_node(path, l) &&
1054                 bch2_btree_node_relock(trans, path, l) &&
1055                 btree_path_check_pos_in_node(path, l, check_pos);
1056 }
1057
1058 static void btree_path_set_level_down(struct btree_trans *trans,
1059                                       struct btree_path *path,
1060                                       unsigned new_level)
1061 {
1062         unsigned l;
1063
1064         path->level = new_level;
1065
1066         for (l = path->level + 1; l < BTREE_MAX_DEPTH; l++)
1067                 if (btree_lock_want(path, l) == BTREE_NODE_UNLOCKED)
1068                         btree_node_unlock(trans, path, l);
1069
1070         btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1071         bch2_btree_path_verify(trans, path);
1072 }
1073
1074 static noinline unsigned __btree_path_up_until_good_node(struct btree_trans *trans,
1075                                                          struct btree_path *path,
1076                                                          int check_pos)
1077 {
1078         unsigned i, l = path->level;
1079 again:
1080         while (btree_path_node(path, l) &&
1081                !btree_path_good_node(trans, path, l, check_pos))
1082                 __btree_path_set_level_up(trans, path, l++);
1083
1084         /* If we need intent locks, take them too: */
1085         for (i = l + 1;
1086              i < path->locks_want && btree_path_node(path, i);
1087              i++)
1088                 if (!bch2_btree_node_relock(trans, path, i)) {
1089                         while (l <= i)
1090                                 __btree_path_set_level_up(trans, path, l++);
1091                         goto again;
1092                 }
1093
1094         return l;
1095 }
1096
1097 static inline unsigned btree_path_up_until_good_node(struct btree_trans *trans,
1098                                                      struct btree_path *path,
1099                                                      int check_pos)
1100 {
1101         return likely(btree_node_locked(path, path->level) &&
1102                       btree_path_check_pos_in_node(path, path->level, check_pos))
1103                 ? path->level
1104                 : __btree_path_up_until_good_node(trans, path, check_pos);
1105 }
1106
1107 /*
1108  * This is the main state machine for walking down the btree - walks down to a
1109  * specified depth
1110  *
1111  * Returns 0 on success, -EIO on error (error reading in a btree node).
1112  *
1113  * On error, caller (peek_node()/peek_key()) must return NULL; the error is
1114  * stashed in the iterator and returned from bch2_trans_exit().
1115  */
1116 int bch2_btree_path_traverse_one(struct btree_trans *trans,
1117                                  btree_path_idx_t path_idx,
1118                                  unsigned flags,
1119                                  unsigned long trace_ip)
1120 {
1121         struct btree_path *path = &trans->paths[path_idx];
1122         unsigned depth_want = path->level;
1123         int ret = -((int) trans->restarted);
1124
1125         if (unlikely(ret))
1126                 goto out;
1127
1128         if (unlikely(!trans->srcu_held))
1129                 bch2_trans_srcu_lock(trans);
1130
1131         /*
1132          * Ensure we obey path->should_be_locked: if it's set, we can't unlock
1133          * and re-traverse the path without a transaction restart:
1134          */
1135         if (path->should_be_locked) {
1136                 ret = bch2_btree_path_relock(trans, path, trace_ip);
1137                 goto out;
1138         }
1139
1140         if (path->cached) {
1141                 ret = bch2_btree_path_traverse_cached(trans, path, flags);
1142                 goto out;
1143         }
1144
1145         path = &trans->paths[path_idx];
1146
1147         if (unlikely(path->level >= BTREE_MAX_DEPTH))
1148                 goto out;
1149
1150         path->level = btree_path_up_until_good_node(trans, path, 0);
1151
1152         EBUG_ON(btree_path_node(path, path->level) &&
1153                 !btree_node_locked(path, path->level));
1154
1155         /*
1156          * Note: path->nodes[path->level] may be temporarily NULL here - that
1157          * would indicate to other code that we got to the end of the btree,
1158          * here it indicates that relocking the root failed - it's critical that
1159          * btree_path_lock_root() comes next and that it can't fail
1160          */
1161         while (path->level > depth_want) {
1162                 ret = btree_path_node(path, path->level)
1163                         ? btree_path_down(trans, path, flags, trace_ip)
1164                         : btree_path_lock_root(trans, path, depth_want, trace_ip);
1165                 if (unlikely(ret)) {
1166                         if (ret == 1) {
1167                                 /*
1168                                  * No nodes at this level - got to the end of
1169                                  * the btree:
1170                                  */
1171                                 ret = 0;
1172                                 goto out;
1173                         }
1174
1175                         __bch2_btree_path_unlock(trans, path);
1176                         path->level = depth_want;
1177                         path->l[path->level].b = ERR_PTR(ret);
1178                         goto out;
1179                 }
1180         }
1181
1182         path->uptodate = BTREE_ITER_UPTODATE;
1183 out:
1184         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) != !!trans->restarted)
1185                 panic("ret %s (%i) trans->restarted %s (%i)\n",
1186                       bch2_err_str(ret), ret,
1187                       bch2_err_str(trans->restarted), trans->restarted);
1188         bch2_btree_path_verify(trans, path);
1189         return ret;
1190 }
1191
1192 static inline void btree_path_copy(struct btree_trans *trans, struct btree_path *dst,
1193                             struct btree_path *src)
1194 {
1195         unsigned i, offset = offsetof(struct btree_path, pos);
1196
1197         memcpy((void *) dst + offset,
1198                (void *) src + offset,
1199                sizeof(struct btree_path) - offset);
1200
1201         for (i = 0; i < BTREE_MAX_DEPTH; i++) {
1202                 unsigned t = btree_node_locked_type(dst, i);
1203
1204                 if (t != BTREE_NODE_UNLOCKED)
1205                         six_lock_increment(&dst->l[i].b->c.lock, t);
1206         }
1207 }
1208
1209 static btree_path_idx_t btree_path_clone(struct btree_trans *trans, btree_path_idx_t src,
1210                                          bool intent)
1211 {
1212         btree_path_idx_t new = btree_path_alloc(trans, src);
1213
1214         btree_path_copy(trans, trans->paths + new, trans->paths + src);
1215         __btree_path_get(trans->paths + new, intent);
1216         return new;
1217 }
1218
1219 __flatten
1220 btree_path_idx_t __bch2_btree_path_make_mut(struct btree_trans *trans,
1221                         btree_path_idx_t path, bool intent, unsigned long ip)
1222 {
1223         __btree_path_put(trans->paths + path, intent);
1224         path = btree_path_clone(trans, path, intent);
1225         trans->paths[path].preserve = false;
1226         return path;
1227 }
1228
1229 btree_path_idx_t __must_check
1230 __bch2_btree_path_set_pos(struct btree_trans *trans,
1231                           btree_path_idx_t path_idx, struct bpos new_pos,
1232                           bool intent, unsigned long ip)
1233 {
1234         int cmp = bpos_cmp(new_pos, trans->paths[path_idx].pos);
1235
1236         bch2_trans_verify_not_in_restart(trans);
1237         EBUG_ON(!trans->paths[path_idx].ref);
1238
1239         path_idx = bch2_btree_path_make_mut(trans, path_idx, intent, ip);
1240
1241         struct btree_path *path = trans->paths + path_idx;
1242         path->pos               = new_pos;
1243         trans->paths_sorted     = false;
1244
1245         if (unlikely(path->cached)) {
1246                 btree_node_unlock(trans, path, 0);
1247                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_up);
1248                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1249                 goto out;
1250         }
1251
1252         unsigned level = btree_path_up_until_good_node(trans, path, cmp);
1253
1254         if (btree_path_node(path, level)) {
1255                 struct btree_path_level *l = &path->l[level];
1256
1257                 BUG_ON(!btree_node_locked(path, level));
1258                 /*
1259                  * We might have to skip over many keys, or just a few: try
1260                  * advancing the node iterator, and if we have to skip over too
1261                  * many keys just reinit it (or if we're rewinding, since that
1262                  * is expensive).
