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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "bkey_methods.h"
   5 #include "bkey_buf.h"
   6 #include "btree_cache.h"
   7 #include "btree_iter.h"
   8 #include "btree_journal_iter.h"
   9 #include "btree_key_cache.h"
  10 #include "btree_locking.h"
  11 #include "btree_update.h"
  12 #include "debug.h"
  13 #include "error.h"
  14 #include "extents.h"
  15 #include "journal.h"
  16 #include "journal_io.h"
  17 #include "replicas.h"
  18 #include "snapshot.h"
  19 #include "trace.h"
  20
  21 #include <linux/random.h>
  22 #include <linux/prefetch.h>
  23
  24 static inline void btree_path_list_remove(struct btree_trans *, struct btree_path *);
  25 static inline void btree_path_list_add(struct btree_trans *,
  26                         btree_path_idx_t, btree_path_idx_t);
  27
  28 static inline unsigned long btree_iter_ip_allocated(struct btree_iter *iter)
  29 {
  30 #ifdef TRACK_PATH_ALLOCATED
  31         return iter->ip_allocated;
  32 #else
  33         return 0;
  34 #endif
  35 }
  36
  37 static btree_path_idx_t btree_path_alloc(struct btree_trans *, btree_path_idx_t);
  38 static void bch2_trans_srcu_lock(struct btree_trans *);
  39
  40 static inline int __btree_path_cmp(const struct btree_path *l,
  41                                    enum btree_id        r_btree_id,
  42                                    bool                 r_cached,
  43                                    struct bpos          r_pos,
  44                                    unsigned             r_level)
  45 {
  46         /*
  47          * Must match lock ordering as defined by __bch2_btree_node_lock:
  48          */
  49         return   cmp_int(l->btree_id,   r_btree_id) ?:
  50                  cmp_int((int) l->cached,       (int) r_cached) ?:
  51                  bpos_cmp(l->pos,       r_pos) ?:
  52                 -cmp_int(l->level,      r_level);
  53 }
  54
  55 static inline int btree_path_cmp(const struct btree_path *l,
  56                                  const struct btree_path *r)
  57 {
  58         return __btree_path_cmp(l, r->btree_id, r->cached, r->pos, r->level);
  59 }
  60
  61 static inline struct bpos bkey_successor(struct btree_iter *iter, struct bpos p)
  62 {
  63         /* Are we iterating over keys in all snapshots? */
  64         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  65                 p = bpos_successor(p);
  66         } else {
  67                 p = bpos_nosnap_successor(p);
  68                 p.snapshot = iter->snapshot;
  69         }
  70
  71         return p;
  72 }
  73
  74 static inline struct bpos bkey_predecessor(struct btree_iter *iter, struct bpos p)
  75 {
  76         /* Are we iterating over keys in all snapshots? */
  77         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  78                 p = bpos_predecessor(p);
  79         } else {
  80                 p = bpos_nosnap_predecessor(p);
  81                 p.snapshot = iter->snapshot;
  82         }
  83
  84         return p;
  85 }
  86
  87 static inline struct bpos btree_iter_search_key(struct btree_iter *iter)
  88 {
  89         struct bpos pos = iter->pos;
  90
  91         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
  92             !bkey_eq(pos, POS_MAX))
  93                 pos = bkey_successor(iter, pos);
  94         return pos;
  95 }
  96
  97 static inline bool btree_path_pos_before_node(struct btree_path *path,
  98                                               struct btree *b)
  99 {
 100         return bpos_lt(path->pos, b->data->min_key);
 101 }
 102
 103 static inline bool btree_path_pos_after_node(struct btree_path *path,
 104                                              struct btree *b)
 105 {
 106         return bpos_gt(path->pos, b->key.k.p);
 107 }
 108
 109 static inline bool btree_path_pos_in_node(struct btree_path *path,
 110                                           struct btree *b)
 111 {
 112         return path->btree_id == b->c.btree_id &&
 113                 !btree_path_pos_before_node(path, b) &&
 114                 !btree_path_pos_after_node(path, b);
 115 }
 116
 117 /* Btree iterator: */
 118
 119 #ifdef CONFIG_BCACHEFS_DEBUG
 120
 121 static void bch2_btree_path_verify_cached(struct btree_trans *trans,
 122                                           struct btree_path *path)
 123 {
 124         struct bkey_cached *ck;
 125         bool locked = btree_node_locked(path, 0);
 126
 127         if (!bch2_btree_node_relock(trans, path, 0))
 128                 return;
 129
 130         ck = (void *) path->l[0].b;
 131         BUG_ON(ck->key.btree_id != path->btree_id ||
 132                !bkey_eq(ck->key.pos, path->pos));
 133
 134         if (!locked)
 135                 btree_node_unlock(trans, path, 0);
 136 }
 137
 138 static void bch2_btree_path_verify_level(struct btree_trans *trans,
 139                                 struct btree_path *path, unsigned level)
 140 {
 141         struct btree_path_level *l;
 142         struct btree_node_iter tmp;
 143         bool locked;
 144         struct bkey_packed *p, *k;
 145         struct printbuf buf1 = PRINTBUF;
 146         struct printbuf buf2 = PRINTBUF;
 147         struct printbuf buf3 = PRINTBUF;
 148         const char *msg;
 149
 150         if (!bch2_debug_check_iterators)
 151                 return;
 152
 153         l       = &path->l[level];
 154         tmp     = l->iter;
 155         locked  = btree_node_locked(path, level);
 156
 157         if (path->cached) {
 158                 if (!level)
 159                         bch2_btree_path_verify_cached(trans, path);
 160                 return;
 161         }
 162
 163         if (!btree_path_node(path, level))
 164                 return;
 165
 166         if (!bch2_btree_node_relock_notrace(trans, path, level))
 167                 return;
 168
 169         BUG_ON(!btree_path_pos_in_node(path, l->b));
 170
 171         bch2_btree_node_iter_verify(&l->iter, l->b);
 172
 173         /*
 174          * For interior nodes, the iterator will have skipped past deleted keys:
 175          */
 176         p = level
 177                 ? bch2_btree_node_iter_prev(&tmp, l->b)
 178                 : bch2_btree_node_iter_prev_all(&tmp, l->b);
 179         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 180
 181         if (p && bkey_iter_pos_cmp(l->b, p, &path->pos) >= 0) {
 182                 msg = "before";
 183                 goto err;
 184         }
 185
 186         if (k && bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 187                 msg = "after";
 188                 goto err;
 189         }
 190
 191         if (!locked)
 192                 btree_node_unlock(trans, path, level);
 193         return;
 194 err:
 195         bch2_bpos_to_text(&buf1, path->pos);
 196
 197         if (p) {
 198                 struct bkey uk = bkey_unpack_key(l->b, p);
 199
 200                 bch2_bkey_to_text(&buf2, &uk);
 201         } else {
 202                 prt_printf(&buf2, "(none)");
 203         }
 204
 205         if (k) {
 206                 struct bkey uk = bkey_unpack_key(l->b, k);
 207
 208                 bch2_bkey_to_text(&buf3, &uk);
 209         } else {
 210                 prt_printf(&buf3, "(none)");
 211         }
 212
 213         panic("path should be %s key at level %u:\n"
 214               "path pos %s\n"
 215               "prev key %s\n"
 216               "cur  key %s\n",
 217               msg, level, buf1.buf, buf2.buf, buf3.buf);
 218 }
 219
 220 static void bch2_btree_path_verify(struct btree_trans *trans,
 221                                    struct btree_path *path)
 222 {
 223         struct bch_fs *c = trans->c;
 224         unsigned i;
 225
 226         EBUG_ON(path->btree_id >= BTREE_ID_NR);
 227
 228         for (i = 0; i < (!path->cached ? BTREE_MAX_DEPTH : 1); i++) {
 229                 if (!path->l[i].b) {
 230                         BUG_ON(!path->cached &&
 231                                bch2_btree_id_root(c, path->btree_id)->b->c.level > i);
 232                         break;
 233                 }
 234
 235                 bch2_btree_path_verify_level(trans, path, i);
 236         }
 237
 238         bch2_btree_path_verify_locks(path);
 239 }
 240
 241 void bch2_trans_verify_paths(struct btree_trans *trans)
 242 {
 243         struct btree_path *path;
 244         unsigned iter;
 245
 246         trans_for_each_path(trans, path, iter)
 247                 bch2_btree_path_verify(trans, path);
 248 }
 249
 250 static void bch2_btree_iter_verify(struct btree_iter *iter)
 251 {
 252         struct btree_trans *trans = iter->trans;
 253
 254         BUG_ON(iter->btree_id >= BTREE_ID_NR);
 255
 256         BUG_ON(!!(iter->flags & BTREE_ITER_CACHED) != btree_iter_path(trans, iter)->cached);
 257
 258         BUG_ON((iter->flags & BTREE_ITER_IS_EXTENTS) &&
 259                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
 260
 261         BUG_ON(!(iter->flags & __BTREE_ITER_ALL_SNAPSHOTS) &&
 262                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 263                !btree_type_has_snapshot_field(iter->btree_id));
 264
 265         if (iter->update_path)
 266                 bch2_btree_path_verify(trans, &trans->paths[iter->update_path]);
 267         bch2_btree_path_verify(trans, btree_iter_path(trans, iter));
 268 }
 269
 270 static void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter)
 271 {
 272         BUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
 273                !iter->pos.snapshot);
 274
 275         BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 276                iter->pos.snapshot != iter->snapshot);
 277
 278         BUG_ON(bkey_lt(iter->pos, bkey_start_pos(&iter->k)) ||
