fs/bcachefs/btree_iter.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "bkey_methods.h"
   5 #include "bkey_buf.h"
   6 #include "btree_cache.h"
   7 #include "btree_iter.h"
   8 #include "btree_journal_iter.h"
   9 #include "btree_key_cache.h"
  10 #include "btree_locking.h"
  11 #include "btree_update.h"
  12 #include "debug.h"
  13 #include "error.h"
  14 #include "extents.h"
  15 #include "journal.h"
  16 #include "journal_io.h"
  17 #include "replicas.h"
  18 #include "snapshot.h"
  19 #include "trace.h"
  20
  21 #include <linux/random.h>
  22 #include <linux/prefetch.h>
  23
  24 static inline void btree_path_list_remove(struct btree_trans *, struct btree_path *);
  25 static inline void btree_path_list_add(struct btree_trans *,
  26                         btree_path_idx_t, btree_path_idx_t);
  27
  28 static inline unsigned long btree_iter_ip_allocated(struct btree_iter *iter)
  29 {
  30 #ifdef TRACK_PATH_ALLOCATED
  31         return iter->ip_allocated;
  32 #else
  33         return 0;
  34 #endif
  35 }
  36
  37 static btree_path_idx_t btree_path_alloc(struct btree_trans *, btree_path_idx_t);
  38 static void bch2_trans_srcu_lock(struct btree_trans *);
  39
  40 static inline int __btree_path_cmp(const struct btree_path *l,
  41                                    enum btree_id        r_btree_id,
  42                                    bool                 r_cached,
  43                                    struct bpos          r_pos,
  44                                    unsigned             r_level)
  45 {
  46         /*
  47          * Must match lock ordering as defined by __bch2_btree_node_lock:
  48          */
  49         return   cmp_int(l->btree_id,   r_btree_id) ?:
  50                  cmp_int((int) l->cached,       (int) r_cached) ?:
  51                  bpos_cmp(l->pos,       r_pos) ?:
  52                 -cmp_int(l->level,      r_level);
  53 }
  54
  55 static inline int btree_path_cmp(const struct btree_path *l,
  56                                  const struct btree_path *r)
  57 {
  58         return __btree_path_cmp(l, r->btree_id, r->cached, r->pos, r->level);
  59 }
  60
  61 static inline struct bpos bkey_successor(struct btree_iter *iter, struct bpos p)
  62 {
  63         /* Are we iterating over keys in all snapshots? */
  64         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  65                 p = bpos_successor(p);
  66         } else {
  67                 p = bpos_nosnap_successor(p);
  68                 p.snapshot = iter->snapshot;
  69         }
  70
  71         return p;
  72 }
  73
  74 static inline struct bpos bkey_predecessor(struct btree_iter *iter, struct bpos p)
  75 {
  76         /* Are we iterating over keys in all snapshots? */
  77         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  78                 p = bpos_predecessor(p);
  79         } else {
  80                 p = bpos_nosnap_predecessor(p);
  81                 p.snapshot = iter->snapshot;
  82         }
  83
  84         return p;
  85 }
  86
  87 static inline struct bpos btree_iter_search_key(struct btree_iter *iter)
  88 {
  89         struct bpos pos = iter->pos;
  90
  91         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
  92             !bkey_eq(pos, POS_MAX))
  93                 pos = bkey_successor(iter, pos);
  94         return pos;
  95 }
  96
  97 static inline bool btree_path_pos_before_node(struct btree_path *path,
  98                                               struct btree *b)
  99 {
 100         return bpos_lt(path->pos, b->data->min_key);
 101 }
 102
 103 static inline bool btree_path_pos_after_node(struct btree_path *path,
 104                                              struct btree *b)
 105 {
 106         return bpos_gt(path->pos, b->key.k.p);
 107 }
 108
 109 static inline bool btree_path_pos_in_node(struct btree_path *path,
 110                                           struct btree *b)
 111 {
 112         return path->btree_id == b->c.btree_id &&
 113                 !btree_path_pos_before_node(path, b) &&
 114                 !btree_path_pos_after_node(path, b);
 115 }
 116
 117 /* Btree iterator: */
 118
 119 #ifdef CONFIG_BCACHEFS_DEBUG
 120
 121 static void bch2_btree_path_verify_cached(struct btree_trans *trans,
 122                                           struct btree_path *path)
 123 {
 124         struct bkey_cached *ck;
 125         bool locked = btree_node_locked(path, 0);
 126
 127         if (!bch2_btree_node_relock(trans, path, 0))
 128                 return;
 129
 130         ck = (void *) path->l[0].b;
 131         BUG_ON(ck->key.btree_id != path->btree_id ||
 132                !bkey_eq(ck->key.pos, path->pos));
 133
 134         if (!locked)
 135                 btree_node_unlock(trans, path, 0);
 136 }
 137
 138 static void bch2_btree_path_verify_level(struct btree_trans *trans,
 139                                 struct btree_path *path, unsigned level)
 140 {
 141         struct btree_path_level *l;
 142         struct btree_node_iter tmp;
 143         bool locked;
 144         struct bkey_packed *p, *k;
 145         struct printbuf buf1 = PRINTBUF;
 146         struct printbuf buf2 = PRINTBUF;
 147         struct printbuf buf3 = PRINTBUF;
 148         const char *msg;
 149
 150         if (!bch2_debug_check_iterators)
 151                 return;
 152
 153         l       = &path->l[level];
 154         tmp     = l->iter;
 155         locked  = btree_node_locked(path, level);
 156
 157         if (path->cached) {
 158                 if (!level)
 159                         bch2_btree_path_verify_cached(trans, path);
 160                 return;
 161         }
 162
 163         if (!btree_path_node(path, level))
 164                 return;
 165
 166         if (!bch2_btree_node_relock_notrace(trans, path, level))
 167                 return;
 168
 169         BUG_ON(!btree_path_pos_in_node(path, l->b));
 170
 171         bch2_btree_node_iter_verify(&l->iter, l->b);
 172
 173         /*
 174          * For interior nodes, the iterator will have skipped past deleted keys:
 175          */
 176         p = level
 177                 ? bch2_btree_node_iter_prev(&tmp, l->b)
 178                 : bch2_btree_node_iter_prev_all(&tmp, l->b);
 179         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 180
 181         if (p && bkey_iter_pos_cmp(l->b, p, &path->pos) >= 0) {
 182                 msg = "before";
 183                 goto err;
 184         }
 185
 186         if (k && bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 187                 msg = "after";
 188                 goto err;
 189         }
 190
 191         if (!locked)
 192                 btree_node_unlock(trans, path, level);
 193         return;
 194 err:
 195         bch2_bpos_to_text(&buf1, path->pos);
 196
 197         if (p) {
 198                 struct bkey uk = bkey_unpack_key(l->b, p);
 199
 200                 bch2_bkey_to_text(&buf2, &uk);
 201         } else {
 202                 prt_printf(&buf2, "(none)");
 203         }
 204
 205         if (k) {
 206                 struct bkey uk = bkey_unpack_key(l->b, k);
 207
 208                 bch2_bkey_to_text(&buf3, &uk);
 209         } else {
 210                 prt_printf(&buf3, "(none)");
 211         }
 212
 213         panic("path should be %s key at level %u:\n"
 214               "path pos %s\n"
 215               "prev key %s\n"
 216               "cur  key %s\n",
 217               msg, level, buf1.buf, buf2.buf, buf3.buf);
 218 }
 219
 220 static void bch2_btree_path_verify(struct btree_trans *trans,
 221                                    struct btree_path *path)
 222 {
 223         struct bch_fs *c = trans->c;
 224         unsigned i;
 225
 226         EBUG_ON(path->btree_id >= BTREE_ID_NR);
 227
 228         for (i = 0; i < (!path->cached ? BTREE_MAX_DEPTH : 1); i++) {
 229                 if (!path->l[i].b) {
 230                         BUG_ON(!path->cached &&
 231                                bch2_btree_id_root(c, path->btree_id)->b->c.level > i);
 232                         break;
 233                 }
 234
 235                 bch2_btree_path_verify_level(trans, path, i);
 236         }
 237
 238         bch2_btree_path_verify_locks(path);
 239 }
 240
 241 void bch2_trans_verify_paths(struct btree_trans *trans)
 242 {
 243         struct btree_path *path;
 244         unsigned iter;
 245
 246         trans_for_each_path(trans, path, iter)
 247                 bch2_btree_path_verify(trans, path);
 248 }
 249
 250 static void bch2_btree_iter_verify(struct btree_iter *iter)
 251 {
 252         struct btree_trans *trans = iter->trans;
 253
 254         BUG_ON(iter->btree_id >= BTREE_ID_NR);
 255
 256         BUG_ON(!!(iter->flags & BTREE_ITER_CACHED) != btree_iter_path(trans, iter)->cached);
 257
 258         BUG_ON((iter->flags & BTREE_ITER_IS_EXTENTS) &&
 259                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
 260
 261         BUG_ON(!(iter->flags & __BTREE_ITER_ALL_SNAPSHOTS) &&
 262                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 263                !btree_type_has_snapshot_field(iter->btree_id));
 264
 265         if (iter->update_path)
 266                 bch2_btree_path_verify(trans, &trans->paths[iter->update_path]);
 267         bch2_btree_path_verify(trans, btree_iter_path(trans, iter));
 268 }
 269
 270 static void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter)
 271 {
 272         BUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
 273                !iter->pos.snapshot);
 274
 275         BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 276                iter->pos.snapshot != iter->snapshot);
 277
 278         BUG_ON(bkey_lt(iter->pos, bkey_start_pos(&iter->k)) ||
 279                bkey_gt(iter->pos, iter->k.p));
 280 }
 281
 282 static int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k)
 283 {
 284         struct btree_trans *trans = iter->trans;
 285         struct btree_iter copy;
 286         struct bkey_s_c prev;
 287         int ret = 0;
 288
 289         if (!bch2_debug_check_iterators)
 290                 return 0;
 291
 292         if (!(iter->flags & BTREE_ITER_FILTER_SNAPSHOTS))
 293                 return 0;
 294
 295         if (bkey_err(k) || !k.k)
 296                 return 0;
 297
 298         BUG_ON(!bch2_snapshot_is_ancestor(trans->c,
 299                                           iter->snapshot,
 300                                           k.k->p.snapshot));
 301
 302         bch2_trans_iter_init(trans, &copy, iter->btree_id, iter->pos,
 303                              BTREE_ITER_NOPRESERVE|
 304                              BTREE_ITER_ALL_SNAPSHOTS);
 305         prev = bch2_btree_iter_prev(&copy);
 306         if (!prev.k)
 307                 goto out;
 308
 309         ret = bkey_err(prev);
 310         if (ret)
 311                 goto out;
 312
 313         if (bkey_eq(prev.k->p, k.k->p) &&
 314             bch2_snapshot_is_ancestor(trans->c, iter->snapshot,
 315                                       prev.k->p.snapshot) > 0) {
 316                 struct printbuf buf1 = PRINTBUF, buf2 = PRINTBUF;
 317
 318                 bch2_bkey_to_text(&buf1, k.k);
 319                 bch2_bkey_to_text(&buf2, prev.k);
 320
 321                 panic("iter snap %u\n"
 322                       "k    %s\n"
 323                       "prev %s\n",
 324                       iter->snapshot,
 325                       buf1.buf, buf2.buf);
 326         }
 327 out:
 328         bch2_trans_iter_exit(trans, &copy);
 329         return ret;
 330 }
 331
 332 void bch2_assert_pos_locked(struct btree_trans *trans, enum btree_id id,
 333                             struct bpos pos, bool key_cache)
 334 {
 335         struct btree_path *path;
 336         struct trans_for_each_path_inorder_iter iter;
 337         struct printbuf buf = PRINTBUF;
 338
 339         btree_trans_sort_paths(trans);
 340
 341         trans_for_each_path_inorder(trans, path, iter) {
 342                 int cmp = cmp_int(path->btree_id, id) ?:
 343                         cmp_int(path->cached, key_cache);
 344
 345                 if (cmp > 0)
 346                         break;
 347                 if (cmp < 0)
 348                         continue;
 349
 350                 if (!btree_node_locked(path, 0) ||
 351                     !path->should_be_locked)
 352                         continue;
 353
 354                 if (!key_cache) {
 355                         if (bkey_ge(pos, path->l[0].b->data->min_key) &&
 356                             bkey_le(pos, path->l[0].b->key.k.p))
 357                                 return;
 358                 } else {
 359                         if (bkey_eq(pos, path->pos))
 360                                 return;
 361                 }
 362         }
 363
 364         bch2_dump_trans_paths_updates(trans);
 365         bch2_bpos_to_text(&buf, pos);
 366
 367         panic("not locked: %s %s%s\n",
 368               bch2_btree_id_str(id), buf.buf,
 369               key_cache ? " cached" : "");
 370 }
 371
 372 #else
 373
 374 static inline void bch2_btree_path_verify_level(struct btree_trans *trans,
 375                                                 struct btree_path *path, unsigned l) {}
 376 static inline void bch2_btree_path_verify(struct btree_trans *trans,
 377                                           struct btree_path *path) {}
 378 static inline void bch2_btree_iter_verify(struct btree_iter *iter) {}
 379 static inline void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter) {}
 380 static inline int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k) { return 0; }
 381
 382 #endif
 383
 384 /* Btree path: fixups after btree updates */
 385
 386 static void btree_node_iter_set_set_pos(struct btree_node_iter *iter,
 387                                         struct btree *b,
 388                                         struct bset_tree *t,
 389                                         struct bkey_packed *k)
 390 {
 391         struct btree_node_iter_set *set;
 392
 393         btree_node_iter_for_each(iter, set)
 394                 if (set->end == t->end_offset) {
 395                         set->k = __btree_node_key_to_offset(b, k);
 396                         bch2_btree_node_iter_sort(iter, b);
 397                         return;
 398                 }
 399
 400         bch2_btree_node_iter_push(iter, b, k, btree_bkey_last(b, t));
 401 }
 402
 403 static void __bch2_btree_path_fix_key_modified(struct btree_path *path,
 404                                                struct btree *b,
 405                                                struct bkey_packed *where)
 406 {
 407         struct btree_path_level *l = &path->l[b->c.level];
 408
 409         if (where != bch2_btree_node_iter_peek_all(&l->iter, l->b))
 410                 return;
 411
 412         if (bkey_iter_pos_cmp(l->b, where, &path->pos) < 0)
 413                 bch2_btree_node_iter_advance(&l->iter, l->b);
 414 }
 415
 416 void bch2_btree_path_fix_key_modified(struct btree_trans *trans,
 417                                       struct btree *b,
 418                                       struct bkey_packed *where)
 419 {
 420         struct btree_path *path;
 421         unsigned i;
 422
 423         trans_for_each_path_with_node(trans, b, path, i) {
 424                 __bch2_btree_path_fix_key_modified(path, b, where);
 425                 bch2_btree_path_verify_level(trans, path, b->c.level);
 426         }
 427 }
 428
 429 static void __bch2_btree_node_iter_fix(struct btree_path *path,
 430                                        struct btree *b,
 431                                        struct btree_node_iter *node_iter,
 432                                        struct bset_tree *t,
 433                                        struct bkey_packed *where,
 434                                        unsigned clobber_u64s,
 435                                        unsigned new_u64s)
 436 {
 437         const struct bkey_packed *end = btree_bkey_last(b, t);
 438         struct btree_node_iter_set *set;
 439         unsigned offset = __btree_node_key_to_offset(b, where);
 440         int shift = new_u64s - clobber_u64s;
 441         unsigned old_end = t->end_offset - shift;
 442         unsigned orig_iter_pos = node_iter->data[0].k;
 443         bool iter_current_key_modified =
 444                 orig_iter_pos >= offset &&
 445                 orig_iter_pos <= offset + clobber_u64s;
 446
 447         btree_node_iter_for_each(node_iter, set)
 448                 if (set->end == old_end)
 449                         goto found;
 450
 451         /* didn't find the bset in the iterator - might have to readd it: */
 452         if (new_u64s &&
 453             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 454                 bch2_btree_node_iter_push(node_iter, b, where, end);
 455                 goto fixup_done;
 456         } else {
 457                 /* Iterator is after key that changed */
