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 "replicas.h"
  17 #include "snapshot.h"
  18 #include "trace.h"
  19
  20 #include <linux/random.h>
  21 #include <linux/prefetch.h>
  22
  23 static inline void btree_path_list_remove(struct btree_trans *, struct btree_path *);
  24 static inline void btree_path_list_add(struct btree_trans *, struct btree_path *,
  25                                        struct btree_path *);
  26
  27 static inline unsigned long btree_iter_ip_allocated(struct btree_iter *iter)
  28 {
  29 #ifdef TRACK_PATH_ALLOCATED
  30         return iter->ip_allocated;
  31 #else
  32         return 0;
  33 #endif
  34 }
  35
  36 static struct btree_path *btree_path_alloc(struct btree_trans *, struct btree_path *);
  37
  38 static inline int __btree_path_cmp(const struct btree_path *l,
  39                                    enum btree_id        r_btree_id,
  40                                    bool                 r_cached,
  41                                    struct bpos          r_pos,
  42                                    unsigned             r_level)
  43 {
  44         /*
  45          * Must match lock ordering as defined by __bch2_btree_node_lock:
  46          */
  47         return   cmp_int(l->btree_id,   r_btree_id) ?:
  48                  cmp_int((int) l->cached,       (int) r_cached) ?:
  49                  bpos_cmp(l->pos,       r_pos) ?:
  50                 -cmp_int(l->level,      r_level);
  51 }
  52
  53 static inline int btree_path_cmp(const struct btree_path *l,
  54                                  const struct btree_path *r)
  55 {
  56         return __btree_path_cmp(l, r->btree_id, r->cached, r->pos, r->level);
  57 }
  58
  59 static inline struct bpos bkey_successor(struct btree_iter *iter, struct bpos p)
  60 {
  61         /* Are we iterating over keys in all snapshots? */
  62         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  63                 p = bpos_successor(p);
  64         } else {
  65                 p = bpos_nosnap_successor(p);
  66                 p.snapshot = iter->snapshot;
  67         }
  68
  69         return p;
  70 }
  71
  72 static inline struct bpos bkey_predecessor(struct btree_iter *iter, struct bpos p)
  73 {
  74         /* Are we iterating over keys in all snapshots? */
  75         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  76                 p = bpos_predecessor(p);
  77         } else {
  78                 p = bpos_nosnap_predecessor(p);
  79                 p.snapshot = iter->snapshot;
  80         }
  81
  82         return p;
  83 }
  84
  85 static inline struct bpos btree_iter_search_key(struct btree_iter *iter)
  86 {
  87         struct bpos pos = iter->pos;
  88
  89         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
  90             !bkey_eq(pos, POS_MAX))
  91                 pos = bkey_successor(iter, pos);
  92         return pos;
  93 }
  94
  95 static inline bool btree_path_pos_before_node(struct btree_path *path,
  96                                               struct btree *b)
  97 {
  98         return bpos_lt(path->pos, b->data->min_key);
  99 }
 100
 101 static inline bool btree_path_pos_after_node(struct btree_path *path,
 102                                              struct btree *b)
 103 {
 104         return bpos_gt(path->pos, b->key.k.p);
 105 }
 106
 107 static inline bool btree_path_pos_in_node(struct btree_path *path,
 108                                           struct btree *b)
 109 {
 110         return path->btree_id == b->c.btree_id &&
 111                 !btree_path_pos_before_node(path, b) &&
 112                 !btree_path_pos_after_node(path, b);
 113 }
 114
 115 /* Btree iterator: */
 116
 117 #ifdef CONFIG_BCACHEFS_DEBUG
 118
 119 static void bch2_btree_path_verify_cached(struct btree_trans *trans,
 120                                           struct btree_path *path)
 121 {
 122         struct bkey_cached *ck;
 123         bool locked = btree_node_locked(path, 0);
 124
 125         if (!bch2_btree_node_relock(trans, path, 0))
 126                 return;
 127
 128         ck = (void *) path->l[0].b;
 129         BUG_ON(ck->key.btree_id != path->btree_id ||
 130                !bkey_eq(ck->key.pos, path->pos));
 131
 132         if (!locked)
 133                 btree_node_unlock(trans, path, 0);
 134 }
 135
 136 static void bch2_btree_path_verify_level(struct btree_trans *trans,
 137                                 struct btree_path *path, unsigned level)
 138 {
 139         struct btree_path_level *l;
 140         struct btree_node_iter tmp;
 141         bool locked;
 142         struct bkey_packed *p, *k;
 143         struct printbuf buf1 = PRINTBUF;
 144         struct printbuf buf2 = PRINTBUF;
 145         struct printbuf buf3 = PRINTBUF;
 146         const char *msg;
 147
 148         if (!bch2_debug_check_iterators)
 149                 return;
 150
 151         l       = &path->l[level];
 152         tmp     = l->iter;
 153         locked  = btree_node_locked(path, level);
 154
 155         if (path->cached) {
 156                 if (!level)
 157                         bch2_btree_path_verify_cached(trans, path);
 158                 return;
 159         }
 160
 161         if (!btree_path_node(path, level))
 162                 return;
 163
 164         if (!bch2_btree_node_relock_notrace(trans, path, level))
 165                 return;
 166
 167         BUG_ON(!btree_path_pos_in_node(path, l->b));
 168
 169         bch2_btree_node_iter_verify(&l->iter, l->b);
 170
 171         /*
 172          * For interior nodes, the iterator will have skipped past deleted keys:
 173          */
 174         p = level
 175                 ? bch2_btree_node_iter_prev(&tmp, l->b)
 176                 : bch2_btree_node_iter_prev_all(&tmp, l->b);
 177         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 178
 179         if (p && bkey_iter_pos_cmp(l->b, p, &path->pos) >= 0) {
 180                 msg = "before";
 181                 goto err;
 182         }
 183
 184         if (k && bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 185                 msg = "after";
 186                 goto err;
 187         }
 188
 189         if (!locked)
 190                 btree_node_unlock(trans, path, level);
 191         return;
 192 err:
 193         bch2_bpos_to_text(&buf1, path->pos);
 194
 195         if (p) {
 196                 struct bkey uk = bkey_unpack_key(l->b, p);
 197
 198                 bch2_bkey_to_text(&buf2, &uk);
 199         } else {
 200                 prt_printf(&buf2, "(none)");
 201         }
 202
 203         if (k) {
 204                 struct bkey uk = bkey_unpack_key(l->b, k);
 205
 206                 bch2_bkey_to_text(&buf3, &uk);
 207         } else {
 208                 prt_printf(&buf3, "(none)");
 209         }
 210
 211         panic("path should be %s key at level %u:\n"
 212               "path pos %s\n"
 213               "prev key %s\n"
 214               "cur  key %s\n",
 215               msg, level, buf1.buf, buf2.buf, buf3.buf);
 216 }
 217
 218 static void bch2_btree_path_verify(struct btree_trans *trans,
 219                                    struct btree_path *path)
 220 {
 221         struct bch_fs *c = trans->c;
 222         unsigned i;
 223
 224         EBUG_ON(path->btree_id >= BTREE_ID_NR);
 225
 226         for (i = 0; i < (!path->cached ? BTREE_MAX_DEPTH : 1); i++) {
 227                 if (!path->l[i].b) {
 228                         BUG_ON(!path->cached &&
 229                                bch2_btree_id_root(c, path->btree_id)->b->c.level > i);
 230                         break;
 231                 }
 232
 233                 bch2_btree_path_verify_level(trans, path, i);
 234         }
 235
 236         bch2_btree_path_verify_locks(path);
 237 }
 238
 239 void bch2_trans_verify_paths(struct btree_trans *trans)
 240 {
 241         struct btree_path *path;
 242
 243         trans_for_each_path(trans, path)
 244                 bch2_btree_path_verify(trans, path);
 245 }
 246
 247 static void bch2_btree_iter_verify(struct btree_iter *iter)
 248 {
 249         struct btree_trans *trans = iter->trans;
 250
 251         BUG_ON(iter->btree_id >= BTREE_ID_NR);
 252
 253         BUG_ON(!!(iter->flags & BTREE_ITER_CACHED) != iter->path->cached);
 254
 255         BUG_ON((iter->flags & BTREE_ITER_IS_EXTENTS) &&
 256                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
 257
 258         BUG_ON(!(iter->flags & __BTREE_ITER_ALL_SNAPSHOTS) &&
 259                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 260                !btree_type_has_snapshots(iter->btree_id));
 261
 262         if (iter->update_path)
 263                 bch2_btree_path_verify(trans, iter->update_path);
 264         bch2_btree_path_verify(trans, iter->path);
 265 }
 266
 267 static void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter)
 268 {
 269         BUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
 270                !iter->pos.snapshot);
 271
 272         BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 273                iter->pos.snapshot != iter->snapshot);
 274
 275         BUG_ON(bkey_lt(iter->pos, bkey_start_pos(&iter->k)) ||
 276                bkey_gt(iter->pos, iter->k.p));
 277 }
 278
 279 static int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k)
 280 {
 281         struct btree_trans *trans = iter->trans;
 282         struct btree_iter copy;
 283         struct bkey_s_c prev;
 284         int ret = 0;
 285
 286         if (!bch2_debug_check_iterators)
 287                 return 0;
 288
 289         if (!(iter->flags & BTREE_ITER_FILTER_SNAPSHOTS))
 290                 return 0;
 291
 292         if (bkey_err(k) || !k.k)
 293                 return 0;
 294
 295         BUG_ON(!bch2_snapshot_is_ancestor(trans->c,
 296                                           iter->snapshot,
 297                                           k.k->p.snapshot));
 298
 299         bch2_trans_iter_init(trans, &copy, iter->btree_id, iter->pos,
 300                              BTREE_ITER_NOPRESERVE|
 301                              BTREE_ITER_ALL_SNAPSHOTS);
 302         prev = bch2_btree_iter_prev(&copy);
 303         if (!prev.k)
 304                 goto out;
 305
 306         ret = bkey_err(prev);
 307         if (ret)
 308                 goto out;
 309
 310         if (bkey_eq(prev.k->p, k.k->p) &&
 311             bch2_snapshot_is_ancestor(trans->c, iter->snapshot,
 312                                       prev.k->p.snapshot) > 0) {
 313                 struct printbuf buf1 = PRINTBUF, buf2 = PRINTBUF;
 314
 315                 bch2_bkey_to_text(&buf1, k.k);
 316                 bch2_bkey_to_text(&buf2, prev.k);
 317
 318                 panic("iter snap %u\n"
 319                       "k    %s\n"
 320                       "prev %s\n",
 321                       iter->snapshot,
 322                       buf1.buf, buf2.buf);
 323         }
 324 out:
 325         bch2_trans_iter_exit(trans, &copy);
 326         return ret;
 327 }
 328
 329 void bch2_assert_pos_locked(struct btree_trans *trans, enum btree_id id,
 330                             struct bpos pos, bool key_cache)
 331 {
 332         struct btree_path *path;
 333         unsigned idx;
 334         struct printbuf buf = PRINTBUF;
 335
 336         btree_trans_sort_paths(trans);
 337
 338         trans_for_each_path_inorder(trans, path, idx) {
 339                 int cmp = cmp_int(path->btree_id, id) ?:
 340                         cmp_int(path->cached, key_cache);
 341
 342                 if (cmp > 0)
 343                         break;
 344                 if (cmp < 0)
 345                         continue;
 346
 347                 if (!btree_node_locked(path, 0) ||
 348                     !path->should_be_locked)
 349                         continue;
 350
 351                 if (!key_cache) {
 352                         if (bkey_ge(pos, path->l[0].b->data->min_key) &&
 353                             bkey_le(pos, path->l[0].b->key.k.p))
 354                                 return;
 355                 } else {
 356                         if (bkey_eq(pos, path->pos))
 357                                 return;
 358                 }
 359         }
 360
 361         bch2_dump_trans_paths_updates(trans);
 362         bch2_bpos_to_text(&buf, pos);
 363
 364         panic("not locked: %s %s%s\n",
 365               bch2_btree_id_str(id), buf.buf,
 366               key_cache ? " cached" : "");
 367 }
 368
 369 #else
 370
 371 static inline void bch2_btree_path_verify_level(struct btree_trans *trans,
 372                                                 struct btree_path *path, unsigned l) {}
 373 static inline void bch2_btree_path_verify(struct btree_trans *trans,
 374                                           struct btree_path *path) {}
 375 static inline void bch2_btree_iter_verify(struct btree_iter *iter) {}
 376 static inline void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter) {}
 377 static inline int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k) { return 0; }
 378
 379 #endif
 380
 381 /* Btree path: fixups after btree updates */
 382
 383 static void btree_node_iter_set_set_pos(struct btree_node_iter *iter,
 384                                         struct btree *b,
 385                                         struct bset_tree *t,
 386                                         struct bkey_packed *k)
 387 {
 388         struct btree_node_iter_set *set;
 389
 390         btree_node_iter_for_each(iter, set)
 391                 if (set->end == t->end_offset) {
 392                         set->k = __btree_node_key_to_offset(b, k);
 393                         bch2_btree_node_iter_sort(iter, b);
 394                         return;
 395                 }
 396
 397         bch2_btree_node_iter_push(iter, b, k, btree_bkey_last(b, t));
 398 }
 399
 400 static void __bch2_btree_path_fix_key_modified(struct btree_path *path,
 401                                                struct btree *b,
 402                                                struct bkey_packed *where)
 403 {
 404         struct btree_path_level *l = &path->l[b->c.level];
 405
 406         if (where != bch2_btree_node_iter_peek_all(&l->iter, l->b))
 407                 return;
 408
 409         if (bkey_iter_pos_cmp(l->b, where, &path->pos) < 0)
 410                 bch2_btree_node_iter_advance(&l->iter, l->b);
 411 }
 412
 413 void bch2_btree_path_fix_key_modified(struct btree_trans *trans,
 414                                       struct btree *b,
 415                                       struct bkey_packed *where)
 416 {
 417         struct btree_path *path;
 418
 419         trans_for_each_path_with_node(trans, b, path) {
 420                 __bch2_btree_path_fix_key_modified(path, b, where);
 421                 bch2_btree_path_verify_level(trans, path, b->c.level);
 422         }
 423 }
 424
 425 static void __bch2_btree_node_iter_fix(struct btree_path *path,
 426                                        struct btree *b,
 427                                        struct btree_node_iter *node_iter,
 428                                        struct bset_tree *t,
 429                                        struct bkey_packed *where,
 430                                        unsigned clobber_u64s,
 431                                        unsigned new_u64s)
 432 {
 433         const struct bkey_packed *end = btree_bkey_last(b, t);
 434         struct btree_node_iter_set *set;
 435         unsigned offset = __btree_node_key_to_offset(b, where);
 436         int shift = new_u64s - clobber_u64s;
 437         unsigned old_end = t->end_offset - shift;
 438         unsigned orig_iter_pos = node_iter->data[0].k;
 439         bool iter_current_key_modified =
 440                 orig_iter_pos >= offset &&
 441                 orig_iter_pos <= offset + clobber_u64s;
 442
 443         btree_node_iter_for_each(node_iter, set)
 444                 if (set->end == old_end)
 445                         goto found;
 446
 447         /* didn't find the bset in the iterator - might have to readd it: */
 448         if (new_u64s &&
 449             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 450                 bch2_btree_node_iter_push(node_iter, b, where, end);