 279                bkey_gt(iter->pos, iter->k.p));
 280 }
 281
 282 static int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k)
 283 {
 284         struct btree_trans *trans = iter->trans;
 285         struct btree_iter copy;
 286         struct bkey_s_c prev;
 287         int ret = 0;
 288
 289         if (!bch2_debug_check_iterators)
 290                 return 0;
 291
 292         if (!(iter->flags & BTREE_ITER_FILTER_SNAPSHOTS))
 293                 return 0;
 294
 295         if (bkey_err(k) || !k.k)
 296                 return 0;
 297
 298         BUG_ON(!bch2_snapshot_is_ancestor(trans->c,
 299                                           iter->snapshot,
 300                                           k.k->p.snapshot));
 301
 302         bch2_trans_iter_init(trans, &copy, iter->btree_id, iter->pos,
 303                              BTREE_ITER_NOPRESERVE|
 304                              BTREE_ITER_ALL_SNAPSHOTS);
 305         prev = bch2_btree_iter_prev(&copy);
 306         if (!prev.k)
 307                 goto out;
 308
 309         ret = bkey_err(prev);
 310         if (ret)
 311                 goto out;
 312
 313         if (bkey_eq(prev.k->p, k.k->p) &&
 314             bch2_snapshot_is_ancestor(trans->c, iter->snapshot,
 315                                       prev.k->p.snapshot) > 0) {
 316                 struct printbuf buf1 = PRINTBUF, buf2 = PRINTBUF;
 317
 318                 bch2_bkey_to_text(&buf1, k.k);
 319                 bch2_bkey_to_text(&buf2, prev.k);
 320
 321                 panic("iter snap %u\n"
 322                       "k    %s\n"
 323                       "prev %s\n",
 324                       iter->snapshot,
 325                       buf1.buf, buf2.buf);
 326         }
 327 out:
 328         bch2_trans_iter_exit(trans, &copy);
 329         return ret;
 330 }
 331
 332 void bch2_assert_pos_locked(struct btree_trans *trans, enum btree_id id,
 333                             struct bpos pos, bool key_cache)
 334 {
 335         struct btree_path *path;
 336         struct trans_for_each_path_inorder_iter iter;
 337         struct printbuf buf = PRINTBUF;
 338
 339         btree_trans_sort_paths(trans);
 340
 341         trans_for_each_path_inorder(trans, path, iter) {
 342                 int cmp = cmp_int(path->btree_id, id) ?:
 343                         cmp_int(path->cached, key_cache);
 344
 345                 if (cmp > 0)
 346                         break;
 347                 if (cmp < 0)
 348                         continue;
 349
 350                 if (!btree_node_locked(path, 0) ||
 351                     !path->should_be_locked)
 352                         continue;
 353
 354                 if (!key_cache) {
 355                         if (bkey_ge(pos, path->l[0].b->data->min_key) &&
 356                             bkey_le(pos, path->l[0].b->key.k.p))
 357                                 return;
 358                 } else {
 359                         if (bkey_eq(pos, path->pos))
 360                                 return;
 361                 }
 362         }
 363
 364         bch2_dump_trans_paths_updates(trans);
 365         bch2_bpos_to_text(&buf, pos);
 366
 367         panic("not locked: %s %s%s\n",
 368               bch2_btree_id_str(id), buf.buf,
 369               key_cache ? " cached" : "");
 370 }
 371
 372 #else
 373
 374 static inline void bch2_btree_path_verify_level(struct btree_trans *trans,
 375                                                 struct btree_path *path, unsigned l) {}
 376 static inline void bch2_btree_path_verify(struct btree_trans *trans,
 377                                           struct btree_path *path) {}
 378 static inline void bch2_btree_iter_verify(struct btree_iter *iter) {}
 379 static inline void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter) {}
 380 static inline int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k) { return 0; }
 381
 382 #endif
 383
 384 /* Btree path: fixups after btree updates */
 385
 386 static void btree_node_iter_set_set_pos(struct btree_node_iter *iter,
 387                                         struct btree *b,
 388                                         struct bset_tree *t,
 389                                         struct bkey_packed *k)
 390 {
 391         struct btree_node_iter_set *set;
 392
 393         btree_node_iter_for_each(iter, set)
 394                 if (set->end == t->end_offset) {
 395                         set->k = __btree_node_key_to_offset(b, k);
 396                         bch2_btree_node_iter_sort(iter, b);
 397                         return;
 398                 }
 399
 400         bch2_btree_node_iter_push(iter, b, k, btree_bkey_last(b, t));
 401 }
 402
 403 static void __bch2_btree_path_fix_key_modified(struct btree_path *path,
 404                                                struct btree *b,
 405                                                struct bkey_packed *where)
 406 {
 407         struct btree_path_level *l = &path->l[b->c.level];
 408
 409         if (where != bch2_btree_node_iter_peek_all(&l->iter, l->b))
 410                 return;
 411
 412         if (bkey_iter_pos_cmp(l->b, where, &path->pos) < 0)
 413                 bch2_btree_node_iter_advance(&l->iter, l->b);
 414 }
 415
 416 void bch2_btree_path_fix_key_modified(struct btree_trans *trans,
 417                                       struct btree *b,
 418                                       struct bkey_packed *where)
 419 {
 420         struct btree_path *path;
 421         unsigned i;
 422
 423         trans_for_each_path_with_node(trans, b, path, i) {
 424                 __bch2_btree_path_fix_key_modified(path, b, where);
 425                 bch2_btree_path_verify_level(trans, path, b->c.level);
 426         }
 427 }
 428
 429 static void __bch2_btree_node_iter_fix(struct btree_path *path,
 430                                        struct btree *b,
 431                                        struct btree_node_iter *node_iter,
 432                                        struct bset_tree *t,
 433                                        struct bkey_packed *where,
 434                                        unsigned clobber_u64s,
 435                                        unsigned new_u64s)
 436 {
 437         const struct bkey_packed *end = btree_bkey_last(b, t);
 438         struct btree_node_iter_set *set;
 439         unsigned offset = __btree_node_key_to_offset(b, where);
 440         int shift = new_u64s - clobber_u64s;
 441         unsigned old_end = t->end_offset - shift;
 442         unsigned orig_iter_pos = node_iter->data[0].k;
 443         bool iter_current_key_modified =
 444                 orig_iter_pos >= offset &&
 445                 orig_iter_pos <= offset + clobber_u64s;
 446
 447         btree_node_iter_for_each(node_iter, set)
 448                 if (set->end == old_end)
 449                         goto found;
 450
 451         /* didn't find the bset in the iterator - might have to readd it: */
 452         if (new_u64s &&
 453             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 454                 bch2_btree_node_iter_push(node_iter, b, where, end);
 455                 goto fixup_done;
 456         } else {
 457                 /* Iterator is after key that changed */
 458                 return;
 459         }
 460 found:
 461         set->end = t->end_offset;
 462
 463         /* Iterator hasn't gotten to the key that changed yet: */
 464         if (set->k < offset)
 465                 return;
 466
 467         if (new_u64s &&
 468             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 469                 set->k = offset;
 470         } else if (set->k < offset + clobber_u64s) {
 471                 set->k = offset + new_u64s;
 472                 if (set->k == set->end)
 473                         bch2_btree_node_iter_set_drop(node_iter, set);
 474         } else {
 475                 /* Iterator is after key that changed */
 476                 set->k = (int) set->k + shift;
 477                 return;
 478         }
 479
 480         bch2_btree_node_iter_sort(node_iter, b);
 481 fixup_done:
 482         if (node_iter->data[0].k != orig_iter_pos)
 483                 iter_current_key_modified = true;
 484
 485         /*
 486          * When a new key is added, and the node iterator now points to that
 487          * key, the iterator might have skipped past deleted keys that should
 488          * come after the key the iterator now points to. We have to rewind to
 489          * before those deleted keys - otherwise
 490          * bch2_btree_node_iter_prev_all() breaks:
 491          */
 492         if (!bch2_btree_node_iter_end(node_iter) &&
 493             iter_current_key_modified &&
 494             b->c.level) {
 495                 struct bkey_packed *k, *k2, *p;
 496
 497                 k = bch2_btree_node_iter_peek_all(node_iter, b);
 498
 499                 for_each_bset(b, t) {
 500                         bool set_pos = false;
 501
 502                         if (node_iter->data[0].end == t->end_offset)
 503                                 continue;
 504
 505                         k2 = bch2_btree_node_iter_bset_pos(node_iter, b, t);
 506
 507                         while ((p = bch2_bkey_prev_all(b, t, k2)) &&
 508                                bkey_iter_cmp(b, k, p) < 0) {
 509                                 k2 = p;
 510                                 set_pos = true;
 511                         }
 512
 513                         if (set_pos)
 514                                 btree_node_iter_set_set_pos(node_iter,
 515                                                             b, t, k2);
 516                 }
 517         }