 458                 return;
 459         }
 460 found:
 461         set->end = t->end_offset;
 462
 463         /* Iterator hasn't gotten to the key that changed yet: */
 464         if (set->k < offset)
 465                 return;
 466
 467         if (new_u64s &&
 468             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 469                 set->k = offset;
 470         } else if (set->k < offset + clobber_u64s) {
 471                 set->k = offset + new_u64s;
 472                 if (set->k == set->end)
 473                         bch2_btree_node_iter_set_drop(node_iter, set);
 474         } else {
 475                 /* Iterator is after key that changed */
 476                 set->k = (int) set->k + shift;
 477                 return;
 478         }
 479
 480         bch2_btree_node_iter_sort(node_iter, b);
 481 fixup_done:
 482         if (node_iter->data[0].k != orig_iter_pos)
 483                 iter_current_key_modified = true;
 484
 485         /*
 486          * When a new key is added, and the node iterator now points to that
 487          * key, the iterator might have skipped past deleted keys that should
 488          * come after the key the iterator now points to. We have to rewind to
 489          * before those deleted keys - otherwise
 490          * bch2_btree_node_iter_prev_all() breaks:
 491          */
 492         if (!bch2_btree_node_iter_end(node_iter) &&
 493             iter_current_key_modified &&
 494             b->c.level) {
 495                 struct bkey_packed *k, *k2, *p;
 496
 497                 k = bch2_btree_node_iter_peek_all(node_iter, b);
 498
 499                 for_each_bset(b, t) {
 500                         bool set_pos = false;
 501
 502                         if (node_iter->data[0].end == t->end_offset)
 503                                 continue;
 504
 505                         k2 = bch2_btree_node_iter_bset_pos(node_iter, b, t);
 506
 507                         while ((p = bch2_bkey_prev_all(b, t, k2)) &&
 508                                bkey_iter_cmp(b, k, p) < 0) {
 509                                 k2 = p;
 510                                 set_pos = true;
 511                         }
 512
 513                         if (set_pos)
 514                                 btree_node_iter_set_set_pos(node_iter,
 515                                                             b, t, k2);
 516                 }
 517         }
 518 }
 519
 520 void bch2_btree_node_iter_fix(struct btree_trans *trans,
 521                               struct btree_path *path,
 522                               struct btree *b,
 523                               struct btree_node_iter *node_iter,
 524                               struct bkey_packed *where,
 525                               unsigned clobber_u64s,
 526                               unsigned new_u64s)
 527 {
 528         struct bset_tree *t = bch2_bkey_to_bset_inlined(b, where);
 529         struct btree_path *linked;
 530         unsigned i;
 531
 532         if (node_iter != &path->l[b->c.level].iter) {
 533                 __bch2_btree_node_iter_fix(path, b, node_iter, t,
 534                                            where, clobber_u64s, new_u64s);
 535
 536                 if (bch2_debug_check_iterators)
 537                         bch2_btree_node_iter_verify(node_iter, b);
 538         }
 539
 540         trans_for_each_path_with_node(trans, b, linked, i) {
 541                 __bch2_btree_node_iter_fix(linked, b,
 542                                            &linked->l[b->c.level].iter, t,
 543                                            where, clobber_u64s, new_u64s);
 544                 bch2_btree_path_verify_level(trans, linked, b->c.level);
 545         }
 546 }
 547
 548 /* Btree path level: pointer to a particular btree node and node iter */
 549
 550 static inline struct bkey_s_c __btree_iter_unpack(struct bch_fs *c,
 551                                                   struct btree_path_level *l,
 552                                                   struct bkey *u,
 553                                                   struct bkey_packed *k)
 554 {
 555         if (unlikely(!k)) {
 556                 /*
 557                  * signal to bch2_btree_iter_peek_slot() that we're currently at
 558                  * a hole
 559                  */
 560                 u->type = KEY_TYPE_deleted;
 561                 return bkey_s_c_null;
 562         }
 563
 564         return bkey_disassemble(l->b, k, u);
 565 }
 566
 567 static inline struct bkey_s_c btree_path_level_peek_all(struct bch_fs *c,
 568                                                         struct btree_path_level *l,
 569                                                         struct bkey *u)
 570 {
 571         return __btree_iter_unpack(c, l, u,
 572                         bch2_btree_node_iter_peek_all(&l->iter, l->b));
 573 }
 574
 575 static inline struct bkey_s_c btree_path_level_peek(struct btree_trans *trans,
 576                                                     struct btree_path *path,
 577                                                     struct btree_path_level *l,
 578                                                     struct bkey *u)
 579 {
 580         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 581                         bch2_btree_node_iter_peek(&l->iter, l->b));
 582
 583         path->pos = k.k ? k.k->p : l->b->key.k.p;
 584         trans->paths_sorted = false;
 585         bch2_btree_path_verify_level(trans, path, l - path->l);
 586         return k;
 587 }
 588
 589 static inline struct bkey_s_c btree_path_level_prev(struct btree_trans *trans,
 590                                                     struct btree_path *path,
 591                                                     struct btree_path_level *l,
 592                                                     struct bkey *u)
 593 {
 594         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 595                         bch2_btree_node_iter_prev(&l->iter, l->b));
 596
 597         path->pos = k.k ? k.k->p : l->b->data->min_key;
 598         trans->paths_sorted = false;
 599         bch2_btree_path_verify_level(trans, path, l - path->l);
 600         return k;
 601 }
 602
 603 static inline bool btree_path_advance_to_pos(struct btree_path *path,
 604                                              struct btree_path_level *l,
 605                                              int max_advance)
 606 {
 607         struct bkey_packed *k;
 608         int nr_advanced = 0;
 609
 610         while ((k = bch2_btree_node_iter_peek_all(&l->iter, l->b)) &&
 611                bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 612                 if (max_advance > 0 && nr_advanced >= max_advance)
 613                         return false;
 614
 615                 bch2_btree_node_iter_advance(&l->iter, l->b);
 616                 nr_advanced++;
 617         }
 618
 619         return true;
 620 }
 621
 622 static inline void __btree_path_level_init(struct btree_path *path,
 623                                            unsigned level)
 624 {
 625         struct btree_path_level *l = &path->l[level];
 626
 627         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
 628
 629         /*
 630          * Iterators to interior nodes should always be pointed at the first non
 631          * whiteout:
 632          */
 633         if (level)
 634                 bch2_btree_node_iter_peek(&l->iter, l->b);
 635 }
 636
 637 void bch2_btree_path_level_init(struct btree_trans *trans,
 638                                 struct btree_path *path,
 639                                 struct btree *b)
 640 {
 641         BUG_ON(path->cached);
 642
 643         EBUG_ON(!btree_path_pos_in_node(path, b));
 644
 645         path->l[b->c.level].lock_seq = six_lock_seq(&b->c.lock);
 646         path->l[b->c.level].b = b;
 647         __btree_path_level_init(path, b->c.level);
 648 }
 649
 650 /* Btree path: fixups after btree node updates: */
 651
 652 static void bch2_trans_revalidate_updates_in_node(struct btree_trans *trans, struct btree *b)
 653 {
 654         struct bch_fs *c = trans->c;
 655
 656         trans_for_each_update(trans, i)
 657                 if (!i->cached &&
 658                     i->level    == b->c.level &&
 659                     i->btree_id == b->c.btree_id &&
 660                     bpos_cmp(i->k->k.p, b->data->min_key) >= 0 &&
 661                     bpos_cmp(i->k->k.p, b->data->max_key) <= 0) {
 662                         i->old_v = bch2_btree_path_peek_slot(trans->paths + i->path, &i->old_k).v;
 663
 664                         if (unlikely(trans->journal_replay_not_finished)) {
 665                                 struct bkey_i *j_k =
 666                                         bch2_journal_keys_peek_slot(c, i->btree_id, i->level,
 667                                                                     i->k->k.p);
 668
 669                                 if (j_k) {
 670                                         i->old_k = j_k->k;
 671                                         i->old_v = &j_k->v;
 672                                 }
 673                         }
 674                 }
 675 }
 676
 677 /*
 678  * A btree node is being replaced - update the iterator to point to the new
 679  * node:
 680  */
 681 void bch2_trans_node_add(struct btree_trans *trans,
 682                          struct btree_path *path,
 683                          struct btree *b)
 684 {
 685         struct btree_path *prev;
 686
 687         BUG_ON(!btree_path_pos_in_node(path, b));
 688
 689         while ((prev = prev_btree_path(trans, path)) &&
 690                btree_path_pos_in_node(prev, b))
 691                 path = prev;
 692
 693         for (;
 694              path && btree_path_pos_in_node(path, b);
 695              path = next_btree_path(trans, path))
 696                 if (path->uptodate == BTREE_ITER_UPTODATE && !path->cached) {
 697                         enum btree_node_locked_type t =
 698                                 btree_lock_want(path, b->c.level);
 699
 700                         if (t != BTREE_NODE_UNLOCKED) {
 701                                 btree_node_unlock(trans, path, b->c.level);
 702                                 six_lock_increment(&b->c.lock, (enum six_lock_type) t);
 703                                 mark_btree_node_locked(trans, path, b->c.level, t);
 704                         }
 705
 706                         bch2_btree_path_level_init(trans, path, b);
 707                 }
 708
 709         bch2_trans_revalidate_updates_in_node(trans, b);
 710 }
 711
 712 /*
 713  * A btree node has been modified in such a way as to invalidate iterators - fix
 714  * them:
 715  */
 716 void bch2_trans_node_reinit_iter(struct btree_trans *trans, struct btree *b)
 717 {
 718         struct btree_path *path;
 719         unsigned i;
 720
 721         trans_for_each_path_with_node(trans, b, path, i)
 722                 __btree_path_level_init(path, b->c.level);
 723
 724         bch2_trans_revalidate_updates_in_node(trans, b);
 725 }
 726
 727 /* Btree path: traverse, set_pos: */
 728
 729 static inline int btree_path_lock_root(struct btree_trans *trans,
 730                                        struct btree_path *path,
 731                                        unsigned depth_want,
 732                                        unsigned long trace_ip)
 733 {
 734         struct bch_fs *c = trans->c;
 735         struct btree *b, **rootp = &bch2_btree_id_root(c, path->btree_id)->b;
 736         enum six_lock_type lock_type;
 737         unsigned i;
 738         int ret;
 739
 740         EBUG_ON(path->nodes_locked);
 741
 742         while (1) {
 743                 b = READ_ONCE(*rootp);
 744                 path->level = READ_ONCE(b->c.level);
 745
 746                 if (unlikely(path->level < depth_want)) {
 747                         /*
 748                          * the root is at a lower depth than the depth we want:
 749                          * got to the end of the btree, or we're walking nodes
 750                          * greater than some depth and there are no nodes >=
 751                          * that depth
 752                          */
 753                         path->level = depth_want;
 754                         for (i = path->level; i < BTREE_MAX_DEPTH; i++)
 755                                 path->l[i].b = NULL;
 756                         return 1;
 757                 }
 758
 759                 lock_type = __btree_lock_want(path, path->level);
 760                 ret = btree_node_lock(trans, path, &b->c,
 761                                       path->level, lock_type, trace_ip);
 762                 if (unlikely(ret)) {
 763                         if (bch2_err_matches(ret, BCH_ERR_lock_fail_root_changed))
 764                                 continue;
 765                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 766                                 return ret;
 767                         BUG();
 768                 }
 769
 770                 if (likely(b == READ_ONCE(*rootp) &&
 771                            b->c.level == path->level &&
 772                            !race_fault())) {
 773                         for (i = 0; i < path->level; i++)
 774                                 path->l[i].b = ERR_PTR(-BCH_ERR_no_btree_node_lock_root);
 775                         path->l[path->level].b = b;
 776                         for (i = path->level + 1; i < BTREE_MAX_DEPTH; i++)
 777                                 path->l[i].b = NULL;
 778
 779                         mark_btree_node_locked(trans, path, path->level,
 780                                                (enum btree_node_locked_type) lock_type);
 781                         bch2_btree_path_level_init(trans, path, b);
 782                         return 0;
 783                 }
 784
 785                 six_unlock_type(&b->c.lock, lock_type);
 786         }
 787 }
 788
 789 noinline
 790 static int btree_path_prefetch(struct btree_trans *trans, struct btree_path *path)
 791 {
 792         struct bch_fs *c = trans->c;
 793         struct btree_path_level *l = path_l(path);
 794         struct btree_node_iter node_iter = l->iter;
 795         struct bkey_packed *k;
 796         struct bkey_buf tmp;
 797         unsigned nr = test_bit(BCH_FS_started, &c->flags)
 798                 ? (path->level > 1 ? 0 :  2)
 799                 : (path->level > 1 ? 1 : 16);
 800         bool was_locked = btree_node_locked(path, path->level);
 801         int ret = 0;
 802
 803         bch2_bkey_buf_init(&tmp);
 804
 805         while (nr-- && !ret) {
 806                 if (!bch2_btree_node_relock(trans, path, path->level))
 807                         break;
 808
 809                 bch2_btree_node_iter_advance(&node_iter, l->b);
 810                 k = bch2_btree_node_iter_peek(&node_iter, l->b);
 811                 if (!k)
 812                         break;
 813
 814                 bch2_bkey_buf_unpack(&tmp, c, l->b, k);
 815                 ret = bch2_btree_node_prefetch(trans, path, tmp.k, path->btree_id,
 816                                                path->level - 1);
 817         }
 818
 819         if (!was_locked)
 820                 btree_node_unlock(trans, path, path->level);
 821
 822         bch2_bkey_buf_exit(&tmp, c);
 823         return ret;
 824 }
 825
 826 static int btree_path_prefetch_j(struct btree_trans *trans, struct btree_path *path,
 827                                  struct btree_and_journal_iter *jiter)
 828 {
 829         struct bch_fs *c = trans->c;
 830         struct bkey_s_c k;
 831         struct bkey_buf tmp;
 832         unsigned nr = test_bit(BCH_FS_started, &c->flags)
 833                 ? (path->level > 1 ? 0 :  2)
 834                 : (path->level > 1 ? 1 : 16);
 835         bool was_locked = btree_node_locked(path, path->level);
 836         int ret = 0;
 837
 838         bch2_bkey_buf_init(&tmp);
 839
 840         while (nr-- && !ret) {
 841                 if (!bch2_btree_node_relock(trans, path, path->level))
 842                         break;
 843
 844                 bch2_btree_and_journal_iter_advance(jiter);
 845                 k = bch2_btree_and_journal_iter_peek(jiter);
 846                 if (!k.k)
 847                         break;
 848
 849                 bch2_bkey_buf_reassemble(&tmp, c, k);
 850                 ret = bch2_btree_node_prefetch(trans, path, tmp.k, path->btree_id,
 851                                                path->level - 1);
 852         }
 853
 854         if (!was_locked)
 855                 btree_node_unlock(trans, path, path->level);
 856
 857         bch2_bkey_buf_exit(&tmp, c);
 858         return ret;
 859 }
 860
 861 static noinline void btree_node_mem_ptr_set(struct btree_trans *trans,
 862                                             struct btree_path *path,