1263                  */
1264                 if (cmp < 0 ||
1265                     !btree_path_advance_to_pos(path, l, 8))
1266                         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
1267
1268                 /*
1269                  * Iterators to interior nodes should always be pointed at the first non
1270                  * whiteout:
1271                  */
1272                 if (unlikely(level))
1273                         bch2_btree_node_iter_peek(&l->iter, l->b);
1274         }
1275
1276         if (unlikely(level != path->level)) {
1277                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1278                 __bch2_btree_path_unlock(trans, path);
1279         }
1280 out:
1281         bch2_btree_path_verify(trans, path);
1282         return path_idx;
1283 }
1284
1285 /* Btree path: main interface: */
1286
1287 static struct btree_path *have_path_at_pos(struct btree_trans *trans, struct btree_path *path)
1288 {
1289         struct btree_path *sib;
1290
1291         sib = prev_btree_path(trans, path);
1292         if (sib && !btree_path_cmp(sib, path))
1293                 return sib;
1294
1295         sib = next_btree_path(trans, path);
1296         if (sib && !btree_path_cmp(sib, path))
1297                 return sib;
1298
1299         return NULL;
1300 }
1301
1302 static struct btree_path *have_node_at_pos(struct btree_trans *trans, struct btree_path *path)
1303 {
1304         struct btree_path *sib;
1305
1306         sib = prev_btree_path(trans, path);
1307         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1308                 return sib;
1309
1310         sib = next_btree_path(trans, path);
1311         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1312                 return sib;
1313
1314         return NULL;
1315 }
1316
1317 static inline void __bch2_path_free(struct btree_trans *trans, btree_path_idx_t path)
1318 {
1319         __bch2_btree_path_unlock(trans, trans->paths + path);
1320         btree_path_list_remove(trans, trans->paths + path);
1321         __clear_bit(path, trans->paths_allocated);
1322 }
1323
1324 void bch2_path_put(struct btree_trans *trans, btree_path_idx_t path_idx, bool intent)
1325 {
1326         struct btree_path *path = trans->paths + path_idx, *dup;
1327
1328         if (!__btree_path_put(path, intent))
1329                 return;
1330
1331         dup = path->preserve
1332                 ? have_path_at_pos(trans, path)
1333                 : have_node_at_pos(trans, path);
1334
1335         if (!dup && !(!path->preserve && !is_btree_node(path, path->level)))
1336                 return;
1337
1338         if (path->should_be_locked &&
1339             !trans->restarted &&
1340             (!dup || !bch2_btree_path_relock_norestart(trans, dup, _THIS_IP_)))
1341                 return;
1342
1343         if (dup) {
1344                 dup->preserve           |= path->preserve;
1345                 dup->should_be_locked   |= path->should_be_locked;
1346         }
1347
1348         __bch2_path_free(trans, path_idx);
1349 }
1350
1351 static void bch2_path_put_nokeep(struct btree_trans *trans, btree_path_idx_t path,
1352                                  bool intent)
1353 {
1354         if (!__btree_path_put(trans->paths + path, intent))
1355                 return;
1356
1357         __bch2_path_free(trans, path);
1358 }
1359
1360 void __noreturn bch2_trans_restart_error(struct btree_trans *trans, u32 restart_count)
1361 {
1362         panic("trans->restart_count %u, should be %u, last restarted by %pS\n",
1363               trans->restart_count, restart_count,
1364               (void *) trans->last_begin_ip);
1365 }
1366
1367 void __noreturn bch2_trans_in_restart_error(struct btree_trans *trans)
1368 {
1369         panic("in transaction restart: %s, last restarted by %pS\n",
1370               bch2_err_str(trans->restarted),
1371               (void *) trans->last_restarted_ip);
1372 }
1373
1374 noinline __cold
1375 void bch2_trans_updates_to_text(struct printbuf *buf, struct btree_trans *trans)
1376 {
1377         struct btree_insert_entry *i;
1378
1379         prt_printf(buf, "transaction updates for %s journal seq %llu",
1380                trans->fn, trans->journal_res.seq);
1381         prt_newline(buf);
1382         printbuf_indent_add(buf, 2);
1383
1384         trans_for_each_update(trans, i) {
1385                 struct bkey_s_c old = { &i->old_k, i->old_v };
1386
1387                 prt_printf(buf, "update: btree=%s cached=%u %pS",
1388                        bch2_btree_id_str(i->btree_id),
1389                        i->cached,
1390                        (void *) i->ip_allocated);
1391                 prt_newline(buf);
1392
1393                 prt_printf(buf, "  old ");
1394                 bch2_bkey_val_to_text(buf, trans->c, old);
1395                 prt_newline(buf);
1396
1397                 prt_printf(buf, "  new ");
1398                 bch2_bkey_val_to_text(buf, trans->c, bkey_i_to_s_c(i->k));
1399                 prt_newline(buf);
1400         }
1401
1402         for (struct jset_entry *e = trans->journal_entries;
1403              e != btree_trans_journal_entries_top(trans);
1404              e = vstruct_next(e))
1405                 bch2_journal_entry_to_text(buf, trans->c, e);
1406
1407         printbuf_indent_sub(buf, 2);
1408 }
1409
1410 noinline __cold
1411 void bch2_dump_trans_updates(struct btree_trans *trans)
1412 {
1413         struct printbuf buf = PRINTBUF;
1414
1415         bch2_trans_updates_to_text(&buf, trans);
1416         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1417         printbuf_exit(&buf);
1418 }
1419
1420 static void bch2_btree_path_to_text(struct printbuf *out, struct btree_trans *trans, btree_path_idx_t path_idx)
1421 {
1422         struct btree_path *path = trans->paths + path_idx;
1423
1424         prt_printf(out, "path: idx %2u ref %u:%u %c %c btree=%s l=%u pos ",
1425                    path_idx, path->ref, path->intent_ref,
1426                    path->preserve ? 'P' : ' ',
1427                    path->should_be_locked ? 'S' : ' ',
1428                    bch2_btree_id_str(path->btree_id),
1429                    path->level);
1430         bch2_bpos_to_text(out, path->pos);
1431
1432         prt_printf(out, " locks %u", path->nodes_locked);
1433 #ifdef TRACK_PATH_ALLOCATED
1434         prt_printf(out, " %pS", (void *) path->ip_allocated);
1435 #endif
1436         prt_newline(out);
1437 }
1438
1439 static noinline __cold
1440 void __bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans,
1441                                 bool nosort)
1442 {
1443         struct trans_for_each_path_inorder_iter iter;
1444
1445         if (!nosort)
1446                 btree_trans_sort_paths(trans);
1447
1448         trans_for_each_path_idx_inorder(trans, iter)
1449                 bch2_btree_path_to_text(out, trans, iter.path_idx);
1450 }
1451
1452 noinline __cold
1453 void bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans)
1454 {
1455         __bch2_trans_paths_to_text(out, trans, false);
1456 }
1457
1458 static noinline __cold
1459 void __bch2_dump_trans_paths_updates(struct btree_trans *trans, bool nosort)
1460 {
1461         struct printbuf buf = PRINTBUF;
1462
1463         __bch2_trans_paths_to_text(&buf, trans, nosort);
1464         bch2_trans_updates_to_text(&buf, trans);
1465
1466         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1467         printbuf_exit(&buf);
1468 }
1469
1470 noinline __cold
1471 void bch2_dump_trans_paths_updates(struct btree_trans *trans)
1472 {
1473         __bch2_dump_trans_paths_updates(trans, false);
1474 }
1475
1476 noinline __cold
1477 static void bch2_trans_update_max_paths(struct btree_trans *trans)
1478 {
1479         struct btree_transaction_stats *s = btree_trans_stats(trans);
1480         struct printbuf buf = PRINTBUF;
1481         size_t nr = bitmap_weight(trans->paths_allocated, trans->nr_paths);
1482
1483         if (!s)
1484                 return;
1485
1486         bch2_trans_paths_to_text(&buf, trans);
1487
1488         if (!buf.allocation_failure) {
1489                 mutex_lock(&s->lock);
1490                 if (nr > s->nr_max_paths) {
1491                         s->nr_max_paths = nr;
1492                         swap(s->max_paths_text, buf.buf);
1493                 }
1494                 mutex_unlock(&s->lock);
1495         }
1496
1497         printbuf_exit(&buf);
1498
1499         trans->nr_paths_max = nr;
1500 }
1501
1502 noinline __cold
1503 int __bch2_btree_trans_too_many_iters(struct btree_trans *trans)
1504 {
1505         if (trace_trans_restart_too_many_iters_enabled()) {
1506                 struct printbuf buf = PRINTBUF;
1507
1508                 bch2_trans_paths_to_text(&buf, trans);
1509                 trace_trans_restart_too_many_iters(trans, _THIS_IP_, buf.buf);
1510                 printbuf_exit(&buf);
1511         }
1512
1513         count_event(trans->c, trans_restart_too_many_iters);
1514
1515         return btree_trans_restart(trans, BCH_ERR_transaction_restart_too_many_iters);
1516 }
1517
1518 static noinline void btree_paths_realloc(struct btree_trans *trans)
1519 {
1520         unsigned nr = trans->nr_paths * 2;
1521
1522         void *p = kzalloc(BITS_TO_LONGS(nr) * sizeof(unsigned long) +
1523                           nr + 8 +
1524                           sizeof(struct btree_trans_paths) +
1525                           nr * sizeof(struct btree_path) +
1526                           nr * sizeof(struct btree_insert_entry), GFP_KERNEL|__GFP_NOFAIL);
1527
1528         unsigned long *paths_allocated = p;
1529         p += BITS_TO_LONGS(nr) * sizeof(unsigned long);
1530         struct btree_path *paths = p;
1531         p += nr * sizeof(struct btree_path);
1532         u8 *sorted = p;
1533         p += nr + 8;
1534         struct btree_insert_entry *updates = p;
1535
1536         *trans_paths_nr(paths) = nr;
1537
1538         memcpy(paths_allocated, trans->paths_allocated, BITS_TO_LONGS(trans->nr_paths) * sizeof(unsigned long));
1539         memcpy(sorted, trans->sorted, trans->nr_sorted);
1540         memcpy(paths, trans->paths, trans->nr_paths * sizeof(struct btree_path));
1541         memcpy(updates, trans->updates, trans->nr_paths * sizeof(struct btree_path));
1542
1543         unsigned long *old = trans->paths_allocated;
1544
1545         rcu_assign_pointer(trans->paths_allocated,      paths_allocated);
1546         rcu_assign_pointer(trans->sorted,               sorted);
1547         rcu_assign_pointer(trans->paths,                paths);
1548         rcu_assign_pointer(trans->updates,              updates);
1549
1550         trans->nr_paths         = nr;
1551
1552         if (old != trans->_paths_allocated)
1553                 kfree_rcu_mightsleep(trans->paths_allocated);
1554 }
1555
1556 static inline btree_path_idx_t btree_path_alloc(struct btree_trans *trans,
1557                                                 btree_path_idx_t pos)
1558 {
1559         btree_path_idx_t idx = find_first_zero_bit(trans->paths_allocated, trans->nr_paths);
1560
1561         if (unlikely(idx == trans->nr_paths))
1562                 btree_paths_realloc(trans);
1563
1564         /*
1565          * Do this before marking the new path as allocated, since it won't be
1566          * initialized yet:
1567          */
1568         if (unlikely(idx > trans->nr_paths_max))
1569                 bch2_trans_update_max_paths(trans);
1570
1571         __set_bit(idx, trans->paths_allocated);
1572
1573         struct btree_path *path = &trans->paths[idx];
1574         path->ref               = 0;
1575         path->intent_ref        = 0;
1576         path->nodes_locked      = 0;
1577
1578         btree_path_list_add(trans, pos, idx);
1579         trans->paths_sorted = false;
1580         return idx;
1581 }
1582
1583 btree_path_idx_t bch2_path_get(struct btree_trans *trans,
1584                              enum btree_id btree_id, struct bpos pos,
1585                              unsigned locks_want, unsigned level,
1586                              unsigned flags, unsigned long ip)
1587 {
1588         struct btree_path *path;
1589         bool cached = flags & BTREE_ITER_CACHED;
1590         bool intent = flags & BTREE_ITER_INTENT;
1591         struct trans_for_each_path_inorder_iter iter;
1592         btree_path_idx_t path_pos = 0, path_idx;
1593
1594         bch2_trans_verify_not_in_restart(trans);
1595         bch2_trans_verify_locks(trans);
1596
1597         btree_trans_sort_paths(trans);
1598
1599         trans_for_each_path_inorder(trans, path, iter) {
1600                 if (__btree_path_cmp(path,
1601                                      btree_id,
1602                                      cached,
1603                                      pos,
1604                                      level) > 0)
1605                         break;
1606
1607                 path_pos = iter.path_idx;
1608         }
1609
1610         if (path_pos &&
1611             trans->paths[path_pos].cached       == cached &&
1612             trans->paths[path_pos].btree_id     == btree_id &&
1613             trans->paths[path_pos].level        == level) {
1614                 __btree_path_get(trans->paths + path_pos, intent);
1615                 path_idx = bch2_btree_path_set_pos(trans, path_pos, pos, intent, ip);
1616                 path = trans->paths + path_idx;
1617         } else {
1618                 path_idx = btree_path_alloc(trans, path_pos);
1619                 path = trans->paths + path_idx;
1620
1621                 __btree_path_get(path, intent);
1622                 path->pos                       = pos;
1623                 path->btree_id                  = btree_id;
1624                 path->cached                    = cached;
1625                 path->uptodate                  = BTREE_ITER_NEED_TRAVERSE;
1626                 path->should_be_locked          = false;
1627                 path->level                     = level;
1628                 path->locks_want                = locks_want;
1629                 path->nodes_locked              = 0;
1630                 for (unsigned i = 0; i < ARRAY_SIZE(path->l); i++)
1631                         path->l[i].b            = ERR_PTR(-BCH_ERR_no_btree_node_init);
1632 #ifdef TRACK_PATH_ALLOCATED
1633                 path->ip_allocated              = ip;
1634 #endif
1635                 trans->paths_sorted             = false;
1636         }
1637
1638         if (!(flags & BTREE_ITER_NOPRESERVE))
1639                 path->preserve = true;
1640
1641         if (path->intent_ref)
1642                 locks_want = max(locks_want, level + 1);
1643
1644         /*
1645          * If the path has locks_want greater than requested, we don't downgrade
1646          * it here - on transaction restart because btree node split needs to
1647          * upgrade locks, we might be putting/getting the iterator again.