 451                 goto fixup_done;
 452         } else {
 453                 /* Iterator is after key that changed */
 454                 return;
 455         }
 456 found:
 457         set->end = t->end_offset;
 458
 459         /* Iterator hasn't gotten to the key that changed yet: */
 460         if (set->k < offset)
 461                 return;
 462
 463         if (new_u64s &&
 464             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 465                 set->k = offset;
 466         } else if (set->k < offset + clobber_u64s) {
 467                 set->k = offset + new_u64s;
 468                 if (set->k == set->end)
 469                         bch2_btree_node_iter_set_drop(node_iter, set);
 470         } else {
 471                 /* Iterator is after key that changed */
 472                 set->k = (int) set->k + shift;
 473                 return;
 474         }
 475
 476         bch2_btree_node_iter_sort(node_iter, b);
 477 fixup_done:
 478         if (node_iter->data[0].k != orig_iter_pos)
 479                 iter_current_key_modified = true;
 480
 481         /*
 482          * When a new key is added, and the node iterator now points to that
 483          * key, the iterator might have skipped past deleted keys that should
 484          * come after the key the iterator now points to. We have to rewind to
 485          * before those deleted keys - otherwise
 486          * bch2_btree_node_iter_prev_all() breaks:
 487          */
 488         if (!bch2_btree_node_iter_end(node_iter) &&
 489             iter_current_key_modified &&
 490             b->c.level) {
 491                 struct bkey_packed *k, *k2, *p;
 492
 493                 k = bch2_btree_node_iter_peek_all(node_iter, b);
 494
 495                 for_each_bset(b, t) {
 496                         bool set_pos = false;
 497
 498                         if (node_iter->data[0].end == t->end_offset)
 499                                 continue;
 500
 501                         k2 = bch2_btree_node_iter_bset_pos(node_iter, b, t);
 502
 503                         while ((p = bch2_bkey_prev_all(b, t, k2)) &&
 504                                bkey_iter_cmp(b, k, p) < 0) {
 505                                 k2 = p;
 506                                 set_pos = true;
 507                         }
 508
 509                         if (set_pos)
 510                                 btree_node_iter_set_set_pos(node_iter,
 511                                                             b, t, k2);
 512                 }
 513         }
 514 }
 515
 516 void bch2_btree_node_iter_fix(struct btree_trans *trans,
 517                               struct btree_path *path,
 518                               struct btree *b,
 519                               struct btree_node_iter *node_iter,
 520                               struct bkey_packed *where,
 521                               unsigned clobber_u64s,
 522                               unsigned new_u64s)
 523 {
 524         struct bset_tree *t = bch2_bkey_to_bset_inlined(b, where);
 525         struct btree_path *linked;
 526
 527         if (node_iter != &path->l[b->c.level].iter) {
 528                 __bch2_btree_node_iter_fix(path, b, node_iter, t,
 529                                            where, clobber_u64s, new_u64s);
 530
 531                 if (bch2_debug_check_iterators)
 532                         bch2_btree_node_iter_verify(node_iter, b);
 533         }
 534
 535         trans_for_each_path_with_node(trans, b, linked) {
 536                 __bch2_btree_node_iter_fix(linked, b,
 537                                            &linked->l[b->c.level].iter, t,
 538                                            where, clobber_u64s, new_u64s);
 539                 bch2_btree_path_verify_level(trans, linked, b->c.level);
 540         }
 541 }
 542
 543 /* Btree path level: pointer to a particular btree node and node iter */
 544
 545 static inline struct bkey_s_c __btree_iter_unpack(struct bch_fs *c,
 546                                                   struct btree_path_level *l,
 547                                                   struct bkey *u,
 548                                                   struct bkey_packed *k)
 549 {
 550         if (unlikely(!k)) {
 551                 /*
 552                  * signal to bch2_btree_iter_peek_slot() that we're currently at
 553                  * a hole
 554                  */
 555                 u->type = KEY_TYPE_deleted;
 556                 return bkey_s_c_null;
 557         }
 558
 559         return bkey_disassemble(l->b, k, u);
 560 }
 561
 562 static inline struct bkey_s_c btree_path_level_peek_all(struct bch_fs *c,
 563                                                         struct btree_path_level *l,
 564                                                         struct bkey *u)
 565 {
 566         return __btree_iter_unpack(c, l, u,
 567                         bch2_btree_node_iter_peek_all(&l->iter, l->b));
 568 }
 569
 570 static inline struct bkey_s_c btree_path_level_peek(struct btree_trans *trans,
 571                                                     struct btree_path *path,
 572                                                     struct btree_path_level *l,
 573                                                     struct bkey *u)
 574 {
 575         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 576                         bch2_btree_node_iter_peek(&l->iter, l->b));
 577
 578         path->pos = k.k ? k.k->p : l->b->key.k.p;
 579         trans->paths_sorted = false;
 580         bch2_btree_path_verify_level(trans, path, l - path->l);
 581         return k;
 582 }
 583
 584 static inline struct bkey_s_c btree_path_level_prev(struct btree_trans *trans,
 585                                                     struct btree_path *path,
 586                                                     struct btree_path_level *l,
 587                                                     struct bkey *u)
 588 {
 589         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 590                         bch2_btree_node_iter_prev(&l->iter, l->b));
 591
 592         path->pos = k.k ? k.k->p : l->b->data->min_key;
 593         trans->paths_sorted = false;
 594         bch2_btree_path_verify_level(trans, path, l - path->l);
 595         return k;
 596 }
 597
 598 static inline bool btree_path_advance_to_pos(struct btree_path *path,
 599                                              struct btree_path_level *l,
 600                                              int max_advance)
 601 {
 602         struct bkey_packed *k;
 603         int nr_advanced = 0;
 604
 605         while ((k = bch2_btree_node_iter_peek_all(&l->iter, l->b)) &&
 606                bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 607                 if (max_advance > 0 && nr_advanced >= max_advance)
 608                         return false;
 609
 610                 bch2_btree_node_iter_advance(&l->iter, l->b);
 611                 nr_advanced++;
 612         }
 613
 614         return true;
 615 }
 616
 617 static inline void __btree_path_level_init(struct btree_path *path,
 618                                            unsigned level)
 619 {
 620         struct btree_path_level *l = &path->l[level];
 621
 622         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
 623
 624         /*
 625          * Iterators to interior nodes should always be pointed at the first non
 626          * whiteout:
 627          */
 628         if (level)
 629                 bch2_btree_node_iter_peek(&l->iter, l->b);
 630 }
 631
 632 void bch2_btree_path_level_init(struct btree_trans *trans,
 633                                 struct btree_path *path,
 634                                 struct btree *b)
 635 {
 636         BUG_ON(path->cached);
 637
 638         EBUG_ON(!btree_path_pos_in_node(path, b));
 639
 640         path->l[b->c.level].lock_seq = six_lock_seq(&b->c.lock);
 641         path->l[b->c.level].b = b;
 642         __btree_path_level_init(path, b->c.level);
 643 }
 644
 645 /* Btree path: fixups after btree node updates: */
 646
 647 static void bch2_trans_revalidate_updates_in_node(struct btree_trans *trans, struct btree *b)
 648 {
 649         struct bch_fs *c = trans->c;
 650         struct btree_insert_entry *i;
 651
 652         trans_for_each_update(trans, i)
 653                 if (!i->cached &&
 654                     i->level    == b->c.level &&
 655                     i->btree_id == b->c.btree_id &&
 656                     bpos_cmp(i->k->k.p, b->data->min_key) >= 0 &&
 657                     bpos_cmp(i->k->k.p, b->data->max_key) <= 0) {
 658                         i->old_v = bch2_btree_path_peek_slot(i->path, &i->old_k).v;
 659
 660                         if (unlikely(trans->journal_replay_not_finished)) {
 661                                 struct bkey_i *j_k =
 662                                         bch2_journal_keys_peek_slot(c, i->btree_id, i->level,
 663                                                                     i->k->k.p);
 664
 665                                 if (j_k) {
 666                                         i->old_k = j_k->k;
 667                                         i->old_v = &j_k->v;
 668                                 }
 669                         }
 670                 }
 671 }
 672
 673 /*
 674  * A btree node is being replaced - update the iterator to point to the new
 675  * node:
 676  */
 677 void bch2_trans_node_add(struct btree_trans *trans, struct btree *b)
 678 {
 679         struct btree_path *path;
 680
 681         trans_for_each_path(trans, path)
 682                 if (path->uptodate == BTREE_ITER_UPTODATE &&
 683                     !path->cached &&
 684                     btree_path_pos_in_node(path, b)) {
 685                         enum btree_node_locked_type t =
 686                                 btree_lock_want(path, b->c.level);
 687
 688                         if (t != BTREE_NODE_UNLOCKED) {
 689                                 btree_node_unlock(trans, path, b->c.level);
 690                                 six_lock_increment(&b->c.lock, (enum six_lock_type) t);
 691                                 mark_btree_node_locked(trans, path, b->c.level, t);
 692                         }
 693
 694                         bch2_btree_path_level_init(trans, path, b);
 695                 }
 696
 697         bch2_trans_revalidate_updates_in_node(trans, b);
 698 }
 699
 700 /*
 701  * A btree node has been modified in such a way as to invalidate iterators - fix
 702  * them:
 703  */
 704 void bch2_trans_node_reinit_iter(struct btree_trans *trans, struct btree *b)
 705 {
 706         struct btree_path *path;
 707
 708         trans_for_each_path_with_node(trans, b, path)
 709                 __btree_path_level_init(path, b->c.level);
 710
 711         bch2_trans_revalidate_updates_in_node(trans, b);
 712 }
 713
 714 /* Btree path: traverse, set_pos: */
 715
 716 static inline int btree_path_lock_root(struct btree_trans *trans,
 717                                        struct btree_path *path,
 718                                        unsigned depth_want,
 719                                        unsigned long trace_ip)
 720 {
 721         struct bch_fs *c = trans->c;
 722         struct btree *b, **rootp = &bch2_btree_id_root(c, path->btree_id)->b;
 723         enum six_lock_type lock_type;
 724         unsigned i;
 725         int ret;
 726
 727         EBUG_ON(path->nodes_locked);
 728
 729         while (1) {
 730                 b = READ_ONCE(*rootp);
 731                 path->level = READ_ONCE(b->c.level);
 732
 733                 if (unlikely(path->level < depth_want)) {
 734                         /*
 735                          * the root is at a lower depth than the depth we want:
 736                          * got to the end of the btree, or we're walking nodes
 737                          * greater than some depth and there are no nodes >=
 738                          * that depth
 739                          */
 740                         path->level = depth_want;
 741                         for (i = path->level; i < BTREE_MAX_DEPTH; i++)
 742                                 path->l[i].b = NULL;
 743                         return 1;
 744                 }
 745
 746                 lock_type = __btree_lock_want(path, path->level);
 747                 ret = btree_node_lock(trans, path, &b->c,
 748                                       path->level, lock_type, trace_ip);
 749                 if (unlikely(ret)) {
 750                         if (bch2_err_matches(ret, BCH_ERR_lock_fail_root_changed))
 751                                 continue;
 752                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 753                                 return ret;
 754                         BUG();
 755                 }
 756
 757                 if (likely(b == READ_ONCE(*rootp) &&
 758                            b->c.level == path->level &&
 759                            !race_fault())) {
 760                         for (i = 0; i < path->level; i++)
 761                                 path->l[i].b = ERR_PTR(-BCH_ERR_no_btree_node_lock_root);
 762                         path->l[path->level].b = b;
 763                         for (i = path->level + 1; i < BTREE_MAX_DEPTH; i++)
 764                                 path->l[i].b = NULL;
 765
 766                         mark_btree_node_locked(trans, path, path->level,
 767                                                (enum btree_node_locked_type) lock_type);
 768                         bch2_btree_path_level_init(trans, path, b);
 769                         return 0;
 770                 }
 771
 772                 six_unlock_type(&b->c.lock, lock_type);
 773         }
 774 }
 775
 776 noinline
 777 static int btree_path_prefetch(struct btree_trans *trans, struct btree_path *path)
 778 {
 779         struct bch_fs *c = trans->c;
 780         struct btree_path_level *l = path_l(path);
 781         struct btree_node_iter node_iter = l->iter;
 782         struct bkey_packed *k;
 783         struct bkey_buf tmp;
 784         unsigned nr = test_bit(BCH_FS_STARTED, &c->flags)
 785                 ? (path->level > 1 ? 0 :  2)
 786                 : (path->level > 1 ? 1 : 16);
 787         bool was_locked = btree_node_locked(path, path->level);
 788         int ret = 0;
 789
 790         bch2_bkey_buf_init(&tmp);
 791
 792         while (nr-- && !ret) {
 793                 if (!bch2_btree_node_relock(trans, path, path->level))
 794                         break;
 795
 796                 bch2_btree_node_iter_advance(&node_iter, l->b);
 797                 k = bch2_btree_node_iter_peek(&node_iter, l->b);
 798                 if (!k)
 799                         break;
 800
 801                 bch2_bkey_buf_unpack(&tmp, c, l->b, k);
 802                 ret = bch2_btree_node_prefetch(trans, path, tmp.k, path->btree_id,
 803                                                path->level - 1);
 804         }
 805
 806         if (!was_locked)
 807                 btree_node_unlock(trans, path, path->level);
 808
 809         bch2_bkey_buf_exit(&tmp, c);
 810         return ret;
 811 }
 812
 813 static int btree_path_prefetch_j(struct btree_trans *trans, struct btree_path *path,
 814                                  struct btree_and_journal_iter *jiter)
 815 {
 816         struct bch_fs *c = trans->c;
 817         struct bkey_s_c k;
 818         struct bkey_buf tmp;
 819         unsigned nr = test_bit(BCH_FS_STARTED, &c->flags)
 820                 ? (path->level > 1 ? 0 :  2)
 821                 : (path->level > 1 ? 1 : 16);
 822         bool was_locked = btree_node_locked(path, path->level);
 823         int ret = 0;
 824
 825         bch2_bkey_buf_init(&tmp);
 826
 827         while (nr-- && !ret) {
 828                 if (!bch2_btree_node_relock(trans, path, path->level))
 829                         break;
 830
 831                 bch2_btree_and_journal_iter_advance(jiter);
 832                 k = bch2_btree_and_journal_iter_peek(jiter);
 833                 if (!k.k)
 834                         break;
 835
 836                 bch2_bkey_buf_reassemble(&tmp, c, k);
 837                 ret = bch2_btree_node_prefetch(trans, path, tmp.k, path->btree_id,