 863                                             unsigned plevel, struct btree *b)
 864 {
 865         struct btree_path_level *l = &path->l[plevel];
 866         bool locked = btree_node_locked(path, plevel);
 867         struct bkey_packed *k;
 868         struct bch_btree_ptr_v2 *bp;
 869
 870         if (!bch2_btree_node_relock(trans, path, plevel))
 871                 return;
 872
 873         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 874         BUG_ON(k->type != KEY_TYPE_btree_ptr_v2);
 875
 876         bp = (void *) bkeyp_val(&l->b->format, k);
 877         bp->mem_ptr = (unsigned long)b;
 878
 879         if (!locked)
 880                 btree_node_unlock(trans, path, plevel);
 881 }
 882
 883 static noinline int btree_node_iter_and_journal_peek(struct btree_trans *trans,
 884                                                      struct btree_path *path,
 885                                                      unsigned flags,
 886                                                      struct bkey_buf *out)
 887 {
 888         struct bch_fs *c = trans->c;
 889         struct btree_path_level *l = path_l(path);
 890         struct btree_and_journal_iter jiter;
 891         struct bkey_s_c k;
 892         int ret = 0;
 893
 894         __bch2_btree_and_journal_iter_init_node_iter(trans, &jiter, l->b, l->iter, path->pos);
 895
 896         k = bch2_btree_and_journal_iter_peek(&jiter);
 897
 898         bch2_bkey_buf_reassemble(out, c, k);
 899
 900         if ((flags & BTREE_ITER_PREFETCH) &&
 901             c->opts.btree_node_prefetch)
 902                 ret = btree_path_prefetch_j(trans, path, &jiter);
 903
 904         bch2_btree_and_journal_iter_exit(&jiter);
 905         return ret;
 906 }
 907
 908 static __always_inline int btree_path_down(struct btree_trans *trans,
 909                                            struct btree_path *path,
 910                                            unsigned flags,
 911                                            unsigned long trace_ip)
 912 {
 913         struct bch_fs *c = trans->c;
 914         struct btree_path_level *l = path_l(path);
 915         struct btree *b;
 916         unsigned level = path->level - 1;
 917         enum six_lock_type lock_type = __btree_lock_want(path, level);
 918         struct bkey_buf tmp;
 919         int ret;
 920
 921         EBUG_ON(!btree_node_locked(path, path->level));
 922
 923         bch2_bkey_buf_init(&tmp);
 924
 925         if (unlikely(trans->journal_replay_not_finished)) {
 926                 ret = btree_node_iter_and_journal_peek(trans, path, flags, &tmp);
 927                 if (ret)
 928                         goto err;
 929         } else {
 930                 struct bkey_packed *k = bch2_btree_node_iter_peek(&l->iter, l->b);
 931                 if (!k) {
 932                         struct printbuf buf = PRINTBUF;
 933
 934                         prt_str(&buf, "node not found at pos ");
 935                         bch2_bpos_to_text(&buf, path->pos);
 936                         prt_str(&buf, " within parent node ");
 937                         bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&l->b->key));
 938
 939                         bch2_fs_fatal_error(c, "%s", buf.buf);
 940                         printbuf_exit(&buf);
 941                         ret = -BCH_ERR_btree_need_topology_repair;
 942                         goto err;
 943                 }
 944
 945                 bch2_bkey_buf_unpack(&tmp, c, l->b, k);
 946
 947                 if ((flags & BTREE_ITER_PREFETCH) &&
 948                     c->opts.btree_node_prefetch) {
 949                         ret = btree_path_prefetch(trans, path);
 950                         if (ret)
 951                                 goto err;
 952                 }
 953         }
 954
 955         b = bch2_btree_node_get(trans, path, tmp.k, level, lock_type, trace_ip);
 956         ret = PTR_ERR_OR_ZERO(b);
 957         if (unlikely(ret))
 958                 goto err;
 959
 960         if (likely(!trans->journal_replay_not_finished &&
 961                    tmp.k->k.type == KEY_TYPE_btree_ptr_v2) &&
 962             unlikely(b != btree_node_mem_ptr(tmp.k)))
 963                 btree_node_mem_ptr_set(trans, path, level + 1, b);
 964
 965         if (btree_node_read_locked(path, level + 1))
 966                 btree_node_unlock(trans, path, level + 1);
 967
 968         mark_btree_node_locked(trans, path, level,
 969                                (enum btree_node_locked_type) lock_type);
 970         path->level = level;
 971         bch2_btree_path_level_init(trans, path, b);
 972
 973         bch2_btree_path_verify_locks(path);
 974 err:
 975         bch2_bkey_buf_exit(&tmp, c);
 976         return ret;
 977 }
 978
 979 static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 980 {
 981         struct bch_fs *c = trans->c;
 982         struct btree_path *path;
 983         unsigned long trace_ip = _RET_IP_;
 984         unsigned i;
 985         int ret = 0;
 986
 987         if (trans->in_traverse_all)
 988                 return -BCH_ERR_transaction_restart_in_traverse_all;
 989
 990         trans->in_traverse_all = true;
 991 retry_all:
 992         trans->restarted = 0;
 993         trans->last_restarted_ip = 0;
 994
 995         trans_for_each_path(trans, path, i)
 996                 path->should_be_locked = false;
 997
 998         btree_trans_sort_paths(trans);
 999
1000         bch2_trans_unlock(trans);
1001         cond_resched();
1002
1003         if (unlikely(trans->memory_allocation_failure)) {
1004                 struct closure cl;
1005
1006                 closure_init_stack(&cl);
1007
1008                 do {
1009                         ret = bch2_btree_cache_cannibalize_lock(trans, &cl);
1010                         closure_sync(&cl);
1011                 } while (ret);
1012         }
1013
1014         /* Now, redo traversals in correct order: */
1015         i = 0;
1016         while (i < trans->nr_sorted) {
1017                 btree_path_idx_t idx = trans->sorted[i];
1018
1019                 /*
1020                  * Traversing a path can cause another path to be added at about
1021                  * the same position:
1022                  */
1023                 if (trans->paths[idx].uptodate) {
1024                         __btree_path_get(&trans->paths[idx], false);
1025                         ret = bch2_btree_path_traverse_one(trans, idx, 0, _THIS_IP_);
1026                         __btree_path_put(&trans->paths[idx], false);
1027
1028                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) ||
1029                             bch2_err_matches(ret, ENOMEM))
1030                                 goto retry_all;
1031                         if (ret)
1032                                 goto err;
1033                 } else {
1034                         i++;
1035                 }
1036         }
1037
1038         /*
1039          * We used to assert that all paths had been traversed here
1040          * (path->uptodate < BTREE_ITER_NEED_TRAVERSE); however, since
1041          * path->should_be_locked is not set yet, we might have unlocked and
1042          * then failed to relock a path - that's fine.
1043          */
1044 err:
1045         bch2_btree_cache_cannibalize_unlock(trans);
1046
1047         trans->in_traverse_all = false;
1048
1049         trace_and_count(c, trans_traverse_all, trans, trace_ip);
1050         return ret;
1051 }
1052
1053 static inline bool btree_path_check_pos_in_node(struct btree_path *path,
1054                                                 unsigned l, int check_pos)
1055 {
1056         if (check_pos < 0 && btree_path_pos_before_node(path, path->l[l].b))
1057                 return false;
1058         if (check_pos > 0 && btree_path_pos_after_node(path, path->l[l].b))
1059                 return false;
1060         return true;
1061 }
1062
1063 static inline bool btree_path_good_node(struct btree_trans *trans,
1064                                         struct btree_path *path,
1065                                         unsigned l, int check_pos)
1066 {
1067         return is_btree_node(path, l) &&
1068                 bch2_btree_node_relock(trans, path, l) &&
1069                 btree_path_check_pos_in_node(path, l, check_pos);
1070 }
1071
1072 static void btree_path_set_level_down(struct btree_trans *trans,
1073                                       struct btree_path *path,
1074                                       unsigned new_level)
1075 {
1076         unsigned l;
1077
1078         path->level = new_level;
1079
1080         for (l = path->level + 1; l < BTREE_MAX_DEPTH; l++)
1081                 if (btree_lock_want(path, l) == BTREE_NODE_UNLOCKED)
1082                         btree_node_unlock(trans, path, l);
1083
1084         btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1085         bch2_btree_path_verify(trans, path);
1086 }
1087
1088 static noinline unsigned __btree_path_up_until_good_node(struct btree_trans *trans,
1089                                                          struct btree_path *path,
1090                                                          int check_pos)
1091 {
1092         unsigned i, l = path->level;
1093 again:
1094         while (btree_path_node(path, l) &&
1095                !btree_path_good_node(trans, path, l, check_pos))
1096                 __btree_path_set_level_up(trans, path, l++);
1097
1098         /* If we need intent locks, take them too: */
1099         for (i = l + 1;
1100              i < path->locks_want && btree_path_node(path, i);
1101              i++)
1102                 if (!bch2_btree_node_relock(trans, path, i)) {
1103                         while (l <= i)
1104                                 __btree_path_set_level_up(trans, path, l++);
1105                         goto again;
1106                 }
1107
1108         return l;
1109 }
1110
1111 static inline unsigned btree_path_up_until_good_node(struct btree_trans *trans,
1112                                                      struct btree_path *path,
1113                                                      int check_pos)
1114 {
1115         return likely(btree_node_locked(path, path->level) &&
1116                       btree_path_check_pos_in_node(path, path->level, check_pos))
1117                 ? path->level
1118                 : __btree_path_up_until_good_node(trans, path, check_pos);
1119 }
1120
1121 /*
1122  * This is the main state machine for walking down the btree - walks down to a
1123  * specified depth
1124  *
1125  * Returns 0 on success, -EIO on error (error reading in a btree node).
1126  *
1127  * On error, caller (peek_node()/peek_key()) must return NULL; the error is
1128  * stashed in the iterator and returned from bch2_trans_exit().
1129  */
1130 int bch2_btree_path_traverse_one(struct btree_trans *trans,
1131                                  btree_path_idx_t path_idx,
1132                                  unsigned flags,
1133                                  unsigned long trace_ip)
1134 {
1135         struct btree_path *path = &trans->paths[path_idx];
1136         unsigned depth_want = path->level;
1137         int ret = -((int) trans->restarted);
1138
1139         if (unlikely(ret))
1140                 goto out;
1141
1142         if (unlikely(!trans->srcu_held))
1143                 bch2_trans_srcu_lock(trans);
1144
1145         /*
1146          * Ensure we obey path->should_be_locked: if it's set, we can't unlock
1147          * and re-traverse the path without a transaction restart:
1148          */
1149         if (path->should_be_locked) {
1150                 ret = bch2_btree_path_relock(trans, path, trace_ip);
1151                 goto out;
1152         }
1153
1154         if (path->cached) {
1155                 ret = bch2_btree_path_traverse_cached(trans, path, flags);
1156                 goto out;
1157         }
1158
1159         path = &trans->paths[path_idx];
1160
1161         if (unlikely(path->level >= BTREE_MAX_DEPTH))
1162                 goto out_uptodate;
1163
1164         path->level = btree_path_up_until_good_node(trans, path, 0);
1165
1166         EBUG_ON(btree_path_node(path, path->level) &&
1167                 !btree_node_locked(path, path->level));
1168
1169         /*
1170          * Note: path->nodes[path->level] may be temporarily NULL here - that
1171          * would indicate to other code that we got to the end of the btree,
1172          * here it indicates that relocking the root failed - it's critical that
1173          * btree_path_lock_root() comes next and that it can't fail
1174          */
1175         while (path->level > depth_want) {
1176                 ret = btree_path_node(path, path->level)
1177                         ? btree_path_down(trans, path, flags, trace_ip)
1178                         : btree_path_lock_root(trans, path, depth_want, trace_ip);
1179                 if (unlikely(ret)) {
1180                         if (ret == 1) {
1181                                 /*
1182                                  * No nodes at this level - got to the end of
1183                                  * the btree:
1184                                  */
1185                                 ret = 0;
1186                                 goto out;
1187                         }
1188
1189                         __bch2_btree_path_unlock(trans, path);
1190                         path->level = depth_want;
1191                         path->l[path->level].b = ERR_PTR(ret);
1192                         goto out;
1193                 }
1194         }
1195 out_uptodate:
1196         path->uptodate = BTREE_ITER_UPTODATE;
1197 out:
1198         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) != !!trans->restarted)
1199                 panic("ret %s (%i) trans->restarted %s (%i)\n",
1200                       bch2_err_str(ret), ret,
1201                       bch2_err_str(trans->restarted), trans->restarted);
1202         bch2_btree_path_verify(trans, path);
1203         return ret;
1204 }
1205
1206 static inline void btree_path_copy(struct btree_trans *trans, struct btree_path *dst,
1207                             struct btree_path *src)
1208 {
1209         unsigned i, offset = offsetof(struct btree_path, pos);
1210
1211         memcpy((void *) dst + offset,
1212                (void *) src + offset,
1213                sizeof(struct btree_path) - offset);
1214
1215         for (i = 0; i < BTREE_MAX_DEPTH; i++) {
1216                 unsigned t = btree_node_locked_type(dst, i);
1217
1218                 if (t != BTREE_NODE_UNLOCKED)
1219                         six_lock_increment(&dst->l[i].b->c.lock, t);
1220         }
1221 }
1222
1223 static btree_path_idx_t btree_path_clone(struct btree_trans *trans, btree_path_idx_t src,
1224                                          bool intent)
1225 {
1226         btree_path_idx_t new = btree_path_alloc(trans, src);
1227         btree_path_copy(trans, trans->paths + new, trans->paths + src);
1228         __btree_path_get(trans->paths + new, intent);
1229         return new;
1230 }
1231
1232 __flatten
1233 btree_path_idx_t __bch2_btree_path_make_mut(struct btree_trans *trans,
1234                         btree_path_idx_t path, bool intent, unsigned long ip)
1235 {
1236         __btree_path_put(trans->paths + path, intent);
1237         path = btree_path_clone(trans, path, intent);
1238         trans->paths[path].preserve = false;
1239         return path;
1240 }
1241
1242 btree_path_idx_t __must_check
1243 __bch2_btree_path_set_pos(struct btree_trans *trans,
1244                           btree_path_idx_t path_idx, struct bpos new_pos,
1245                           bool intent, unsigned long ip)
1246 {
1247         int cmp = bpos_cmp(new_pos, trans->paths[path_idx].pos);
1248
1249         bch2_trans_verify_not_in_restart(trans);
1250         EBUG_ON(!trans->paths[path_idx].ref);
1251
1252         path_idx = bch2_btree_path_make_mut(trans, path_idx, intent, ip);
1253
1254         struct btree_path *path = trans->paths + path_idx;
1255         path->pos               = new_pos;
1256         trans->paths_sorted     = false;
1257
1258         if (unlikely(path->cached)) {
1259                 btree_node_unlock(trans, path, 0);
1260                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_up);
1261                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1262                 goto out;
1263         }
1264
1265         unsigned level = btree_path_up_until_good_node(trans, path, cmp);
1266
1267         if (btree_path_node(path, level)) {
1268                 struct btree_path_level *l = &path->l[level];
1269
1270                 BUG_ON(!btree_node_locked(path, level));
1271                 /*
1272                  * We might have to skip over many keys, or just a few: try
1273                  * advancing the node iterator, and if we have to skip over too
1274                  * many keys just reinit it (or if we're rewinding, since that
1275                  * is expensive).