1648          * Downgrading iterators only happens via bch2_trans_downgrade(), after
1649          * a successful transaction commit.
1650          */
1651
1652         locks_want = min(locks_want, BTREE_MAX_DEPTH);
1653         if (locks_want > path->locks_want)
1654                 bch2_btree_path_upgrade_noupgrade_sibs(trans, path, locks_want, NULL);
1655
1656         return path_idx;
1657 }
1658
1659 struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *path, struct bkey *u)
1660 {
1661
1662         struct btree_path_level *l = path_l(path);
1663         struct bkey_packed *_k;
1664         struct bkey_s_c k;
1665
1666         if (unlikely(!l->b))
1667                 return bkey_s_c_null;
1668
1669         EBUG_ON(path->uptodate != BTREE_ITER_UPTODATE);
1670         EBUG_ON(!btree_node_locked(path, path->level));
1671
1672         if (!path->cached) {
1673                 _k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
1674                 k = _k ? bkey_disassemble(l->b, _k, u) : bkey_s_c_null;
1675
1676                 EBUG_ON(k.k && bkey_deleted(k.k) && bpos_eq(k.k->p, path->pos));
1677
1678                 if (!k.k || !bpos_eq(path->pos, k.k->p))
1679                         goto hole;
1680         } else {
1681                 struct bkey_cached *ck = (void *) path->l[0].b;
1682
1683                 EBUG_ON(ck &&
1684                         (path->btree_id != ck->key.btree_id ||
1685                          !bkey_eq(path->pos, ck->key.pos)));
1686                 if (!ck || !ck->valid)
1687                         return bkey_s_c_null;
1688
1689                 *u = ck->k->k;
1690                 k = bkey_i_to_s_c(ck->k);
1691         }
1692
1693         return k;
1694 hole:
1695         bkey_init(u);
1696         u->p = path->pos;
1697         return (struct bkey_s_c) { u, NULL };
1698 }
1699
1700 /* Btree iterators: */
1701
1702 int __must_check
1703 __bch2_btree_iter_traverse(struct btree_iter *iter)
1704 {
1705         return bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1706 }
1707
1708 int __must_check
1709 bch2_btree_iter_traverse(struct btree_iter *iter)
1710 {
1711         struct btree_trans *trans = iter->trans;
1712         int ret;
1713
1714         iter->path = bch2_btree_path_set_pos(trans, iter->path,
1715                                         btree_iter_search_key(iter),
1716                                         iter->flags & BTREE_ITER_INTENT,
1717                                         btree_iter_ip_allocated(iter));
1718
1719         ret = bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1720         if (ret)
1721                 return ret;
1722
1723         btree_path_set_should_be_locked(trans->paths + iter->path);
1724         return 0;
1725 }
1726
1727 /* Iterate across nodes (leaf and interior nodes) */
1728
1729 struct btree *bch2_btree_iter_peek_node(struct btree_iter *iter)
1730 {
1731         struct btree_trans *trans = iter->trans;
1732         struct btree *b = NULL;
1733         int ret;
1734
1735         EBUG_ON(trans->paths[iter->path].cached);
1736         bch2_btree_iter_verify(iter);
1737
1738         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1739         if (ret)
1740                 goto err;
1741
1742         struct btree_path *path = btree_iter_path(trans, iter);
1743         b = btree_path_node(path, path->level);
1744         if (!b)
1745                 goto out;
1746
1747         BUG_ON(bpos_lt(b->key.k.p, iter->pos));
1748
1749         bkey_init(&iter->k);
1750         iter->k.p = iter->pos = b->key.k.p;
1751
1752         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1753                                         iter->flags & BTREE_ITER_INTENT,
1754                                         btree_iter_ip_allocated(iter));
1755         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
1756 out:
1757         bch2_btree_iter_verify_entry_exit(iter);
1758         bch2_btree_iter_verify(iter);
1759
1760         return b;
1761 err:
1762         b = ERR_PTR(ret);
1763         goto out;
1764 }
1765
1766 struct btree *bch2_btree_iter_peek_node_and_restart(struct btree_iter *iter)
1767 {
1768         struct btree *b;
1769
1770         while (b = bch2_btree_iter_peek_node(iter),
1771                bch2_err_matches(PTR_ERR_OR_ZERO(b), BCH_ERR_transaction_restart))
1772                 bch2_trans_begin(iter->trans);
1773
1774         return b;
1775 }
1776
1777 struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
1778 {
1779         struct btree_trans *trans = iter->trans;
1780         struct btree *b = NULL;
1781         int ret;
1782
1783         EBUG_ON(trans->paths[iter->path].cached);
1784         bch2_trans_verify_not_in_restart(trans);
1785         bch2_btree_iter_verify(iter);
1786
1787         struct btree_path *path = btree_iter_path(trans, iter);
1788
1789         /* already at end? */
1790         if (!btree_path_node(path, path->level))
1791                 return NULL;
1792
1793         /* got to end? */
1794         if (!btree_path_node(path, path->level + 1)) {
1795                 btree_path_set_level_up(trans, path);
1796                 return NULL;
1797         }
1798
1799         if (!bch2_btree_node_relock(trans, path, path->level + 1)) {
1800                 __bch2_btree_path_unlock(trans, path);
1801                 path->l[path->level].b          = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1802                 path->l[path->level + 1].b      = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1803                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1804                 trace_and_count(trans->c, trans_restart_relock_next_node, trans, _THIS_IP_, path);
1805                 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
1806                 goto err;
1807         }
1808
1809         b = btree_path_node(path, path->level + 1);
1810
1811         if (bpos_eq(iter->pos, b->key.k.p)) {
1812                 __btree_path_set_level_up(trans, path, path->level++);
1813         } else {
1814                 /*
1815                  * Haven't gotten to the end of the parent node: go back down to
1816                  * the next child node
1817                  */
1818                 iter->path = bch2_btree_path_set_pos(trans, iter->path,
1819                                         bpos_successor(iter->pos),
1820                                         iter->flags & BTREE_ITER_INTENT,
1821                                         btree_iter_ip_allocated(iter));
1822
1823                 path = btree_iter_path(trans, iter);
1824                 btree_path_set_level_down(trans, path, iter->min_depth);
1825
1826                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1827                 if (ret)
1828                         goto err;
1829
1830                 path = btree_iter_path(trans, iter);
1831                 b = path->l[path->level].b;
1832         }
1833
1834         bkey_init(&iter->k);
1835         iter->k.p = iter->pos = b->key.k.p;
1836
1837         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1838                                         iter->flags & BTREE_ITER_INTENT,
1839                                         btree_iter_ip_allocated(iter));
1840         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
1841         EBUG_ON(btree_iter_path(trans, iter)->uptodate);
1842 out:
1843         bch2_btree_iter_verify_entry_exit(iter);
1844         bch2_btree_iter_verify(iter);
1845
1846         return b;
1847 err:
1848         b = ERR_PTR(ret);
1849         goto out;
1850 }
1851
1852 /* Iterate across keys (in leaf nodes only) */
1853
1854 inline bool bch2_btree_iter_advance(struct btree_iter *iter)
1855 {
1856         struct bpos pos = iter->k.p;
1857         bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1858                      ? bpos_eq(pos, SPOS_MAX)
1859                      : bkey_eq(pos, SPOS_MAX));
1860
1861         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1862                 pos = bkey_successor(iter, pos);
1863         bch2_btree_iter_set_pos(iter, pos);
1864         return ret;
1865 }
1866
1867 inline bool bch2_btree_iter_rewind(struct btree_iter *iter)
1868 {
1869         struct bpos pos = bkey_start_pos(&iter->k);
1870         bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1871                      ? bpos_eq(pos, POS_MIN)
1872                      : bkey_eq(pos, POS_MIN));
1873
1874         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1875                 pos = bkey_predecessor(iter, pos);
1876         bch2_btree_iter_set_pos(iter, pos);
1877         return ret;
1878 }
1879
1880 static noinline
1881 struct bkey_i *__bch2_btree_trans_peek_updates(struct btree_iter *iter)
1882 {
1883         struct btree_trans *trans = iter->trans;
1884         struct btree_insert_entry *i;
1885         struct bkey_i *ret = NULL;
1886
1887         trans_for_each_update(trans, i) {
1888                 if (i->btree_id < iter->btree_id)
1889                         continue;