 518 }
 519
 520 void bch2_btree_node_iter_fix(struct btree_trans *trans,
 521                               struct btree_path *path,
 522                               struct btree *b,
 523                               struct btree_node_iter *node_iter,
 524                               struct bkey_packed *where,
 525                               unsigned clobber_u64s,
 526                               unsigned new_u64s)
 527 {
 528         struct bset_tree *t = bch2_bkey_to_bset_inlined(b, where);
 529         struct btree_path *linked;
 530         unsigned i;
 531
 532         if (node_iter != &path->l[b->c.level].iter) {
 533                 __bch2_btree_node_iter_fix(path, b, node_iter, t,
 534                                            where, clobber_u64s, new_u64s);
 535
 536                 if (bch2_debug_check_iterators)
 537                         bch2_btree_node_iter_verify(node_iter, b);
 538         }
 539
 540         trans_for_each_path_with_node(trans, b, linked, i) {
 541                 __bch2_btree_node_iter_fix(linked, b,
 542                                            &linked->l[b->c.level].iter, t,
 543                                            where, clobber_u64s, new_u64s);
 544                 bch2_btree_path_verify_level(trans, linked, b->c.level);
 545         }
 546 }
 547
 548 /* Btree path level: pointer to a particular btree node and node iter */
 549
 550 static inline struct bkey_s_c __btree_iter_unpack(struct bch_fs *c,
 551                                                   struct btree_path_level *l,
 552                                                   struct bkey *u,
 553                                                   struct bkey_packed *k)
 554 {
 555         if (unlikely(!k)) {
 556                 /*
 557                  * signal to bch2_btree_iter_peek_slot() that we're currently at
 558                  * a hole
 559                  */
 560                 u->type = KEY_TYPE_deleted;
 561                 return bkey_s_c_null;
 562         }
 563
 564         return bkey_disassemble(l->b, k, u);
 565 }
 566
 567 static inline struct bkey_s_c btree_path_level_peek_all(struct bch_fs *c,
 568                                                         struct btree_path_level *l,
 569                                                         struct bkey *u)
 570 {
 571         return __btree_iter_unpack(c, l, u,
 572                         bch2_btree_node_iter_peek_all(&l->iter, l->b));
 573 }
 574
 575 static inline struct bkey_s_c btree_path_level_peek(struct btree_trans *trans,
 576                                                     struct btree_path *path,
 577                                                     struct btree_path_level *l,
 578                                                     struct bkey *u)
 579 {
 580         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 581                         bch2_btree_node_iter_peek(&l->iter, l->b));
 582
 583         path->pos = k.k ? k.k->p : l->b->key.k.p;
 584         trans->paths_sorted = false;
 585         bch2_btree_path_verify_level(trans, path, l - path->l);
 586         return k;
 587 }
 588
 589 static inline struct bkey_s_c btree_path_level_prev(struct btree_trans *trans,
 590                                                     struct btree_path *path,
 591                                                     struct btree_path_level *l,
 592                                                     struct bkey *u)
 593 {
 594         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 595                         bch2_btree_node_iter_prev(&l->iter, l->b));
 596
 597         path->pos = k.k ? k.k->p : l->b->data->min_key;
 598         trans->paths_sorted = false;
 599         bch2_btree_path_verify_level(trans, path, l - path->l);
 600         return k;
 601 }
 602
 603 static inline bool btree_path_advance_to_pos(struct btree_path *path,
 604                                              struct btree_path_level *l,
 605                                              int max_advance)
 606 {
 607         struct bkey_packed *k;
 608         int nr_advanced = 0;
 609
 610         while ((k = bch2_btree_node_iter_peek_all(&l->iter, l->b)) &&
 611                bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 612                 if (max_advance > 0 && nr_advanced >= max_advance)
 613                         return false;
 614
 615                 bch2_btree_node_iter_advance(&l->iter, l->b);
 616                 nr_advanced++;
 617         }
 618
 619         return true;
 620 }
 621
 622 static inline void __btree_path_level_init(struct btree_path *path,
 623                                            unsigned level)
 624 {
 625         struct btree_path_level *l = &path->l[level];
 626
 627         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
 628
 629         /*
 630          * Iterators to interior nodes should always be pointed at the first non
 631          * whiteout:
 632          */
 633         if (level)
 634                 bch2_btree_node_iter_peek(&l->iter, l->b);
 635 }
 636
 637 void bch2_btree_path_level_init(struct btree_trans *trans,
 638                                 struct btree_path *path,
 639                                 struct btree *b)
 640 {
 641         BUG_ON(path->cached);
 642
 643         EBUG_ON(!btree_path_pos_in_node(path, b));
 644
 645         path->l[b->c.level].lock_seq = six_lock_seq(&b->c.lock);
 646         path->l[b->c.level].b = b;
 647         __btree_path_level_init(path, b->c.level);
 648 }
 649
 650 /* Btree path: fixups after btree node updates: */
 651
 652 static void bch2_trans_revalidate_updates_in_node(struct btree_trans *trans, struct btree *b)
 653 {
 654         struct bch_fs *c = trans->c;
 655
 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(&jiter, c, 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                 bch2_bkey_buf_unpack(&tmp, c, l->b,
 931                                  bch2_btree_node_iter_peek(&l->iter, l->b));
 932
 933                 if ((flags & BTREE_ITER_PREFETCH) &&
 934                     c->opts.btree_node_prefetch) {
 935                         ret = btree_path_prefetch(trans, path);
 936                         if (ret)
 937                                 goto err;
 938                 }
 939         }
 940
 941         b = bch2_btree_node_get(trans, path, tmp.k, level, lock_type, trace_ip);
 942         ret = PTR_ERR_OR_ZERO(b);
 943         if (unlikely(ret))
 944                 goto err;
 945
 946         if (likely(!trans->journal_replay_not_finished &&
 947                    tmp.k->k.type == KEY_TYPE_btree_ptr_v2) &&
 948             unlikely(b != btree_node_mem_ptr(tmp.k)))
 949                 btree_node_mem_ptr_set(trans, path, level + 1, b);
 950
 951         if (btree_node_read_locked(path, level + 1))
 952                 btree_node_unlock(trans, path, level + 1);
 953
 954         mark_btree_node_locked(trans, path, level,
 955                                (enum btree_node_locked_type) lock_type);
 956         path->level = level;
 957         bch2_btree_path_level_init(trans, path, b);
 958
 959         bch2_btree_path_verify_locks(path);
 960 err:
 961         bch2_bkey_buf_exit(&tmp, c);
 962         return ret;
 963 }
 964
 965
 966 static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 967 {
 968         struct bch_fs *c = trans->c;
 969         struct btree_path *path;
 970         unsigned long trace_ip = _RET_IP_;
 971         unsigned i;
 972         int ret = 0;
 973
 974         if (trans->in_traverse_all)
 975                 return -BCH_ERR_transaction_restart_in_traverse_all;
 976
 977         trans->in_traverse_all = true;
 978 retry_all:
 979         trans->restarted = 0;
 980         trans->last_restarted_ip = 0;
 981
 982         trans_for_each_path(trans, path, i)
 983                 path->should_be_locked = false;
 984
 985         btree_trans_sort_paths(trans);
 986
 987         bch2_trans_unlock(trans);
 988         cond_resched();
 989
 990         if (unlikely(trans->memory_allocation_failure)) {
 991                 struct closure cl;
 992
 993                 closure_init_stack(&cl);
 994
 995                 do {
 996                         ret = bch2_btree_cache_cannibalize_lock(trans, &cl);
 997                         closure_sync(&cl);
 998                 } while (ret);
 999         }
1000
1001         /* Now, redo traversals in correct order: */
1002         i = 0;
1003         while (i < trans->nr_sorted) {
1004                 btree_path_idx_t idx = trans->sorted[i];
1005
1006                 /*
1007                  * Traversing a path can cause another path to be added at about
1008                  * the same position:
1009                  */
1010                 if (trans->paths[idx].uptodate) {
1011                         __btree_path_get(&trans->paths[idx], false);
1012                         ret = bch2_btree_path_traverse_one(trans, idx, 0, _THIS_IP_);
1013                         __btree_path_put(&trans->paths[idx], false);
1014
1015                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) ||
1016                             bch2_err_matches(ret, ENOMEM))
1017                                 goto retry_all;
1018                         if (ret)
1019                                 goto err;
1020                 } else {
1021                         i++;
1022                 }
1023         }
1024
1025         /*
1026          * We used to assert that all paths had been traversed here
1027          * (path->uptodate < BTREE_ITER_NEED_TRAVERSE); however, since
1028          * path->should_be_locked is not set yet, we might have unlocked and
1029          * then failed to relock a path - that's fine.