 838                                                path->level - 1);
 839         }
 840
 841         if (!was_locked)
 842                 btree_node_unlock(trans, path, path->level);
 843
 844         bch2_bkey_buf_exit(&tmp, c);
 845         return ret;
 846 }
 847
 848 static noinline void btree_node_mem_ptr_set(struct btree_trans *trans,
 849                                             struct btree_path *path,
 850                                             unsigned plevel, struct btree *b)
 851 {
 852         struct btree_path_level *l = &path->l[plevel];
 853         bool locked = btree_node_locked(path, plevel);
 854         struct bkey_packed *k;
 855         struct bch_btree_ptr_v2 *bp;
 856
 857         if (!bch2_btree_node_relock(trans, path, plevel))
 858                 return;
 859
 860         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 861         BUG_ON(k->type != KEY_TYPE_btree_ptr_v2);
 862
 863         bp = (void *) bkeyp_val(&l->b->format, k);
 864         bp->mem_ptr = (unsigned long)b;
 865
 866         if (!locked)
 867                 btree_node_unlock(trans, path, plevel);
 868 }
 869
 870 static noinline int btree_node_iter_and_journal_peek(struct btree_trans *trans,
 871                                                      struct btree_path *path,
 872                                                      unsigned flags,
 873                                                      struct bkey_buf *out)
 874 {
 875         struct bch_fs *c = trans->c;
 876         struct btree_path_level *l = path_l(path);
 877         struct btree_and_journal_iter jiter;
 878         struct bkey_s_c k;
 879         int ret = 0;
 880
 881         __bch2_btree_and_journal_iter_init_node_iter(&jiter, c, l->b, l->iter, path->pos);
 882
 883         k = bch2_btree_and_journal_iter_peek(&jiter);
 884
 885         bch2_bkey_buf_reassemble(out, c, k);
 886
 887         if (flags & BTREE_ITER_PREFETCH)
 888                 ret = btree_path_prefetch_j(trans, path, &jiter);
 889
 890         bch2_btree_and_journal_iter_exit(&jiter);
 891         return ret;
 892 }
 893
 894 static __always_inline int btree_path_down(struct btree_trans *trans,
 895                                            struct btree_path *path,
 896                                            unsigned flags,
 897                                            unsigned long trace_ip)
 898 {
 899         struct bch_fs *c = trans->c;
 900         struct btree_path_level *l = path_l(path);
 901         struct btree *b;
 902         unsigned level = path->level - 1;
 903         enum six_lock_type lock_type = __btree_lock_want(path, level);
 904         struct bkey_buf tmp;
 905         int ret;
 906
 907         EBUG_ON(!btree_node_locked(path, path->level));
 908
 909         bch2_bkey_buf_init(&tmp);
 910
 911         if (unlikely(trans->journal_replay_not_finished)) {
 912                 ret = btree_node_iter_and_journal_peek(trans, path, flags, &tmp);
 913                 if (ret)
 914                         goto err;
 915         } else {
 916                 bch2_bkey_buf_unpack(&tmp, c, l->b,
 917                                  bch2_btree_node_iter_peek(&l->iter, l->b));
 918
 919                 if (flags & BTREE_ITER_PREFETCH) {
 920                         ret = btree_path_prefetch(trans, path);
 921                         if (ret)
 922                                 goto err;
 923                 }
 924         }
 925
 926         b = bch2_btree_node_get(trans, path, tmp.k, level, lock_type, trace_ip);
 927         ret = PTR_ERR_OR_ZERO(b);
 928         if (unlikely(ret))
 929                 goto err;
 930
 931         if (likely(!trans->journal_replay_not_finished &&
 932                    tmp.k->k.type == KEY_TYPE_btree_ptr_v2) &&
 933             unlikely(b != btree_node_mem_ptr(tmp.k)))
 934                 btree_node_mem_ptr_set(trans, path, level + 1, b);
 935
 936         if (btree_node_read_locked(path, level + 1))
 937                 btree_node_unlock(trans, path, level + 1);
 938
 939         mark_btree_node_locked(trans, path, level,
 940                                (enum btree_node_locked_type) lock_type);
 941         path->level = level;
 942         bch2_btree_path_level_init(trans, path, b);
 943
 944         bch2_btree_path_verify_locks(path);
 945 err:
 946         bch2_bkey_buf_exit(&tmp, c);
 947         return ret;
 948 }
 949
 950
 951 static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 952 {
 953         struct bch_fs *c = trans->c;
 954         struct btree_path *path;
 955         unsigned long trace_ip = _RET_IP_;
 956         int i, ret = 0;
 957
 958         if (trans->in_traverse_all)
 959                 return -BCH_ERR_transaction_restart_in_traverse_all;
 960
 961         trans->in_traverse_all = true;
 962 retry_all:
 963         trans->restarted = 0;
 964         trans->last_restarted_ip = 0;
 965
 966         trans_for_each_path(trans, path)
 967                 path->should_be_locked = false;
 968
 969         btree_trans_sort_paths(trans);
 970
 971         bch2_trans_unlock(trans);
 972         cond_resched();
 973
 974         if (unlikely(trans->memory_allocation_failure)) {
 975                 struct closure cl;
 976
 977                 closure_init_stack(&cl);
 978
 979                 do {
 980                         ret = bch2_btree_cache_cannibalize_lock(c, &cl);
 981                         closure_sync(&cl);
 982                 } while (ret);
 983         }
 984
 985         /* Now, redo traversals in correct order: */
 986         i = 0;
 987         while (i < trans->nr_sorted) {
 988                 path = trans->paths + trans->sorted[i];
 989
 990                 /*
 991                  * Traversing a path can cause another path to be added at about
 992                  * the same position:
 993                  */
 994                 if (path->uptodate) {
 995                         __btree_path_get(path, false);
 996                         ret = bch2_btree_path_traverse_one(trans, path, 0, _THIS_IP_);
 997                         __btree_path_put(path, false);
 998
 999                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) ||
1000                             bch2_err_matches(ret, ENOMEM))
1001                                 goto retry_all;
1002                         if (ret)
1003                                 goto err;
1004                 } else {
1005                         i++;
1006                 }
1007         }
1008
1009         /*
1010          * We used to assert that all paths had been traversed here
1011          * (path->uptodate < BTREE_ITER_NEED_TRAVERSE); however, since
1012          * path->should_be_locked is not set yet, we might have unlocked and
1013          * then failed to relock a path - that's fine.
1014          */
1015 err:
1016         bch2_btree_cache_cannibalize_unlock(c);
1017
1018         trans->in_traverse_all = false;
1019
1020         trace_and_count(c, trans_traverse_all, trans, trace_ip);
1021         return ret;
1022 }
1023
1024 static inline bool btree_path_check_pos_in_node(struct btree_path *path,
1025                                                 unsigned l, int check_pos)
1026 {
1027         if (check_pos < 0 && btree_path_pos_before_node(path, path->l[l].b))
1028                 return false;
1029         if (check_pos > 0 && btree_path_pos_after_node(path, path->l[l].b))
1030                 return false;
1031         return true;
1032 }
1033
1034 static inline bool btree_path_good_node(struct btree_trans *trans,
1035                                         struct btree_path *path,
1036                                         unsigned l, int check_pos)
1037 {
1038         return is_btree_node(path, l) &&
1039                 bch2_btree_node_relock(trans, path, l) &&
1040                 btree_path_check_pos_in_node(path, l, check_pos);
1041 }
1042
1043 static void btree_path_set_level_down(struct btree_trans *trans,
1044                                       struct btree_path *path,
1045                                       unsigned new_level)
1046 {
1047         unsigned l;
1048
1049         path->level = new_level;
1050
1051         for (l = path->level + 1; l < BTREE_MAX_DEPTH; l++)
1052                 if (btree_lock_want(path, l) == BTREE_NODE_UNLOCKED)
1053                         btree_node_unlock(trans, path, l);
1054
1055         btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1056         bch2_btree_path_verify(trans, path);
1057 }
1058
1059 static noinline unsigned __btree_path_up_until_good_node(struct btree_trans *trans,
1060                                                          struct btree_path *path,
1061                                                          int check_pos)
1062 {
1063         unsigned i, l = path->level;
1064 again:
1065         while (btree_path_node(path, l) &&
1066                !btree_path_good_node(trans, path, l, check_pos))
1067                 __btree_path_set_level_up(trans, path, l++);
1068
1069         /* If we need intent locks, take them too: */
1070         for (i = l + 1;
1071              i < path->locks_want && btree_path_node(path, i);
1072              i++)
1073                 if (!bch2_btree_node_relock(trans, path, i)) {
1074                         while (l <= i)
1075                                 __btree_path_set_level_up(trans, path, l++);
1076                         goto again;
1077                 }
1078
1079         return l;
1080 }
1081
1082 static inline unsigned btree_path_up_until_good_node(struct btree_trans *trans,
1083                                                      struct btree_path *path,
1084                                                      int check_pos)
1085 {
1086         return likely(btree_node_locked(path, path->level) &&
1087                       btree_path_check_pos_in_node(path, path->level, check_pos))
1088                 ? path->level
1089                 : __btree_path_up_until_good_node(trans, path, check_pos);
1090 }
1091
1092 /*
1093  * This is the main state machine for walking down the btree - walks down to a
1094  * specified depth
1095  *
1096  * Returns 0 on success, -EIO on error (error reading in a btree node).
1097  *
1098  * On error, caller (peek_node()/peek_key()) must return NULL; the error is
1099  * stashed in the iterator and returned from bch2_trans_exit().
1100  */
1101 int bch2_btree_path_traverse_one(struct btree_trans *trans,
1102                                  struct btree_path *path,
1103                                  unsigned flags,
1104                                  unsigned long trace_ip)
1105 {
1106         unsigned depth_want = path->level;
1107         int ret = -((int) trans->restarted);
1108
1109         if (unlikely(ret))
1110                 goto out;
1111
1112         if (unlikely(!trans->srcu_held))
1113                 bch2_trans_srcu_lock(trans);
1114
1115         /*
1116          * Ensure we obey path->should_be_locked: if it's set, we can't unlock
1117          * and re-traverse the path without a transaction restart:
1118          */
1119         if (path->should_be_locked) {
1120                 ret = bch2_btree_path_relock(trans, path, trace_ip);
1121                 goto out;
1122         }
1123
1124         if (path->cached) {
1125                 ret = bch2_btree_path_traverse_cached(trans, path, flags);
1126                 goto out;
1127         }
1128
1129         if (unlikely(path->level >= BTREE_MAX_DEPTH))
1130                 goto out;
1131
1132         path->level = btree_path_up_until_good_node(trans, path, 0);
1133
1134         EBUG_ON(btree_path_node(path, path->level) &&
1135                 !btree_node_locked(path, path->level));
1136
1137         /*
1138          * Note: path->nodes[path->level] may be temporarily NULL here - that
1139          * would indicate to other code that we got to the end of the btree,
1140          * here it indicates that relocking the root failed - it's critical that
1141          * btree_path_lock_root() comes next and that it can't fail
1142          */
1143         while (path->level > depth_want) {
1144                 ret = btree_path_node(path, path->level)
1145                         ? btree_path_down(trans, path, flags, trace_ip)
1146                         : btree_path_lock_root(trans, path, depth_want, trace_ip);
1147                 if (unlikely(ret)) {
1148                         if (ret == 1) {
1149                                 /*
1150                                  * No nodes at this level - got to the end of
1151                                  * the btree:
1152                                  */
1153                                 ret = 0;
1154                                 goto out;
1155                         }
1156
1157                         __bch2_btree_path_unlock(trans, path);
1158                         path->level = depth_want;
1159                         path->l[path->level].b = ERR_PTR(ret);
1160                         goto out;
1161                 }
1162         }
1163
1164         path->uptodate = BTREE_ITER_UPTODATE;
1165 out:
1166         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) != !!trans->restarted)
1167                 panic("ret %s (%i) trans->restarted %s (%i)\n",
1168                       bch2_err_str(ret), ret,
1169                       bch2_err_str(trans->restarted), trans->restarted);
1170         bch2_btree_path_verify(trans, path);
1171         return ret;
1172 }
1173
1174 static inline void btree_path_copy(struct btree_trans *trans, struct btree_path *dst,
1175                             struct btree_path *src)
1176 {
1177         unsigned i, offset = offsetof(struct btree_path, pos);
1178
1179         memcpy((void *) dst + offset,
1180                (void *) src + offset,
1181                sizeof(struct btree_path) - offset);
1182
1183         for (i = 0; i < BTREE_MAX_DEPTH; i++) {
1184                 unsigned t = btree_node_locked_type(dst, i);
1185
1186                 if (t != BTREE_NODE_UNLOCKED)
1187                         six_lock_increment(&dst->l[i].b->c.lock, t);
1188         }
1189 }
1190
1191 static struct btree_path *btree_path_clone(struct btree_trans *trans, struct btree_path *src,
1192                                            bool intent)
1193 {
1194         struct btree_path *new = btree_path_alloc(trans, src);
1195
1196         btree_path_copy(trans, new, src);
1197         __btree_path_get(new, intent);
1198         return new;
1199 }
1200
1201 __flatten
1202 struct btree_path *__bch2_btree_path_make_mut(struct btree_trans *trans,
1203                          struct btree_path *path, bool intent,
1204                          unsigned long ip)
1205 {
1206         __btree_path_put(path, intent);
1207         path = btree_path_clone(trans, path, intent);
1208         path->preserve = false;
1209         return path;
1210 }
1211
1212 struct btree_path * __must_check
1213 __bch2_btree_path_set_pos(struct btree_trans *trans,
1214                    struct btree_path *path, struct bpos new_pos,
1215                    bool intent, unsigned long ip, int cmp)
1216 {
1217         unsigned level = path->level;
1218
1219         bch2_trans_verify_not_in_restart(trans);
1220         EBUG_ON(!path->ref);
1221
1222         path = bch2_btree_path_make_mut(trans, path, intent, ip);
1223
1224         path->pos               = new_pos;
1225         trans->paths_sorted     = false;
1226
1227         if (unlikely(path->cached)) {
1228                 btree_node_unlock(trans, path, 0);
1229                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_up);
1230                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1231                 goto out;
1232         }
1233
1234         level = btree_path_up_until_good_node(trans, path, cmp);
1235
1236         if (btree_path_node(path, level)) {
1237                 struct btree_path_level *l = &path->l[level];
1238
1239                 BUG_ON(!btree_node_locked(path, level));
1240                 /*
1241                  * We might have to skip over many keys, or just a few: try
1242                  * advancing the node iterator, and if we have to skip over too
1243                  * many keys just reinit it (or if we're rewinding, since that
1244                  * is expensive).