1890                 if (i->btree_id > iter->btree_id)
1891                         break;
1892                 if (bpos_lt(i->k->k.p, btree_iter_path(trans, iter)->pos))
1893                         continue;
1894                 if (i->key_cache_already_flushed)
1895                         continue;
1896                 if (!ret || bpos_lt(i->k->k.p, ret->k.p))
1897                         ret = i->k;
1898         }
1899
1900         return ret;
1901 }
1902
1903 static inline struct bkey_i *btree_trans_peek_updates(struct btree_iter *iter)
1904 {
1905         return iter->flags & BTREE_ITER_WITH_UPDATES
1906                 ? __bch2_btree_trans_peek_updates(iter)
1907                 : NULL;
1908 }
1909
1910 static struct bkey_i *bch2_btree_journal_peek(struct btree_trans *trans,
1911                                               struct btree_iter *iter,
1912                                               struct bpos end_pos)
1913 {
1914         struct btree_path *path = btree_iter_path(trans, iter);
1915
1916         return bch2_journal_keys_peek_upto(trans->c, iter->btree_id,
1917                                            path->level,
1918                                            path->pos,
1919                                            end_pos,
1920                                            &iter->journal_idx);
1921 }
1922
1923 static noinline
1924 struct bkey_s_c btree_trans_peek_slot_journal(struct btree_trans *trans,
1925                                               struct btree_iter *iter)
1926 {
1927         struct btree_path *path = btree_iter_path(trans, iter);
1928         struct bkey_i *k = bch2_btree_journal_peek(trans, iter, path->pos);
1929
1930         if (k) {
1931                 iter->k = k->k;
1932                 return bkey_i_to_s_c(k);
1933         } else {
1934                 return bkey_s_c_null;
1935         }
1936 }
1937
1938 static noinline
1939 struct bkey_s_c btree_trans_peek_journal(struct btree_trans *trans,
1940                                          struct btree_iter *iter,
1941                                          struct bkey_s_c k)
1942 {
1943         struct btree_path *path = btree_iter_path(trans, iter);
1944         struct bkey_i *next_journal =
1945                 bch2_btree_journal_peek(trans, iter,
1946                                 k.k ? k.k->p : path_l(path)->b->key.k.p);
1947
1948         if (next_journal) {
1949                 iter->k = next_journal->k;
1950                 k = bkey_i_to_s_c(next_journal);
1951         }
1952
1953         return k;
1954 }
1955
1956 /*
1957  * Checks btree key cache for key at iter->pos and returns it if present, or
1958  * bkey_s_c_null:
1959  */
1960 static noinline
1961 struct bkey_s_c btree_trans_peek_key_cache(struct btree_iter *iter, struct bpos pos)
1962 {
1963         struct btree_trans *trans = iter->trans;
1964         struct bch_fs *c = trans->c;
1965         struct bkey u;
1966         struct bkey_s_c k;
1967         int ret;
1968
1969         if ((iter->flags & BTREE_ITER_KEY_CACHE_FILL) &&
1970             bpos_eq(iter->pos, pos))
1971                 return bkey_s_c_null;
1972
1973         if (!bch2_btree_key_cache_find(c, iter->btree_id, pos))
1974                 return bkey_s_c_null;
1975
1976         if (!iter->key_cache_path)
1977                 iter->key_cache_path = bch2_path_get(trans, iter->btree_id, pos,
1978                                                      iter->flags & BTREE_ITER_INTENT, 0,
1979                                                      iter->flags|BTREE_ITER_CACHED|
1980                                                      BTREE_ITER_CACHED_NOFILL,
1981                                                      _THIS_IP_);
1982
1983         iter->key_cache_path = bch2_btree_path_set_pos(trans, iter->key_cache_path, pos,
1984                                         iter->flags & BTREE_ITER_INTENT,
1985                                         btree_iter_ip_allocated(iter));
1986
1987         ret =   bch2_btree_path_traverse(trans, iter->key_cache_path,
1988                                          iter->flags|BTREE_ITER_CACHED) ?:
1989                 bch2_btree_path_relock(trans, btree_iter_path(trans, iter), _THIS_IP_);
1990         if (unlikely(ret))
1991                 return bkey_s_c_err(ret);
1992
1993         btree_path_set_should_be_locked(trans->paths + iter->key_cache_path);
1994
1995         k = bch2_btree_path_peek_slot(trans->paths + iter->key_cache_path, &u);
1996         if (k.k && !bkey_err(k)) {
1997                 iter->k = u;
1998                 k.k = &iter->k;
1999         }
2000         return k;
2001 }
2002
2003 static struct bkey_s_c __bch2_btree_iter_peek(struct btree_iter *iter, struct bpos search_key)
2004 {
2005         struct btree_trans *trans = iter->trans;
2006         struct bkey_i *next_update;
2007         struct bkey_s_c k, k2;
2008         int ret;
2009
2010         EBUG_ON(btree_iter_path(trans, iter)->cached);
2011         bch2_btree_iter_verify(iter);
2012
2013         while (1) {
2014                 struct btree_path_level *l;
2015
2016                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2017                                         iter->flags & BTREE_ITER_INTENT,
2018                                         btree_iter_ip_allocated(iter));
2019
2020                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2021                 if (unlikely(ret)) {
2022                         /* ensure that iter->k is consistent with iter->pos: */
2023                         bch2_btree_iter_set_pos(iter, iter->pos);
2024                         k = bkey_s_c_err(ret);
2025                         goto out;
2026                 }
2027
2028                 struct btree_path *path = btree_iter_path(trans, iter);
2029                 l = path_l(path);
2030
2031                 if (unlikely(!l->b)) {
2032                         /* No btree nodes at requested level: */
2033                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2034                         k = bkey_s_c_null;
2035                         goto out;
2036                 }
2037
2038                 btree_path_set_should_be_locked(path);
2039
2040                 k = btree_path_level_peek_all(trans->c, l, &iter->k);
2041
2042                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2043                     k.k &&
2044                     (k2 = btree_trans_peek_key_cache(iter, k.k->p)).k) {
2045                         k = k2;
2046                         ret = bkey_err(k);
2047                         if (ret) {
2048                                 bch2_btree_iter_set_pos(iter, iter->pos);
2049                                 goto out;
2050                         }
2051                 }
2052
2053                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL))
2054                         k = btree_trans_peek_journal(trans, iter, k);
2055
2056                 next_update = btree_trans_peek_updates(iter);
2057
2058                 if (next_update &&
2059                     bpos_le(next_update->k.p,
2060                             k.k ? k.k->p : l->b->key.k.p)) {
2061                         iter->k = next_update->k;
2062                         k = bkey_i_to_s_c(next_update);
2063                 }
2064
2065                 if (k.k && bkey_deleted(k.k)) {
2066                         /*
2067                          * If we've got a whiteout, and it's after the search
2068                          * key, advance the search key to the whiteout instead
2069                          * of just after the whiteout - it might be a btree
2070                          * whiteout, with a real key at the same position, since
2071                          * in the btree deleted keys sort before non deleted.
2072                          */
2073                         search_key = !bpos_eq(search_key, k.k->p)
2074                                 ? k.k->p
2075                                 : bpos_successor(k.k->p);
2076                         continue;
2077                 }
2078
2079                 if (likely(k.k)) {
2080                         break;
2081                 } else if (likely(!bpos_eq(l->b->key.k.p, SPOS_MAX))) {
2082                         /* Advance to next leaf node: */
2083                         search_key = bpos_successor(l->b->key.k.p);
2084                 } else {
2085                         /* End of btree: */
2086                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2087                         k = bkey_s_c_null;
2088                         goto out;
2089                 }
2090         }
2091 out:
2092         bch2_btree_iter_verify(iter);
2093
2094         return k;
2095 }
2096
2097 /**
2098  * bch2_btree_iter_peek_upto() - returns first key greater than or equal to
2099  * iterator's current position
2100  * @iter:       iterator to peek from
2101  * @end:        search limit: returns keys less than or equal to @end
2102  *
2103  * Returns:     key if found, or an error extractable with bkey_err().