1030          */
1031 err:
1032         bch2_btree_cache_cannibalize_unlock(trans);
1033
1034         trans->in_traverse_all = false;
1035
1036         trace_and_count(c, trans_traverse_all, trans, trace_ip);
1037         return ret;
1038 }
1039
1040 static inline bool btree_path_check_pos_in_node(struct btree_path *path,
1041                                                 unsigned l, int check_pos)
1042 {
1043         if (check_pos < 0 && btree_path_pos_before_node(path, path->l[l].b))
1044                 return false;
1045         if (check_pos > 0 && btree_path_pos_after_node(path, path->l[l].b))
1046                 return false;
1047         return true;
1048 }
1049
1050 static inline bool btree_path_good_node(struct btree_trans *trans,
1051                                         struct btree_path *path,
1052                                         unsigned l, int check_pos)
1053 {
1054         return is_btree_node(path, l) &&
1055                 bch2_btree_node_relock(trans, path, l) &&
1056                 btree_path_check_pos_in_node(path, l, check_pos);
1057 }
1058
1059 static void btree_path_set_level_down(struct btree_trans *trans,
1060                                       struct btree_path *path,
1061                                       unsigned new_level)
1062 {
1063         unsigned l;
1064
1065         path->level = new_level;
1066
1067         for (l = path->level + 1; l < BTREE_MAX_DEPTH; l++)
1068                 if (btree_lock_want(path, l) == BTREE_NODE_UNLOCKED)
1069                         btree_node_unlock(trans, path, l);
1070
1071         btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1072         bch2_btree_path_verify(trans, path);
1073 }
1074
1075 static noinline unsigned __btree_path_up_until_good_node(struct btree_trans *trans,
1076                                                          struct btree_path *path,
1077                                                          int check_pos)
1078 {
1079         unsigned i, l = path->level;
1080 again:
1081         while (btree_path_node(path, l) &&
1082                !btree_path_good_node(trans, path, l, check_pos))
1083                 __btree_path_set_level_up(trans, path, l++);
1084
1085         /* If we need intent locks, take them too: */
1086         for (i = l + 1;
1087              i < path->locks_want && btree_path_node(path, i);
1088              i++)
1089                 if (!bch2_btree_node_relock(trans, path, i)) {
1090                         while (l <= i)
1091                                 __btree_path_set_level_up(trans, path, l++);
1092                         goto again;
1093                 }
1094
1095         return l;
1096 }
1097
1098 static inline unsigned btree_path_up_until_good_node(struct btree_trans *trans,
1099                                                      struct btree_path *path,
1100                                                      int check_pos)
1101 {
1102         return likely(btree_node_locked(path, path->level) &&
1103                       btree_path_check_pos_in_node(path, path->level, check_pos))
1104                 ? path->level
1105                 : __btree_path_up_until_good_node(trans, path, check_pos);
1106 }
1107
1108 /*
1109  * This is the main state machine for walking down the btree - walks down to a
1110  * specified depth
1111  *
1112  * Returns 0 on success, -EIO on error (error reading in a btree node).
1113  *
1114  * On error, caller (peek_node()/peek_key()) must return NULL; the error is
1115  * stashed in the iterator and returned from bch2_trans_exit().
1116  */
1117 int bch2_btree_path_traverse_one(struct btree_trans *trans,
1118                                  btree_path_idx_t path_idx,
1119                                  unsigned flags,
1120                                  unsigned long trace_ip)
1121 {
1122         struct btree_path *path = &trans->paths[path_idx];
1123         unsigned depth_want = path->level;
1124         int ret = -((int) trans->restarted);
1125
1126         if (unlikely(ret))
1127                 goto out;
1128
1129         if (unlikely(!trans->srcu_held))
1130                 bch2_trans_srcu_lock(trans);
1131
1132         /*
1133          * Ensure we obey path->should_be_locked: if it's set, we can't unlock
1134          * and re-traverse the path without a transaction restart:
1135          */
1136         if (path->should_be_locked) {
1137                 ret = bch2_btree_path_relock(trans, path, trace_ip);
1138                 goto out;
1139         }
1140
1141         if (path->cached) {
1142                 ret = bch2_btree_path_traverse_cached(trans, path, flags);
1143                 goto out;
1144         }
1145
1146         path = &trans->paths[path_idx];
1147
1148         if (unlikely(path->level >= BTREE_MAX_DEPTH))
1149                 goto out;
1150
1151         path->level = btree_path_up_until_good_node(trans, path, 0);
1152
1153         EBUG_ON(btree_path_node(path, path->level) &&
1154                 !btree_node_locked(path, path->level));
1155
1156         /*
1157          * Note: path->nodes[path->level] may be temporarily NULL here - that
1158          * would indicate to other code that we got to the end of the btree,
1159          * here it indicates that relocking the root failed - it's critical that
1160          * btree_path_lock_root() comes next and that it can't fail
1161          */
1162         while (path->level > depth_want) {
1163                 ret = btree_path_node(path, path->level)
1164                         ? btree_path_down(trans, path, flags, trace_ip)
1165                         : btree_path_lock_root(trans, path, depth_want, trace_ip);
1166                 if (unlikely(ret)) {
1167                         if (ret == 1) {
1168                                 /*
1169                                  * No nodes at this level - got to the end of
1170                                  * the btree:
1171                                  */
1172                                 ret = 0;
1173                                 goto out;
1174                         }
1175
1176                         __bch2_btree_path_unlock(trans, path);
1177                         path->level = depth_want;
1178                         path->l[path->level].b = ERR_PTR(ret);
1179                         goto out;
1180                 }
1181         }
1182
1183         path->uptodate = BTREE_ITER_UPTODATE;
1184 out:
1185         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) != !!trans->restarted)
1186                 panic("ret %s (%i) trans->restarted %s (%i)\n",
1187                       bch2_err_str(ret), ret,
1188                       bch2_err_str(trans->restarted), trans->restarted);
1189         bch2_btree_path_verify(trans, path);
1190         return ret;
1191 }
1192
1193 static inline void btree_path_copy(struct btree_trans *trans, struct btree_path *dst,
1194                             struct btree_path *src)
1195 {
1196         unsigned i, offset = offsetof(struct btree_path, pos);
1197
1198         memcpy((void *) dst + offset,
1199                (void *) src + offset,
1200                sizeof(struct btree_path) - offset);
1201
1202         for (i = 0; i < BTREE_MAX_DEPTH; i++) {
1203                 unsigned t = btree_node_locked_type(dst, i);
1204
1205                 if (t != BTREE_NODE_UNLOCKED)
1206                         six_lock_increment(&dst->l[i].b->c.lock, t);
1207         }
1208 }
1209
1210 static btree_path_idx_t btree_path_clone(struct btree_trans *trans, btree_path_idx_t src,
1211                                          bool intent)
1212 {
1213         btree_path_idx_t new = btree_path_alloc(trans, src);
1214         btree_path_copy(trans, trans->paths + new, trans->paths + src);
1215         __btree_path_get(trans->paths + new, intent);
1216         return new;
1217 }
1218
1219 __flatten
1220 btree_path_idx_t __bch2_btree_path_make_mut(struct btree_trans *trans,
1221                         btree_path_idx_t path, bool intent, unsigned long ip)
1222 {
1223         __btree_path_put(trans->paths + path, intent);
1224         path = btree_path_clone(trans, path, intent);
1225         trans->paths[path].preserve = false;
1226         return path;
1227 }
1228
1229 btree_path_idx_t __must_check
1230 __bch2_btree_path_set_pos(struct btree_trans *trans,
1231                           btree_path_idx_t path_idx, struct bpos new_pos,
1232                           bool intent, unsigned long ip)
1233 {
1234         int cmp = bpos_cmp(new_pos, trans->paths[path_idx].pos);
1235
1236         bch2_trans_verify_not_in_restart(trans);
1237         EBUG_ON(!trans->paths[path_idx].ref);
1238
1239         path_idx = bch2_btree_path_make_mut(trans, path_idx, intent, ip);
1240
1241         struct btree_path *path = trans->paths + path_idx;
1242         path->pos               = new_pos;
1243         trans->paths_sorted     = false;
1244
1245         if (unlikely(path->cached)) {
1246                 btree_node_unlock(trans, path, 0);
1247                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_up);
1248                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1249                 goto out;
1250         }
1251
1252         unsigned level = btree_path_up_until_good_node(trans, path, cmp);
1253
1254         if (btree_path_node(path, level)) {
1255                 struct btree_path_level *l = &path->l[level];
1256
1257                 BUG_ON(!btree_node_locked(path, level));
1258                 /*
1259                  * We might have to skip over many keys, or just a few: try
1260                  * advancing the node iterator, and if we have to skip over too
1261                  * many keys just reinit it (or if we're rewinding, since that
1262                  * is expensive).