1276                  */
1277                 if (cmp < 0 ||
1278                     !btree_path_advance_to_pos(path, l, 8))
1279                         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
1280
1281                 /*
1282                  * Iterators to interior nodes should always be pointed at the first non
1283                  * whiteout:
1284                  */
1285                 if (unlikely(level))
1286                         bch2_btree_node_iter_peek(&l->iter, l->b);
1287         }
1288
1289         if (unlikely(level != path->level)) {
1290                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1291                 __bch2_btree_path_unlock(trans, path);
1292         }
1293 out:
1294         bch2_btree_path_verify(trans, path);
1295         return path_idx;
1296 }
1297
1298 /* Btree path: main interface: */
1299
1300 static struct btree_path *have_path_at_pos(struct btree_trans *trans, struct btree_path *path)
1301 {
1302         struct btree_path *sib;
1303
1304         sib = prev_btree_path(trans, path);
1305         if (sib && !btree_path_cmp(sib, path))
1306                 return sib;
1307
1308         sib = next_btree_path(trans, path);
1309         if (sib && !btree_path_cmp(sib, path))
1310                 return sib;
1311
1312         return NULL;
1313 }
1314
1315 static struct btree_path *have_node_at_pos(struct btree_trans *trans, struct btree_path *path)
1316 {
1317         struct btree_path *sib;
1318
1319         sib = prev_btree_path(trans, path);
1320         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1321                 return sib;
1322
1323         sib = next_btree_path(trans, path);
1324         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1325                 return sib;
1326
1327         return NULL;
1328 }
1329
1330 static inline void __bch2_path_free(struct btree_trans *trans, btree_path_idx_t path)
1331 {
1332         __bch2_btree_path_unlock(trans, trans->paths + path);
1333         btree_path_list_remove(trans, trans->paths + path);
1334         __clear_bit(path, trans->paths_allocated);
1335 }
1336
1337 void bch2_path_put(struct btree_trans *trans, btree_path_idx_t path_idx, bool intent)
1338 {
1339         struct btree_path *path = trans->paths + path_idx, *dup;
1340
1341         if (!__btree_path_put(path, intent))
1342                 return;
1343
1344         dup = path->preserve
1345                 ? have_path_at_pos(trans, path)
1346                 : have_node_at_pos(trans, path);
1347
1348         if (!dup && !(!path->preserve && !is_btree_node(path, path->level)))
1349                 return;
1350
1351         if (path->should_be_locked &&
1352             !trans->restarted &&
1353             (!dup || !bch2_btree_path_relock_norestart(trans, dup)))
1354                 return;
1355
1356         if (dup) {
1357                 dup->preserve           |= path->preserve;
1358                 dup->should_be_locked   |= path->should_be_locked;
1359         }
1360
1361         __bch2_path_free(trans, path_idx);
1362 }
1363
1364 static void bch2_path_put_nokeep(struct btree_trans *trans, btree_path_idx_t path,
1365                                  bool intent)
1366 {
1367         if (!__btree_path_put(trans->paths + path, intent))
1368                 return;
1369
1370         __bch2_path_free(trans, path);
1371 }
1372
1373 void __noreturn bch2_trans_restart_error(struct btree_trans *trans, u32 restart_count)
1374 {
1375         panic("trans->restart_count %u, should be %u, last restarted by %pS\n",
1376               trans->restart_count, restart_count,
1377               (void *) trans->last_begin_ip);
1378 }
1379
1380 void __noreturn bch2_trans_in_restart_error(struct btree_trans *trans)
1381 {
1382         panic("in transaction restart: %s, last restarted by %pS\n",
1383               bch2_err_str(trans->restarted),
1384               (void *) trans->last_restarted_ip);
1385 }
1386
1387 noinline __cold
1388 void bch2_trans_updates_to_text(struct printbuf *buf, struct btree_trans *trans)
1389 {
1390         prt_printf(buf, "transaction updates for %s journal seq %llu",
1391                trans->fn, trans->journal_res.seq);
1392         prt_newline(buf);
1393         printbuf_indent_add(buf, 2);
1394
1395         trans_for_each_update(trans, i) {
1396                 struct bkey_s_c old = { &i->old_k, i->old_v };
1397
1398                 prt_printf(buf, "update: btree=%s cached=%u %pS",
1399                        bch2_btree_id_str(i->btree_id),
1400                        i->cached,
1401                        (void *) i->ip_allocated);
1402                 prt_newline(buf);
1403
1404                 prt_printf(buf, "  old ");
1405                 bch2_bkey_val_to_text(buf, trans->c, old);
1406                 prt_newline(buf);
1407
1408                 prt_printf(buf, "  new ");
1409                 bch2_bkey_val_to_text(buf, trans->c, bkey_i_to_s_c(i->k));
1410                 prt_newline(buf);
1411         }
1412
1413         for (struct jset_entry *e = trans->journal_entries;
1414              e != btree_trans_journal_entries_top(trans);
1415              e = vstruct_next(e))
1416                 bch2_journal_entry_to_text(buf, trans->c, e);
1417
1418         printbuf_indent_sub(buf, 2);
1419 }
1420
1421 noinline __cold
1422 void bch2_dump_trans_updates(struct btree_trans *trans)
1423 {
1424         struct printbuf buf = PRINTBUF;
1425
1426         bch2_trans_updates_to_text(&buf, trans);
1427         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1428         printbuf_exit(&buf);
1429 }
1430
1431 static void bch2_btree_path_to_text(struct printbuf *out, struct btree_trans *trans, btree_path_idx_t path_idx)
1432 {
1433         struct btree_path *path = trans->paths + path_idx;
1434
1435         prt_printf(out, "path: idx %2u ref %u:%u %c %c btree=%s l=%u pos ",
1436                    path_idx, path->ref, path->intent_ref,
1437                    path->preserve ? 'P' : ' ',
1438                    path->should_be_locked ? 'S' : ' ',
1439                    bch2_btree_id_str(path->btree_id),
1440                    path->level);
1441         bch2_bpos_to_text(out, path->pos);
1442
1443         prt_printf(out, " locks %u", path->nodes_locked);
1444 #ifdef TRACK_PATH_ALLOCATED
1445         prt_printf(out, " %pS", (void *) path->ip_allocated);
1446 #endif
1447         prt_newline(out);
1448 }
1449
1450 static noinline __cold
1451 void __bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans,
1452                                 bool nosort)
1453 {
1454         struct trans_for_each_path_inorder_iter iter;
1455
1456         if (!nosort)
1457                 btree_trans_sort_paths(trans);
1458
1459         trans_for_each_path_idx_inorder(trans, iter)
1460                 bch2_btree_path_to_text(out, trans, iter.path_idx);
1461 }
1462
1463 noinline __cold
1464 void bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans)
1465 {
1466         __bch2_trans_paths_to_text(out, trans, false);
1467 }
1468
1469 static noinline __cold
1470 void __bch2_dump_trans_paths_updates(struct btree_trans *trans, bool nosort)
1471 {
1472         struct printbuf buf = PRINTBUF;
1473
1474         __bch2_trans_paths_to_text(&buf, trans, nosort);
1475         bch2_trans_updates_to_text(&buf, trans);
1476
1477         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1478         printbuf_exit(&buf);
1479 }
1480
1481 noinline __cold
1482 void bch2_dump_trans_paths_updates(struct btree_trans *trans)
1483 {
1484         __bch2_dump_trans_paths_updates(trans, false);
1485 }
1486
1487 noinline __cold
1488 static void bch2_trans_update_max_paths(struct btree_trans *trans)
1489 {
1490         struct btree_transaction_stats *s = btree_trans_stats(trans);
1491         struct printbuf buf = PRINTBUF;
1492         size_t nr = bitmap_weight(trans->paths_allocated, trans->nr_paths);
1493
1494         bch2_trans_paths_to_text(&buf, trans);
1495
1496         if (!buf.allocation_failure) {
1497                 mutex_lock(&s->lock);
1498                 if (nr > s->nr_max_paths) {
1499                         s->nr_max_paths = nr;
1500                         swap(s->max_paths_text, buf.buf);
1501                 }
1502                 mutex_unlock(&s->lock);
1503         }
1504
1505         printbuf_exit(&buf);
1506
1507         trans->nr_paths_max = nr;
1508 }
1509
1510 noinline __cold
1511 int __bch2_btree_trans_too_many_iters(struct btree_trans *trans)
1512 {
1513         if (trace_trans_restart_too_many_iters_enabled()) {
1514                 struct printbuf buf = PRINTBUF;
1515
1516                 bch2_trans_paths_to_text(&buf, trans);
1517                 trace_trans_restart_too_many_iters(trans, _THIS_IP_, buf.buf);
1518                 printbuf_exit(&buf);
1519         }
1520
1521         count_event(trans->c, trans_restart_too_many_iters);
1522
1523         return btree_trans_restart(trans, BCH_ERR_transaction_restart_too_many_iters);
1524 }
1525
1526 static noinline void btree_path_overflow(struct btree_trans *trans)
1527 {
1528         bch2_dump_trans_paths_updates(trans);
1529         bch_err(trans->c, "trans path overflow");
1530 }
1531
1532 static noinline void btree_paths_realloc(struct btree_trans *trans)
1533 {
1534         unsigned nr = trans->nr_paths * 2;
1535
1536         void *p = kvzalloc(BITS_TO_LONGS(nr) * sizeof(unsigned long) +
1537                           sizeof(struct btree_trans_paths) +
1538                           nr * sizeof(struct btree_path) +
1539                           nr * sizeof(btree_path_idx_t) + 8 +
1540                           nr * sizeof(struct btree_insert_entry), GFP_KERNEL|__GFP_NOFAIL);
1541
1542         unsigned long *paths_allocated = p;
1543         memcpy(paths_allocated, trans->paths_allocated, BITS_TO_LONGS(trans->nr_paths) * sizeof(unsigned long));
1544         p += BITS_TO_LONGS(nr) * sizeof(unsigned long);
1545
1546         p += sizeof(struct btree_trans_paths);
1547         struct btree_path *paths = p;
1548         *trans_paths_nr(paths) = nr;
1549         memcpy(paths, trans->paths, trans->nr_paths * sizeof(struct btree_path));
1550         p += nr * sizeof(struct btree_path);
1551
1552         btree_path_idx_t *sorted = p;
1553         memcpy(sorted, trans->sorted, trans->nr_sorted * sizeof(btree_path_idx_t));
1554         p += nr * sizeof(btree_path_idx_t) + 8;
1555
1556         struct btree_insert_entry *updates = p;
1557         memcpy(updates, trans->updates, trans->nr_paths * sizeof(struct btree_insert_entry));
1558
1559         unsigned long *old = trans->paths_allocated;
1560
1561         rcu_assign_pointer(trans->paths_allocated,      paths_allocated);
1562         rcu_assign_pointer(trans->paths,                paths);
1563         rcu_assign_pointer(trans->sorted,               sorted);
1564         rcu_assign_pointer(trans->updates,              updates);
1565
1566         trans->nr_paths         = nr;
1567
1568         if (old != trans->_paths_allocated)
1569                 kfree_rcu_mightsleep(old);
1570 }
1571
1572 static inline btree_path_idx_t btree_path_alloc(struct btree_trans *trans,
1573                                                 btree_path_idx_t pos)
1574 {
1575         btree_path_idx_t idx = find_first_zero_bit(trans->paths_allocated, trans->nr_paths);
1576
1577         if (unlikely(idx == trans->nr_paths)) {
1578                 if (trans->nr_paths == BTREE_ITER_MAX) {
1579                         btree_path_overflow(trans);
1580                         return 0;
1581                 }
1582
1583                 btree_paths_realloc(trans);
1584         }
1585
1586         /*
1587          * Do this before marking the new path as allocated, since it won't be
1588          * initialized yet:
1589          */
1590         if (unlikely(idx > trans->nr_paths_max))
1591                 bch2_trans_update_max_paths(trans);
1592
1593         __set_bit(idx, trans->paths_allocated);
1594
1595         struct btree_path *path = &trans->paths[idx];
1596         path->ref               = 0;
1597         path->intent_ref        = 0;
1598         path->nodes_locked      = 0;
1599
1600         btree_path_list_add(trans, pos, idx);
1601         trans->paths_sorted = false;
1602         return idx;
1603 }
1604
1605 btree_path_idx_t bch2_path_get(struct btree_trans *trans,
1606                              enum btree_id btree_id, struct bpos pos,
1607                              unsigned locks_want, unsigned level,
1608                              unsigned flags, unsigned long ip)
1609 {
1610         struct btree_path *path;
1611         bool cached = flags & BTREE_ITER_CACHED;
1612         bool intent = flags & BTREE_ITER_INTENT;
1613         struct trans_for_each_path_inorder_iter iter;
1614         btree_path_idx_t path_pos = 0, path_idx;
1615
1616         bch2_trans_verify_not_in_restart(trans);
1617         bch2_trans_verify_locks(trans);
1618
1619         btree_trans_sort_paths(trans);
1620
1621         trans_for_each_path_inorder(trans, path, iter) {
1622                 if (__btree_path_cmp(path,
1623                                      btree_id,
1624                                      cached,
1625                                      pos,
1626                                      level) > 0)
1627                         break;
1628
1629                 path_pos = iter.path_idx;
1630         }
1631
1632         if (path_pos &&
1633             trans->paths[path_pos].cached       == cached &&
1634             trans->paths[path_pos].btree_id     == btree_id &&
1635             trans->paths[path_pos].level        == level) {
1636                 __btree_path_get(trans->paths + path_pos, intent);
1637                 path_idx = bch2_btree_path_set_pos(trans, path_pos, pos, intent, ip);
1638                 path = trans->paths + path_idx;
1639         } else {
1640                 path_idx = btree_path_alloc(trans, path_pos);
1641                 path = trans->paths + path_idx;
1642
1643                 __btree_path_get(path, intent);
1644                 path->pos                       = pos;
1645                 path->btree_id                  = btree_id;
1646                 path->cached                    = cached;
1647                 path->uptodate                  = BTREE_ITER_NEED_TRAVERSE;
1648                 path->should_be_locked          = false;
1649                 path->level                     = level;
1650                 path->locks_want                = locks_want;
1651                 path->nodes_locked              = 0;
1652                 for (unsigned i = 0; i < ARRAY_SIZE(path->l); i++)
1653                         path->l[i].b            = ERR_PTR(-BCH_ERR_no_btree_node_init);
1654 #ifdef TRACK_PATH_ALLOCATED
1655                 path->ip_allocated              = ip;
1656 #endif
1657                 trans->paths_sorted             = false;
1658         }
1659
1660         if (!(flags & BTREE_ITER_NOPRESERVE))
1661                 path->preserve = true;
1662
1663         if (path->intent_ref)
1664                 locks_want = max(locks_want, level + 1);
1665
1666         /*
1667          * If the path has locks_want greater than requested, we don't downgrade
1668          * it here - on transaction restart because btree node split needs to
1669          * upgrade locks, we might be putting/getting the iterator again.
1670          * Downgrading iterators only happens via bch2_trans_downgrade(), after
1671          * a successful transaction commit.