2104  */
2105 struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *iter, struct bpos end)
2106 {
2107         struct btree_trans *trans = iter->trans;
2108         struct bpos search_key = btree_iter_search_key(iter);
2109         struct bkey_s_c k;
2110         struct bpos iter_pos;
2111         int ret;
2112
2113         EBUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) && bkey_eq(end, POS_MAX));
2114
2115         if (iter->update_path) {
2116                 bch2_path_put_nokeep(trans, iter->update_path,
2117                                      iter->flags & BTREE_ITER_INTENT);
2118                 iter->update_path = 0;
2119         }
2120
2121         bch2_btree_iter_verify_entry_exit(iter);
2122
2123         while (1) {
2124                 k = __bch2_btree_iter_peek(iter, search_key);
2125                 if (unlikely(!k.k))
2126                         goto end;
2127                 if (unlikely(bkey_err(k)))
2128                         goto out_no_locked;
2129
2130                 /*
2131                  * iter->pos should be mononotically increasing, and always be
2132                  * equal to the key we just returned - except extents can
2133                  * straddle iter->pos:
2134                  */
2135                 if (!(iter->flags & BTREE_ITER_IS_EXTENTS))
2136                         iter_pos = k.k->p;
2137                 else
2138                         iter_pos = bkey_max(iter->pos, bkey_start_pos(k.k));
2139
2140                 if (unlikely(!(iter->flags & BTREE_ITER_IS_EXTENTS)
2141                              ? bkey_gt(iter_pos, end)
2142                              : bkey_ge(iter_pos, end)))
2143                         goto end;
2144
2145                 if (iter->update_path &&
2146                     !bkey_eq(trans->paths[iter->update_path].pos, k.k->p)) {
2147                         bch2_path_put_nokeep(trans, iter->update_path,
2148                                              iter->flags & BTREE_ITER_INTENT);
2149                         iter->update_path = 0;
2150                 }
2151
2152                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2153                     (iter->flags & BTREE_ITER_INTENT) &&
2154                     !(iter->flags & BTREE_ITER_IS_EXTENTS) &&
2155                     !iter->update_path) {
2156                         struct bpos pos = k.k->p;
2157
2158                         if (pos.snapshot < iter->snapshot) {
2159                                 search_key = bpos_successor(k.k->p);
2160                                 continue;
2161                         }
2162
2163                         pos.snapshot = iter->snapshot;
2164
2165                         /*
2166                          * advance, same as on exit for iter->path, but only up
2167                          * to snapshot
2168                          */
2169                         __btree_path_get(trans->paths + iter->path, iter->flags & BTREE_ITER_INTENT);
2170                         iter->update_path = iter->path;
2171
2172                         iter->update_path = bch2_btree_path_set_pos(trans,
2173                                                 iter->update_path, pos,
2174                                                 iter->flags & BTREE_ITER_INTENT,
2175                                                 _THIS_IP_);
2176                         ret = bch2_btree_path_traverse(trans, iter->update_path, iter->flags);
2177                         if (unlikely(ret)) {
2178                                 k = bkey_s_c_err(ret);
2179                                 goto out_no_locked;
2180                         }
2181                 }
2182
2183                 /*
2184                  * We can never have a key in a leaf node at POS_MAX, so
2185                  * we don't have to check these successor() calls:
2186                  */
2187                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2188                     !bch2_snapshot_is_ancestor(trans->c,
2189                                                iter->snapshot,
2190                                                k.k->p.snapshot)) {
2191                         search_key = bpos_successor(k.k->p);
2192                         continue;
2193                 }
2194
2195                 if (bkey_whiteout(k.k) &&
2196                     !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2197                         search_key = bkey_successor(iter, k.k->p);
2198                         continue;
2199                 }
2200
2201                 break;
2202         }
2203
2204         iter->pos = iter_pos;
2205
2206         iter->path = bch2_btree_path_set_pos(trans, iter->path, k.k->p,
2207                                 iter->flags & BTREE_ITER_INTENT,
2208                                 btree_iter_ip_allocated(iter));
2209
2210         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
2211 out_no_locked:
2212         if (iter->update_path) {
2213                 ret = bch2_btree_path_relock(trans, trans->paths + iter->update_path, _THIS_IP_);
2214                 if (unlikely(ret))
2215                         k = bkey_s_c_err(ret);
2216                 else
2217                         btree_path_set_should_be_locked(trans->paths + iter->update_path);
2218         }
2219
2220         if (!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS))
2221                 iter->pos.snapshot = iter->snapshot;
2222
2223         ret = bch2_btree_iter_verify_ret(iter, k);
2224         if (unlikely(ret)) {
2225                 bch2_btree_iter_set_pos(iter, iter->pos);
2226                 k = bkey_s_c_err(ret);
2227         }
2228
2229         bch2_btree_iter_verify_entry_exit(iter);
2230
2231         return k;
2232 end:
2233         bch2_btree_iter_set_pos(iter, end);
2234         k = bkey_s_c_null;
2235         goto out_no_locked;
2236 }
2237
2238 /**
2239  * bch2_btree_iter_next() - returns first key greater than iterator's current
2240  * position
2241  * @iter:       iterator to peek from
2242  *
2243  * Returns:     key if found, or an error extractable with bkey_err().
2244  */
2245 struct bkey_s_c bch2_btree_iter_next(struct btree_iter *iter)
2246 {
2247         if (!bch2_btree_iter_advance(iter))
2248                 return bkey_s_c_null;
2249
2250         return bch2_btree_iter_peek(iter);
2251 }
2252
2253 /**
2254  * bch2_btree_iter_peek_prev() - returns first key less than or equal to
2255  * iterator's current position
2256  * @iter:       iterator to peek from
2257  *
2258  * Returns:     key if found, or an error extractable with bkey_err().
2259  */
2260 struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
2261 {
2262         struct btree_trans *trans = iter->trans;
2263         struct bpos search_key = iter->pos;
2264         struct bkey_s_c k;
2265         struct bkey saved_k;
2266         const struct bch_val *saved_v;
2267         btree_path_idx_t saved_path = 0;
2268         int ret;
2269
2270         EBUG_ON(btree_iter_path(trans, iter)->cached ||
2271                 btree_iter_path(trans, iter)->level);
2272         EBUG_ON(iter->flags & BTREE_ITER_WITH_UPDATES);
2273
2274         if (iter->flags & BTREE_ITER_WITH_JOURNAL)
2275                 return bkey_s_c_err(-EIO);
2276
2277         bch2_btree_iter_verify(iter);
2278         bch2_btree_iter_verify_entry_exit(iter);
2279
2280         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2281                 search_key.snapshot = U32_MAX;
2282
2283         while (1) {
2284                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2285                                                 iter->flags & BTREE_ITER_INTENT,
2286                                                 btree_iter_ip_allocated(iter));
2287
2288                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2289                 if (unlikely(ret)) {
2290                         /* ensure that iter->k is consistent with iter->pos: */
2291                         bch2_btree_iter_set_pos(iter, iter->pos);
2292                         k = bkey_s_c_err(ret);
2293                         goto out_no_locked;
2294                 }
2295
2296                 struct btree_path *path = btree_iter_path(trans, iter);
2297
2298                 k = btree_path_level_peek(trans, path, &path->l[0], &iter->k);
2299                 if (!k.k ||
2300                     ((iter->flags & BTREE_ITER_IS_EXTENTS)
2301                      ? bpos_ge(bkey_start_pos(k.k), search_key)
2302                      : bpos_gt(k.k->p, search_key)))
2303                         k = btree_path_level_prev(trans, path, &path->l[0], &iter->k);
2304
2305                 if (likely(k.k)) {
2306                         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) {
2307                                 if (k.k->p.snapshot == iter->snapshot)
2308                                         goto got_key;
2309
2310                                 /*
2311                                  * If we have a saved candidate, and we're no
2312                                  * longer at the same _key_ (not pos), return
2313                                  * that candidate
2314                                  */
2315                                 if (saved_path && !bkey_eq(k.k->p, saved_k.p)) {
2316                                         bch2_path_put_nokeep(trans, iter->path,
2317                                                       iter->flags & BTREE_ITER_INTENT);
2318                                         iter->path = saved_path;
2319                                         saved_path = 0;
2320                                         iter->k = saved_k;
2321                                         k.v     = saved_v;
2322                                         goto got_key;
2323                                 }
2324
2325                                 if (bch2_snapshot_is_ancestor(iter->trans->c,
2326                                                               iter->snapshot,
2327                                                               k.k->p.snapshot)) {
2328                                         if (saved_path)
2329                                                 bch2_path_put_nokeep(trans, saved_path,
2330                                                       iter->flags & BTREE_ITER_INTENT);
2331                                         saved_path = btree_path_clone(trans, iter->path,
2332                                                                 iter->flags & BTREE_ITER_INTENT);
2333                                         path = btree_iter_path(trans, iter);
2334                                         saved_k = *k.k;
2335                                         saved_v = k.v;
2336                                 }
2337
2338                                 search_key = bpos_predecessor(k.k->p);
2339                                 continue;
2340                         }
2341 got_key:
2342                         if (bkey_whiteout(k.k) &&
2343                             !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2344                                 search_key = bkey_predecessor(iter, k.k->p);
2345                                 if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2346                                         search_key.snapshot = U32_MAX;
2347                                 continue;
2348                         }
2349
2350                         btree_path_set_should_be_locked(path);
2351                         break;
2352                 } else if (likely(!bpos_eq(path->l[0].b->data->min_key, POS_MIN))) {
2353                         /* Advance to previous leaf node: */
2354                         search_key = bpos_predecessor(path->l[0].b->data->min_key);
2355                 } else {
2356                         /* Start of btree: */
2357                         bch2_btree_iter_set_pos(iter, POS_MIN);
2358                         k = bkey_s_c_null;
2359                         goto out_no_locked;
2360                 }
2361         }
2362
2363         EBUG_ON(bkey_gt(bkey_start_pos(k.k), iter->pos));
2364
2365         /* Extents can straddle iter->pos: */
2366         if (bkey_lt(k.k->p, iter->pos))
2367                 iter->pos = k.k->p;
2368
2369         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2370                 iter->pos.snapshot = iter->snapshot;
2371 out_no_locked:
2372         if (saved_path)
2373                 bch2_path_put_nokeep(trans, saved_path, iter->flags & BTREE_ITER_INTENT);
2374
2375         bch2_btree_iter_verify_entry_exit(iter);
2376         bch2_btree_iter_verify(iter);
2377
2378         return k;
2379 }
2380
2381 /**
2382  * bch2_btree_iter_prev() - returns first key less than iterator's current
2383  * position
2384  * @iter:       iterator to peek from
2385  *
2386  * Returns:     key if found, or an error extractable with bkey_err().