1263                  */
1264                 if (cmp < 0 ||
1265                     !btree_path_advance_to_pos(path, l, 8))
1266                         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
1267
1268                 /*
1269                  * Iterators to interior nodes should always be pointed at the first non
1270                  * whiteout:
1271                  */
1272                 if (unlikely(level))
1273                         bch2_btree_node_iter_peek(&l->iter, l->b);
1274         }
1275
1276         if (unlikely(level != path->level)) {
1277                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1278                 __bch2_btree_path_unlock(trans, path);
1279         }
1280 out:
1281         bch2_btree_path_verify(trans, path);
1282         return path_idx;
1283 }
1284
1285 /* Btree path: main interface: */
1286
1287 static struct btree_path *have_path_at_pos(struct btree_trans *trans, struct btree_path *path)
1288 {
1289         struct btree_path *sib;
1290
1291         sib = prev_btree_path(trans, path);
1292         if (sib && !btree_path_cmp(sib, path))
1293                 return sib;
1294
1295         sib = next_btree_path(trans, path);
1296         if (sib && !btree_path_cmp(sib, path))
1297                 return sib;
1298
1299         return NULL;
1300 }
1301
1302 static struct btree_path *have_node_at_pos(struct btree_trans *trans, struct btree_path *path)
1303 {
1304         struct btree_path *sib;
1305
1306         sib = prev_btree_path(trans, path);
1307         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1308                 return sib;
1309
1310         sib = next_btree_path(trans, path);
1311         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1312                 return sib;
1313
1314         return NULL;
1315 }
1316
1317 static inline void __bch2_path_free(struct btree_trans *trans, btree_path_idx_t path)
1318 {
1319         __bch2_btree_path_unlock(trans, trans->paths + path);
1320         btree_path_list_remove(trans, trans->paths + path);
1321         __clear_bit(path, trans->paths_allocated);
1322 }
1323
1324 void bch2_path_put(struct btree_trans *trans, btree_path_idx_t path_idx, bool intent)
1325 {
1326         struct btree_path *path = trans->paths + path_idx, *dup;
1327
1328         if (!__btree_path_put(path, intent))
1329                 return;
1330
1331         dup = path->preserve
1332                 ? have_path_at_pos(trans, path)
1333                 : have_node_at_pos(trans, path);
1334
1335         if (!dup && !(!path->preserve && !is_btree_node(path, path->level)))
1336                 return;
1337
1338         if (path->should_be_locked &&
1339             !trans->restarted &&
1340             (!dup || !bch2_btree_path_relock_norestart(trans, dup, _THIS_IP_)))
1341                 return;
1342
1343         if (dup) {
1344                 dup->preserve           |= path->preserve;
1345                 dup->should_be_locked   |= path->should_be_locked;
1346         }
1347
1348         __bch2_path_free(trans, path_idx);
1349 }
1350
1351 static void bch2_path_put_nokeep(struct btree_trans *trans, btree_path_idx_t path,
1352                                  bool intent)
1353 {
1354         if (!__btree_path_put(trans->paths + path, intent))
1355                 return;
1356
1357         __bch2_path_free(trans, path);
1358 }
1359
1360 void __noreturn bch2_trans_restart_error(struct btree_trans *trans, u32 restart_count)
1361 {
1362         panic("trans->restart_count %u, should be %u, last restarted by %pS\n",
1363               trans->restart_count, restart_count,
1364               (void *) trans->last_begin_ip);
1365 }
1366
1367 void __noreturn bch2_trans_in_restart_error(struct btree_trans *trans)
1368 {
1369         panic("in transaction restart: %s, last restarted by %pS\n",
1370               bch2_err_str(trans->restarted),
1371               (void *) trans->last_restarted_ip);
1372 }
1373
1374 noinline __cold
1375 void bch2_trans_updates_to_text(struct printbuf *buf, struct btree_trans *trans)
1376 {
1377         prt_printf(buf, "transaction updates for %s journal seq %llu",
1378                trans->fn, trans->journal_res.seq);
1379         prt_newline(buf);
1380         printbuf_indent_add(buf, 2);
1381
1382         trans_for_each_update(trans, i) {
1383                 struct bkey_s_c old = { &i->old_k, i->old_v };
1384
1385                 prt_printf(buf, "update: btree=%s cached=%u %pS",
1386                        bch2_btree_id_str(i->btree_id),
1387                        i->cached,
1388                        (void *) i->ip_allocated);
1389                 prt_newline(buf);
1390
1391                 prt_printf(buf, "  old ");
1392                 bch2_bkey_val_to_text(buf, trans->c, old);
1393                 prt_newline(buf);
1394
1395                 prt_printf(buf, "  new ");
1396                 bch2_bkey_val_to_text(buf, trans->c, bkey_i_to_s_c(i->k));
1397                 prt_newline(buf);
1398         }
1399
1400         for (struct jset_entry *e = trans->journal_entries;
1401              e != btree_trans_journal_entries_top(trans);
1402              e = vstruct_next(e))
1403                 bch2_journal_entry_to_text(buf, trans->c, e);
1404
1405         printbuf_indent_sub(buf, 2);
1406 }
1407
1408 noinline __cold
1409 void bch2_dump_trans_updates(struct btree_trans *trans)
1410 {
1411         struct printbuf buf = PRINTBUF;
1412
1413         bch2_trans_updates_to_text(&buf, trans);
1414         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1415         printbuf_exit(&buf);
1416 }
1417
1418 static void bch2_btree_path_to_text(struct printbuf *out, struct btree_trans *trans, btree_path_idx_t path_idx)
1419 {
1420         struct btree_path *path = trans->paths + path_idx;
1421
1422         prt_printf(out, "path: idx %2u ref %u:%u %c %c btree=%s l=%u pos ",
1423                    path_idx, path->ref, path->intent_ref,
1424                    path->preserve ? 'P' : ' ',
1425                    path->should_be_locked ? 'S' : ' ',
1426                    bch2_btree_id_str(path->btree_id),
1427                    path->level);
1428         bch2_bpos_to_text(out, path->pos);
1429
1430         prt_printf(out, " locks %u", path->nodes_locked);
1431 #ifdef TRACK_PATH_ALLOCATED
1432         prt_printf(out, " %pS", (void *) path->ip_allocated);
1433 #endif
1434         prt_newline(out);
1435 }
1436
1437 static noinline __cold
1438 void __bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans,
1439                                 bool nosort)
1440 {
1441         struct trans_for_each_path_inorder_iter iter;
1442
1443         if (!nosort)
1444                 btree_trans_sort_paths(trans);
1445
1446         trans_for_each_path_idx_inorder(trans, iter)
1447                 bch2_btree_path_to_text(out, trans, iter.path_idx);
1448 }
1449
1450 noinline __cold
1451 void bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans)
1452 {
1453         __bch2_trans_paths_to_text(out, trans, false);
1454 }
1455
1456 static noinline __cold
1457 void __bch2_dump_trans_paths_updates(struct btree_trans *trans, bool nosort)
1458 {
1459         struct printbuf buf = PRINTBUF;
1460
1461         __bch2_trans_paths_to_text(&buf, trans, nosort);
1462         bch2_trans_updates_to_text(&buf, trans);
1463
1464         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1465         printbuf_exit(&buf);
1466 }
1467
1468 noinline __cold
1469 void bch2_dump_trans_paths_updates(struct btree_trans *trans)
1470 {
1471         __bch2_dump_trans_paths_updates(trans, false);
1472 }
1473
1474 noinline __cold
1475 static void bch2_trans_update_max_paths(struct btree_trans *trans)
1476 {
1477         struct btree_transaction_stats *s = btree_trans_stats(trans);
1478         struct printbuf buf = PRINTBUF;
1479         size_t nr = bitmap_weight(trans->paths_allocated, trans->nr_paths);
1480
1481         bch2_trans_paths_to_text(&buf, trans);
1482
1483         if (!buf.allocation_failure) {
1484                 mutex_lock(&s->lock);
1485                 if (nr > s->nr_max_paths) {
1486                         s->nr_max_paths = nr;
1487                         swap(s->max_paths_text, buf.buf);
1488                 }
1489                 mutex_unlock(&s->lock);
1490         }
1491
1492         printbuf_exit(&buf);
1493
1494         trans->nr_paths_max = nr;
1495 }
1496
1497 noinline __cold
1498 int __bch2_btree_trans_too_many_iters(struct btree_trans *trans)
1499 {
1500         if (trace_trans_restart_too_many_iters_enabled()) {
1501                 struct printbuf buf = PRINTBUF;
1502
1503                 bch2_trans_paths_to_text(&buf, trans);
1504                 trace_trans_restart_too_many_iters(trans, _THIS_IP_, buf.buf);
1505                 printbuf_exit(&buf);
1506         }
1507
1508         count_event(trans->c, trans_restart_too_many_iters);
1509
1510         return btree_trans_restart(trans, BCH_ERR_transaction_restart_too_many_iters);
1511 }
1512
1513 static noinline void btree_path_overflow(struct btree_trans *trans)
1514 {
1515         bch2_dump_trans_paths_updates(trans);
1516         bch_err(trans->c, "trans path overflow");
1517 }
1518
1519 static noinline void btree_paths_realloc(struct btree_trans *trans)
1520 {
1521         unsigned nr = trans->nr_paths * 2;
1522
1523         void *p = kzalloc(BITS_TO_LONGS(nr) * sizeof(unsigned long) +
1524                           sizeof(struct btree_trans_paths) +
1525                           nr * sizeof(struct btree_path) +
1526                           nr * sizeof(btree_path_idx_t) + 8 +
1527                           nr * sizeof(struct btree_insert_entry), GFP_KERNEL|__GFP_NOFAIL);
1528
1529         unsigned long *paths_allocated = p;
1530         memcpy(paths_allocated, trans->paths_allocated, BITS_TO_LONGS(trans->nr_paths) * sizeof(unsigned long));
1531         p += BITS_TO_LONGS(nr) * sizeof(unsigned long);
1532
1533         p += sizeof(struct btree_trans_paths);
1534         struct btree_path *paths = p;
1535         *trans_paths_nr(paths) = nr;
1536         memcpy(paths, trans->paths, trans->nr_paths * sizeof(struct btree_path));
1537         p += nr * sizeof(struct btree_path);
1538
1539         btree_path_idx_t *sorted = p;
1540         memcpy(sorted, trans->sorted, trans->nr_sorted * sizeof(btree_path_idx_t));
1541         p += nr * sizeof(btree_path_idx_t) + 8;
1542
1543         struct btree_insert_entry *updates = p;
1544         memcpy(updates, trans->updates, trans->nr_paths * sizeof(struct btree_insert_entry));
1545
1546         unsigned long *old = trans->paths_allocated;
1547
1548         rcu_assign_pointer(trans->paths_allocated,      paths_allocated);
1549         rcu_assign_pointer(trans->paths,                paths);
1550         rcu_assign_pointer(trans->sorted,               sorted);
1551         rcu_assign_pointer(trans->updates,              updates);
1552
1553         trans->nr_paths         = nr;
1554