1672          */
1673
1674         locks_want = min(locks_want, BTREE_MAX_DEPTH);
1675         if (locks_want > path->locks_want)
1676                 bch2_btree_path_upgrade_noupgrade_sibs(trans, path, locks_want, NULL);
1677
1678         return path_idx;
1679 }
1680
1681 struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *path, struct bkey *u)
1682 {
1683
1684         struct btree_path_level *l = path_l(path);
1685         struct bkey_packed *_k;
1686         struct bkey_s_c k;
1687
1688         if (unlikely(!l->b))
1689                 return bkey_s_c_null;
1690
1691         EBUG_ON(path->uptodate != BTREE_ITER_UPTODATE);
1692         EBUG_ON(!btree_node_locked(path, path->level));
1693
1694         if (!path->cached) {
1695                 _k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
1696                 k = _k ? bkey_disassemble(l->b, _k, u) : bkey_s_c_null;
1697
1698                 EBUG_ON(k.k && bkey_deleted(k.k) && bpos_eq(k.k->p, path->pos));
1699
1700                 if (!k.k || !bpos_eq(path->pos, k.k->p))
1701                         goto hole;
1702         } else {
1703                 struct bkey_cached *ck = (void *) path->l[0].b;
1704
1705                 EBUG_ON(ck &&
1706                         (path->btree_id != ck->key.btree_id ||
1707                          !bkey_eq(path->pos, ck->key.pos)));
1708                 if (!ck || !ck->valid)
1709                         return bkey_s_c_null;
1710
1711                 *u = ck->k->k;
1712                 k = bkey_i_to_s_c(ck->k);
1713         }
1714
1715         return k;
1716 hole:
1717         bkey_init(u);
1718         u->p = path->pos;
1719         return (struct bkey_s_c) { u, NULL };
1720 }
1721
1722 /* Btree iterators: */
1723
1724 int __must_check
1725 __bch2_btree_iter_traverse(struct btree_iter *iter)
1726 {
1727         return bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1728 }
1729
1730 int __must_check
1731 bch2_btree_iter_traverse(struct btree_iter *iter)
1732 {
1733         struct btree_trans *trans = iter->trans;
1734         int ret;
1735
1736         iter->path = bch2_btree_path_set_pos(trans, iter->path,
1737                                         btree_iter_search_key(iter),
1738                                         iter->flags & BTREE_ITER_INTENT,
1739                                         btree_iter_ip_allocated(iter));
1740
1741         ret = bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1742         if (ret)
1743                 return ret;
1744
1745         struct btree_path *path = btree_iter_path(trans, iter);
1746         if (btree_path_node(path, path->level))
1747                 btree_path_set_should_be_locked(path);
1748         return 0;
1749 }
1750
1751 /* Iterate across nodes (leaf and interior nodes) */
1752
1753 struct btree *bch2_btree_iter_peek_node(struct btree_iter *iter)
1754 {
1755         struct btree_trans *trans = iter->trans;
1756         struct btree *b = NULL;
1757         int ret;
1758
1759         EBUG_ON(trans->paths[iter->path].cached);
1760         bch2_btree_iter_verify(iter);
1761
1762         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1763         if (ret)
1764                 goto err;
1765
1766         struct btree_path *path = btree_iter_path(trans, iter);
1767         b = btree_path_node(path, path->level);
1768         if (!b)
1769                 goto out;
1770
1771         BUG_ON(bpos_lt(b->key.k.p, iter->pos));
1772
1773         bkey_init(&iter->k);
1774         iter->k.p = iter->pos = b->key.k.p;
1775
1776         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1777                                         iter->flags & BTREE_ITER_INTENT,
1778                                         btree_iter_ip_allocated(iter));
1779         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
1780 out:
1781         bch2_btree_iter_verify_entry_exit(iter);
1782         bch2_btree_iter_verify(iter);
1783
1784         return b;
1785 err:
1786         b = ERR_PTR(ret);
1787         goto out;
1788 }
1789
1790 struct btree *bch2_btree_iter_peek_node_and_restart(struct btree_iter *iter)
1791 {
1792         struct btree *b;
1793
1794         while (b = bch2_btree_iter_peek_node(iter),
1795                bch2_err_matches(PTR_ERR_OR_ZERO(b), BCH_ERR_transaction_restart))
1796                 bch2_trans_begin(iter->trans);
1797
1798         return b;
1799 }
1800
1801 struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
1802 {
1803         struct btree_trans *trans = iter->trans;
1804         struct btree *b = NULL;
1805         int ret;
1806
1807         EBUG_ON(trans->paths[iter->path].cached);
1808         bch2_trans_verify_not_in_restart(trans);
1809         bch2_btree_iter_verify(iter);
1810
1811         struct btree_path *path = btree_iter_path(trans, iter);
1812
1813         /* already at end? */
1814         if (!btree_path_node(path, path->level))
1815                 return NULL;
1816
1817         /* got to end? */
1818         if (!btree_path_node(path, path->level + 1)) {
1819                 btree_path_set_level_up(trans, path);
1820                 return NULL;
1821         }
1822
1823         if (!bch2_btree_node_relock(trans, path, path->level + 1)) {
1824                 __bch2_btree_path_unlock(trans, path);
1825                 path->l[path->level].b          = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1826                 path->l[path->level + 1].b      = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1827                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1828                 trace_and_count(trans->c, trans_restart_relock_next_node, trans, _THIS_IP_, path);
1829                 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
1830                 goto err;
1831         }
1832
1833         b = btree_path_node(path, path->level + 1);
1834
1835         if (bpos_eq(iter->pos, b->key.k.p)) {
1836                 __btree_path_set_level_up(trans, path, path->level++);
1837         } else {
1838                 /*
1839                  * Haven't gotten to the end of the parent node: go back down to
1840                  * the next child node
1841                  */
1842                 iter->path = bch2_btree_path_set_pos(trans, iter->path,
1843                                         bpos_successor(iter->pos),
1844                                         iter->flags & BTREE_ITER_INTENT,
1845                                         btree_iter_ip_allocated(iter));
1846
1847                 path = btree_iter_path(trans, iter);
1848                 btree_path_set_level_down(trans, path, iter->min_depth);
1849
1850                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1851                 if (ret)
1852                         goto err;
1853
1854                 path = btree_iter_path(trans, iter);
1855                 b = path->l[path->level].b;
1856         }
1857
1858         bkey_init(&iter->k);
1859         iter->k.p = iter->pos = b->key.k.p;
1860
1861         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1862                                         iter->flags & BTREE_ITER_INTENT,
1863                                         btree_iter_ip_allocated(iter));
1864         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
1865         EBUG_ON(btree_iter_path(trans, iter)->uptodate);
1866 out:
1867         bch2_btree_iter_verify_entry_exit(iter);
1868         bch2_btree_iter_verify(iter);
1869
1870         return b;
1871 err:
1872         b = ERR_PTR(ret);
1873         goto out;
1874 }
1875
1876 /* Iterate across keys (in leaf nodes only) */
1877
1878 inline bool bch2_btree_iter_advance(struct btree_iter *iter)
1879 {
1880         struct bpos pos = iter->k.p;
1881         bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1882                      ? bpos_eq(pos, SPOS_MAX)
1883                      : bkey_eq(pos, SPOS_MAX));
1884
1885         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1886                 pos = bkey_successor(iter, pos);
1887         bch2_btree_iter_set_pos(iter, pos);
1888         return ret;
1889 }
1890
1891 inline bool bch2_btree_iter_rewind(struct btree_iter *iter)
1892 {
1893         struct bpos pos = bkey_start_pos(&iter->k);
1894         bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1895                      ? bpos_eq(pos, POS_MIN)
1896                      : bkey_eq(pos, POS_MIN));
1897
1898         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1899                 pos = bkey_predecessor(iter, pos);
1900         bch2_btree_iter_set_pos(iter, pos);
1901         return ret;
1902 }
1903
1904 static noinline
1905 void bch2_btree_trans_peek_prev_updates(struct btree_trans *trans, struct btree_iter *iter,
1906                                         struct bkey_s_c *k)
1907 {
1908         struct bpos end = path_l(btree_iter_path(trans, iter))->b->data->min_key;
1909
1910         trans_for_each_update(trans, i)
1911                 if (!i->key_cache_already_flushed &&
1912                     i->btree_id == iter->btree_id &&
1913                     bpos_le(i->k->k.p, iter->pos) &&
1914                     bpos_ge(i->k->k.p, k->k ? k->k->p : end)) {
1915                         iter->k = i->k->k;
1916                         *k = bkey_i_to_s_c(i->k);
1917                 }
1918 }
1919
1920 static noinline
1921 void bch2_btree_trans_peek_updates(struct btree_trans *trans, struct btree_iter *iter,
1922                                    struct bkey_s_c *k)
1923 {
1924         struct btree_path *path = btree_iter_path(trans, iter);
1925         struct bpos end = path_l(path)->b->key.k.p;
1926
1927         trans_for_each_update(trans, i)
1928                 if (!i->key_cache_already_flushed &&
1929                     i->btree_id == iter->btree_id &&
1930                     bpos_ge(i->k->k.p, path->pos) &&
1931                     bpos_le(i->k->k.p, k->k ? k->k->p : end)) {
1932                         iter->k = i->k->k;
1933                         *k = bkey_i_to_s_c(i->k);
1934                 }
1935 }
1936
1937 static noinline
1938 void bch2_btree_trans_peek_slot_updates(struct btree_trans *trans, struct btree_iter *iter,
1939                                         struct bkey_s_c *k)
1940 {
1941         trans_for_each_update(trans, i)
1942                 if (!i->key_cache_already_flushed &&
1943                     i->btree_id == iter->btree_id &&
1944                     bpos_eq(i->k->k.p, iter->pos)) {
1945                         iter->k = i->k->k;
1946                         *k = bkey_i_to_s_c(i->k);
1947                 }
1948 }
1949
1950 static struct bkey_i *bch2_btree_journal_peek(struct btree_trans *trans,
1951                                               struct btree_iter *iter,
1952                                               struct bpos end_pos)
1953 {
1954         struct btree_path *path = btree_iter_path(trans, iter);
1955
1956         return bch2_journal_keys_peek_upto(trans->c, iter->btree_id,
1957                                            path->level,
1958                                            path->pos,
1959                                            end_pos,
1960                                            &iter->journal_idx);
1961 }
1962
1963 static noinline
1964 struct bkey_s_c btree_trans_peek_slot_journal(struct btree_trans *trans,
1965                                               struct btree_iter *iter)
1966 {
1967         struct btree_path *path = btree_iter_path(trans, iter);
1968         struct bkey_i *k = bch2_btree_journal_peek(trans, iter, path->pos);
1969
1970         if (k) {
1971                 iter->k = k->k;
1972                 return bkey_i_to_s_c(k);
1973         } else {
1974                 return bkey_s_c_null;
1975         }
1976 }
1977
1978 static noinline
1979 struct bkey_s_c btree_trans_peek_journal(struct btree_trans *trans,
1980                                          struct btree_iter *iter,
1981                                          struct bkey_s_c k)
1982 {
1983         struct btree_path *path = btree_iter_path(trans, iter);
1984         struct bkey_i *next_journal =
1985                 bch2_btree_journal_peek(trans, iter,
1986                                 k.k ? k.k->p : path_l(path)->b->key.k.p);
1987
1988         if (next_journal) {
1989                 iter->k = next_journal->k;
1990                 k = bkey_i_to_s_c(next_journal);
1991         }
1992
1993         return k;
1994 }
1995
1996 /*
1997  * Checks btree key cache for key at iter->pos and returns it if present, or
1998  * bkey_s_c_null:
1999  */
2000 static noinline
2001 struct bkey_s_c btree_trans_peek_key_cache(struct btree_iter *iter, struct bpos pos)
2002 {
2003         struct btree_trans *trans = iter->trans;
2004         struct bch_fs *c = trans->c;
2005         struct bkey u;
2006         struct bkey_s_c k;
2007         int ret;
2008
2009         if ((iter->flags & BTREE_ITER_KEY_CACHE_FILL) &&
2010             bpos_eq(iter->pos, pos))
2011                 return bkey_s_c_null;
2012
2013         if (!bch2_btree_key_cache_find(c, iter->btree_id, pos))
2014                 return bkey_s_c_null;
2015
2016         if (!iter->key_cache_path)
2017                 iter->key_cache_path = bch2_path_get(trans, iter->btree_id, pos,
2018                                                      iter->flags & BTREE_ITER_INTENT, 0,
2019                                                      iter->flags|BTREE_ITER_CACHED|
2020                                                      BTREE_ITER_CACHED_NOFILL,
2021                                                      _THIS_IP_);
2022
2023         iter->key_cache_path = bch2_btree_path_set_pos(trans, iter->key_cache_path, pos,
2024                                         iter->flags & BTREE_ITER_INTENT,
2025                                         btree_iter_ip_allocated(iter));
2026
2027         ret =   bch2_btree_path_traverse(trans, iter->key_cache_path,
2028                                          iter->flags|BTREE_ITER_CACHED) ?:
2029                 bch2_btree_path_relock(trans, btree_iter_path(trans, iter), _THIS_IP_);
2030         if (unlikely(ret))
2031                 return bkey_s_c_err(ret);
2032
2033         btree_path_set_should_be_locked(trans->paths + iter->key_cache_path);
2034
2035         k = bch2_btree_path_peek_slot(trans->paths + iter->key_cache_path, &u);
2036         if (k.k && !bkey_err(k)) {
2037                 iter->k = u;
2038                 k.k = &iter->k;
2039         }
2040         return k;
2041 }
2042
2043 static struct bkey_s_c __bch2_btree_iter_peek(struct btree_iter *iter, struct bpos search_key)
2044 {
2045         struct btree_trans *trans = iter->trans;
2046         struct bkey_s_c k, k2;
2047         int ret;
2048
2049         EBUG_ON(btree_iter_path(trans, iter)->cached);
2050         bch2_btree_iter_verify(iter);
2051
2052         while (1) {
2053                 struct btree_path_level *l;
2054
2055                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2056                                         iter->flags & BTREE_ITER_INTENT,
2057                                         btree_iter_ip_allocated(iter));
2058
2059                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2060                 if (unlikely(ret)) {
2061                         /* ensure that iter->k is consistent with iter->pos: */
2062                         bch2_btree_iter_set_pos(iter, iter->pos);
2063                         k = bkey_s_c_err(ret);
2064                         goto out;
2065                 }
2066
2067                 struct btree_path *path = btree_iter_path(trans, iter);
2068                 l = path_l(path);
2069
2070                 if (unlikely(!l->b)) {
2071                         /* No btree nodes at requested level: */
2072                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2073                         k = bkey_s_c_null;
2074                         goto out;
2075                 }
2076
2077                 btree_path_set_should_be_locked(path);
2078
2079                 k = btree_path_level_peek_all(trans->c, l, &iter->k);
2080
2081                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2082                     k.k &&
2083                     (k2 = btree_trans_peek_key_cache(iter, k.k->p)).k) {
2084                         k = k2;
2085                         ret = bkey_err(k);
2086                         if (ret) {
2087                                 bch2_btree_iter_set_pos(iter, iter->pos);
2088                                 goto out;
2089                         }
2090                 }
2091
2092                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL))
2093                         k = btree_trans_peek_journal(trans, iter, k);
2094
2095                 if (unlikely((iter->flags & BTREE_ITER_WITH_UPDATES) &&
2096                              trans->nr_updates))
2097                         bch2_btree_trans_peek_updates(trans, iter, &k);
2098
2099                 if (k.k && bkey_deleted(k.k)) {
2100                         /*
2101                          * If we've got a whiteout, and it's after the search
2102                          * key, advance the search key to the whiteout instead
2103                          * of just after the whiteout - it might be a btree
2104                          * whiteout, with a real key at the same position, since
2105                          * in the btree deleted keys sort before non deleted.