1245                  */
1246                 if (cmp < 0 ||
1247                     !btree_path_advance_to_pos(path, l, 8))
1248                         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
1249
1250                 /*
1251                  * Iterators to interior nodes should always be pointed at the first non
1252                  * whiteout:
1253                  */
1254                 if (unlikely(level))
1255                         bch2_btree_node_iter_peek(&l->iter, l->b);
1256         }
1257
1258         if (unlikely(level != path->level)) {
1259                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1260                 __bch2_btree_path_unlock(trans, path);
1261         }
1262 out:
1263         bch2_btree_path_verify(trans, path);
1264         return path;
1265 }
1266
1267 /* Btree path: main interface: */
1268
1269 static struct btree_path *have_path_at_pos(struct btree_trans *trans, struct btree_path *path)
1270 {
1271         struct btree_path *sib;
1272
1273         sib = prev_btree_path(trans, path);
1274         if (sib && !btree_path_cmp(sib, path))
1275                 return sib;
1276
1277         sib = next_btree_path(trans, path);
1278         if (sib && !btree_path_cmp(sib, path))
1279                 return sib;
1280
1281         return NULL;
1282 }
1283
1284 static struct btree_path *have_node_at_pos(struct btree_trans *trans, struct btree_path *path)
1285 {
1286         struct btree_path *sib;
1287
1288         sib = prev_btree_path(trans, path);
1289         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1290                 return sib;
1291
1292         sib = next_btree_path(trans, path);
1293         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1294                 return sib;
1295
1296         return NULL;
1297 }
1298
1299 static inline void __bch2_path_free(struct btree_trans *trans, struct btree_path *path)
1300 {
1301         __bch2_btree_path_unlock(trans, path);
1302         btree_path_list_remove(trans, path);
1303         trans->paths_allocated &= ~(1ULL << path->idx);
1304 }
1305
1306 void bch2_path_put(struct btree_trans *trans, struct btree_path *path, bool intent)
1307 {
1308         struct btree_path *dup;
1309
1310         EBUG_ON(trans->paths + path->idx != path);
1311         EBUG_ON(!path->ref);
1312
1313         if (!__btree_path_put(path, intent))
1314                 return;
1315
1316         dup = path->preserve
1317                 ? have_path_at_pos(trans, path)
1318                 : have_node_at_pos(trans, path);
1319
1320         if (!dup && !(!path->preserve && !is_btree_node(path, path->level)))
1321                 return;
1322
1323         if (path->should_be_locked &&
1324             !trans->restarted &&
1325             (!dup || !bch2_btree_path_relock_norestart(trans, dup, _THIS_IP_)))
1326                 return;
1327
1328         if (dup) {
1329                 dup->preserve           |= path->preserve;
1330                 dup->should_be_locked   |= path->should_be_locked;
1331         }
1332
1333         __bch2_path_free(trans, path);
1334 }
1335
1336 static void bch2_path_put_nokeep(struct btree_trans *trans, struct btree_path *path,
1337                                  bool intent)
1338 {
1339         EBUG_ON(trans->paths + path->idx != path);
1340         EBUG_ON(!path->ref);
1341
1342         if (!__btree_path_put(path, intent))
1343                 return;
1344
1345         __bch2_path_free(trans, path);
1346 }
1347
1348 void __noreturn bch2_trans_restart_error(struct btree_trans *trans, u32 restart_count)
1349 {
1350         panic("trans->restart_count %u, should be %u, last restarted by %pS\n",
1351               trans->restart_count, restart_count,
1352               (void *) trans->last_begin_ip);
1353 }
1354
1355 void __noreturn bch2_trans_in_restart_error(struct btree_trans *trans)
1356 {
1357         panic("in transaction restart: %s, last restarted by %pS\n",
1358               bch2_err_str(trans->restarted),
1359               (void *) trans->last_restarted_ip);
1360 }
1361
1362 noinline __cold
1363 void bch2_trans_updates_to_text(struct printbuf *buf, struct btree_trans *trans)
1364 {
1365         struct btree_insert_entry *i;
1366         struct btree_write_buffered_key *wb;
1367
1368         prt_printf(buf, "transaction updates for %s journal seq %llu",
1369                trans->fn, trans->journal_res.seq);
1370         prt_newline(buf);
1371         printbuf_indent_add(buf, 2);
1372
1373         trans_for_each_update(trans, i) {
1374                 struct bkey_s_c old = { &i->old_k, i->old_v };
1375
1376                 prt_printf(buf, "update: btree=%s cached=%u %pS",
1377                        bch2_btree_id_str(i->btree_id),
1378                        i->cached,
1379                        (void *) i->ip_allocated);
1380                 prt_newline(buf);
1381
1382                 prt_printf(buf, "  old ");
1383                 bch2_bkey_val_to_text(buf, trans->c, old);
1384                 prt_newline(buf);
1385
1386                 prt_printf(buf, "  new ");
1387                 bch2_bkey_val_to_text(buf, trans->c, bkey_i_to_s_c(i->k));
1388                 prt_newline(buf);
1389         }
1390
1391         trans_for_each_wb_update(trans, wb) {
1392                 prt_printf(buf, "update: btree=%s wb=1 %pS",
1393                        bch2_btree_id_str(wb->btree),
1394                        (void *) i->ip_allocated);
1395                 prt_newline(buf);
1396
1397                 prt_printf(buf, "  new ");
1398                 bch2_bkey_val_to_text(buf, trans->c, bkey_i_to_s_c(&wb->k));
1399                 prt_newline(buf);
1400         }
1401
1402         printbuf_indent_sub(buf, 2);
1403 }
1404
1405 noinline __cold
1406 void bch2_dump_trans_updates(struct btree_trans *trans)
1407 {
1408         struct printbuf buf = PRINTBUF;
1409
1410         bch2_trans_updates_to_text(&buf, trans);
1411         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1412         printbuf_exit(&buf);
1413 }
1414
1415 noinline __cold
1416 void bch2_btree_path_to_text(struct printbuf *out, struct btree_path *path)
1417 {
1418         prt_printf(out, "path: idx %2u ref %u:%u %c %c btree=%s l=%u pos ",
1419                    path->idx, path->ref, path->intent_ref,
1420                    path->preserve ? 'P' : ' ',
1421                    path->should_be_locked ? 'S' : ' ',
1422                    bch2_btree_id_str(path->btree_id),
1423                    path->level);
1424         bch2_bpos_to_text(out, path->pos);
1425
1426         prt_printf(out, " locks %u", path->nodes_locked);
1427 #ifdef TRACK_PATH_ALLOCATED
1428         prt_printf(out, " %pS", (void *) path->ip_allocated);
1429 #endif
1430         prt_newline(out);
1431 }
1432
1433 static noinline __cold
1434 void __bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans,
1435                                 bool nosort)
1436 {
1437         struct btree_path *path;
1438         unsigned idx;
1439
1440         if (!nosort)
1441                 btree_trans_sort_paths(trans);
1442
1443         trans_for_each_path_inorder(trans, path, idx)
1444                 bch2_btree_path_to_text(out, path);
1445 }
1446
1447 noinline __cold
1448 void bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans)
1449 {
1450         __bch2_trans_paths_to_text(out, trans, false);
1451 }
1452
1453 static noinline __cold
1454 void __bch2_dump_trans_paths_updates(struct btree_trans *trans, bool nosort)
1455 {
1456         struct printbuf buf = PRINTBUF;
1457
1458         __bch2_trans_paths_to_text(&buf, trans, nosort);
1459         bch2_trans_updates_to_text(&buf, trans);
1460
1461         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1462         printbuf_exit(&buf);
1463 }
1464
1465 noinline __cold
1466 void bch2_dump_trans_paths_updates(struct btree_trans *trans)
1467 {
1468         __bch2_dump_trans_paths_updates(trans, false);
1469 }
1470
1471 noinline __cold
1472 static void bch2_trans_update_max_paths(struct btree_trans *trans)
1473 {
1474         struct btree_transaction_stats *s = btree_trans_stats(trans);
1475         struct printbuf buf = PRINTBUF;
1476
1477         if (!s)
1478                 return;
1479
1480         bch2_trans_paths_to_text(&buf, trans);
1481
1482         if (!buf.allocation_failure) {
1483                 mutex_lock(&s->lock);
1484                 if (s->nr_max_paths < hweight64(trans->paths_allocated)) {
1485                         s->nr_max_paths = trans->nr_max_paths =
1486                                 hweight64(trans->paths_allocated);
1487                         swap(s->max_paths_text, buf.buf);
1488                 }
1489                 mutex_unlock(&s->lock);
1490         }
1491
1492         printbuf_exit(&buf);
1493
1494         trans->nr_max_paths = hweight64(trans->paths_allocated);
1495 }
1496
1497 static noinline void btree_path_overflow(struct btree_trans *trans)
1498 {
1499         bch2_dump_trans_paths_updates(trans);
1500         panic("trans path overflow\n");
1501 }
1502
1503 static inline struct btree_path *btree_path_alloc(struct btree_trans *trans,
1504                                                   struct btree_path *pos)
1505 {
1506         struct btree_path *path;
1507         unsigned idx;
1508
1509         if (unlikely(trans->paths_allocated ==
1510                      ~((~0ULL << 1) << (BTREE_ITER_MAX - 1))))
1511                 btree_path_overflow(trans);
1512
1513         idx = __ffs64(~trans->paths_allocated);
1514
1515         /*
1516          * Do this before marking the new path as allocated, since it won't be
1517          * initialized yet:
1518          */
1519         if (unlikely(idx > trans->nr_max_paths))
1520                 bch2_trans_update_max_paths(trans);
1521
1522         trans->paths_allocated |= 1ULL << idx;
1523
1524         path = &trans->paths[idx];
1525         path->idx               = idx;
1526         path->ref               = 0;
1527         path->intent_ref        = 0;
1528         path->nodes_locked      = 0;
1529         path->alloc_seq++;
1530
1531         btree_path_list_add(trans, pos, path);
1532         trans->paths_sorted = false;
1533         return path;
1534 }
1535
1536 struct btree_path *bch2_path_get(struct btree_trans *trans,
1537                                  enum btree_id btree_id, struct bpos pos,
1538                                  unsigned locks_want, unsigned level,
1539                                  unsigned flags, unsigned long ip)
1540 {
1541         struct btree_path *path, *path_pos = NULL;
1542         bool cached = flags & BTREE_ITER_CACHED;
1543         bool intent = flags & BTREE_ITER_INTENT;
1544         int i;
1545
1546         bch2_trans_verify_not_in_restart(trans);
1547         bch2_trans_verify_locks(trans);
1548
1549         btree_trans_sort_paths(trans);
1550
1551         trans_for_each_path_inorder(trans, path, i) {
1552                 if (__btree_path_cmp(path,
1553                                      btree_id,
1554                                      cached,
1555                                      pos,
1556                                      level) > 0)
1557                         break;
1558
1559                 path_pos = path;
1560         }
1561
1562         if (path_pos &&
1563             path_pos->cached    == cached &&
1564             path_pos->btree_id  == btree_id &&
1565             path_pos->level     == level) {
1566                 __btree_path_get(path_pos, intent);
1567                 path = bch2_btree_path_set_pos(trans, path_pos, pos, intent, ip);
1568         } else {
1569                 path = btree_path_alloc(trans, path_pos);
1570                 path_pos = NULL;
1571
1572                 __btree_path_get(path, intent);
1573                 path->pos                       = pos;
1574                 path->btree_id                  = btree_id;
1575                 path->cached                    = cached;
1576                 path->uptodate                  = BTREE_ITER_NEED_TRAVERSE;
1577                 path->should_be_locked          = false;
1578                 path->level                     = level;
1579                 path->locks_want                = locks_want;
1580                 path->nodes_locked              = 0;
1581                 for (i = 0; i < ARRAY_SIZE(path->l); i++)
1582                         path->l[i].b            = ERR_PTR(-BCH_ERR_no_btree_node_init);
1583 #ifdef TRACK_PATH_ALLOCATED
1584                 path->ip_allocated              = ip;
1585 #endif
1586                 trans->paths_sorted             = false;
1587         }
1588
1589         if (!(flags & BTREE_ITER_NOPRESERVE))
1590                 path->preserve = true;
1591
1592         if (path->intent_ref)
1593                 locks_want = max(locks_want, level + 1);
1594
1595         /*
1596          * If the path has locks_want greater than requested, we don't downgrade
1597          * it here - on transaction restart because btree node split needs to
1598          * upgrade locks, we might be putting/getting the iterator again.
1599          * Downgrading iterators only happens via bch2_trans_downgrade(), after
1600          * a successful transaction commit.