2387  */
2388 struct bkey_s_c bch2_btree_iter_prev(struct btree_iter *iter)
2389 {
2390         if (!bch2_btree_iter_rewind(iter))
2391                 return bkey_s_c_null;
2392
2393         return bch2_btree_iter_peek_prev(iter);
2394 }
2395
2396 struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
2397 {
2398         struct btree_trans *trans = iter->trans;
2399         struct bpos search_key;
2400         struct bkey_s_c k;
2401         int ret;
2402
2403         bch2_btree_iter_verify(iter);
2404         bch2_btree_iter_verify_entry_exit(iter);
2405         EBUG_ON(btree_iter_path(trans, iter)->level && (iter->flags & BTREE_ITER_WITH_KEY_CACHE));
2406
2407         /* extents can't span inode numbers: */
2408         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
2409             unlikely(iter->pos.offset == KEY_OFFSET_MAX)) {
2410                 if (iter->pos.inode == KEY_INODE_MAX)
2411                         return bkey_s_c_null;
2412
2413                 bch2_btree_iter_set_pos(iter, bpos_nosnap_successor(iter->pos));
2414         }
2415
2416         search_key = btree_iter_search_key(iter);
2417         iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2418                                         iter->flags & BTREE_ITER_INTENT,
2419                                         btree_iter_ip_allocated(iter));
2420
2421         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2422         if (unlikely(ret)) {
2423                 k = bkey_s_c_err(ret);
2424                 goto out_no_locked;
2425         }
2426
2427         if ((iter->flags & BTREE_ITER_CACHED) ||
2428             !(iter->flags & (BTREE_ITER_IS_EXTENTS|BTREE_ITER_FILTER_SNAPSHOTS))) {
2429                 struct bkey_i *next_update;
2430
2431                 if ((next_update = btree_trans_peek_updates(iter)) &&
2432                     bpos_eq(next_update->k.p, iter->pos)) {
2433                         iter->k = next_update->k;
2434                         k = bkey_i_to_s_c(next_update);
2435                         goto out;
2436                 }
2437
2438                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL) &&
2439                     (k = btree_trans_peek_slot_journal(trans, iter)).k)
2440                         goto out;
2441
2442                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2443                     (k = btree_trans_peek_key_cache(iter, iter->pos)).k) {
2444                         if (!bkey_err(k))
2445                                 iter->k = *k.k;
2446                         /* We're not returning a key from iter->path: */
2447                         goto out_no_locked;
2448                 }
2449
2450                 k = bch2_btree_path_peek_slot(trans->paths + iter->path, &iter->k);
2451                 if (unlikely(!k.k))
2452                         goto out_no_locked;
2453         } else {
2454                 struct bpos next;
2455                 struct bpos end = iter->pos;
2456
2457                 if (iter->flags & BTREE_ITER_IS_EXTENTS)
2458                         end.offset = U64_MAX;
2459
2460                 EBUG_ON(btree_iter_path(trans, iter)->level);
2461
2462                 if (iter->flags & BTREE_ITER_INTENT) {
2463                         struct btree_iter iter2;
2464
2465                         bch2_trans_copy_iter(&iter2, iter);
2466                         k = bch2_btree_iter_peek_upto(&iter2, end);
2467
2468                         if (k.k && !bkey_err(k)) {
2469                                 iter->k = iter2.k;
2470                                 k.k = &iter->k;
2471                         }
2472                         bch2_trans_iter_exit(trans, &iter2);
2473                 } else {
2474                         struct bpos pos = iter->pos;
2475
2476                         k = bch2_btree_iter_peek_upto(iter, end);
2477                         if (unlikely(bkey_err(k)))
2478                                 bch2_btree_iter_set_pos(iter, pos);
2479                         else
2480                                 iter->pos = pos;
2481                 }
2482
2483                 if (unlikely(bkey_err(k)))
2484                         goto out_no_locked;
2485
2486                 next = k.k ? bkey_start_pos(k.k) : POS_MAX;
2487
2488                 if (bkey_lt(iter->pos, next)) {
2489                         bkey_init(&iter->k);
2490                         iter->k.p = iter->pos;
2491
2492                         if (iter->flags & BTREE_ITER_IS_EXTENTS) {
2493                                 bch2_key_resize(&iter->k,
2494                                                 min_t(u64, KEY_SIZE_MAX,
2495                                                       (next.inode == iter->pos.inode
2496                                                        ? next.offset
2497                                                        : KEY_OFFSET_MAX) -
2498                                                       iter->pos.offset));
2499                                 EBUG_ON(!iter->k.size);
2500                         }
2501
2502                         k = (struct bkey_s_c) { &iter->k, NULL };
2503                 }
2504         }
2505 out:
2506         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
2507 out_no_locked:
2508         bch2_btree_iter_verify_entry_exit(iter);
2509         bch2_btree_iter_verify(iter);
2510         ret = bch2_btree_iter_verify_ret(iter, k);
2511         if (unlikely(ret))
2512                 return bkey_s_c_err(ret);
2513
2514         return k;
2515 }
2516
2517 struct bkey_s_c bch2_btree_iter_next_slot(struct btree_iter *iter)
2518 {
2519         if (!bch2_btree_iter_advance(iter))
2520                 return bkey_s_c_null;
2521
2522         return bch2_btree_iter_peek_slot(iter);
2523 }
2524
2525 struct bkey_s_c bch2_btree_iter_prev_slot(struct btree_iter *iter)
2526 {
2527         if (!bch2_btree_iter_rewind(iter))
2528                 return bkey_s_c_null;
2529
2530         return bch2_btree_iter_peek_slot(iter);
2531 }
2532
2533 struct bkey_s_c bch2_btree_iter_peek_and_restart_outlined(struct btree_iter *iter)
2534 {
2535         struct bkey_s_c k;
2536
2537         while (btree_trans_too_many_iters(iter->trans) ||
2538                (k = bch2_btree_iter_peek_type(iter, iter->flags),
2539                 bch2_err_matches(bkey_err(k), BCH_ERR_transaction_restart)))
2540                 bch2_trans_begin(iter->trans);
2541
2542         return k;
2543 }
2544
2545 /* new transactional stuff: */
2546
2547 #ifdef CONFIG_BCACHEFS_DEBUG
2548 static void btree_trans_verify_sorted_refs(struct btree_trans *trans)
2549 {
2550         struct btree_path *path;
2551         unsigned i;
2552
2553         BUG_ON(trans->nr_sorted != bitmap_weight(trans->paths_allocated, trans->nr_paths) - 1);
2554
2555         trans_for_each_path(trans, path, i) {
2556                 BUG_ON(path->sorted_idx >= trans->nr_sorted);
2557                 BUG_ON(trans->sorted[path->sorted_idx] != i);
2558         }
2559
2560         for (i = 0; i < trans->nr_sorted; i++) {
2561                 unsigned idx = trans->sorted[i];
2562
2563                 BUG_ON(!test_bit(idx, trans->paths_allocated));
2564                 BUG_ON(trans->paths[idx].sorted_idx != i);
2565         }
2566 }
2567
2568 static void btree_trans_verify_sorted(struct btree_trans *trans)
2569 {
2570         struct btree_path *path, *prev = NULL;
2571         struct trans_for_each_path_inorder_iter iter;
2572
2573         if (!bch2_debug_check_iterators)
2574                 return;
2575
2576         trans_for_each_path_inorder(trans, path, iter) {
2577                 if (prev && btree_path_cmp(prev, path) > 0) {
2578                         __bch2_dump_trans_paths_updates(trans, true);
2579                         panic("trans paths out of order!\n");
2580                 }
2581                 prev = path;
2582         }
2583 }
2584 #else
2585 static inline void btree_trans_verify_sorted_refs(struct btree_trans *trans) {}
2586 static inline void btree_trans_verify_sorted(struct btree_trans *trans) {}
2587 #endif
2588
2589 void __bch2_btree_trans_sort_paths(struct btree_trans *trans)
2590 {
2591         int i, l = 0, r = trans->nr_sorted, inc = 1;
2592         bool swapped;
2593
2594         btree_trans_verify_sorted_refs(trans);
2595
2596         if (trans->paths_sorted)
2597                 goto out;
2598
2599         /*
2600          * Cocktail shaker sort: this is efficient because iterators will be
2601          * mostly sorted.
2602          */
2603         do {
2604                 swapped = false;
2605
2606                 for (i = inc > 0 ? l : r - 2;
2607                      i + 1 < r && i >= l;
2608                      i += inc) {
2609                         if (btree_path_cmp(trans->paths + trans->sorted[i],
2610                                            trans->paths + trans->sorted[i + 1]) > 0) {
2611                                 swap(trans->sorted[i], trans->sorted[i + 1]);
2612                                 trans->paths[trans->sorted[i]].sorted_idx = i;
2613                                 trans->paths[trans->sorted[i + 1]].sorted_idx = i + 1;
2614                                 swapped = true;
2615                         }
2616                 }
2617
2618                 if (inc > 0)
2619                         --r;
2620                 else
2621                         l++;
2622                 inc = -inc;
2623         } while (swapped);
2624
2625         trans->paths_sorted = true;
2626 out:
2627         btree_trans_verify_sorted(trans);
2628 }
2629
2630 static inline void btree_path_list_remove(struct btree_trans *trans,
2631                                           struct btree_path *path)
2632 {
2633         unsigned i;
2634
2635         EBUG_ON(path->sorted_idx >= trans->nr_sorted);
2636 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2637         trans->nr_sorted--;
2638         memmove_u64s_down_small(trans->sorted + path->sorted_idx,
2639                                 trans->sorted + path->sorted_idx + 1,
2640                                 DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx, 8));
2641 #else
2642         array_remove_item(trans->sorted, trans->nr_sorted, path->sorted_idx);
2643 #endif
2644         for (i = path->sorted_idx; i < trans->nr_sorted; i++)
2645                 trans->paths[trans->sorted[i]].sorted_idx = i;
2646
2647         path->sorted_idx = U8_MAX;
2648 }
2649
2650 static inline void btree_path_list_add(struct btree_trans *trans,
2651                                        btree_path_idx_t pos,
2652                                        btree_path_idx_t path_idx)
2653 {
2654         struct btree_path *path = trans->paths + path_idx;
2655         unsigned i;
2656
2657         path->sorted_idx = pos ? trans->paths[pos].sorted_idx + 1 : trans->nr_sorted;
2658
2659 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2660         memmove_u64s_up_small(trans->sorted + path->sorted_idx + 1,
2661                               trans->sorted + path->sorted_idx,
2662                               DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx, 8));
2663         trans->nr_sorted++;