2106                          */
2107                         search_key = !bpos_eq(search_key, k.k->p)
2108                                 ? k.k->p
2109                                 : bpos_successor(k.k->p);
2110                         continue;
2111                 }
2112
2113                 if (likely(k.k)) {
2114                         break;
2115                 } else if (likely(!bpos_eq(l->b->key.k.p, SPOS_MAX))) {
2116                         /* Advance to next leaf node: */
2117                         search_key = bpos_successor(l->b->key.k.p);
2118                 } else {
2119                         /* End of btree: */
2120                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2121                         k = bkey_s_c_null;
2122                         goto out;
2123                 }
2124         }
2125 out:
2126         bch2_btree_iter_verify(iter);
2127
2128         return k;
2129 }
2130
2131 /**
2132  * bch2_btree_iter_peek_upto() - returns first key greater than or equal to
2133  * iterator's current position
2134  * @iter:       iterator to peek from
2135  * @end:        search limit: returns keys less than or equal to @end
2136  *
2137  * Returns:     key if found, or an error extractable with bkey_err().
2138  */
2139 struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *iter, struct bpos end)
2140 {
2141         struct btree_trans *trans = iter->trans;
2142         struct bpos search_key = btree_iter_search_key(iter);
2143         struct bkey_s_c k;
2144         struct bpos iter_pos;
2145         int ret;
2146
2147         EBUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) && bkey_eq(end, POS_MAX));
2148
2149         if (iter->update_path) {
2150                 bch2_path_put_nokeep(trans, iter->update_path,
2151                                      iter->flags & BTREE_ITER_INTENT);
2152                 iter->update_path = 0;
2153         }
2154
2155         bch2_btree_iter_verify_entry_exit(iter);
2156
2157         while (1) {
2158                 k = __bch2_btree_iter_peek(iter, search_key);
2159                 if (unlikely(!k.k))
2160                         goto end;
2161                 if (unlikely(bkey_err(k)))
2162                         goto out_no_locked;
2163
2164                 /*
2165                  * We need to check against @end before FILTER_SNAPSHOTS because
2166                  * if we get to a different inode that requested we might be
2167                  * seeing keys for a different snapshot tree that will all be
2168                  * filtered out.
2169                  *
2170                  * But we can't do the full check here, because bkey_start_pos()
2171                  * isn't monotonically increasing before FILTER_SNAPSHOTS, and
2172                  * that's what we check against in extents mode:
2173                  */
2174                 if (unlikely(!(iter->flags & BTREE_ITER_IS_EXTENTS)
2175                              ? bkey_gt(k.k->p, end)
2176                              : k.k->p.inode > end.inode))
2177                         goto end;
2178
2179                 if (iter->update_path &&
2180                     !bkey_eq(trans->paths[iter->update_path].pos, k.k->p)) {
2181                         bch2_path_put_nokeep(trans, iter->update_path,
2182                                              iter->flags & BTREE_ITER_INTENT);
2183                         iter->update_path = 0;
2184                 }
2185
2186                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2187                     (iter->flags & BTREE_ITER_INTENT) &&
2188                     !(iter->flags & BTREE_ITER_IS_EXTENTS) &&
2189                     !iter->update_path) {
2190                         struct bpos pos = k.k->p;
2191
2192                         if (pos.snapshot < iter->snapshot) {
2193                                 search_key = bpos_successor(k.k->p);
2194                                 continue;
2195                         }
2196
2197                         pos.snapshot = iter->snapshot;
2198
2199                         /*
2200                          * advance, same as on exit for iter->path, but only up
2201                          * to snapshot
2202                          */
2203                         __btree_path_get(trans->paths + iter->path, iter->flags & BTREE_ITER_INTENT);
2204                         iter->update_path = iter->path;
2205
2206                         iter->update_path = bch2_btree_path_set_pos(trans,
2207                                                 iter->update_path, pos,
2208                                                 iter->flags & BTREE_ITER_INTENT,
2209                                                 _THIS_IP_);
2210                         ret = bch2_btree_path_traverse(trans, iter->update_path, iter->flags);
2211                         if (unlikely(ret)) {
2212                                 k = bkey_s_c_err(ret);
2213                                 goto out_no_locked;
2214                         }
2215                 }
2216
2217                 /*
2218                  * We can never have a key in a leaf node at POS_MAX, so
2219                  * we don't have to check these successor() calls:
2220                  */
2221                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2222                     !bch2_snapshot_is_ancestor(trans->c,
2223                                                iter->snapshot,
2224                                                k.k->p.snapshot)) {
2225                         search_key = bpos_successor(k.k->p);
2226                         continue;
2227                 }
2228
2229                 if (bkey_whiteout(k.k) &&
2230                     !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2231                         search_key = bkey_successor(iter, k.k->p);
2232                         continue;
2233                 }
2234
2235                 /*
2236                  * iter->pos should be mononotically increasing, and always be
2237                  * equal to the key we just returned - except extents can
2238                  * straddle iter->pos:
2239                  */
2240                 if (!(iter->flags & BTREE_ITER_IS_EXTENTS))
2241                         iter_pos = k.k->p;
2242                 else
2243                         iter_pos = bkey_max(iter->pos, bkey_start_pos(k.k));
2244
2245                 if (unlikely(!(iter->flags & BTREE_ITER_IS_EXTENTS)
2246                              ? bkey_gt(iter_pos, end)
2247                              : bkey_ge(iter_pos, end)))
2248                         goto end;
2249
2250                 break;
2251         }
2252
2253         iter->pos = iter_pos;
2254
2255         iter->path = bch2_btree_path_set_pos(trans, iter->path, k.k->p,
2256                                 iter->flags & BTREE_ITER_INTENT,
2257                                 btree_iter_ip_allocated(iter));
2258
2259         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
2260 out_no_locked:
2261         if (iter->update_path) {
2262                 ret = bch2_btree_path_relock(trans, trans->paths + iter->update_path, _THIS_IP_);
2263                 if (unlikely(ret))
2264                         k = bkey_s_c_err(ret);
2265                 else
2266                         btree_path_set_should_be_locked(trans->paths + iter->update_path);
2267         }
2268
2269         if (!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS))
2270                 iter->pos.snapshot = iter->snapshot;
2271
2272         ret = bch2_btree_iter_verify_ret(iter, k);
2273         if (unlikely(ret)) {
2274                 bch2_btree_iter_set_pos(iter, iter->pos);
2275                 k = bkey_s_c_err(ret);
2276         }
2277
2278         bch2_btree_iter_verify_entry_exit(iter);
2279
2280         return k;
2281 end:
2282         bch2_btree_iter_set_pos(iter, end);
2283         k = bkey_s_c_null;
2284         goto out_no_locked;
2285 }
2286
2287 /**
2288  * bch2_btree_iter_next() - returns first key greater than iterator's current
2289  * position
2290  * @iter:       iterator to peek from
2291  *
2292  * Returns:     key if found, or an error extractable with bkey_err().
2293  */
2294 struct bkey_s_c bch2_btree_iter_next(struct btree_iter *iter)
2295 {
2296         if (!bch2_btree_iter_advance(iter))
2297                 return bkey_s_c_null;
2298
2299         return bch2_btree_iter_peek(iter);
2300 }
2301
2302 /**
2303  * bch2_btree_iter_peek_prev() - returns first key less than or equal to
2304  * iterator's current position
2305  * @iter:       iterator to peek from
2306  *
2307  * Returns:     key if found, or an error extractable with bkey_err().
2308  */
2309 struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
2310 {
2311         struct btree_trans *trans = iter->trans;
2312         struct bpos search_key = iter->pos;
2313         struct bkey_s_c k;
2314         struct bkey saved_k;
2315         const struct bch_val *saved_v;
2316         btree_path_idx_t saved_path = 0;
2317         int ret;
2318
2319         EBUG_ON(btree_iter_path(trans, iter)->cached ||
2320                 btree_iter_path(trans, iter)->level);
2321
2322         if (iter->flags & BTREE_ITER_WITH_JOURNAL)
2323                 return bkey_s_c_err(-BCH_ERR_btree_iter_with_journal_not_supported);
2324
2325         bch2_btree_iter_verify(iter);
2326         bch2_btree_iter_verify_entry_exit(iter);
2327
2328         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2329                 search_key.snapshot = U32_MAX;
2330
2331         while (1) {
2332                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2333                                                 iter->flags & BTREE_ITER_INTENT,
2334                                                 btree_iter_ip_allocated(iter));
2335
2336                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2337                 if (unlikely(ret)) {
2338                         /* ensure that iter->k is consistent with iter->pos: */
2339                         bch2_btree_iter_set_pos(iter, iter->pos);
2340                         k = bkey_s_c_err(ret);
2341                         goto out_no_locked;
2342                 }
2343
2344                 struct btree_path *path = btree_iter_path(trans, iter);
2345
2346                 k = btree_path_level_peek(trans, path, &path->l[0], &iter->k);
2347                 if (!k.k ||
2348                     ((iter->flags & BTREE_ITER_IS_EXTENTS)
2349                      ? bpos_ge(bkey_start_pos(k.k), search_key)
2350                      : bpos_gt(k.k->p, search_key)))
2351                         k = btree_path_level_prev(trans, path, &path->l[0], &iter->k);
2352
2353                 if (unlikely((iter->flags & BTREE_ITER_WITH_UPDATES) &&
2354                              trans->nr_updates))
2355                         bch2_btree_trans_peek_prev_updates(trans, iter, &k);
2356
2357                 if (likely(k.k)) {
2358                         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) {
2359                                 if (k.k->p.snapshot == iter->snapshot)
2360                                         goto got_key;
2361
2362                                 /*
2363                                  * If we have a saved candidate, and we're no
2364                                  * longer at the same _key_ (not pos), return
2365                                  * that candidate
2366                                  */
2367                                 if (saved_path && !bkey_eq(k.k->p, saved_k.p)) {
2368                                         bch2_path_put_nokeep(trans, iter->path,
2369                                                       iter->flags & BTREE_ITER_INTENT);
2370                                         iter->path = saved_path;
2371                                         saved_path = 0;
2372                                         iter->k = saved_k;
2373                                         k.v     = saved_v;
2374                                         goto got_key;
2375                                 }
2376
2377                                 if (bch2_snapshot_is_ancestor(trans->c,
2378                                                               iter->snapshot,
2379                                                               k.k->p.snapshot)) {
2380                                         if (saved_path)
2381                                                 bch2_path_put_nokeep(trans, saved_path,
2382                                                       iter->flags & BTREE_ITER_INTENT);
2383                                         saved_path = btree_path_clone(trans, iter->path,
2384                                                                 iter->flags & BTREE_ITER_INTENT);
2385                                         path = btree_iter_path(trans, iter);
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                         btree_path_set_should_be_locked(path);
2403                         break;
2404                 } else if (likely(!bpos_eq(path->l[0].b->data->min_key, POS_MIN))) {
2405                         /* Advance to previous leaf node: */
2406                         search_key = bpos_predecessor(path->l[0].b->data->min_key);
2407                 } else {
2408                         /* Start of btree: */
2409                         bch2_btree_iter_set_pos(iter, POS_MIN);
2410                         k = bkey_s_c_null;
2411                         goto out_no_locked;
2412                 }
2413         }
2414
2415         EBUG_ON(bkey_gt(bkey_start_pos(k.k), iter->pos));
2416
2417         /* Extents can straddle iter->pos: */
2418         if (bkey_lt(k.k->p, iter->pos))
2419                 iter->pos = k.k->p;
2420
2421         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2422                 iter->pos.snapshot = iter->snapshot;
2423 out_no_locked:
2424         if (saved_path)
2425                 bch2_path_put_nokeep(trans, saved_path, iter->flags & BTREE_ITER_INTENT);
2426
2427         bch2_btree_iter_verify_entry_exit(iter);
2428         bch2_btree_iter_verify(iter);
2429
2430         return k;
2431 }
2432
2433 /**
2434  * bch2_btree_iter_prev() - returns first key less than iterator's current
2435  * position
2436  * @iter:       iterator to peek from
2437  *
2438  * Returns:     key if found, or an error extractable with bkey_err().