1601          */
1602
1603         locks_want = min(locks_want, BTREE_MAX_DEPTH);
1604         if (locks_want > path->locks_want)
1605                 bch2_btree_path_upgrade_noupgrade_sibs(trans, path, locks_want, NULL);
1606
1607         return path;
1608 }
1609
1610 struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *path, struct bkey *u)
1611 {
1612
1613         struct btree_path_level *l = path_l(path);
1614         struct bkey_packed *_k;
1615         struct bkey_s_c k;
1616
1617         if (unlikely(!l->b))
1618                 return bkey_s_c_null;
1619
1620         EBUG_ON(path->uptodate != BTREE_ITER_UPTODATE);
1621         EBUG_ON(!btree_node_locked(path, path->level));
1622
1623         if (!path->cached) {
1624                 _k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
1625                 k = _k ? bkey_disassemble(l->b, _k, u) : bkey_s_c_null;
1626
1627                 EBUG_ON(k.k && bkey_deleted(k.k) && bpos_eq(k.k->p, path->pos));
1628
1629                 if (!k.k || !bpos_eq(path->pos, k.k->p))
1630                         goto hole;
1631         } else {
1632                 struct bkey_cached *ck = (void *) path->l[0].b;
1633
1634                 EBUG_ON(ck &&
1635                         (path->btree_id != ck->key.btree_id ||
1636                          !bkey_eq(path->pos, ck->key.pos)));
1637                 if (!ck || !ck->valid)
1638                         return bkey_s_c_null;
1639
1640                 *u = ck->k->k;
1641                 k = bkey_i_to_s_c(ck->k);
1642         }
1643
1644         return k;
1645 hole:
1646         bkey_init(u);
1647         u->p = path->pos;
1648         return (struct bkey_s_c) { u, NULL };
1649 }
1650
1651 /* Btree iterators: */
1652
1653 int __must_check
1654 __bch2_btree_iter_traverse(struct btree_iter *iter)
1655 {
1656         return bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1657 }
1658
1659 int __must_check
1660 bch2_btree_iter_traverse(struct btree_iter *iter)
1661 {
1662         int ret;
1663
1664         iter->path = bch2_btree_path_set_pos(iter->trans, iter->path,
1665                                         btree_iter_search_key(iter),
1666                                         iter->flags & BTREE_ITER_INTENT,
1667                                         btree_iter_ip_allocated(iter));
1668
1669         ret = bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1670         if (ret)
1671                 return ret;
1672
1673         btree_path_set_should_be_locked(iter->path);
1674         return 0;
1675 }
1676
1677 /* Iterate across nodes (leaf and interior nodes) */
1678
1679 struct btree *bch2_btree_iter_peek_node(struct btree_iter *iter)
1680 {
1681         struct btree_trans *trans = iter->trans;
1682         struct btree *b = NULL;
1683         int ret;
1684
1685         EBUG_ON(iter->path->cached);
1686         bch2_btree_iter_verify(iter);
1687
1688         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1689         if (ret)
1690                 goto err;
1691
1692         b = btree_path_node(iter->path, iter->path->level);
1693         if (!b)
1694                 goto out;
1695
1696         BUG_ON(bpos_lt(b->key.k.p, iter->pos));
1697
1698         bkey_init(&iter->k);
1699         iter->k.p = iter->pos = b->key.k.p;
1700
1701         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1702                                         iter->flags & BTREE_ITER_INTENT,
1703                                         btree_iter_ip_allocated(iter));
1704         btree_path_set_should_be_locked(iter->path);
1705 out:
1706         bch2_btree_iter_verify_entry_exit(iter);
1707         bch2_btree_iter_verify(iter);
1708
1709         return b;
1710 err:
1711         b = ERR_PTR(ret);
1712         goto out;
1713 }
1714
1715 struct btree *bch2_btree_iter_peek_node_and_restart(struct btree_iter *iter)
1716 {
1717         struct btree *b;
1718
1719         while (b = bch2_btree_iter_peek_node(iter),
1720                bch2_err_matches(PTR_ERR_OR_ZERO(b), BCH_ERR_transaction_restart))
1721                 bch2_trans_begin(iter->trans);
1722
1723         return b;
1724 }
1725
1726 struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
1727 {
1728         struct btree_trans *trans = iter->trans;
1729         struct btree_path *path = iter->path;
1730         struct btree *b = NULL;
1731         int ret;
1732
1733         bch2_trans_verify_not_in_restart(trans);
1734         EBUG_ON(iter->path->cached);
1735         bch2_btree_iter_verify(iter);
1736
1737         /* already at end? */
1738         if (!btree_path_node(path, path->level))
1739                 return NULL;
1740
1741         /* got to end? */
1742         if (!btree_path_node(path, path->level + 1)) {
1743                 btree_path_set_level_up(trans, path);
1744                 return NULL;
1745         }
1746
1747         if (!bch2_btree_node_relock(trans, path, path->level + 1)) {
1748                 __bch2_btree_path_unlock(trans, path);
1749                 path->l[path->level].b          = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1750                 path->l[path->level + 1].b      = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1751                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1752                 trace_and_count(trans->c, trans_restart_relock_next_node, trans, _THIS_IP_, path);
1753                 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
1754                 goto err;
1755         }
1756
1757         b = btree_path_node(path, path->level + 1);
1758
1759         if (bpos_eq(iter->pos, b->key.k.p)) {
1760                 __btree_path_set_level_up(trans, path, path->level++);
1761         } else {
1762                 /*
1763                  * Haven't gotten to the end of the parent node: go back down to
1764                  * the next child node
1765                  */
1766                 path = iter->path =
1767                         bch2_btree_path_set_pos(trans, path, bpos_successor(iter->pos),
1768                                            iter->flags & BTREE_ITER_INTENT,
1769                                            btree_iter_ip_allocated(iter));
1770
1771                 btree_path_set_level_down(trans, path, iter->min_depth);
1772
1773                 ret = bch2_btree_path_traverse(trans, path, iter->flags);
1774                 if (ret)
1775                         goto err;
1776
1777                 b = path->l[path->level].b;
1778         }
1779
1780         bkey_init(&iter->k);
1781         iter->k.p = iter->pos = b->key.k.p;
1782
1783         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1784                                         iter->flags & BTREE_ITER_INTENT,
1785                                         btree_iter_ip_allocated(iter));
1786         btree_path_set_should_be_locked(iter->path);
1787         BUG_ON(iter->path->uptodate);
1788 out:
1789         bch2_btree_iter_verify_entry_exit(iter);
1790         bch2_btree_iter_verify(iter);
1791
1792         return b;
1793 err:
1794         b = ERR_PTR(ret);
1795         goto out;
1796 }
1797
1798 /* Iterate across keys (in leaf nodes only) */
1799
1800 inline bool bch2_btree_iter_advance(struct btree_iter *iter)
1801 {
1802         if (likely(!(iter->flags & BTREE_ITER_ALL_LEVELS))) {
1803                 struct bpos pos = iter->k.p;
1804                 bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1805                              ? bpos_eq(pos, SPOS_MAX)
1806                              : bkey_eq(pos, SPOS_MAX));
1807
1808                 if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1809                         pos = bkey_successor(iter, pos);
1810                 bch2_btree_iter_set_pos(iter, pos);
1811                 return ret;
1812         } else {
1813                 if (!btree_path_node(iter->path, iter->path->level))
1814                         return true;
1815
1816                 iter->advanced = true;
1817                 return false;
1818         }
1819 }
1820
1821 inline bool bch2_btree_iter_rewind(struct btree_iter *iter)
1822 {
1823         struct bpos pos = bkey_start_pos(&iter->k);
1824         bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1825                      ? bpos_eq(pos, POS_MIN)
1826                      : bkey_eq(pos, POS_MIN));
1827
1828         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1829                 pos = bkey_predecessor(iter, pos);
1830         bch2_btree_iter_set_pos(iter, pos);
1831         return ret;
1832 }
1833
1834 static noinline
1835 struct bkey_i *__bch2_btree_trans_peek_updates(struct btree_iter *iter)
1836 {
1837         struct btree_insert_entry *i;
1838         struct bkey_i *ret = NULL;
1839
1840         trans_for_each_update(iter->trans, i) {
1841                 if (i->btree_id < iter->btree_id)
1842                         continue;
1843                 if (i->btree_id > iter->btree_id)
1844                         break;
1845                 if (bpos_lt(i->k->k.p, iter->path->pos))
1846                         continue;
1847                 if (i->key_cache_already_flushed)
1848                         continue;
1849                 if (!ret || bpos_lt(i->k->k.p, ret->k.p))
1850                         ret = i->k;
1851         }
1852
1853         return ret;
1854 }
1855
1856 static inline struct bkey_i *btree_trans_peek_updates(struct btree_iter *iter)
1857 {
1858         return iter->flags & BTREE_ITER_WITH_UPDATES
1859                 ? __bch2_btree_trans_peek_updates(iter)
1860                 : NULL;
1861 }
1862
1863 static struct bkey_i *bch2_btree_journal_peek(struct btree_trans *trans,
1864                                               struct btree_iter *iter,
1865                                               struct bpos end_pos)
1866 {
1867         struct bkey_i *k;
1868
1869         if (bpos_lt(iter->path->pos, iter->journal_pos))
1870                 iter->journal_idx = 0;
1871
1872         k = bch2_journal_keys_peek_upto(trans->c, iter->btree_id,
1873                                         iter->path->level,
1874                                         iter->path->pos,
1875                                         end_pos,
1876                                         &iter->journal_idx);
1877
1878         iter->journal_pos = k ? k->k.p : end_pos;
1879         return k;
1880 }
1881
1882 static noinline
1883 struct bkey_s_c btree_trans_peek_slot_journal(struct btree_trans *trans,
1884                                               struct btree_iter *iter)
1885 {
1886         struct bkey_i *k = bch2_btree_journal_peek(trans, iter, iter->path->pos);
1887
1888         if (k) {
1889                 iter->k = k->k;
1890                 return bkey_i_to_s_c(k);
1891         } else {
1892                 return bkey_s_c_null;
1893         }
1894 }
1895
1896 static noinline
1897 struct bkey_s_c btree_trans_peek_journal(struct btree_trans *trans,
1898                                          struct btree_iter *iter,
1899                                          struct bkey_s_c k)
1900 {
1901         struct bkey_i *next_journal =
1902                 bch2_btree_journal_peek(trans, iter,
1903                                 k.k ? k.k->p : path_l(iter->path)->b->key.k.p);
1904
1905         if (next_journal) {
1906                 iter->k = next_journal->k;
1907                 k = bkey_i_to_s_c(next_journal);
1908         }
1909
1910         return k;
1911 }
1912
1913 /*
1914  * Checks btree key cache for key at iter->pos and returns it if present, or
1915  * bkey_s_c_null:
1916  */
1917 static noinline
1918 struct bkey_s_c btree_trans_peek_key_cache(struct btree_iter *iter, struct bpos pos)
1919 {
1920         struct btree_trans *trans = iter->trans;
1921         struct bch_fs *c = trans->c;
1922         struct bkey u;
1923         struct bkey_s_c k;
1924         int ret;
1925
1926         if ((iter->flags & BTREE_ITER_KEY_CACHE_FILL) &&
1927             bpos_eq(iter->pos, pos))
1928                 return bkey_s_c_null;
1929
1930         if (!bch2_btree_key_cache_find(c, iter->btree_id, pos))
1931                 return bkey_s_c_null;
1932
1933         if (!iter->key_cache_path)
1934                 iter->key_cache_path = bch2_path_get(trans, iter->btree_id, pos,
1935                                                      iter->flags & BTREE_ITER_INTENT, 0,
1936                                                      iter->flags|BTREE_ITER_CACHED|
1937                                                      BTREE_ITER_CACHED_NOFILL,
1938                                                      _THIS_IP_);
1939
1940         iter->key_cache_path = bch2_btree_path_set_pos(trans, iter->key_cache_path, pos,
1941                                         iter->flags & BTREE_ITER_INTENT,
1942                                         btree_iter_ip_allocated(iter));
1943
1944         ret =   bch2_btree_path_traverse(trans, iter->key_cache_path,
1945                                          iter->flags|BTREE_ITER_CACHED) ?:
1946                 bch2_btree_path_relock(trans, iter->path, _THIS_IP_);
1947         if (unlikely(ret))
1948                 return bkey_s_c_err(ret);
1949
1950         btree_path_set_should_be_locked(iter->key_cache_path);
1951
1952         k = bch2_btree_path_peek_slot(iter->key_cache_path, &u);
1953         if (k.k && !bkey_err(k)) {
1954                 iter->k = u;
1955                 k.k = &iter->k;
1956         }
1957         return k;
1958 }
1959
1960 static struct bkey_s_c __bch2_btree_iter_peek(struct btree_iter *iter, struct bpos search_key)
1961 {
1962         struct btree_trans *trans = iter->trans;
1963         struct bkey_i *next_update;
1964         struct bkey_s_c k, k2;
1965         int ret;
1966
1967         EBUG_ON(iter->path->cached);
1968         bch2_btree_iter_verify(iter);
1969
1970         while (1) {
1971                 struct btree_path_level *l;
1972
1973                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
1974                                         iter->flags & BTREE_ITER_INTENT,
1975                                         btree_iter_ip_allocated(iter));
1976
1977                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1978                 if (unlikely(ret)) {
1979                         /* ensure that iter->k is consistent with iter->pos: */
1980                         bch2_btree_iter_set_pos(iter, iter->pos);
1981                         k = bkey_s_c_err(ret);
1982                         goto out;
1983                 }
1984
1985                 l = path_l(iter->path);
1986
1987                 if (unlikely(!l->b)) {
1988                         /* No btree nodes at requested level: */
1989                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
1990                         k = bkey_s_c_null;
1991                         goto out;
1992                 }
1993
1994                 btree_path_set_should_be_locked(iter->path);
1995
1996                 k = btree_path_level_peek_all(trans->c, l, &iter->k);
1997
1998                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
1999                     k.k &&
2000                     (k2 = btree_trans_peek_key_cache(iter, k.k->p)).k) {
2001                         k = k2;
2002                         ret = bkey_err(k);
2003                         if (ret) {
2004                                 bch2_btree_iter_set_pos(iter, iter->pos);
2005                                 goto out;
2006                         }
2007                 }
2008
2009                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL))
2010                         k = btree_trans_peek_journal(trans, iter, k);
2011
2012                 next_update = btree_trans_peek_updates(iter);
2013
2014                 if (next_update &&
2015                     bpos_le(next_update->k.p,
2016                             k.k ? k.k->p : l->b->key.k.p)) {
2017                         iter->k = next_update->k;
2018                         k = bkey_i_to_s_c(next_update);
2019                 }
2020
2021                 if (k.k && bkey_deleted(k.k)) {
2022                         /*
2023                          * If we've got a whiteout, and it's after the search
2024                          * key, advance the search key to the whiteout instead
2025                          * of just after the whiteout - it might be a btree
2026                          * whiteout, with a real key at the same position, since
2027                          * in the btree deleted keys sort before non deleted.
2028                          */
2029                         search_key = !bpos_eq(search_key, k.k->p)
2030                                 ? k.k->p
2031                                 : bpos_successor(k.k->p);
2032                         continue;
2033                 }
2034
2035                 if (likely(k.k)) {
2036                         break;
2037                 } else if (likely(!bpos_eq(l->b->key.k.p, SPOS_MAX))) {
2038                         /* Advance to next leaf node: */
2039                         search_key = bpos_successor(l->b->key.k.p);
2040                 } else {
2041                         /* End of btree: */
2042                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2043                         k = bkey_s_c_null;
2044                         goto out;
2045                 }
2046         }
2047 out:
2048         bch2_btree_iter_verify(iter);
2049
2050         return k;
2051 }
2052
2053 /**
2054  * bch2_btree_iter_peek_upto() - returns first key greater than or equal to
2055  * iterator's current position
2056  * @iter:       iterator to peek from
2057  * @end:        search limit: returns keys less than or equal to @end
2058  *
2059  * Returns:     key if found, or an error extractable with bkey_err().