1555         if (old != trans->_paths_allocated)
1556                 kfree_rcu_mightsleep(old);
1557 }
1558
1559 static inline btree_path_idx_t btree_path_alloc(struct btree_trans *trans,
1560                                                 btree_path_idx_t pos)
1561 {
1562         btree_path_idx_t idx = find_first_zero_bit(trans->paths_allocated, trans->nr_paths);
1563
1564         if (unlikely(idx == trans->nr_paths)) {
1565                 if (trans->nr_paths == BTREE_ITER_MAX) {
1566                         btree_path_overflow(trans);
1567                         return 0;
1568                 }
1569
1570                 btree_paths_realloc(trans);
1571         }
1572
1573         /*
1574          * Do this before marking the new path as allocated, since it won't be
1575          * initialized yet:
1576          */
1577         if (unlikely(idx > trans->nr_paths_max))
1578                 bch2_trans_update_max_paths(trans);
1579
1580         __set_bit(idx, trans->paths_allocated);
1581
1582         struct btree_path *path = &trans->paths[idx];
1583         path->ref               = 0;
1584         path->intent_ref        = 0;
1585         path->nodes_locked      = 0;
1586
1587         btree_path_list_add(trans, pos, idx);
1588         trans->paths_sorted = false;
1589         return idx;
1590 }
1591
1592 btree_path_idx_t bch2_path_get(struct btree_trans *trans,
1593                              enum btree_id btree_id, struct bpos pos,
1594                              unsigned locks_want, unsigned level,
1595                              unsigned flags, unsigned long ip)
1596 {
1597         struct btree_path *path;
1598         bool cached = flags & BTREE_ITER_CACHED;
1599         bool intent = flags & BTREE_ITER_INTENT;
1600         struct trans_for_each_path_inorder_iter iter;
1601         btree_path_idx_t path_pos = 0, path_idx;
1602
1603         bch2_trans_verify_not_in_restart(trans);
1604         bch2_trans_verify_locks(trans);
1605
1606         btree_trans_sort_paths(trans);
1607
1608         trans_for_each_path_inorder(trans, path, iter) {
1609                 if (__btree_path_cmp(path,
1610                                      btree_id,
1611                                      cached,
1612                                      pos,
1613                                      level) > 0)
1614                         break;
1615
1616                 path_pos = iter.path_idx;
1617         }
1618
1619         if (path_pos &&
1620             trans->paths[path_pos].cached       == cached &&
1621             trans->paths[path_pos].btree_id     == btree_id &&
1622             trans->paths[path_pos].level        == level) {
1623                 __btree_path_get(trans->paths + path_pos, intent);
1624                 path_idx = bch2_btree_path_set_pos(trans, path_pos, pos, intent, ip);
1625                 path = trans->paths + path_idx;
1626         } else {
1627                 path_idx = btree_path_alloc(trans, path_pos);
1628                 path = trans->paths + path_idx;
1629
1630                 __btree_path_get(path, intent);
1631                 path->pos                       = pos;
1632                 path->btree_id                  = btree_id;
1633                 path->cached                    = cached;
1634                 path->uptodate                  = BTREE_ITER_NEED_TRAVERSE;
1635                 path->should_be_locked          = false;
1636                 path->level                     = level;
1637                 path->locks_want                = locks_want;
1638                 path->nodes_locked              = 0;
1639                 for (unsigned i = 0; i < ARRAY_SIZE(path->l); i++)
1640                         path->l[i].b            = ERR_PTR(-BCH_ERR_no_btree_node_init);
1641 #ifdef TRACK_PATH_ALLOCATED
1642                 path->ip_allocated              = ip;
1643 #endif
1644                 trans->paths_sorted             = false;
1645         }
1646
1647         if (!(flags & BTREE_ITER_NOPRESERVE))
1648                 path->preserve = true;
1649
1650         if (path->intent_ref)
1651                 locks_want = max(locks_want, level + 1);
1652
1653         /*
1654          * If the path has locks_want greater than requested, we don't downgrade
1655          * it here - on transaction restart because btree node split needs to
1656          * upgrade locks, we might be putting/getting the iterator again.
1657          * Downgrading iterators only happens via bch2_trans_downgrade(), after
1658          * a successful transaction commit.
1659          */
1660
1661         locks_want = min(locks_want, BTREE_MAX_DEPTH);
1662         if (locks_want > path->locks_want)
1663                 bch2_btree_path_upgrade_noupgrade_sibs(trans, path, locks_want, NULL);
1664
1665         return path_idx;
1666 }
1667
1668 struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *path, struct bkey *u)
1669 {
1670
1671         struct btree_path_level *l = path_l(path);
1672         struct bkey_packed *_k;
1673         struct bkey_s_c k;
1674
1675         if (unlikely(!l->b))
1676                 return bkey_s_c_null;
1677
1678         EBUG_ON(path->uptodate != BTREE_ITER_UPTODATE);
1679         EBUG_ON(!btree_node_locked(path, path->level));
1680
1681         if (!path->cached) {
1682                 _k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
1683                 k = _k ? bkey_disassemble(l->b, _k, u) : bkey_s_c_null;
1684
1685                 EBUG_ON(k.k && bkey_deleted(k.k) && bpos_eq(k.k->p, path->pos));
1686
1687                 if (!k.k || !bpos_eq(path->pos, k.k->p))
1688                         goto hole;
1689         } else {
1690                 struct bkey_cached *ck = (void *) path->l[0].b;
1691
1692                 EBUG_ON(ck &&
1693                         (path->btree_id != ck->key.btree_id ||
1694                          !bkey_eq(path->pos, ck->key.pos)));
1695                 if (!ck || !ck->valid)
1696                         return bkey_s_c_null;
1697
1698                 *u = ck->k->k;
1699                 k = bkey_i_to_s_c(ck->k);
1700         }
1701
1702         return k;
1703 hole:
1704         bkey_init(u);
1705         u->p = path->pos;
1706         return (struct bkey_s_c) { u, NULL };
1707 }
1708
1709 /* Btree iterators: */
1710
1711 int __must_check
1712 __bch2_btree_iter_traverse(struct btree_iter *iter)
1713 {
1714         return bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1715 }
1716
1717 int __must_check
1718 bch2_btree_iter_traverse(struct btree_iter *iter)
1719 {
1720         struct btree_trans *trans = iter->trans;
1721         int ret;
1722
1723         iter->path = bch2_btree_path_set_pos(trans, iter->path,
1724                                         btree_iter_search_key(iter),
1725                                         iter->flags & BTREE_ITER_INTENT,
1726                                         btree_iter_ip_allocated(iter));
1727
1728         ret = bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1729         if (ret)
1730                 return ret;
1731
1732         btree_path_set_should_be_locked(trans->paths + iter->path);
1733         return 0;
1734 }
1735
1736 /* Iterate across nodes (leaf and interior nodes) */
1737
1738 struct btree *bch2_btree_iter_peek_node(struct btree_iter *iter)
1739 {
1740         struct btree_trans *trans = iter->trans;
1741         struct btree *b = NULL;
1742         int ret;
1743
1744         EBUG_ON(trans->paths[iter->path].cached);
1745         bch2_btree_iter_verify(iter);
1746
1747         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1748         if (ret)
1749                 goto err;
1750
1751         struct btree_path *path = btree_iter_path(trans, iter);
1752         b = btree_path_node(path, path->level);
1753         if (!b)
1754                 goto out;
1755
1756         BUG_ON(bpos_lt(b->key.k.p, iter->pos));
1757
1758         bkey_init(&iter->k);
1759         iter->k.p = iter->pos = b->key.k.p;
1760
1761         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1762                                         iter->flags & BTREE_ITER_INTENT,
1763                                         btree_iter_ip_allocated(iter));
1764         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
1765 out:
1766         bch2_btree_iter_verify_entry_exit(iter);
1767         bch2_btree_iter_verify(iter);
1768
1769         return b;
1770 err:
1771         b = ERR_PTR(ret);
1772         goto out;
1773 }
1774
1775 struct btree *bch2_btree_iter_peek_node_and_restart(struct btree_iter *iter)
1776 {
1777         struct btree *b;
1778
1779         while (b = bch2_btree_iter_peek_node(iter),
1780                bch2_err_matches(PTR_ERR_OR_ZERO(b), BCH_ERR_transaction_restart))
1781                 bch2_trans_begin(iter->trans);
1782
1783         return b;
1784 }
1785
1786 struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
1787 {
1788         struct btree_trans *trans = iter->trans;
1789         struct btree *b = NULL;
1790         int ret;
1791
1792         EBUG_ON(trans->paths[iter->path].cached);
1793         bch2_trans_verify_not_in_restart(trans);
1794         bch2_btree_iter_verify(iter);
1795
1796         struct btree_path *path = btree_iter_path(trans, iter);
1797
1798         /* already at end? */
1799         if (!btree_path_node(path, path->level))
1800                 return NULL;
1801
1802         /* got to end? */
1803         if (!btree_path_node(path, path->level + 1)) {
1804                 btree_path_set_level_up(trans, path);
1805                 return NULL;
1806         }
1807
1808         if (!bch2_btree_node_relock(trans, path, path->level + 1)) {
1809                 __bch2_btree_path_unlock(trans, path);
1810                 path->l[path->level].b          = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1811                 path->l[path->level + 1].b      = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1812                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1813                 trace_and_count(trans->c, trans_restart_relock_next_node, trans, _THIS_IP_, path);
1814                 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
1815                 goto err;
1816         }
1817
1818         b = btree_path_node(path, path->level + 1);
1819
1820         if (bpos_eq(iter->pos, b->key.k.p)) {
1821                 __btree_path_set_level_up(trans, path, path->level++);
1822         } else {
1823                 /*
1824                  * Haven't gotten to the end of the parent node: go back down to
1825                  * the next child node
1826                  */
1827                 iter->path = bch2_btree_path_set_pos(trans, iter->path,
1828                                         bpos_successor(iter->pos),
1829                                         iter->flags & BTREE_ITER_INTENT,
1830                                         btree_iter_ip_allocated(iter));
1831
1832                 path = btree_iter_path(trans, iter);