2439  */
2440 struct bkey_s_c bch2_btree_iter_prev(struct btree_iter *iter)
2441 {
2442         if (!bch2_btree_iter_rewind(iter))
2443                 return bkey_s_c_null;
2444
2445         return bch2_btree_iter_peek_prev(iter);
2446 }
2447
2448 struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
2449 {
2450         struct btree_trans *trans = iter->trans;
2451         struct bpos search_key;
2452         struct bkey_s_c k;
2453         int ret;
2454
2455         bch2_btree_iter_verify(iter);
2456         bch2_btree_iter_verify_entry_exit(iter);
2457         EBUG_ON(btree_iter_path(trans, iter)->level && (iter->flags & BTREE_ITER_WITH_KEY_CACHE));
2458
2459         /* extents can't span inode numbers: */
2460         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
2461             unlikely(iter->pos.offset == KEY_OFFSET_MAX)) {
2462                 if (iter->pos.inode == KEY_INODE_MAX)
2463                         return bkey_s_c_null;
2464
2465                 bch2_btree_iter_set_pos(iter, bpos_nosnap_successor(iter->pos));
2466         }
2467
2468         search_key = btree_iter_search_key(iter);
2469         iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2470                                         iter->flags & BTREE_ITER_INTENT,
2471                                         btree_iter_ip_allocated(iter));
2472
2473         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2474         if (unlikely(ret)) {
2475                 k = bkey_s_c_err(ret);
2476                 goto out_no_locked;
2477         }
2478
2479         if ((iter->flags & BTREE_ITER_CACHED) ||
2480             !(iter->flags & (BTREE_ITER_IS_EXTENTS|BTREE_ITER_FILTER_SNAPSHOTS))) {
2481                 k = bkey_s_c_null;
2482
2483                 if (unlikely((iter->flags & BTREE_ITER_WITH_UPDATES) &&
2484                              trans->nr_updates)) {
2485                         bch2_btree_trans_peek_slot_updates(trans, iter, &k);
2486                         if (k.k)
2487                                 goto out;
2488                 }
2489
2490                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL) &&
2491                     (k = btree_trans_peek_slot_journal(trans, iter)).k)
2492                         goto out;
2493
2494                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2495                     (k = btree_trans_peek_key_cache(iter, iter->pos)).k) {
2496                         if (!bkey_err(k))
2497                                 iter->k = *k.k;
2498                         /* We're not returning a key from iter->path: */
2499                         goto out_no_locked;
2500                 }
2501
2502                 k = bch2_btree_path_peek_slot(trans->paths + iter->path, &iter->k);
2503                 if (unlikely(!k.k))
2504                         goto out_no_locked;
2505         } else {
2506                 struct bpos next;
2507                 struct bpos end = iter->pos;
2508
2509                 if (iter->flags & BTREE_ITER_IS_EXTENTS)
2510                         end.offset = U64_MAX;
2511
2512                 EBUG_ON(btree_iter_path(trans, iter)->level);
2513
2514                 if (iter->flags & BTREE_ITER_INTENT) {
2515                         struct btree_iter iter2;
2516
2517                         bch2_trans_copy_iter(&iter2, iter);
2518                         k = bch2_btree_iter_peek_upto(&iter2, end);
2519
2520                         if (k.k && !bkey_err(k)) {
2521                                 swap(iter->key_cache_path, iter2.key_cache_path);
2522                                 iter->k = iter2.k;
2523                                 k.k = &iter->k;
2524                         }
2525                         bch2_trans_iter_exit(trans, &iter2);
2526                 } else {
2527                         struct bpos pos = iter->pos;
2528
2529                         k = bch2_btree_iter_peek_upto(iter, end);
2530                         if (unlikely(bkey_err(k)))
2531                                 bch2_btree_iter_set_pos(iter, pos);
2532                         else
2533                                 iter->pos = pos;
2534                 }
2535
2536                 if (unlikely(bkey_err(k)))
2537                         goto out_no_locked;
2538
2539                 next = k.k ? bkey_start_pos(k.k) : POS_MAX;
2540
2541                 if (bkey_lt(iter->pos, next)) {
2542                         bkey_init(&iter->k);
2543                         iter->k.p = iter->pos;
2544
2545                         if (iter->flags & BTREE_ITER_IS_EXTENTS) {
2546                                 bch2_key_resize(&iter->k,
2547                                                 min_t(u64, KEY_SIZE_MAX,
2548                                                       (next.inode == iter->pos.inode
2549                                                        ? next.offset
2550                                                        : KEY_OFFSET_MAX) -
2551                                                       iter->pos.offset));
2552                                 EBUG_ON(!iter->k.size);
2553                         }
2554
2555                         k = (struct bkey_s_c) { &iter->k, NULL };
2556                 }
2557         }
2558 out:
2559         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
2560 out_no_locked:
2561         bch2_btree_iter_verify_entry_exit(iter);
2562         bch2_btree_iter_verify(iter);
2563         ret = bch2_btree_iter_verify_ret(iter, k);
2564         if (unlikely(ret))
2565                 return bkey_s_c_err(ret);
2566
2567         return k;
2568 }
2569
2570 struct bkey_s_c bch2_btree_iter_next_slot(struct btree_iter *iter)
2571 {
2572         if (!bch2_btree_iter_advance(iter))
2573                 return bkey_s_c_null;
2574
2575         return bch2_btree_iter_peek_slot(iter);
2576 }
2577
2578 struct bkey_s_c bch2_btree_iter_prev_slot(struct btree_iter *iter)
2579 {
2580         if (!bch2_btree_iter_rewind(iter))
2581                 return bkey_s_c_null;
2582
2583         return bch2_btree_iter_peek_slot(iter);
2584 }
2585
2586 struct bkey_s_c bch2_btree_iter_peek_and_restart_outlined(struct btree_iter *iter)
2587 {
2588         struct bkey_s_c k;
2589
2590         while (btree_trans_too_many_iters(iter->trans) ||
2591                (k = bch2_btree_iter_peek_type(iter, iter->flags),
2592                 bch2_err_matches(bkey_err(k), BCH_ERR_transaction_restart)))
2593                 bch2_trans_begin(iter->trans);
2594
2595         return k;
2596 }
2597
2598 /* new transactional stuff: */
2599
2600 #ifdef CONFIG_BCACHEFS_DEBUG
2601 static void btree_trans_verify_sorted_refs(struct btree_trans *trans)
2602 {
2603         struct btree_path *path;
2604         unsigned i;
2605
2606         BUG_ON(trans->nr_sorted != bitmap_weight(trans->paths_allocated, trans->nr_paths) - 1);
2607
2608         trans_for_each_path(trans, path, i) {
2609                 BUG_ON(path->sorted_idx >= trans->nr_sorted);
2610                 BUG_ON(trans->sorted[path->sorted_idx] != i);
2611         }
2612
2613         for (i = 0; i < trans->nr_sorted; i++) {
2614                 unsigned idx = trans->sorted[i];
2615
2616                 BUG_ON(!test_bit(idx, trans->paths_allocated));
2617                 BUG_ON(trans->paths[idx].sorted_idx != i);
2618         }
2619 }
2620
2621 static void btree_trans_verify_sorted(struct btree_trans *trans)
2622 {
2623         struct btree_path *path, *prev = NULL;
2624         struct trans_for_each_path_inorder_iter iter;
2625
2626         if (!bch2_debug_check_iterators)
2627                 return;
2628
2629         trans_for_each_path_inorder(trans, path, iter) {
2630                 if (prev && btree_path_cmp(prev, path) > 0) {
2631                         __bch2_dump_trans_paths_updates(trans, true);
2632                         panic("trans paths out of order!\n");
2633                 }
2634                 prev = path;
2635         }
2636 }
2637 #else
2638 static inline void btree_trans_verify_sorted_refs(struct btree_trans *trans) {}
2639 static inline void btree_trans_verify_sorted(struct btree_trans *trans) {}
2640 #endif
2641
2642 void __bch2_btree_trans_sort_paths(struct btree_trans *trans)
2643 {
2644         int i, l = 0, r = trans->nr_sorted, inc = 1;
2645         bool swapped;
2646
2647         btree_trans_verify_sorted_refs(trans);
2648
2649         if (trans->paths_sorted)
2650                 goto out;
2651
2652         /*
2653          * Cocktail shaker sort: this is efficient because iterators will be
2654          * mostly sorted.
2655          */
2656         do {
2657                 swapped = false;
2658
2659                 for (i = inc > 0 ? l : r - 2;
2660                      i + 1 < r && i >= l;
2661                      i += inc) {
2662                         if (btree_path_cmp(trans->paths + trans->sorted[i],
2663                                            trans->paths + trans->sorted[i + 1]) > 0) {
2664                                 swap(trans->sorted[i], trans->sorted[i + 1]);
2665                                 trans->paths[trans->sorted[i]].sorted_idx = i;
2666                                 trans->paths[trans->sorted[i + 1]].sorted_idx = i + 1;
2667                                 swapped = true;
2668                         }
2669                 }
2670
2671                 if (inc > 0)
2672                         --r;
2673                 else
2674                         l++;
2675                 inc = -inc;
2676         } while (swapped);
2677
2678         trans->paths_sorted = true;
2679 out:
2680         btree_trans_verify_sorted(trans);
2681 }
2682
2683 static inline void btree_path_list_remove(struct btree_trans *trans,
2684                                           struct btree_path *path)
2685 {
2686         EBUG_ON(path->sorted_idx >= trans->nr_sorted);
2687 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2688         trans->nr_sorted--;
2689         memmove_u64s_down_small(trans->sorted + path->sorted_idx,
2690                                 trans->sorted + path->sorted_idx + 1,
2691                                 DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx,
2692                                              sizeof(u64) / sizeof(btree_path_idx_t)));
2693 #else
2694         array_remove_item(trans->sorted, trans->nr_sorted, path->sorted_idx);
2695 #endif
2696         for (unsigned i = path->sorted_idx; i < trans->nr_sorted; i++)
2697                 trans->paths[trans->sorted[i]].sorted_idx = i;
2698 }
2699
2700 static inline void btree_path_list_add(struct btree_trans *trans,
2701                                        btree_path_idx_t pos,
2702                                        btree_path_idx_t path_idx)
2703 {
2704         struct btree_path *path = trans->paths + path_idx;
2705
2706         path->sorted_idx = pos ? trans->paths[pos].sorted_idx + 1 : trans->nr_sorted;
2707
2708 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2709         memmove_u64s_up_small(trans->sorted + path->sorted_idx + 1,
2710                               trans->sorted + path->sorted_idx,
2711                               DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx,
2712                                            sizeof(u64) / sizeof(btree_path_idx_t)));
2713         trans->nr_sorted++;
2714         trans->sorted[path->sorted_idx] = path_idx;
2715 #else
2716         array_insert_item(trans->sorted, trans->nr_sorted, path->sorted_idx, path_idx);
2717 #endif
2718
2719         for (unsigned i = path->sorted_idx; i < trans->nr_sorted; i++)
2720                 trans->paths[trans->sorted[i]].sorted_idx = i;
2721
2722         btree_trans_verify_sorted_refs(trans);
2723 }
2724
2725 void bch2_trans_iter_exit(struct btree_trans *trans, struct btree_iter *iter)
2726 {
2727         if (iter->update_path)
2728                 bch2_path_put_nokeep(trans, iter->update_path,
2729                               iter->flags & BTREE_ITER_INTENT);
2730         if (iter->path)
2731                 bch2_path_put(trans, iter->path,
2732                               iter->flags & BTREE_ITER_INTENT);
2733         if (iter->key_cache_path)
2734                 bch2_path_put(trans, iter->key_cache_path,
2735                               iter->flags & BTREE_ITER_INTENT);
2736         iter->path              = 0;
2737         iter->update_path       = 0;
2738         iter->key_cache_path    = 0;
2739         iter->trans             = NULL;
2740 }
2741
2742 void bch2_trans_iter_init_outlined(struct btree_trans *trans,
2743                           struct btree_iter *iter,
2744                           enum btree_id btree_id, struct bpos pos,
2745                           unsigned flags)
2746 {
2747         bch2_trans_iter_init_common(trans, iter, btree_id, pos, 0, 0,
2748                                bch2_btree_iter_flags(trans, btree_id, flags),
2749                                _RET_IP_);
2750 }
2751
2752 void bch2_trans_node_iter_init(struct btree_trans *trans,
2753                                struct btree_iter *iter,
2754                                enum btree_id btree_id,
2755                                struct bpos pos,
2756                                unsigned locks_want,
2757                                unsigned depth,
2758                                unsigned flags)
2759 {
2760         flags |= BTREE_ITER_NOT_EXTENTS;
2761         flags |= __BTREE_ITER_ALL_SNAPSHOTS;
2762         flags |= BTREE_ITER_ALL_SNAPSHOTS;
2763
2764         bch2_trans_iter_init_common(trans, iter, btree_id, pos, locks_want, depth,
2765                                __bch2_btree_iter_flags(trans, btree_id, flags),
2766                                _RET_IP_);
2767
2768         iter->min_depth = depth;
2769
2770         struct btree_path *path = btree_iter_path(trans, iter);
2771         BUG_ON(path->locks_want  < min(locks_want, BTREE_MAX_DEPTH));
2772         BUG_ON(path->level      != depth);
2773         BUG_ON(iter->min_depth  != depth);
2774 }
2775
2776 void bch2_trans_copy_iter(struct btree_iter *dst, struct btree_iter *src)
2777 {
2778         struct btree_trans *trans = src->trans;
2779
2780         *dst = *src;
2781 #ifdef TRACK_PATH_ALLOCATED
2782         dst->ip_allocated = _RET_IP_;
2783 #endif
2784         if (src->path)
2785                 __btree_path_get(trans->paths + src->path, src->flags & BTREE_ITER_INTENT);
2786         if (src->update_path)
2787                 __btree_path_get(trans->paths + src->update_path, src->flags & BTREE_ITER_INTENT);
2788         dst->key_cache_path = 0;
2789 }
2790
2791 void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
2792 {
2793         struct bch_fs *c = trans->c;
2794         unsigned new_top = trans->mem_top + size;
2795         unsigned old_bytes = trans->mem_bytes;
2796         unsigned new_bytes = roundup_pow_of_two(new_top);
2797         int ret;
2798         void *new_mem;
2799         void *p;
2800
2801         WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);
2802
2803         struct btree_transaction_stats *s = btree_trans_stats(trans);
2804         s->max_mem = max(s->max_mem, new_bytes);
2805
2806         if (trans->used_mempool) {
2807                 if (trans->mem_bytes >= new_bytes)
2808                         goto out_change_top;
2809
2810                 /* No more space from mempool item, need malloc new one */
2811                 new_mem = kmalloc(new_bytes, GFP_NOWAIT|__GFP_NOWARN);
2812                 if (unlikely(!new_mem)) {
2813                         bch2_trans_unlock(trans);
2814
2815                         new_mem = kmalloc(new_bytes, GFP_KERNEL);
2816                         if (!new_mem)
2817                                 return ERR_PTR(-BCH_ERR_ENOMEM_trans_kmalloc);
2818
2819                         ret = bch2_trans_relock(trans);
2820                         if (ret) {
2821                                 kfree(new_mem);
2822                                 return ERR_PTR(ret);
2823                         }
2824                 }
2825                 memcpy(new_mem, trans->mem, trans->mem_top);
2826                 trans->used_mempool = false;
2827                 mempool_free(trans->mem, &c->btree_trans_mem_pool);
2828                 goto out_new_mem;
2829         }
2830
2831         new_mem = krealloc(trans->mem, new_bytes, GFP_NOWAIT|__GFP_NOWARN);
2832         if (unlikely(!new_mem)) {
2833                 bch2_trans_unlock(trans);
2834
2835                 new_mem = krealloc(trans->mem, new_bytes, GFP_KERNEL);
2836                 if (!new_mem && new_bytes <= BTREE_TRANS_MEM_MAX) {
2837                         new_mem = mempool_alloc(&c->btree_trans_mem_pool, GFP_KERNEL);
2838                         new_bytes = BTREE_TRANS_MEM_MAX;
2839                         memcpy(new_mem, trans->mem, trans->mem_top);
2840                         trans->used_mempool = true;
2841                         kfree(trans->mem);
2842                 }
2843
2844                 if (!new_mem)
2845                         return ERR_PTR(-BCH_ERR_ENOMEM_trans_kmalloc);
2846
2847                 trans->mem = new_mem;
2848                 trans->mem_bytes = new_bytes;
2849
2850                 ret = bch2_trans_relock(trans);
2851                 if (ret)
2852                         return ERR_PTR(ret);
2853         }
2854 out_new_mem:
2855         trans->mem = new_mem;
2856         trans->mem_bytes = new_bytes;
2857
2858         if (old_bytes) {
2859                 trace_and_count(c, trans_restart_mem_realloced, trans, _RET_IP_, new_bytes);
2860                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_mem_realloced));
2861         }
2862 out_change_top:
2863         p = trans->mem + trans->mem_top;
2864         trans->mem_top += size;
2865         memset(p, 0, size);
2866         return p;
2867 }
2868
2869 static inline void check_srcu_held_too_long(struct btree_trans *trans)
2870 {
2871         WARN(trans->srcu_held && time_after(jiffies, trans->srcu_lock_time + HZ * 10),
2872              "btree trans held srcu lock (delaying memory reclaim) for %lu seconds",
2873              (jiffies - trans->srcu_lock_time) / HZ);
2874 }
2875
2876 void bch2_trans_srcu_unlock(struct btree_trans *trans)
2877 {
2878         if (trans->srcu_held) {
2879                 struct bch_fs *c = trans->c;
2880                 struct btree_path *path;
2881                 unsigned i;
2882
2883                 trans_for_each_path(trans, path, i)
2884                         if (path->cached && !btree_node_locked(path, 0))
2885                                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_srcu_reset);
2886
2887                 check_srcu_held_too_long(trans);
2888                 srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
2889                 trans->srcu_held = false;
2890         }
2891 }
2892
2893 static void bch2_trans_srcu_lock(struct btree_trans *trans)
2894 {
2895         if (!trans->srcu_held) {
2896                 trans->srcu_idx = srcu_read_lock(&trans->c->btree_trans_barrier);
2897                 trans->srcu_lock_time   = jiffies;
2898                 trans->srcu_held = true;
2899         }
2900 }
2901
2902 /**
2903  * bch2_trans_begin() - reset a transaction after a interrupted attempt
2904  * @trans: transaction to reset
2905  *
2906  * Returns:     current restart counter, to be used with trans_was_restarted()
2907  *
2908  * While iterating over nodes or updating nodes a attempt to lock a btree node
2909  * may return BCH_ERR_transaction_restart when the trylock fails. When this
2910  * occurs bch2_trans_begin() should be called and the transaction retried.