2060  */
2061 struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *iter, struct bpos end)
2062 {
2063         struct btree_trans *trans = iter->trans;
2064         struct bpos search_key = btree_iter_search_key(iter);
2065         struct bkey_s_c k;
2066         struct bpos iter_pos;
2067         int ret;
2068
2069         EBUG_ON(iter->flags & BTREE_ITER_ALL_LEVELS);
2070         EBUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) && bkey_eq(end, POS_MAX));
2071
2072         if (iter->update_path) {
2073                 bch2_path_put_nokeep(trans, iter->update_path,
2074                                      iter->flags & BTREE_ITER_INTENT);
2075                 iter->update_path = NULL;
2076         }
2077
2078         bch2_btree_iter_verify_entry_exit(iter);
2079
2080         while (1) {
2081                 k = __bch2_btree_iter_peek(iter, search_key);
2082                 if (unlikely(!k.k))
2083                         goto end;
2084                 if (unlikely(bkey_err(k)))
2085                         goto out_no_locked;
2086
2087                 /*
2088                  * iter->pos should be mononotically increasing, and always be
2089                  * equal to the key we just returned - except extents can
2090                  * straddle iter->pos:
2091                  */
2092                 if (!(iter->flags & BTREE_ITER_IS_EXTENTS))
2093                         iter_pos = k.k->p;
2094                 else
2095                         iter_pos = bkey_max(iter->pos, bkey_start_pos(k.k));
2096
2097                 if (unlikely(!(iter->flags & BTREE_ITER_IS_EXTENTS)
2098                              ? bkey_gt(iter_pos, end)
2099                              : bkey_ge(iter_pos, end)))
2100                         goto end;
2101
2102                 if (iter->update_path &&
2103                     !bkey_eq(iter->update_path->pos, k.k->p)) {
2104                         bch2_path_put_nokeep(trans, iter->update_path,
2105                                              iter->flags & BTREE_ITER_INTENT);
2106                         iter->update_path = NULL;
2107                 }
2108
2109                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2110                     (iter->flags & BTREE_ITER_INTENT) &&
2111                     !(iter->flags & BTREE_ITER_IS_EXTENTS) &&
2112                     !iter->update_path) {
2113                         struct bpos pos = k.k->p;
2114
2115                         if (pos.snapshot < iter->snapshot) {
2116                                 search_key = bpos_successor(k.k->p);
2117                                 continue;
2118                         }
2119
2120                         pos.snapshot = iter->snapshot;
2121
2122                         /*
2123                          * advance, same as on exit for iter->path, but only up
2124                          * to snapshot
2125                          */
2126                         __btree_path_get(iter->path, iter->flags & BTREE_ITER_INTENT);
2127                         iter->update_path = iter->path;
2128
2129                         iter->update_path = bch2_btree_path_set_pos(trans,
2130                                                 iter->update_path, pos,
2131                                                 iter->flags & BTREE_ITER_INTENT,
2132                                                 _THIS_IP_);
2133                         ret = bch2_btree_path_traverse(trans, iter->update_path, iter->flags);
2134                         if (unlikely(ret)) {
2135                                 k = bkey_s_c_err(ret);
2136                                 goto out_no_locked;
2137                         }
2138                 }
2139
2140                 /*
2141                  * We can never have a key in a leaf node at POS_MAX, so
2142                  * we don't have to check these successor() calls:
2143                  */
2144                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2145                     !bch2_snapshot_is_ancestor(trans->c,
2146                                                iter->snapshot,
2147                                                k.k->p.snapshot)) {
2148                         search_key = bpos_successor(k.k->p);
2149                         continue;
2150                 }
2151
2152                 if (bkey_whiteout(k.k) &&
2153                     !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2154                         search_key = bkey_successor(iter, k.k->p);
2155                         continue;
2156                 }
2157
2158                 break;
2159         }
2160
2161         iter->pos = iter_pos;
2162
2163         iter->path = bch2_btree_path_set_pos(trans, iter->path, k.k->p,
2164                                 iter->flags & BTREE_ITER_INTENT,
2165                                 btree_iter_ip_allocated(iter));
2166
2167         btree_path_set_should_be_locked(iter->path);
2168 out_no_locked:
2169         if (iter->update_path) {
2170                 ret = bch2_btree_path_relock(trans, iter->update_path, _THIS_IP_);
2171                 if (unlikely(ret))
2172                         k = bkey_s_c_err(ret);
2173                 else
2174                         btree_path_set_should_be_locked(iter->update_path);
2175         }
2176
2177         if (!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS))
2178                 iter->pos.snapshot = iter->snapshot;
2179
2180         ret = bch2_btree_iter_verify_ret(iter, k);
2181         if (unlikely(ret)) {
2182                 bch2_btree_iter_set_pos(iter, iter->pos);
2183                 k = bkey_s_c_err(ret);
2184         }
2185
2186         bch2_btree_iter_verify_entry_exit(iter);
2187
2188         return k;
2189 end:
2190         bch2_btree_iter_set_pos(iter, end);
2191         k = bkey_s_c_null;
2192         goto out_no_locked;
2193 }
2194
2195 /**
2196  * bch2_btree_iter_peek_all_levels() - returns the first key greater than or
2197  * equal to iterator's current position, returning keys from every level of the
2198  * btree. For keys at different levels of the btree that compare equal, the key
2199  * from the lower level (leaf) is returned first.
2200  * @iter:       iterator to peek from
2201  *
2202  * Returns:     key if found, or an error extractable with bkey_err().
2203  */
2204 struct bkey_s_c bch2_btree_iter_peek_all_levels(struct btree_iter *iter)
2205 {
2206         struct btree_trans *trans = iter->trans;
2207         struct bkey_s_c k;
2208         int ret;
2209
2210         EBUG_ON(iter->path->cached);
2211         bch2_btree_iter_verify(iter);
2212         BUG_ON(iter->path->level < iter->min_depth);
2213         BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
2214         EBUG_ON(!(iter->flags & BTREE_ITER_ALL_LEVELS));
2215
2216         while (1) {
2217                 iter->path = bch2_btree_path_set_pos(trans, iter->path, iter->pos,
2218                                         iter->flags & BTREE_ITER_INTENT,
2219                                         btree_iter_ip_allocated(iter));
2220
2221                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2222                 if (unlikely(ret)) {
2223                         /* ensure that iter->k is consistent with iter->pos: */
2224                         bch2_btree_iter_set_pos(iter, iter->pos);
2225                         k = bkey_s_c_err(ret);
2226                         goto out_no_locked;
2227                 }
2228
2229                 /* Already at end? */
2230                 if (!btree_path_node(iter->path, iter->path->level)) {
2231                         k = bkey_s_c_null;
2232                         goto out_no_locked;
2233                 }
2234
2235                 k = btree_path_level_peek_all(trans->c,
2236                                 &iter->path->l[iter->path->level], &iter->k);
2237
2238                 /* Check if we should go up to the parent node: */
2239                 if (!k.k ||
2240                     (iter->advanced &&
2241                      bpos_eq(path_l(iter->path)->b->key.k.p, iter->pos))) {
2242                         iter->pos = path_l(iter->path)->b->key.k.p;
2243                         btree_path_set_level_up(trans, iter->path);
2244                         iter->advanced = false;
2245                         continue;
2246                 }
2247
2248                 /*
2249                  * Check if we should go back down to a leaf:
2250                  * If we're not in a leaf node, we only return the current key
2251                  * if it exactly matches iter->pos - otherwise we first have to
2252                  * go back to the leaf:
2253                  */
2254                 if (iter->path->level != iter->min_depth &&
2255                     (iter->advanced ||
2256                      !k.k ||
2257                      !bpos_eq(iter->pos, k.k->p))) {
2258                         btree_path_set_level_down(trans, iter->path, iter->min_depth);
2259                         iter->pos = bpos_successor(iter->pos);
2260                         iter->advanced = false;
2261                         continue;
2262                 }
2263
2264                 /* Check if we should go to the next key: */
2265                 if (iter->path->level == iter->min_depth &&
2266                     iter->advanced &&
2267                     k.k &&
2268                     bpos_eq(iter->pos, k.k->p)) {
2269                         iter->pos = bpos_successor(iter->pos);
2270                         iter->advanced = false;
2271                         continue;
2272                 }
2273
2274                 if (iter->advanced &&
2275                     iter->path->level == iter->min_depth &&
2276                     !bpos_eq(k.k->p, iter->pos))
2277                         iter->advanced = false;
2278
2279                 BUG_ON(iter->advanced);
2280                 BUG_ON(!k.k);
2281                 break;
2282         }
2283
2284         iter->pos = k.k->p;
2285         btree_path_set_should_be_locked(iter->path);
2286 out_no_locked:
2287         bch2_btree_iter_verify(iter);
2288
2289         return k;
2290 }
2291
2292 /**
2293  * bch2_btree_iter_next() - returns first key greater than iterator's current
2294  * position
2295  * @iter:       iterator to peek from
2296  *
2297  * Returns:     key if found, or an error extractable with bkey_err().
2298  */
2299 struct bkey_s_c bch2_btree_iter_next(struct btree_iter *iter)
2300 {
2301         if (!bch2_btree_iter_advance(iter))
2302                 return bkey_s_c_null;
2303
2304         return bch2_btree_iter_peek(iter);
2305 }
2306
2307 /**
2308  * bch2_btree_iter_peek_prev() - returns first key less than or equal to
2309  * iterator's current position
2310  * @iter:       iterator to peek from
2311  *
2312  * Returns:     key if found, or an error extractable with bkey_err().
2313  */
2314 struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
2315 {
2316         struct btree_trans *trans = iter->trans;
2317         struct bpos search_key = iter->pos;
2318         struct btree_path *saved_path = NULL;
2319         struct bkey_s_c k;
2320         struct bkey saved_k;
2321         const struct bch_val *saved_v;
2322         int ret;
2323
2324         EBUG_ON(iter->path->cached || iter->path->level);
2325         EBUG_ON(iter->flags & BTREE_ITER_WITH_UPDATES);
2326
2327         if (iter->flags & BTREE_ITER_WITH_JOURNAL)
2328                 return bkey_s_c_err(-EIO);
2329
2330         bch2_btree_iter_verify(iter);
2331         bch2_btree_iter_verify_entry_exit(iter);
2332
2333         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2334                 search_key.snapshot = U32_MAX;
2335
2336         while (1) {
2337                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2338                                                 iter->flags & BTREE_ITER_INTENT,
2339                                                 btree_iter_ip_allocated(iter));
2340
2341                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2342                 if (unlikely(ret)) {
2343                         /* ensure that iter->k is consistent with iter->pos: */
2344                         bch2_btree_iter_set_pos(iter, iter->pos);
2345                         k = bkey_s_c_err(ret);
2346                         goto out_no_locked;
2347                 }
2348
2349                 k = btree_path_level_peek(trans, iter->path,
2350                                           &iter->path->l[0], &iter->k);
2351                 if (!k.k ||
2352                     ((iter->flags & BTREE_ITER_IS_EXTENTS)
2353                      ? bpos_ge(bkey_start_pos(k.k), search_key)
2354                      : bpos_gt(k.k->p, search_key)))
2355                         k = btree_path_level_prev(trans, iter->path,
2356                                                   &iter->path->l[0], &iter->k);
2357
2358                 if (likely(k.k)) {
2359                         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) {
2360                                 if (k.k->p.snapshot == iter->snapshot)
2361                                         goto got_key;
2362
2363                                 /*
2364                                  * If we have a saved candidate, and we're no
2365                                  * longer at the same _key_ (not pos), return
2366                                  * that candidate
2367                                  */
2368                                 if (saved_path && !bkey_eq(k.k->p, saved_k.p)) {
2369                                         bch2_path_put_nokeep(trans, iter->path,
2370                                                       iter->flags & BTREE_ITER_INTENT);
2371                                         iter->path = saved_path;
2372                                         saved_path = NULL;
2373                                         iter->k = saved_k;
2374                                         k.v     = saved_v;
2375                                         goto got_key;
2376                                 }
2377
2378                                 if (bch2_snapshot_is_ancestor(iter->trans->c,
2379                                                               iter->snapshot,
2380                                                               k.k->p.snapshot)) {
2381                                         if (saved_path)
2382                                                 bch2_path_put_nokeep(trans, saved_path,
2383                                                       iter->flags & BTREE_ITER_INTENT);
2384                                         saved_path = btree_path_clone(trans, iter->path,
2385                                                                 iter->flags & BTREE_ITER_INTENT);
2386                                         saved_k = *k.k;
2387                                         saved_v = k.v;
2388                                 }
2389
2390                                 search_key = bpos_predecessor(k.k->p);
2391                                 continue;
2392                         }
2393 got_key:
2394                         if (bkey_whiteout(k.k) &&
2395                             !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2396                                 search_key = bkey_predecessor(iter, k.k->p);
2397                                 if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2398                                         search_key.snapshot = U32_MAX;
2399                                 continue;
2400                         }
2401
2402                         break;
2403                 } else if (likely(!bpos_eq(iter->path->l[0].b->data->min_key, POS_MIN))) {
2404                         /* Advance to previous leaf node: */
2405                         search_key = bpos_predecessor(iter->path->l[0].b->data->min_key);
2406                 } else {
2407                         /* Start of btree: */
2408                         bch2_btree_iter_set_pos(iter, POS_MIN);
2409                         k = bkey_s_c_null;
2410                         goto out_no_locked;
2411                 }
2412         }
2413
2414         EBUG_ON(bkey_gt(bkey_start_pos(k.k), iter->pos));
2415
2416         /* Extents can straddle iter->pos: */
2417         if (bkey_lt(k.k->p, iter->pos))
2418                 iter->pos = k.k->p;
2419
2420         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2421                 iter->pos.snapshot = iter->snapshot;
2422
2423         btree_path_set_should_be_locked(iter->path);
2424 out_no_locked:
2425         if (saved_path)
2426                 bch2_path_put_nokeep(trans, saved_path, iter->flags & BTREE_ITER_INTENT);
2427
2428         bch2_btree_iter_verify_entry_exit(iter);
2429         bch2_btree_iter_verify(iter);
2430
2431         return k;
2432 }
2433
2434 /**
2435  * bch2_btree_iter_prev() - returns first key less than iterator's current
2436  * position
2437  * @iter:       iterator to peek from
2438  *
2439  * Returns:     key if found, or an error extractable with bkey_err().