2664         trans->sorted[path->sorted_idx] = path_idx;
2665 #else
2666         array_insert_item(trans->sorted, trans->nr_sorted, path->sorted_idx, path_idx);
2667 #endif
2668
2669         for (i = path->sorted_idx; i < trans->nr_sorted; i++)
2670                 trans->paths[trans->sorted[i]].sorted_idx = i;
2671
2672         btree_trans_verify_sorted_refs(trans);
2673 }
2674
2675 void bch2_trans_iter_exit(struct btree_trans *trans, struct btree_iter *iter)
2676 {
2677         if (iter->update_path)
2678                 bch2_path_put_nokeep(trans, iter->update_path,
2679                               iter->flags & BTREE_ITER_INTENT);
2680         if (iter->path)
2681                 bch2_path_put(trans, iter->path,
2682                               iter->flags & BTREE_ITER_INTENT);
2683         if (iter->key_cache_path)
2684                 bch2_path_put(trans, iter->key_cache_path,
2685                               iter->flags & BTREE_ITER_INTENT);
2686         iter->path              = 0;
2687         iter->update_path       = 0;
2688         iter->key_cache_path    = 0;
2689         iter->trans             = NULL;
2690 }
2691
2692 void bch2_trans_iter_init_outlined(struct btree_trans *trans,
2693                           struct btree_iter *iter,
2694                           enum btree_id btree_id, struct bpos pos,
2695                           unsigned flags)
2696 {
2697         bch2_trans_iter_init_common(trans, iter, btree_id, pos, 0, 0,
2698                                bch2_btree_iter_flags(trans, btree_id, flags),
2699                                _RET_IP_);
2700 }
2701
2702 void bch2_trans_node_iter_init(struct btree_trans *trans,
2703                                struct btree_iter *iter,
2704                                enum btree_id btree_id,
2705                                struct bpos pos,
2706                                unsigned locks_want,
2707                                unsigned depth,
2708                                unsigned flags)
2709 {
2710         flags |= BTREE_ITER_NOT_EXTENTS;
2711         flags |= __BTREE_ITER_ALL_SNAPSHOTS;
2712         flags |= BTREE_ITER_ALL_SNAPSHOTS;
2713
2714         bch2_trans_iter_init_common(trans, iter, btree_id, pos, locks_want, depth,
2715                                __bch2_btree_iter_flags(trans, btree_id, flags),
2716                                _RET_IP_);
2717
2718         iter->min_depth = depth;
2719
2720         struct btree_path *path = btree_iter_path(trans, iter);
2721         BUG_ON(path->locks_want  < min(locks_want, BTREE_MAX_DEPTH));
2722         BUG_ON(path->level      != depth);
2723         BUG_ON(iter->min_depth  != depth);
2724 }
2725
2726 void bch2_trans_copy_iter(struct btree_iter *dst, struct btree_iter *src)
2727 {
2728         struct btree_trans *trans = src->trans;
2729
2730         *dst = *src;
2731         if (src->path)
2732                 __btree_path_get(trans->paths + src->path, src->flags & BTREE_ITER_INTENT);
2733         if (src->update_path)
2734                 __btree_path_get(trans->paths + src->update_path, src->flags & BTREE_ITER_INTENT);
2735         dst->key_cache_path = 0;
2736 }
2737
2738 void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
2739 {
2740         struct bch_fs *c = trans->c;
2741         unsigned new_top = trans->mem_top + size;
2742         unsigned old_bytes = trans->mem_bytes;
2743         unsigned new_bytes = roundup_pow_of_two(new_top);
2744         int ret;
2745         void *new_mem;
2746         void *p;
2747
2748         WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);
2749
2750         struct btree_transaction_stats *s = btree_trans_stats(trans);
2751         if (s)
2752                 s->max_mem = max(s->max_mem, new_bytes);
2753
2754         new_mem = krealloc(trans->mem, new_bytes, GFP_NOWAIT|__GFP_NOWARN);
2755         if (unlikely(!new_mem)) {
2756                 bch2_trans_unlock(trans);
2757
2758                 new_mem = krealloc(trans->mem, new_bytes, GFP_KERNEL);
2759                 if (!new_mem && new_bytes <= BTREE_TRANS_MEM_MAX) {
2760                         new_mem = mempool_alloc(&c->btree_trans_mem_pool, GFP_KERNEL);
2761                         new_bytes = BTREE_TRANS_MEM_MAX;
2762                         kfree(trans->mem);
2763                 }
2764
2765                 if (!new_mem)
2766                         return ERR_PTR(-BCH_ERR_ENOMEM_trans_kmalloc);
2767
2768                 trans->mem = new_mem;
2769                 trans->mem_bytes = new_bytes;
2770
2771                 ret = bch2_trans_relock(trans);
2772                 if (ret)
2773                         return ERR_PTR(ret);
2774         }
2775
2776         trans->mem = new_mem;
2777         trans->mem_bytes = new_bytes;
2778
2779         if (old_bytes) {
2780                 trace_and_count(c, trans_restart_mem_realloced, trans, _RET_IP_, new_bytes);
2781                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_mem_realloced));
2782         }
2783
2784         p = trans->mem + trans->mem_top;
2785         trans->mem_top += size;
2786         memset(p, 0, size);
2787         return p;
2788 }
2789
2790 static inline void check_srcu_held_too_long(struct btree_trans *trans)
2791 {
2792         WARN(trans->srcu_held && time_after(jiffies, trans->srcu_lock_time + HZ * 10),
2793              "btree trans held srcu lock (delaying memory reclaim) for %lu seconds",
2794              (jiffies - trans->srcu_lock_time) / HZ);
2795 }
2796
2797 void bch2_trans_srcu_unlock(struct btree_trans *trans)
2798 {
2799         if (trans->srcu_held) {
2800                 struct bch_fs *c = trans->c;
2801                 struct btree_path *path;
2802                 unsigned i;
2803
2804                 trans_for_each_path(trans, path, i)
2805                         if (path->cached && !btree_node_locked(path, 0))
2806                                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_srcu_reset);
2807
2808                 check_srcu_held_too_long(trans);
2809                 srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
2810                 trans->srcu_held = false;
2811         }
2812 }
2813
2814 static void bch2_trans_srcu_lock(struct btree_trans *trans)
2815 {
2816         if (!trans->srcu_held) {
2817                 trans->srcu_idx = srcu_read_lock(&trans->c->btree_trans_barrier);
2818                 trans->srcu_lock_time   = jiffies;
2819                 trans->srcu_held = true;
2820         }
2821 }
2822
2823 /**
2824  * bch2_trans_begin() - reset a transaction after a interrupted attempt
2825  * @trans: transaction to reset
2826  *
2827  * Returns:     current restart counter, to be used with trans_was_restarted()
2828  *
2829  * While iterating over nodes or updating nodes a attempt to lock a btree node
2830  * may return BCH_ERR_transaction_restart when the trylock fails. When this
2831  * occurs bch2_trans_begin() should be called and the transaction retried.
2832  */
2833 u32 bch2_trans_begin(struct btree_trans *trans)
2834 {
2835         struct btree_path *path;
2836         unsigned i;
2837         u64 now;
2838
2839         bch2_trans_reset_updates(trans);
2840
2841         trans->restart_count++;
2842         trans->mem_top                  = 0;
2843         trans->journal_entries          = NULL;
2844
2845         trans_for_each_path(trans, path, i) {
2846                 path->should_be_locked = false;
2847
2848                 /*
2849                  * If the transaction wasn't restarted, we're presuming to be
2850                  * doing something new: dont keep iterators excpt the ones that
2851                  * are in use - except for the subvolumes btree:
2852                  */
2853                 if (!trans->restarted && path->btree_id != BTREE_ID_subvolumes)
2854                         path->preserve = false;
2855
2856                 /*
2857                  * XXX: we probably shouldn't be doing this if the transaction
2858                  * was restarted, but currently we still overflow transaction
2859                  * iterators if we do that
2860                  */
2861                 if (!path->ref && !path->preserve)
2862                         __bch2_path_free(trans, i);
2863                 else
2864                         path->preserve = false;
2865         }
2866
2867         now = local_clock();
2868         if (!trans->restarted &&
2869             (need_resched() ||
2870              now - trans->last_begin_time > BTREE_TRANS_MAX_LOCK_HOLD_TIME_NS)) {
2871                 drop_locks_do(trans, (cond_resched(), 0));
2872                 now = local_clock();
2873         }
2874         trans->last_begin_time = now;
2875
2876         if (unlikely(trans->srcu_held &&
2877                      time_after(jiffies, trans->srcu_lock_time + msecs_to_jiffies(10))))
2878                 bch2_trans_srcu_unlock(trans);
2879
2880         trans->last_begin_ip = _RET_IP_;
2881         if (trans->restarted) {
2882                 bch2_btree_path_traverse_all(trans);
2883                 trans->notrace_relock_fail = false;
2884         }
2885
2886         return trans->restart_count;
2887 }
2888
2889 const char *bch2_btree_transaction_fns[BCH_TRANSACTIONS_NR];
2890
2891 unsigned bch2_trans_get_fn_idx(const char *fn)
2892 {
2893         unsigned i;
2894
2895         for (i = 0; i < ARRAY_SIZE(bch2_btree_transaction_fns); i++)
2896                 if (!bch2_btree_transaction_fns[i] ||
2897                     bch2_btree_transaction_fns[i] == fn) {
2898                         bch2_btree_transaction_fns[i] = fn;
2899                         return i;
2900                 }
2901
2902         pr_warn_once("BCH_TRANSACTIONS_NR not big enough!");
2903         return i;
2904 }
2905
2906 struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx)
2907         __acquires(&c->btree_trans_barrier)
2908 {
2909         struct btree_trans *trans;
2910
2911         if (IS_ENABLED(__KERNEL__)) {
2912                 trans = this_cpu_xchg(c->btree_trans_bufs->trans, NULL);
2913                 if (trans) {
2914                         memset(trans, 0, offsetof(struct btree_trans, list));
2915                         goto got_trans;
2916                 }
2917         }
2918
2919         trans = mempool_alloc(&c->btree_trans_pool, GFP_NOFS);
2920         memset(trans, 0, sizeof(*trans));
2921         closure_init_stack(&trans->ref);
2922
2923         seqmutex_lock(&c->btree_trans_lock);
2924         if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG)) {
2925                 struct btree_trans *pos;
2926                 pid_t pid = current->pid;
2927
2928                 trans->locking_wait.task = current;
2929
2930                 list_for_each_entry(pos, &c->btree_trans_list, list) {
2931                         struct task_struct *pos_task = READ_ONCE(pos->locking_wait.task);
2932                         /*
2933                          * We'd much prefer to be stricter here and completely
2934                          * disallow multiple btree_trans in the same thread -
2935                          * but the data move path calls bch2_write when we
2936                          * already have a btree_trans initialized.