2911  */
2912 u32 bch2_trans_begin(struct btree_trans *trans)
2913 {
2914         struct btree_path *path;
2915         unsigned i;
2916         u64 now;
2917
2918         bch2_trans_reset_updates(trans);
2919
2920         trans->restart_count++;
2921         trans->mem_top                  = 0;
2922         trans->journal_entries          = NULL;
2923
2924         trans_for_each_path(trans, path, i) {
2925                 path->should_be_locked = false;
2926
2927                 /*
2928                  * If the transaction wasn't restarted, we're presuming to be
2929                  * doing something new: dont keep iterators excpt the ones that
2930                  * are in use - except for the subvolumes btree:
2931                  */
2932                 if (!trans->restarted && path->btree_id != BTREE_ID_subvolumes)
2933                         path->preserve = false;
2934
2935                 /*
2936                  * XXX: we probably shouldn't be doing this if the transaction
2937                  * was restarted, but currently we still overflow transaction
2938                  * iterators if we do that
2939                  */
2940                 if (!path->ref && !path->preserve)
2941                         __bch2_path_free(trans, i);
2942                 else
2943                         path->preserve = false;
2944         }
2945
2946         now = local_clock();
2947
2948         if (!IS_ENABLED(CONFIG_BCACHEFS_NO_LATENCY_ACCT) &&
2949             time_after64(now, trans->last_begin_time + 10))
2950                 __bch2_time_stats_update(&btree_trans_stats(trans)->duration,
2951                                          trans->last_begin_time, now);
2952
2953         if (!trans->restarted &&
2954             (need_resched() ||
2955              time_after64(now, trans->last_begin_time + BTREE_TRANS_MAX_LOCK_HOLD_TIME_NS))) {
2956                 drop_locks_do(trans, (cond_resched(), 0));
2957                 now = local_clock();
2958         }
2959         trans->last_begin_time = now;
2960
2961         if (unlikely(trans->srcu_held &&
2962                      time_after(jiffies, trans->srcu_lock_time + msecs_to_jiffies(10))))
2963                 bch2_trans_srcu_unlock(trans);
2964
2965         trans->last_begin_ip = _RET_IP_;
2966         if (trans->restarted) {
2967                 bch2_btree_path_traverse_all(trans);
2968                 trans->notrace_relock_fail = false;
2969         }
2970
2971         return trans->restart_count;
2972 }
2973
2974 const char *bch2_btree_transaction_fns[BCH_TRANSACTIONS_NR] = { "(unknown)" };
2975
2976 unsigned bch2_trans_get_fn_idx(const char *fn)
2977 {
2978         for (unsigned i = 0; i < ARRAY_SIZE(bch2_btree_transaction_fns); i++)
2979                 if (!bch2_btree_transaction_fns[i] ||
2980                     bch2_btree_transaction_fns[i] == fn) {
2981                         bch2_btree_transaction_fns[i] = fn;
2982                         return i;
2983                 }
2984
2985         pr_warn_once("BCH_TRANSACTIONS_NR not big enough!");
2986         return 0;
2987 }
2988
2989 struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx)
2990         __acquires(&c->btree_trans_barrier)
2991 {
2992         struct btree_trans *trans;
2993
2994         if (IS_ENABLED(__KERNEL__)) {
2995                 trans = this_cpu_xchg(c->btree_trans_bufs->trans, NULL);
2996                 if (trans) {
2997                         memset(trans, 0, offsetof(struct btree_trans, list));
2998                         goto got_trans;
2999                 }
3000         }
3001
3002         trans = mempool_alloc(&c->btree_trans_pool, GFP_NOFS);
3003         memset(trans, 0, sizeof(*trans));
3004         closure_init_stack(&trans->ref);
3005
3006         seqmutex_lock(&c->btree_trans_lock);
3007         if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG)) {
3008                 struct btree_trans *pos;
3009                 pid_t pid = current->pid;
3010
3011                 trans->locking_wait.task = current;
3012
3013                 list_for_each_entry(pos, &c->btree_trans_list, list) {
3014                         struct task_struct *pos_task = READ_ONCE(pos->locking_wait.task);
3015                         /*
3016                          * We'd much prefer to be stricter here and completely
3017                          * disallow multiple btree_trans in the same thread -
3018                          * but the data move path calls bch2_write when we
3019                          * already have a btree_trans initialized.
3020                          */
3021                         BUG_ON(pos_task &&
3022                                pid == pos_task->pid &&
3023                                bch2_trans_locked(pos));
3024
3025                         if (pos_task && pid < pos_task->pid) {
3026                                 list_add_tail(&trans->list, &pos->list);
3027                                 goto list_add_done;
3028                         }
3029                 }
3030         }
3031         list_add_tail(&trans->list, &c->btree_trans_list);
3032 list_add_done:
3033         seqmutex_unlock(&c->btree_trans_lock);
3034 got_trans:
3035         trans->c                = c;
3036         trans->last_begin_time  = local_clock();
3037         trans->fn_idx           = fn_idx;
3038         trans->locking_wait.task = current;
3039         trans->journal_replay_not_finished =
3040                 unlikely(!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags)) &&
3041                 atomic_inc_not_zero(&c->journal_keys.ref);
3042         trans->nr_paths         = ARRAY_SIZE(trans->_paths);
3043         trans->paths_allocated  = trans->_paths_allocated;
3044         trans->sorted           = trans->_sorted;
3045         trans->paths            = trans->_paths;
3046         trans->updates          = trans->_updates;
3047
3048         *trans_paths_nr(trans->paths) = BTREE_ITER_INITIAL;
3049
3050         trans->paths_allocated[0] = 1;
3051
3052         if (fn_idx < BCH_TRANSACTIONS_NR) {
3053                 trans->fn = bch2_btree_transaction_fns[fn_idx];
3054
3055                 struct btree_transaction_stats *s = &c->btree_transaction_stats[fn_idx];
3056
3057                 if (s->max_mem) {
3058                         unsigned expected_mem_bytes = roundup_pow_of_two(s->max_mem);
3059
3060                         trans->mem = kmalloc(expected_mem_bytes, GFP_KERNEL);
3061                         if (likely(trans->mem))
3062                                 trans->mem_bytes = expected_mem_bytes;
3063                 }
3064
3065                 trans->nr_paths_max = s->nr_max_paths;
3066                 trans->journal_entries_size = s->journal_entries_size;
3067         }
3068
3069         trans->srcu_idx         = srcu_read_lock(&c->btree_trans_barrier);
3070         trans->srcu_lock_time   = jiffies;
3071         trans->srcu_held        = true;
3072         return trans;
3073 }
3074
3075 static void check_btree_paths_leaked(struct btree_trans *trans)
3076 {
3077 #ifdef CONFIG_BCACHEFS_DEBUG
3078         struct bch_fs *c = trans->c;
3079         struct btree_path *path;
3080         unsigned i;
3081
3082         trans_for_each_path(trans, path, i)
3083                 if (path->ref)
3084                         goto leaked;
3085         return;
3086 leaked:
3087         bch_err(c, "btree paths leaked from %s!", trans->fn);
3088         trans_for_each_path(trans, path, i)
3089                 if (path->ref)
3090                         printk(KERN_ERR "  btree %s %pS\n",
3091                                bch2_btree_id_str(path->btree_id),
3092                                (void *) path->ip_allocated);
3093         /* Be noisy about this: */
3094         bch2_fatal_error(c);
3095 #endif
3096 }
3097
3098 void bch2_trans_put(struct btree_trans *trans)
3099         __releases(&c->btree_trans_barrier)
3100 {
3101         struct bch_fs *c = trans->c;
3102
3103         bch2_trans_unlock(trans);
3104
3105         trans_for_each_update(trans, i)
3106                 __btree_path_put(trans->paths + i->path, true);
3107         trans->nr_updates       = 0;
3108         trans->locking_wait.task = NULL;
3109
3110         check_btree_paths_leaked(trans);
3111
3112         if (trans->srcu_held) {
3113                 check_srcu_held_too_long(trans);
3114                 srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
3115         }
3116
3117         if (trans->fs_usage_deltas) {
3118                 if (trans->fs_usage_deltas->size + sizeof(trans->fs_usage_deltas) ==
3119                     REPLICAS_DELTA_LIST_MAX)
3120                         mempool_free(trans->fs_usage_deltas,
3121                                      &c->replicas_delta_pool);
3122                 else
3123                         kfree(trans->fs_usage_deltas);
3124         }
3125
3126         if (unlikely(trans->journal_replay_not_finished))
3127                 bch2_journal_keys_put(c);
3128
3129         unsigned long *paths_allocated = trans->paths_allocated;
3130         trans->paths_allocated  = NULL;
3131         trans->paths            = NULL;
3132
3133         if (paths_allocated != trans->_paths_allocated)
3134                 kvfree_rcu_mightsleep(paths_allocated);
3135
3136         if (trans->used_mempool)
3137                 mempool_free(trans->mem, &c->btree_trans_mem_pool);
3138         else
3139                 kfree(trans->mem);
3140
3141         /* Userspace doesn't have a real percpu implementation: */
3142         if (IS_ENABLED(__KERNEL__))
3143                 trans = this_cpu_xchg(c->btree_trans_bufs->trans, trans);
3144
3145         if (trans) {
3146                 closure_sync(&trans->ref);
3147
3148                 seqmutex_lock(&c->btree_trans_lock);
3149                 list_del(&trans->list);
3150                 seqmutex_unlock(&c->btree_trans_lock);
3151
3152                 mempool_free(trans, &c->btree_trans_pool);
3153         }
3154 }
3155
3156 static void __maybe_unused
3157 bch2_btree_bkey_cached_common_to_text(struct printbuf *out,
3158                                       struct btree_bkey_cached_common *b)
3159 {
3160         struct six_lock_count c = six_lock_counts(&b->lock);
3161         struct task_struct *owner;
3162         pid_t pid;
3163
3164         rcu_read_lock();
3165         owner = READ_ONCE(b->lock.owner);
3166         pid = owner ? owner->pid : 0;
3167         rcu_read_unlock();
3168
3169         prt_tab(out);
3170         prt_printf(out, "%px %c l=%u %s:", b, b->cached ? 'c' : 'b',
3171                    b->level, bch2_btree_id_str(b->btree_id));
3172         bch2_bpos_to_text(out, btree_node_pos(b));
3173
3174         prt_tab(out);
3175         prt_printf(out, " locks %u:%u:%u held by pid %u",
3176                    c.n[0], c.n[1], c.n[2], pid);
3177 }
3178
3179 void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
3180 {
3181         struct btree_bkey_cached_common *b;
3182         static char lock_types[] = { 'r', 'i', 'w' };
3183         struct task_struct *task = READ_ONCE(trans->locking_wait.task);
3184         unsigned l, idx;
3185
3186         /* before rcu_read_lock(): */
3187         bch2_printbuf_make_room(out, 4096);
3188
3189         if (!out->nr_tabstops) {
3190                 printbuf_tabstop_push(out, 16);
3191                 printbuf_tabstop_push(out, 32);
3192         }
3193
3194         prt_printf(out, "%i %s\n", task ? task->pid : 0, trans->fn);
3195
3196         /* trans->paths is rcu protected vs. freeing */
3197         rcu_read_lock();
3198         out->atomic++;
3199
3200         struct btree_path *paths = rcu_dereference(trans->paths);
3201         if (!paths)
3202                 goto out;
3203
3204         unsigned long *paths_allocated = trans_paths_allocated(paths);
3205
3206         trans_for_each_path_idx_from(paths_allocated, *trans_paths_nr(paths), idx, 1) {
3207                 struct btree_path *path = paths + idx;
3208                 if (!path->nodes_locked)
3209                         continue;
3210
3211                 prt_printf(out, "  path %u %c l=%u %s:",
3212                        idx,
3213                        path->cached ? 'c' : 'b',
3214                        path->level,
3215                        bch2_btree_id_str(path->btree_id));
3216                 bch2_bpos_to_text(out, path->pos);
3217                 prt_newline(out);
3218
3219                 for (l = 0; l < BTREE_MAX_DEPTH; l++) {
3220                         if (btree_node_locked(path, l) &&
3221                             !IS_ERR_OR_NULL(b = (void *) READ_ONCE(path->l[l].b))) {
3222                                 prt_printf(out, "    %c l=%u ",
3223                                            lock_types[btree_node_locked_type(path, l)], l);
3224                                 bch2_btree_bkey_cached_common_to_text(out, b);
3225                                 prt_newline(out);
3226                         }
3227                 }
3228         }
3229
3230         b = READ_ONCE(trans->locking);
3231         if (b) {
3232                 prt_printf(out, "  blocked for %lluus on",
3233                            div_u64(local_clock() - trans->locking_wait.start_time,
3234                                    1000));
3235                 prt_newline(out);
3236                 prt_printf(out, "    %c", lock_types[trans->locking_wait.lock_want]);
3237                 bch2_btree_bkey_cached_common_to_text(out, b);
3238                 prt_newline(out);
3239         }
3240 out:
3241         --out->atomic;
3242         rcu_read_unlock();
3243 }
3244
3245 void bch2_fs_btree_iter_exit(struct bch_fs *c)
3246 {
3247         struct btree_transaction_stats *s;
3248         struct btree_trans *trans;
3249         int cpu;
3250
3251         if (c->btree_trans_bufs)
3252                 for_each_possible_cpu(cpu) {
3253                         struct btree_trans *trans =
3254                                 per_cpu_ptr(c->btree_trans_bufs, cpu)->trans;
3255
3256                         if (trans) {
3257                                 closure_sync(&trans->ref);
3258
3259                                 seqmutex_lock(&c->btree_trans_lock);
3260                                 list_del(&trans->list);
3261                                 seqmutex_unlock(&c->btree_trans_lock);
3262                         }
3263                         kfree(trans);
3264                 }
3265         free_percpu(c->btree_trans_bufs);
3266
3267         trans = list_first_entry_or_null(&c->btree_trans_list, struct btree_trans, list);
3268         if (trans)
3269                 panic("%s leaked btree_trans\n", trans->fn);
3270
3271         for (s = c->btree_transaction_stats;
3272              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3273              s++) {
3274                 kfree(s->max_paths_text);
3275                 bch2_time_stats_exit(&s->lock_hold_times);
3276         }
3277
3278         if (c->btree_trans_barrier_initialized)
3279                 cleanup_srcu_struct(&c->btree_trans_barrier);
3280         mempool_exit(&c->btree_trans_mem_pool);
3281         mempool_exit(&c->btree_trans_pool);
3282 }
3283
3284 void bch2_fs_btree_iter_init_early(struct bch_fs *c)
3285 {
3286         struct btree_transaction_stats *s;
3287
3288         for (s = c->btree_transaction_stats;
3289              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3290              s++) {
3291                 bch2_time_stats_init(&s->duration);
3292                 bch2_time_stats_init(&s->lock_hold_times);
3293                 mutex_init(&s->lock);
3294         }
3295
3296         INIT_LIST_HEAD(&c->btree_trans_list);
3297         seqmutex_init(&c->btree_trans_lock);
3298 }
3299
3300 int bch2_fs_btree_iter_init(struct bch_fs *c)
3301 {
3302         int ret;
3303
3304         c->btree_trans_bufs = alloc_percpu(struct btree_trans_buf);
3305         if (!c->btree_trans_bufs)
3306                 return -ENOMEM;
3307
3308         ret   = mempool_init_kmalloc_pool(&c->btree_trans_pool, 1,
3309                                           sizeof(struct btree_trans)) ?:
3310                 mempool_init_kmalloc_pool(&c->btree_trans_mem_pool, 1,
3311                                           BTREE_TRANS_MEM_MAX) ?:
3312                 init_srcu_struct(&c->btree_trans_barrier);
3313         if (!ret)
3314                 c->btree_trans_barrier_initialized = true;
3315         return ret;
3316 }