2440  */
2441 struct bkey_s_c bch2_btree_iter_prev(struct btree_iter *iter)
2442 {
2443         if (!bch2_btree_iter_rewind(iter))
2444                 return bkey_s_c_null;
2445
2446         return bch2_btree_iter_peek_prev(iter);
2447 }
2448
2449 struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
2450 {
2451         struct btree_trans *trans = iter->trans;
2452         struct bpos search_key;
2453         struct bkey_s_c k;
2454         int ret;
2455
2456         bch2_btree_iter_verify(iter);
2457         bch2_btree_iter_verify_entry_exit(iter);
2458         EBUG_ON(iter->flags & BTREE_ITER_ALL_LEVELS);
2459         EBUG_ON(iter->path->level && (iter->flags & BTREE_ITER_WITH_KEY_CACHE));
2460
2461         /* extents can't span inode numbers: */
2462         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
2463             unlikely(iter->pos.offset == KEY_OFFSET_MAX)) {
2464                 if (iter->pos.inode == KEY_INODE_MAX)
2465                         return bkey_s_c_null;
2466
2467                 bch2_btree_iter_set_pos(iter, bpos_nosnap_successor(iter->pos));
2468         }
2469
2470         search_key = btree_iter_search_key(iter);
2471         iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2472                                         iter->flags & BTREE_ITER_INTENT,
2473                                         btree_iter_ip_allocated(iter));
2474
2475         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2476         if (unlikely(ret)) {
2477                 k = bkey_s_c_err(ret);
2478                 goto out_no_locked;
2479         }
2480
2481         if ((iter->flags & BTREE_ITER_CACHED) ||
2482             !(iter->flags & (BTREE_ITER_IS_EXTENTS|BTREE_ITER_FILTER_SNAPSHOTS))) {
2483                 struct bkey_i *next_update;
2484
2485                 if ((next_update = btree_trans_peek_updates(iter)) &&
2486                     bpos_eq(next_update->k.p, iter->pos)) {
2487                         iter->k = next_update->k;
2488                         k = bkey_i_to_s_c(next_update);
2489                         goto out;
2490                 }
2491
2492                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL) &&
2493                     (k = btree_trans_peek_slot_journal(trans, iter)).k)
2494                         goto out;
2495
2496                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2497                     (k = btree_trans_peek_key_cache(iter, iter->pos)).k) {
2498                         if (!bkey_err(k))
2499                                 iter->k = *k.k;
2500                         /* We're not returning a key from iter->path: */
2501                         goto out_no_locked;
2502                 }
2503
2504                 k = bch2_btree_path_peek_slot(iter->path, &iter->k);
2505                 if (unlikely(!k.k))
2506                         goto out_no_locked;
2507         } else {
2508                 struct bpos next;
2509                 struct bpos end = iter->pos;
2510
2511                 if (iter->flags & BTREE_ITER_IS_EXTENTS)
2512                         end.offset = U64_MAX;
2513
2514                 EBUG_ON(iter->path->level);
2515
2516                 if (iter->flags & BTREE_ITER_INTENT) {
2517                         struct btree_iter iter2;
2518
2519                         bch2_trans_copy_iter(&iter2, iter);
2520                         k = bch2_btree_iter_peek_upto(&iter2, end);
2521
2522                         if (k.k && !bkey_err(k)) {
2523                                 iter->k = iter2.k;
2524                                 k.k = &iter->k;
2525                         }
2526                         bch2_trans_iter_exit(trans, &iter2);
2527                 } else {
2528                         struct bpos pos = iter->pos;
2529
2530                         k = bch2_btree_iter_peek_upto(iter, end);
2531                         if (unlikely(bkey_err(k)))
2532                                 bch2_btree_iter_set_pos(iter, pos);
2533                         else
2534                                 iter->pos = pos;
2535                 }
2536
2537                 if (unlikely(bkey_err(k)))
2538                         goto out_no_locked;
2539
2540                 next = k.k ? bkey_start_pos(k.k) : POS_MAX;
2541
2542                 if (bkey_lt(iter->pos, next)) {
2543                         bkey_init(&iter->k);
2544                         iter->k.p = iter->pos;
2545
2546                         if (iter->flags & BTREE_ITER_IS_EXTENTS) {
2547                                 bch2_key_resize(&iter->k,
2548                                                 min_t(u64, KEY_SIZE_MAX,
2549                                                       (next.inode == iter->pos.inode
2550                                                        ? next.offset
2551                                                        : KEY_OFFSET_MAX) -
2552                                                       iter->pos.offset));
2553                                 EBUG_ON(!iter->k.size);
2554                         }
2555
2556                         k = (struct bkey_s_c) { &iter->k, NULL };
2557                 }
2558         }
2559 out:
2560         btree_path_set_should_be_locked(iter->path);
2561 out_no_locked:
2562         bch2_btree_iter_verify_entry_exit(iter);
2563         bch2_btree_iter_verify(iter);
2564         ret = bch2_btree_iter_verify_ret(iter, k);
2565         if (unlikely(ret))
2566                 return bkey_s_c_err(ret);
2567
2568         return k;
2569 }
2570
2571 struct bkey_s_c bch2_btree_iter_next_slot(struct btree_iter *iter)
2572 {
2573         if (!bch2_btree_iter_advance(iter))
2574                 return bkey_s_c_null;
2575
2576         return bch2_btree_iter_peek_slot(iter);
2577 }
2578
2579 struct bkey_s_c bch2_btree_iter_prev_slot(struct btree_iter *iter)
2580 {
2581         if (!bch2_btree_iter_rewind(iter))
2582                 return bkey_s_c_null;
2583
2584         return bch2_btree_iter_peek_slot(iter);
2585 }
2586
2587 struct bkey_s_c bch2_btree_iter_peek_and_restart_outlined(struct btree_iter *iter)
2588 {
2589         struct bkey_s_c k;
2590
2591         while (btree_trans_too_many_iters(iter->trans) ||
2592                (k = bch2_btree_iter_peek_type(iter, iter->flags),
2593                 bch2_err_matches(bkey_err(k), BCH_ERR_transaction_restart)))
2594                 bch2_trans_begin(iter->trans);
2595
2596         return k;
2597 }
2598
2599 /* new transactional stuff: */
2600
2601 #ifdef CONFIG_BCACHEFS_DEBUG
2602 static void btree_trans_verify_sorted_refs(struct btree_trans *trans)
2603 {
2604         struct btree_path *path;
2605         unsigned i;
2606
2607         BUG_ON(trans->nr_sorted != hweight64(trans->paths_allocated));
2608
2609         trans_for_each_path(trans, path) {
2610                 BUG_ON(path->sorted_idx >= trans->nr_sorted);
2611                 BUG_ON(trans->sorted[path->sorted_idx] != path->idx);
2612         }
2613
2614         for (i = 0; i < trans->nr_sorted; i++) {
2615                 unsigned idx = trans->sorted[i];
2616
2617                 EBUG_ON(!(trans->paths_allocated & (1ULL << idx)));
2618                 BUG_ON(trans->paths[idx].sorted_idx != i);
2619         }
2620 }
2621
2622 static void btree_trans_verify_sorted(struct btree_trans *trans)
2623 {
2624         struct btree_path *path, *prev = NULL;
2625         unsigned i;
2626
2627         if (!bch2_debug_check_iterators)
2628                 return;
2629
2630         trans_for_each_path_inorder(trans, path, i) {
2631                 if (prev && btree_path_cmp(prev, path) > 0) {
2632                         __bch2_dump_trans_paths_updates(trans, true);
2633                         panic("trans paths out of order!\n");
2634                 }
2635                 prev = path;
2636         }
2637 }
2638 #else
2639 static inline void btree_trans_verify_sorted_refs(struct btree_trans *trans) {}
2640 static inline void btree_trans_verify_sorted(struct btree_trans *trans) {}
2641 #endif
2642
2643 void __bch2_btree_trans_sort_paths(struct btree_trans *trans)
2644 {
2645         int i, l = 0, r = trans->nr_sorted, inc = 1;
2646         bool swapped;
2647
2648         btree_trans_verify_sorted_refs(trans);
2649
2650         if (trans->paths_sorted)
2651                 goto out;
2652
2653         /*
2654          * Cocktail shaker sort: this is efficient because iterators will be
2655          * mostly sorted.
2656          */
2657         do {
2658                 swapped = false;
2659
2660                 for (i = inc > 0 ? l : r - 2;
2661                      i + 1 < r && i >= l;
2662                      i += inc) {
2663                         if (btree_path_cmp(trans->paths + trans->sorted[i],
2664                                            trans->paths + trans->sorted[i + 1]) > 0) {
2665                                 swap(trans->sorted[i], trans->sorted[i + 1]);
2666                                 trans->paths[trans->sorted[i]].sorted_idx = i;
2667                                 trans->paths[trans->sorted[i + 1]].sorted_idx = i + 1;
2668                                 swapped = true;
2669                         }
2670                 }
2671
2672                 if (inc > 0)
2673                         --r;
2674                 else
2675                         l++;
2676                 inc = -inc;
2677         } while (swapped);
2678
2679         trans->paths_sorted = true;
2680 out:
2681         btree_trans_verify_sorted(trans);
2682 }
2683
2684 static inline void btree_path_list_remove(struct btree_trans *trans,
2685                                           struct btree_path *path)
2686 {
2687         unsigned i;
2688
2689         EBUG_ON(path->sorted_idx >= trans->nr_sorted);
2690 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2691         trans->nr_sorted--;
2692         memmove_u64s_down_small(trans->sorted + path->sorted_idx,
2693                                 trans->sorted + path->sorted_idx + 1,
2694                                 DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx, 8));
2695 #else
2696         array_remove_item(trans->sorted, trans->nr_sorted, path->sorted_idx);
2697 #endif
2698         for (i = path->sorted_idx; i < trans->nr_sorted; i++)
2699                 trans->paths[trans->sorted[i]].sorted_idx = i;
2700
2701         path->sorted_idx = U8_MAX;
2702 }
2703
2704 static inline void btree_path_list_add(struct btree_trans *trans,
2705                                        struct btree_path *pos,
2706                                        struct btree_path *path)
2707 {
2708         unsigned i;
2709
2710         path->sorted_idx = pos ? pos->sorted_idx + 1 : trans->nr_sorted;
2711
2712 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2713         memmove_u64s_up_small(trans->sorted + path->sorted_idx + 1,
2714                               trans->sorted + path->sorted_idx,
2715                               DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx, 8));
2716         trans->nr_sorted++;
2717         trans->sorted[path->sorted_idx] = path->idx;
2718 #else
2719         array_insert_item(trans->sorted, trans->nr_sorted, path->sorted_idx, path->idx);
2720 #endif
2721
2722         for (i = path->sorted_idx; i < trans->nr_sorted; i++)
2723                 trans->paths[trans->sorted[i]].sorted_idx = i;
2724
2725         btree_trans_verify_sorted_refs(trans);
2726 }
2727
2728 void bch2_trans_iter_exit(struct btree_trans *trans, struct btree_iter *iter)
2729 {
2730         if (iter->update_path)
2731                 bch2_path_put_nokeep(trans, iter->update_path,
2732                               iter->flags & BTREE_ITER_INTENT);
2733         if (iter->path)
2734                 bch2_path_put(trans, iter->path,
2735                               iter->flags & BTREE_ITER_INTENT);
2736         if (iter->key_cache_path)
2737                 bch2_path_put(trans, iter->key_cache_path,
2738                               iter->flags & BTREE_ITER_INTENT);
2739         iter->path = NULL;
2740         iter->update_path = NULL;
2741         iter->key_cache_path = NULL;
2742 }
2743
2744 void bch2_trans_iter_init_outlined(struct btree_trans *trans,
2745                           struct btree_iter *iter,
2746                           enum btree_id btree_id, struct bpos pos,
2747                           unsigned flags)
2748 {
2749         bch2_trans_iter_init_common(trans, iter, btree_id, pos, 0, 0,
2750                                bch2_btree_iter_flags(trans, btree_id, flags),
2751                                _RET_IP_);
2752 }
2753
2754 void bch2_trans_node_iter_init(struct btree_trans *trans,
2755                                struct btree_iter *iter,
2756                                enum btree_id btree_id,
2757                                struct bpos pos,
2758                                unsigned locks_want,
2759                                unsigned depth,
2760                                unsigned flags)
2761 {
2762         flags |= BTREE_ITER_NOT_EXTENTS;
2763         flags |= __BTREE_ITER_ALL_SNAPSHOTS;
2764         flags |= BTREE_ITER_ALL_SNAPSHOTS;
2765
2766         bch2_trans_iter_init_common(trans, iter, btree_id, pos, locks_want, depth,
2767                                __bch2_btree_iter_flags(trans, btree_id, flags),
2768                                _RET_IP_);
2769
2770         iter->min_depth = depth;
2771
2772         BUG_ON(iter->path->locks_want    < min(locks_want, BTREE_MAX_DEPTH));
2773         BUG_ON(iter->path->level        != depth);
2774         BUG_ON(iter->min_depth          != depth);
2775 }
2776
2777 void bch2_trans_copy_iter(struct btree_iter *dst, struct btree_iter *src)
2778 {
2779         *dst = *src;
2780         if (src->path)
2781                 __btree_path_get(src->path, src->flags & BTREE_ITER_INTENT);
2782         if (src->update_path)
2783                 __btree_path_get(src->update_path, src->flags & BTREE_ITER_INTENT);
2784         dst->key_cache_path = NULL;
2785 }
2786
2787 void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
2788 {
2789         unsigned new_top = trans->mem_top + size;
2790         size_t old_bytes = trans->mem_bytes;
2791         size_t new_bytes = roundup_pow_of_two(new_top);
2792         int ret;
2793         void *new_mem;
2794         void *p;
2795
2796         trans->mem_max = max(trans->mem_max, new_top);
2797
2798         WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);
2799
2800         new_mem = krealloc(trans->mem, new_bytes, GFP_NOWAIT|__GFP_NOWARN);
2801         if (unlikely(!new_mem)) {
2802                 bch2_trans_unlock(trans);
2803
2804                 new_mem = krealloc(trans->mem, new_bytes, GFP_KERNEL);
2805                 if (!new_mem && new_bytes <= BTREE_TRANS_MEM_MAX) {
2806                         new_mem = mempool_alloc(&trans->c->btree_trans_mem_pool, GFP_KERNEL);
2807                         new_bytes = BTREE_TRANS_MEM_MAX;
2808                         kfree(trans->mem);
2809                 }
2810
2811                 if (!new_mem)
2812                         return ERR_PTR(-BCH_ERR_ENOMEM_trans_kmalloc);
2813
2814                 trans->mem = new_mem;
2815                 trans->mem_bytes = new_bytes;
2816
2817                 ret = bch2_trans_relock(trans);
2818                 if (ret)
2819                         return ERR_PTR(ret);
2820         }
2821
2822         trans->mem = new_mem;
2823         trans->mem_bytes = new_bytes;
2824
2825         if (old_bytes) {
2826                 trace_and_count(trans->c, trans_restart_mem_realloced, trans, _RET_IP_, new_bytes);
2827                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_mem_realloced));
2828         }
2829
2830         p = trans->mem + trans->mem_top;
2831         trans->mem_top += size;
2832         memset(p, 0, size);
2833         return p;
2834 }
2835
2836 static inline void check_srcu_held_too_long(struct btree_trans *trans)
2837 {
2838         WARN(time_after(jiffies, trans->srcu_lock_time + HZ * 10),
2839              "btree trans held srcu lock (delaying memory reclaim) by more than 10 seconds");
2840 }
2841
2842 void bch2_trans_srcu_unlock(struct btree_trans *trans)
2843 {
2844         if (trans->srcu_held) {
2845                 struct bch_fs *c = trans->c;
2846                 struct btree_path *path;
2847
2848                 trans_for_each_path(trans, path)
2849                         if (path->cached && !btree_node_locked(path, 0))
2850                                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_srcu_reset);
2851
2852                 check_srcu_held_too_long(trans);
2853                 srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
2854                 trans->srcu_held = false;
2855         }
2856 }
2857
2858 void bch2_trans_srcu_lock(struct btree_trans *trans)
2859 {
2860         if (!trans->srcu_held) {
2861                 trans->srcu_idx = srcu_read_lock(&trans->c->btree_trans_barrier);
2862                 trans->srcu_lock_time   = jiffies;
2863                 trans->srcu_held = true;
2864         }
2865 }
2866
2867 /**
2868  * bch2_trans_begin() - reset a transaction after a interrupted attempt
2869  * @trans: transaction to reset
2870  *
2871  * Returns:     current restart counter, to be used with trans_was_restarted()
2872  *
2873  * While iterating over nodes or updating nodes a attempt to lock a btree node
2874  * may return BCH_ERR_transaction_restart when the trylock fails. When this
2875  * occurs bch2_trans_begin() should be called and the transaction retried.