1833                 btree_path_set_level_down(trans, path, iter->min_depth);
1834
1835                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1836                 if (ret)
1837                         goto err;
1838
1839                 path = btree_iter_path(trans, iter);
1840                 b = path->l[path->level].b;
1841         }
1842
1843         bkey_init(&iter->k);
1844         iter->k.p = iter->pos = b->key.k.p;
1845
1846         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1847                                         iter->flags & BTREE_ITER_INTENT,
1848                                         btree_iter_ip_allocated(iter));
1849         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
1850         EBUG_ON(btree_iter_path(trans, iter)->uptodate);
1851 out:
1852         bch2_btree_iter_verify_entry_exit(iter);
1853         bch2_btree_iter_verify(iter);
1854
1855         return b;
1856 err:
1857         b = ERR_PTR(ret);
1858         goto out;
1859 }
1860
1861 /* Iterate across keys (in leaf nodes only) */
1862
1863 inline bool bch2_btree_iter_advance(struct btree_iter *iter)
1864 {
1865         struct bpos pos = iter->k.p;
1866         bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1867                      ? bpos_eq(pos, SPOS_MAX)
1868                      : bkey_eq(pos, SPOS_MAX));
1869
1870         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1871                 pos = bkey_successor(iter, pos);
1872         bch2_btree_iter_set_pos(iter, pos);
1873         return ret;
1874 }
1875
1876 inline bool bch2_btree_iter_rewind(struct btree_iter *iter)
1877 {
1878         struct bpos pos = bkey_start_pos(&iter->k);
1879         bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1880                      ? bpos_eq(pos, POS_MIN)
1881                      : bkey_eq(pos, POS_MIN));
1882
1883         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1884                 pos = bkey_predecessor(iter, pos);
1885         bch2_btree_iter_set_pos(iter, pos);
1886         return ret;
1887 }
1888
1889 static noinline
1890 void bch2_btree_trans_peek_prev_updates(struct btree_trans *trans, struct btree_iter *iter,
1891                                         struct bkey_s_c *k)
1892 {
1893         struct bpos end = path_l(btree_iter_path(trans, iter))->b->data->min_key;
1894
1895         trans_for_each_update(trans, i)
1896                 if (!i->key_cache_already_flushed &&
1897                     i->btree_id == iter->btree_id &&
1898                     bpos_le(i->k->k.p, iter->pos) &&
1899                     bpos_ge(i->k->k.p, k->k ? k->k->p : end)) {
1900                         iter->k = i->k->k;
1901                         *k = bkey_i_to_s_c(i->k);
1902                 }
1903 }
1904
1905 static noinline
1906 void bch2_btree_trans_peek_updates(struct btree_trans *trans, struct btree_iter *iter,
1907                                    struct bkey_s_c *k)
1908 {
1909         struct btree_path *path = btree_iter_path(trans, iter);
1910         struct bpos end = path_l(path)->b->key.k.p;
1911
1912         trans_for_each_update(trans, i)
1913                 if (!i->key_cache_already_flushed &&
1914                     i->btree_id == iter->btree_id &&
1915                     bpos_ge(i->k->k.p, path->pos) &&
1916                     bpos_le(i->k->k.p, k->k ? k->k->p : end)) {
1917                         iter->k = i->k->k;
1918                         *k = bkey_i_to_s_c(i->k);
1919                 }
1920 }
1921
1922 static noinline
1923 void bch2_btree_trans_peek_slot_updates(struct btree_trans *trans, struct btree_iter *iter,
1924                                         struct bkey_s_c *k)
1925 {
1926         trans_for_each_update(trans, i)
1927                 if (!i->key_cache_already_flushed &&
1928                     i->btree_id == iter->btree_id &&
1929                     bpos_eq(i->k->k.p, iter->pos)) {
1930                         iter->k = i->k->k;
1931                         *k = bkey_i_to_s_c(i->k);
1932                 }
1933 }
1934
1935 static struct bkey_i *bch2_btree_journal_peek(struct btree_trans *trans,
1936                                               struct btree_iter *iter,
1937                                               struct bpos end_pos)
1938 {
1939         struct btree_path *path = btree_iter_path(trans, iter);
1940
1941         return bch2_journal_keys_peek_upto(trans->c, iter->btree_id,
1942                                            path->level,
1943                                            path->pos,
1944                                            end_pos,
1945                                            &iter->journal_idx);
1946 }
1947
1948 static noinline
1949 struct bkey_s_c btree_trans_peek_slot_journal(struct btree_trans *trans,
1950                                               struct btree_iter *iter)
1951 {
1952         struct btree_path *path = btree_iter_path(trans, iter);
1953         struct bkey_i *k = bch2_btree_journal_peek(trans, iter, path->pos);
1954
1955         if (k) {
1956                 iter->k = k->k;
1957                 return bkey_i_to_s_c(k);
1958         } else {
1959                 return bkey_s_c_null;
1960         }
1961 }
1962
1963 static noinline
1964 struct bkey_s_c btree_trans_peek_journal(struct btree_trans *trans,
1965                                          struct btree_iter *iter,
1966                                          struct bkey_s_c k)
1967 {
1968         struct btree_path *path = btree_iter_path(trans, iter);
1969         struct bkey_i *next_journal =
1970                 bch2_btree_journal_peek(trans, iter,
1971                                 k.k ? k.k->p : path_l(path)->b->key.k.p);
1972
1973         if (next_journal) {
1974                 iter->k = next_journal->k;
1975                 k = bkey_i_to_s_c(next_journal);
1976         }
1977
1978         return k;
1979 }
1980
1981 /*
1982  * Checks btree key cache for key at iter->pos and returns it if present, or
1983  * bkey_s_c_null:
1984  */
1985 static noinline
1986 struct bkey_s_c btree_trans_peek_key_cache(struct btree_iter *iter, struct bpos pos)
1987 {
1988         struct btree_trans *trans = iter->trans;
1989         struct bch_fs *c = trans->c;
1990         struct bkey u;
1991         struct bkey_s_c k;
1992         int ret;
1993
1994         if ((iter->flags & BTREE_ITER_KEY_CACHE_FILL) &&
1995             bpos_eq(iter->pos, pos))
1996                 return bkey_s_c_null;
1997
1998         if (!bch2_btree_key_cache_find(c, iter->btree_id, pos))
1999                 return bkey_s_c_null;
2000
2001         if (!iter->key_cache_path)
2002                 iter->key_cache_path = bch2_path_get(trans, iter->btree_id, pos,
2003                                                      iter->flags & BTREE_ITER_INTENT, 0,
2004                                                      iter->flags|BTREE_ITER_CACHED|
2005                                                      BTREE_ITER_CACHED_NOFILL,
2006                                                      _THIS_IP_);
2007
2008         iter->key_cache_path = bch2_btree_path_set_pos(trans, iter->key_cache_path, pos,
2009                                         iter->flags & BTREE_ITER_INTENT,
2010                                         btree_iter_ip_allocated(iter));
2011
2012         ret =   bch2_btree_path_traverse(trans, iter->key_cache_path,
2013                                          iter->flags|BTREE_ITER_CACHED) ?:
2014                 bch2_btree_path_relock(trans, btree_iter_path(trans, iter), _THIS_IP_);
2015         if (unlikely(ret))
2016                 return bkey_s_c_err(ret);
2017
2018         btree_path_set_should_be_locked(trans->paths + iter->key_cache_path);
2019
2020         k = bch2_btree_path_peek_slot(trans->paths + iter->key_cache_path, &u);
2021         if (k.k && !bkey_err(k)) {
2022                 iter->k = u;
2023                 k.k = &iter->k;
2024         }
2025         return k;
2026 }
2027
2028 static struct bkey_s_c __bch2_btree_iter_peek(struct btree_iter *iter, struct bpos search_key)
2029 {
2030         struct btree_trans *trans = iter->trans;
2031         struct bkey_s_c k, k2;
2032         int ret;
2033
2034         EBUG_ON(btree_iter_path(trans, iter)->cached);
2035         bch2_btree_iter_verify(iter);
2036
2037         while (1) {
2038                 struct btree_path_level *l;
2039
2040                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2041                                         iter->flags & BTREE_ITER_INTENT,
2042                                         btree_iter_ip_allocated(iter));
2043
2044                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2045                 if (unlikely(ret)) {
2046                         /* ensure that iter->k is consistent with iter->pos: */
2047                         bch2_btree_iter_set_pos(iter, iter->pos);
2048                         k = bkey_s_c_err(ret);
2049                         goto out;
2050                 }
2051
2052                 struct btree_path *path = btree_iter_path(trans, iter);
2053                 l = path_l(path);
2054
2055                 if (unlikely(!l->b)) {
2056                         /* No btree nodes at requested level: */
2057                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2058                         k = bkey_s_c_null;
2059                         goto out;
2060                 }
2061
2062                 btree_path_set_should_be_locked(path);
2063
2064                 k = btree_path_level_peek_all(trans->c, l, &iter->k);
2065
2066                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2067                     k.k &&
2068                     (k2 = btree_trans_peek_key_cache(iter, k.k->p)).k) {
2069                         k = k2;
2070                         ret = bkey_err(k);
2071                         if (ret) {
2072                                 bch2_btree_iter_set_pos(iter, iter->pos);
2073                                 goto out;
2074                         }
2075                 }
2076
2077                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL))
2078                         k = btree_trans_peek_journal(trans, iter, k);
2079
2080                 if (unlikely((iter->flags & BTREE_ITER_WITH_UPDATES) &&
2081                              trans->nr_updates))
2082                         bch2_btree_trans_peek_updates(trans, iter, &k);
2083
2084                 if (k.k && bkey_deleted(k.k)) {
2085                         /*
2086                          * If we've got a whiteout, and it's after the search
2087                          * key, advance the search key to the whiteout instead
2088                          * of just after the whiteout - it might be a btree
2089                          * whiteout, with a real key at the same position, since
2090                          * in the btree deleted keys sort before non deleted.