2937                          */
2938                         BUG_ON(pos_task &&
2939                                pid == pos_task->pid &&
2940                                bch2_trans_locked(pos));
2941
2942                         if (pos_task && pid < pos_task->pid) {
2943                                 list_add_tail(&trans->list, &pos->list);
2944                                 goto list_add_done;
2945                         }
2946                 }
2947         }
2948         list_add_tail(&trans->list, &c->btree_trans_list);
2949 list_add_done:
2950         seqmutex_unlock(&c->btree_trans_lock);
2951 got_trans:
2952         trans->c                = c;
2953         trans->last_begin_time  = local_clock();
2954         trans->fn_idx           = fn_idx;
2955         trans->locking_wait.task = current;
2956         trans->journal_replay_not_finished =
2957                 unlikely(!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags)) &&
2958                 atomic_inc_not_zero(&c->journal_keys.ref);
2959         trans->nr_paths         = ARRAY_SIZE(trans->_paths);
2960         trans->paths_allocated  = trans->_paths_allocated;
2961         trans->sorted           = trans->_sorted;
2962         trans->paths            = trans->_paths;
2963         trans->updates          = trans->_updates;
2964
2965         *trans_paths_nr(trans->paths) = BTREE_ITER_MAX;
2966
2967         trans->paths_allocated[0] = 1;
2968
2969         if (fn_idx < BCH_TRANSACTIONS_NR) {
2970                 trans->fn = bch2_btree_transaction_fns[fn_idx];
2971
2972                 struct btree_transaction_stats *s = &c->btree_transaction_stats[fn_idx];
2973
2974                 if (s->max_mem) {
2975                         unsigned expected_mem_bytes = roundup_pow_of_two(s->max_mem);
2976
2977                         trans->mem = kmalloc(expected_mem_bytes, GFP_KERNEL);
2978                         if (likely(trans->mem))
2979                                 trans->mem_bytes = expected_mem_bytes;
2980                 }
2981
2982                 trans->nr_paths_max = s->nr_max_paths;
2983                 trans->journal_entries_size = s->journal_entries_size;
2984         }
2985
2986         trans->srcu_idx         = srcu_read_lock(&c->btree_trans_barrier);
2987         trans->srcu_lock_time   = jiffies;
2988         trans->srcu_held        = true;
2989         return trans;
2990 }
2991
2992 static void check_btree_paths_leaked(struct btree_trans *trans)
2993 {
2994 #ifdef CONFIG_BCACHEFS_DEBUG
2995         struct bch_fs *c = trans->c;
2996         struct btree_path *path;
2997         unsigned i;
2998
2999         trans_for_each_path(trans, path, i)
3000                 if (path->ref)
3001                         goto leaked;
3002         return;
3003 leaked:
3004         bch_err(c, "btree paths leaked from %s!", trans->fn);
3005         trans_for_each_path(trans, path, i)
3006                 if (path->ref)
3007                         printk(KERN_ERR "  btree %s %pS\n",
3008                                bch2_btree_id_str(path->btree_id),
3009                                (void *) path->ip_allocated);
3010         /* Be noisy about this: */
3011         bch2_fatal_error(c);
3012 #endif
3013 }
3014
3015 void bch2_trans_put(struct btree_trans *trans)
3016         __releases(&c->btree_trans_barrier)
3017 {
3018         struct btree_insert_entry *i;
3019         struct bch_fs *c = trans->c;
3020
3021         bch2_trans_unlock(trans);
3022
3023         trans_for_each_update(trans, i)
3024                 __btree_path_put(trans->paths + i->path, true);
3025         trans->nr_updates       = 0;
3026         trans->locking_wait.task = NULL;
3027
3028         check_btree_paths_leaked(trans);
3029
3030         if (trans->srcu_held) {
3031                 check_srcu_held_too_long(trans);
3032                 srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
3033         }
3034
3035         if (trans->fs_usage_deltas) {
3036                 if (trans->fs_usage_deltas->size + sizeof(trans->fs_usage_deltas) ==
3037                     REPLICAS_DELTA_LIST_MAX)
3038                         mempool_free(trans->fs_usage_deltas,
3039                                      &c->replicas_delta_pool);
3040                 else
3041                         kfree(trans->fs_usage_deltas);
3042         }
3043
3044         if (unlikely(trans->journal_replay_not_finished))
3045                 bch2_journal_keys_put(c);
3046
3047         unsigned long *paths_allocated = trans->paths_allocated;
3048         trans->paths_allocated  = NULL;
3049         trans->paths            = NULL;
3050
3051         if (paths_allocated != trans->_paths_allocated)
3052                 kfree_rcu_mightsleep(paths_allocated);
3053
3054         if (trans->mem_bytes == BTREE_TRANS_MEM_MAX)
3055                 mempool_free(trans->mem, &c->btree_trans_mem_pool);
3056         else
3057                 kfree(trans->mem);
3058
3059         /* Userspace doesn't have a real percpu implementation: */
3060         if (IS_ENABLED(__KERNEL__))
3061                 trans = this_cpu_xchg(c->btree_trans_bufs->trans, trans);
3062
3063         if (trans) {
3064                 closure_sync(&trans->ref);
3065
3066                 seqmutex_lock(&c->btree_trans_lock);
3067                 list_del(&trans->list);
3068                 seqmutex_unlock(&c->btree_trans_lock);
3069
3070                 mempool_free(trans, &c->btree_trans_pool);
3071         }
3072 }
3073
3074 static void __maybe_unused
3075 bch2_btree_bkey_cached_common_to_text(struct printbuf *out,
3076                                       struct btree_bkey_cached_common *b)
3077 {
3078         struct six_lock_count c = six_lock_counts(&b->lock);
3079         struct task_struct *owner;
3080         pid_t pid;
3081
3082         rcu_read_lock();
3083         owner = READ_ONCE(b->lock.owner);
3084         pid = owner ? owner->pid : 0;
3085         rcu_read_unlock();
3086
3087         prt_tab(out);
3088         prt_printf(out, "%px %c l=%u %s:", b, b->cached ? 'c' : 'b',
3089                    b->level, bch2_btree_id_str(b->btree_id));
3090         bch2_bpos_to_text(out, btree_node_pos(b));
3091
3092         prt_tab(out);
3093         prt_printf(out, " locks %u:%u:%u held by pid %u",
3094                    c.n[0], c.n[1], c.n[2], pid);
3095 }
3096
3097 void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
3098 {
3099         struct btree_bkey_cached_common *b;
3100         static char lock_types[] = { 'r', 'i', 'w' };
3101         struct task_struct *task = READ_ONCE(trans->locking_wait.task);
3102         unsigned l, idx;
3103
3104         /* before rcu_read_lock(): */
3105         bch2_printbuf_make_room(out, 4096);
3106
3107         if (!out->nr_tabstops) {
3108                 printbuf_tabstop_push(out, 16);
3109                 printbuf_tabstop_push(out, 32);
3110         }
3111
3112         prt_printf(out, "%i %s\n", task ? task->pid : 0, trans->fn);
3113
3114         /* trans->paths is rcu protected vs. freeing */
3115         rcu_read_lock();
3116         out->atomic++;
3117
3118         struct btree_path *paths = rcu_dereference(trans->paths);
3119         if (!paths)
3120                 goto out;
3121
3122         unsigned long *paths_allocated = trans_paths_allocated(paths);
3123
3124         trans_for_each_path_idx_from(paths_allocated, *trans_paths_nr(paths), idx, 1) {
3125                 struct btree_path *path = paths + idx;
3126                 if (!path->nodes_locked)
3127                         continue;
3128
3129                 prt_printf(out, "  path %u %c l=%u %s:",
3130                        idx,
3131                        path->cached ? 'c' : 'b',
3132                        path->level,
3133                        bch2_btree_id_str(path->btree_id));
3134                 bch2_bpos_to_text(out, path->pos);
3135                 prt_newline(out);
3136
3137                 for (l = 0; l < BTREE_MAX_DEPTH; l++) {
3138                         if (btree_node_locked(path, l) &&
3139                             !IS_ERR_OR_NULL(b = (void *) READ_ONCE(path->l[l].b))) {
3140                                 prt_printf(out, "    %c l=%u ",
3141                                            lock_types[btree_node_locked_type(path, l)], l);
3142                                 bch2_btree_bkey_cached_common_to_text(out, b);
3143                                 prt_newline(out);
3144                         }
3145                 }
3146         }
3147
3148         b = READ_ONCE(trans->locking);
3149         if (b) {
3150                 prt_printf(out, "  blocked for %lluus on",
3151                            div_u64(local_clock() - trans->locking_wait.start_time,
3152                                    1000));
3153                 prt_newline(out);
3154                 prt_printf(out, "    %c", lock_types[trans->locking_wait.lock_want]);
3155                 bch2_btree_bkey_cached_common_to_text(out, b);
3156                 prt_newline(out);
3157         }
3158 out:
3159         --out->atomic;
3160         rcu_read_unlock();
3161 }
3162
3163 void bch2_fs_btree_iter_exit(struct bch_fs *c)
3164 {
3165         struct btree_transaction_stats *s;
3166         struct btree_trans *trans;
3167         int cpu;
3168
3169         if (c->btree_trans_bufs)
3170                 for_each_possible_cpu(cpu) {
3171                         struct btree_trans *trans =
3172                                 per_cpu_ptr(c->btree_trans_bufs, cpu)->trans;
3173
3174                         if (trans) {
3175                                 closure_sync(&trans->ref);
3176
3177                                 seqmutex_lock(&c->btree_trans_lock);
3178                                 list_del(&trans->list);
3179                                 seqmutex_unlock(&c->btree_trans_lock);
3180                         }
3181                         kfree(trans);
3182                 }
3183         free_percpu(c->btree_trans_bufs);
3184
3185         trans = list_first_entry_or_null(&c->btree_trans_list, struct btree_trans, list);
3186         if (trans)
3187                 panic("%s leaked btree_trans\n", trans->fn);
3188
3189         for (s = c->btree_transaction_stats;
3190              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3191              s++) {
3192                 kfree(s->max_paths_text);
3193                 bch2_time_stats_exit(&s->lock_hold_times);
3194         }
3195
3196         if (c->btree_trans_barrier_initialized)
3197                 cleanup_srcu_struct(&c->btree_trans_barrier);
3198         mempool_exit(&c->btree_trans_mem_pool);
3199         mempool_exit(&c->btree_trans_pool);
3200 }
3201
3202 void bch2_fs_btree_iter_init_early(struct bch_fs *c)
3203 {
3204         struct btree_transaction_stats *s;
3205
3206         for (s = c->btree_transaction_stats;
3207              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3208              s++) {
3209                 bch2_time_stats_init(&s->lock_hold_times);
3210                 mutex_init(&s->lock);
3211         }
3212
3213         INIT_LIST_HEAD(&c->btree_trans_list);
3214         seqmutex_init(&c->btree_trans_lock);
3215 }
3216
3217 int bch2_fs_btree_iter_init(struct bch_fs *c)
3218 {
3219         int ret;
3220
3221         c->btree_trans_bufs = alloc_percpu(struct btree_trans_buf);
3222         if (!c->btree_trans_bufs)
3223                 return -ENOMEM;
3224
3225         ret   = mempool_init_kmalloc_pool(&c->btree_trans_pool, 1,
3226                                           sizeof(struct btree_trans)) ?:
3227                 mempool_init_kmalloc_pool(&c->btree_trans_mem_pool, 1,
3228                                           BTREE_TRANS_MEM_MAX) ?:
3229                 init_srcu_struct(&c->btree_trans_barrier);
3230         if (!ret)
3231                 c->btree_trans_barrier_initialized = true;
3232         return ret;
3233 }