2876  */
2877 u32 bch2_trans_begin(struct btree_trans *trans)
2878 {
2879         struct btree_path *path;
2880         u64 now;
2881
2882         bch2_trans_reset_updates(trans);
2883
2884         trans->restart_count++;
2885         trans->mem_top                  = 0;
2886
2887         trans_for_each_path(trans, path) {
2888                 path->should_be_locked = false;
2889
2890                 /*
2891                  * If the transaction wasn't restarted, we're presuming to be
2892                  * doing something new: dont keep iterators excpt the ones that
2893                  * are in use - except for the subvolumes btree:
2894                  */
2895                 if (!trans->restarted && path->btree_id != BTREE_ID_subvolumes)
2896                         path->preserve = false;
2897
2898                 /*
2899                  * XXX: we probably shouldn't be doing this if the transaction
2900                  * was restarted, but currently we still overflow transaction
2901                  * iterators if we do that
2902                  */
2903                 if (!path->ref && !path->preserve)
2904                         __bch2_path_free(trans, path);
2905                 else
2906                         path->preserve = false;
2907         }
2908
2909         now = local_clock();
2910         if (!trans->restarted &&
2911             (need_resched() ||
2912              now - trans->last_begin_time > BTREE_TRANS_MAX_LOCK_HOLD_TIME_NS)) {
2913                 drop_locks_do(trans, (cond_resched(), 0));
2914                 now = local_clock();
2915         }
2916         trans->last_begin_time = now;
2917
2918         if (unlikely(trans->srcu_held &&
2919                      time_after(jiffies, trans->srcu_lock_time + msecs_to_jiffies(10))))
2920                 bch2_trans_srcu_unlock(trans);
2921
2922         trans->last_begin_ip = _RET_IP_;
2923         if (trans->restarted) {
2924                 bch2_btree_path_traverse_all(trans);
2925                 trans->notrace_relock_fail = false;
2926         }
2927
2928         return trans->restart_count;
2929 }
2930
2931 static struct btree_trans *bch2_trans_alloc(struct bch_fs *c)
2932 {
2933         struct btree_trans *trans;
2934
2935         if (IS_ENABLED(__KERNEL__)) {
2936                 trans = this_cpu_xchg(c->btree_trans_bufs->trans, NULL);
2937                 if (trans)
2938                         return trans;
2939         }
2940
2941         trans = mempool_alloc(&c->btree_trans_pool, GFP_NOFS);
2942         /*
2943          * paths need to be zeroed, bch2_check_for_deadlock looks at
2944          * paths in other threads
2945          */
2946         memset(&trans->paths, 0, sizeof(trans->paths));
2947         return trans;
2948 }
2949
2950 const char *bch2_btree_transaction_fns[BCH_TRANSACTIONS_NR];
2951
2952 unsigned bch2_trans_get_fn_idx(const char *fn)
2953 {
2954         unsigned i;
2955
2956         for (i = 0; i < ARRAY_SIZE(bch2_btree_transaction_fns); i++)
2957                 if (!bch2_btree_transaction_fns[i] ||
2958                     bch2_btree_transaction_fns[i] == fn) {
2959                         bch2_btree_transaction_fns[i] = fn;
2960                         return i;
2961                 }
2962
2963         pr_warn_once("BCH_TRANSACTIONS_NR not big enough!");
2964         return i;
2965 }
2966
2967 struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx)
2968         __acquires(&c->btree_trans_barrier)
2969 {
2970         struct btree_trans *trans;
2971         struct btree_transaction_stats *s;
2972
2973         bch2_assert_btree_nodes_not_locked();
2974
2975         trans = bch2_trans_alloc(c);
2976
2977         memset(trans, 0, sizeof(*trans));
2978         trans->c                = c;
2979         trans->fn               = fn_idx < ARRAY_SIZE(bch2_btree_transaction_fns)
2980                 ? bch2_btree_transaction_fns[fn_idx] : NULL;
2981         trans->last_begin_time  = local_clock();
2982         trans->fn_idx           = fn_idx;
2983         trans->locking_wait.task = current;
2984         trans->journal_replay_not_finished =
2985                 !test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags);
2986         closure_init_stack(&trans->ref);
2987
2988         s = btree_trans_stats(trans);
2989         if (s && s->max_mem) {
2990                 unsigned expected_mem_bytes = roundup_pow_of_two(s->max_mem);
2991
2992                 trans->mem = kmalloc(expected_mem_bytes, GFP_KERNEL);
2993
2994                 if (!unlikely(trans->mem)) {
2995                         trans->mem = mempool_alloc(&c->btree_trans_mem_pool, GFP_KERNEL);
2996                         trans->mem_bytes = BTREE_TRANS_MEM_MAX;
2997                 } else {
2998                         trans->mem_bytes = expected_mem_bytes;
2999                 }
3000         }
3001
3002         if (s) {
3003                 trans->nr_max_paths = s->nr_max_paths;
3004                 trans->wb_updates_size = s->wb_updates_size;
3005         }
3006
3007         trans->srcu_idx         = srcu_read_lock(&c->btree_trans_barrier);
3008         trans->srcu_lock_time   = jiffies;
3009         trans->srcu_held        = true;
3010
3011         if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG_TRANSACTIONS)) {
3012                 struct btree_trans *pos;
3013
3014                 seqmutex_lock(&c->btree_trans_lock);
3015                 list_for_each_entry(pos, &c->btree_trans_list, list) {
3016                         /*
3017                          * We'd much prefer to be stricter here and completely
3018                          * disallow multiple btree_trans in the same thread -
3019                          * but the data move path calls bch2_write when we
3020                          * already have a btree_trans initialized.
3021                          */
3022                         BUG_ON(trans->locking_wait.task->pid == pos->locking_wait.task->pid &&
3023                                bch2_trans_locked(pos));
3024
3025                         if (trans->locking_wait.task->pid < pos->locking_wait.task->pid) {
3026                                 list_add_tail(&trans->list, &pos->list);
3027                                 goto list_add_done;
3028                         }
3029                 }
3030                 list_add_tail(&trans->list, &c->btree_trans_list);
3031 list_add_done:
3032                 seqmutex_unlock(&c->btree_trans_lock);
3033         }
3034
3035         return trans;
3036 }
3037
3038 static void check_btree_paths_leaked(struct btree_trans *trans)
3039 {
3040 #ifdef CONFIG_BCACHEFS_DEBUG
3041         struct bch_fs *c = trans->c;
3042         struct btree_path *path;
3043
3044         trans_for_each_path(trans, path)
3045                 if (path->ref)
3046                         goto leaked;
3047         return;
3048 leaked:
3049         bch_err(c, "btree paths leaked from %s!", trans->fn);
3050         trans_for_each_path(trans, path)
3051                 if (path->ref)
3052                         printk(KERN_ERR "  btree %s %pS\n",
3053                                bch2_btree_id_str(path->btree_id),
3054                                (void *) path->ip_allocated);
3055         /* Be noisy about this: */
3056         bch2_fatal_error(c);
3057 #endif
3058 }
3059
3060 void bch2_trans_put(struct btree_trans *trans)
3061         __releases(&c->btree_trans_barrier)
3062 {
3063         struct btree_insert_entry *i;
3064         struct bch_fs *c = trans->c;
3065         struct btree_transaction_stats *s = btree_trans_stats(trans);
3066
3067         bch2_trans_unlock(trans);
3068
3069         if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG_TRANSACTIONS)) {
3070                 seqmutex_lock(&c->btree_trans_lock);
3071                 list_del(&trans->list);
3072                 seqmutex_unlock(&c->btree_trans_lock);
3073         }
3074
3075         closure_sync(&trans->ref);
3076
3077         if (s)
3078                 s->max_mem = max(s->max_mem, trans->mem_max);
3079
3080         trans_for_each_update(trans, i)
3081                 __btree_path_put(i->path, true);
3082         trans->nr_updates               = 0;
3083
3084         check_btree_paths_leaked(trans);
3085
3086         if (trans->srcu_held) {
3087                 check_srcu_held_too_long(trans);
3088                 srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
3089         }
3090
3091         bch2_journal_preres_put(&c->journal, &trans->journal_preres);
3092
3093         kfree(trans->extra_journal_entries.data);
3094
3095         if (trans->fs_usage_deltas) {
3096                 if (trans->fs_usage_deltas->size + sizeof(trans->fs_usage_deltas) ==
3097                     REPLICAS_DELTA_LIST_MAX)
3098                         mempool_free(trans->fs_usage_deltas,
3099                                      &c->replicas_delta_pool);
3100                 else
3101                         kfree(trans->fs_usage_deltas);
3102         }
3103
3104         if (trans->mem_bytes == BTREE_TRANS_MEM_MAX)
3105                 mempool_free(trans->mem, &c->btree_trans_mem_pool);
3106         else
3107                 kfree(trans->mem);
3108
3109         /* Userspace doesn't have a real percpu implementation: */
3110         if (IS_ENABLED(__KERNEL__))
3111                 trans = this_cpu_xchg(c->btree_trans_bufs->trans, trans);
3112         if (trans)
3113                 mempool_free(trans, &c->btree_trans_pool);
3114 }
3115
3116 static void __maybe_unused
3117 bch2_btree_bkey_cached_common_to_text(struct printbuf *out,
3118                                       struct btree_bkey_cached_common *b)
3119 {
3120         struct six_lock_count c = six_lock_counts(&b->lock);
3121         struct task_struct *owner;
3122         pid_t pid;
3123
3124         rcu_read_lock();
3125         owner = READ_ONCE(b->lock.owner);
3126         pid = owner ? owner->pid : 0;
3127         rcu_read_unlock();
3128
3129         prt_tab(out);
3130         prt_printf(out, "%px %c l=%u %s:", b, b->cached ? 'c' : 'b',
3131                    b->level, bch2_btree_id_str(b->btree_id));
3132         bch2_bpos_to_text(out, btree_node_pos(b));
3133
3134         prt_tab(out);
3135         prt_printf(out, " locks %u:%u:%u held by pid %u",
3136                    c.n[0], c.n[1], c.n[2], pid);
3137 }
3138
3139 void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
3140 {
3141         struct btree_path *path;
3142         struct btree_bkey_cached_common *b;
3143         static char lock_types[] = { 'r', 'i', 'w' };
3144         unsigned l, idx;
3145
3146         if (!out->nr_tabstops) {
3147                 printbuf_tabstop_push(out, 16);
3148                 printbuf_tabstop_push(out, 32);
3149         }
3150
3151         prt_printf(out, "%i %s\n", trans->locking_wait.task->pid, trans->fn);
3152
3153         trans_for_each_path_safe(trans, path, idx) {
3154                 if (!path->nodes_locked)
3155                         continue;
3156
3157                 prt_printf(out, "  path %u %c l=%u %s:",
3158                        path->idx,
3159                        path->cached ? 'c' : 'b',
3160                        path->level,
3161                        bch2_btree_id_str(path->btree_id));
3162                 bch2_bpos_to_text(out, path->pos);
3163                 prt_newline(out);
3164
3165                 for (l = 0; l < BTREE_MAX_DEPTH; l++) {
3166                         if (btree_node_locked(path, l) &&
3167                             !IS_ERR_OR_NULL(b = (void *) READ_ONCE(path->l[l].b))) {
3168                                 prt_printf(out, "    %c l=%u ",
3169                                            lock_types[btree_node_locked_type(path, l)], l);
3170                                 bch2_btree_bkey_cached_common_to_text(out, b);
3171                                 prt_newline(out);
3172                         }
3173                 }
3174         }
3175
3176         b = READ_ONCE(trans->locking);
3177         if (b) {
3178                 prt_printf(out, "  blocked for %lluus on",
3179                            div_u64(local_clock() - trans->locking_wait.start_time,
3180                                    1000));
3181                 prt_newline(out);
3182                 prt_printf(out, "    %c", lock_types[trans->locking_wait.lock_want]);
3183                 bch2_btree_bkey_cached_common_to_text(out, b);
3184                 prt_newline(out);
3185         }
3186 }
3187
3188 void bch2_fs_btree_iter_exit(struct bch_fs *c)
3189 {
3190         struct btree_transaction_stats *s;
3191         struct btree_trans *trans;
3192         int cpu;
3193
3194         trans = list_first_entry_or_null(&c->btree_trans_list, struct btree_trans, list);
3195         if (trans)
3196                 panic("%s leaked btree_trans\n", trans->fn);
3197
3198         if (c->btree_trans_bufs)
3199                 for_each_possible_cpu(cpu)
3200                         kfree(per_cpu_ptr(c->btree_trans_bufs, cpu)->trans);
3201         free_percpu(c->btree_trans_bufs);
3202
3203         for (s = c->btree_transaction_stats;
3204              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3205              s++) {
3206                 kfree(s->max_paths_text);
3207                 bch2_time_stats_exit(&s->lock_hold_times);
3208         }
3209
3210         if (c->btree_trans_barrier_initialized)
3211                 cleanup_srcu_struct(&c->btree_trans_barrier);
3212         mempool_exit(&c->btree_trans_mem_pool);
3213         mempool_exit(&c->btree_trans_pool);
3214 }
3215
3216 int bch2_fs_btree_iter_init(struct bch_fs *c)
3217 {
3218         struct btree_transaction_stats *s;
3219         int ret;
3220
3221         for (s = c->btree_transaction_stats;
3222              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3223              s++) {
3224                 bch2_time_stats_init(&s->lock_hold_times);
3225                 mutex_init(&s->lock);
3226         }
3227
3228         INIT_LIST_HEAD(&c->btree_trans_list);
3229         seqmutex_init(&c->btree_trans_lock);
3230
3231         c->btree_trans_bufs = alloc_percpu(struct btree_trans_buf);
3232         if (!c->btree_trans_bufs)
3233                 return -ENOMEM;
3234
3235         ret   = mempool_init_kmalloc_pool(&c->btree_trans_pool, 1,
3236                                           sizeof(struct btree_trans)) ?:
3237                 mempool_init_kmalloc_pool(&c->btree_trans_mem_pool, 1,
3238                                           BTREE_TRANS_MEM_MAX) ?:
3239                 init_srcu_struct(&c->btree_trans_barrier);
3240         if (!ret)
3241                 c->btree_trans_barrier_initialized = true;
3242         return ret;
3243 }