2091                          */
2092                         search_key = !bpos_eq(search_key, k.k->p)
2093                                 ? k.k->p
2094                                 : bpos_successor(k.k->p);
2095                         continue;
2096                 }
2097
2098                 if (likely(k.k)) {
2099                         break;
2100                 } else if (likely(!bpos_eq(l->b->key.k.p, SPOS_MAX))) {
2101                         /* Advance to next leaf node: */
2102                         search_key = bpos_successor(l->b->key.k.p);
2103                 } else {
2104                         /* End of btree: */
2105                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2106                         k = bkey_s_c_null;
2107                         goto out;
2108                 }
2109         }
2110 out:
2111         bch2_btree_iter_verify(iter);
2112
2113         return k;
2114 }
2115
2116 /**
2117  * bch2_btree_iter_peek_upto() - returns first key greater than or equal to
2118  * iterator's current position
2119  * @iter:       iterator to peek from
2120  * @end:        search limit: returns keys less than or equal to @end
2121  *
2122  * Returns:     key if found, or an error extractable with bkey_err().
2123  */
2124 struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *iter, struct bpos end)
2125 {
2126         struct btree_trans *trans = iter->trans;
2127         struct bpos search_key = btree_iter_search_key(iter);
2128         struct bkey_s_c k;
2129         struct bpos iter_pos;
2130         int ret;
2131
2132         EBUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) && bkey_eq(end, POS_MAX));
2133
2134         if (iter->update_path) {
2135                 bch2_path_put_nokeep(trans, iter->update_path,
2136                                      iter->flags & BTREE_ITER_INTENT);
2137                 iter->update_path = 0;
2138         }
2139
2140         bch2_btree_iter_verify_entry_exit(iter);
2141
2142         while (1) {
2143                 k = __bch2_btree_iter_peek(iter, search_key);
2144                 if (unlikely(!k.k))
2145                         goto end;
2146                 if (unlikely(bkey_err(k)))
2147                         goto out_no_locked;
2148
2149                 /*
2150                  * We need to check against @end before FILTER_SNAPSHOTS because
2151                  * if we get to a different inode that requested we might be
2152                  * seeing keys for a different snapshot tree that will all be
2153                  * filtered out.
2154                  *
2155                  * But we can't do the full check here, because bkey_start_pos()
2156                  * isn't monotonically increasing before FILTER_SNAPSHOTS, and
2157                  * that's what we check against in extents mode:
2158                  */
2159                 if (k.k->p.inode > end.inode)
2160                         goto end;
2161
2162                 if (iter->update_path &&
2163                     !bkey_eq(trans->paths[iter->update_path].pos, k.k->p)) {
2164                         bch2_path_put_nokeep(trans, iter->update_path,
2165                                              iter->flags & BTREE_ITER_INTENT);
2166                         iter->update_path = 0;
2167                 }
2168
2169                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2170                     (iter->flags & BTREE_ITER_INTENT) &&
2171                     !(iter->flags & BTREE_ITER_IS_EXTENTS) &&
2172                     !iter->update_path) {
2173                         struct bpos pos = k.k->p;
2174
2175                         if (pos.snapshot < iter->snapshot) {
2176                                 search_key = bpos_successor(k.k->p);
2177                                 continue;
2178                         }
2179
2180                         pos.snapshot = iter->snapshot;
2181
2182                         /*
2183                          * advance, same as on exit for iter->path, but only up
2184                          * to snapshot
2185                          */
2186                         __btree_path_get(trans->paths + iter->path, iter->flags & BTREE_ITER_INTENT);
2187                         iter->update_path = iter->path;
2188
2189                         iter->update_path = bch2_btree_path_set_pos(trans,
2190                                                 iter->update_path, pos,
2191                                                 iter->flags & BTREE_ITER_INTENT,
2192                                                 _THIS_IP_);
2193                         ret = bch2_btree_path_traverse(trans, iter->update_path, iter->flags);
2194                         if (unlikely(ret)) {
2195                                 k = bkey_s_c_err(ret);
2196                                 goto out_no_locked;
2197                         }
2198                 }
2199
2200                 /*
2201                  * We can never have a key in a leaf node at POS_MAX, so
2202                  * we don't have to check these successor() calls:
2203                  */
2204                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2205                     !bch2_snapshot_is_ancestor(trans->c,
2206                                                iter->snapshot,
2207                                                k.k->p.snapshot)) {
2208                         search_key = bpos_successor(k.k->p);
2209                         continue;
2210                 }
2211
2212                 if (bkey_whiteout(k.k) &&
2213                     !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2214                         search_key = bkey_successor(iter, k.k->p);
2215                         continue;
2216                 }
2217
2218                 /*
2219                  * iter->pos should be mononotically increasing, and always be
2220                  * equal to the key we just returned - except extents can
2221                  * straddle iter->pos:
2222                  */
2223                 if (!(iter->flags & BTREE_ITER_IS_EXTENTS))
2224                         iter_pos = k.k->p;
2225                 else
2226                         iter_pos = bkey_max(iter->pos, bkey_start_pos(k.k));
2227
2228                 if (unlikely(!(iter->flags & BTREE_ITER_IS_EXTENTS)
2229                              ? bkey_gt(iter_pos, end)
2230                              : bkey_ge(iter_pos, end)))
2231                         goto end;
2232
2233                 break;
2234         }
2235
2236         iter->pos = iter_pos;
2237
2238         iter->path = bch2_btree_path_set_pos(trans, iter->path, k.k->p,
2239                                 iter->flags & BTREE_ITER_INTENT,
2240                                 btree_iter_ip_allocated(iter));
2241
2242         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
2243 out_no_locked:
2244         if (iter->update_path) {
2245                 ret = bch2_btree_path_relock(trans, trans->paths + iter->update_path, _THIS_IP_);
2246                 if (unlikely(ret))
2247                         k = bkey_s_c_err(ret);
2248                 else
2249                         btree_path_set_should_be_locked(trans->paths + iter->update_path);
2250         }
2251
2252         if (!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS))
2253                 iter->pos.snapshot = iter->snapshot;
2254
2255         ret = bch2_btree_iter_verify_ret(iter, k);
2256         if (unlikely(ret)) {
2257                 bch2_btree_iter_set_pos(iter, iter->pos);
2258                 k = bkey_s_c_err(ret);
2259         }
2260
2261         bch2_btree_iter_verify_entry_exit(iter);
2262
2263         return k;
2264 end:
2265         bch2_btree_iter_set_pos(iter, end);
2266         k = bkey_s_c_null;
2267         goto out_no_locked;
2268 }
2269
2270 /**
2271  * bch2_btree_iter_next() - returns first key greater than iterator's current
2272  * position
2273  * @iter:       iterator to peek from
2274  *
2275  * Returns:     key if found, or an error extractable with bkey_err().
2276  */
2277 struct bkey_s_c bch2_btree_iter_next(struct btree_iter *iter)
2278 {
2279         if (!bch2_btree_iter_advance(iter))
2280                 return bkey_s_c_null;
2281
2282         return bch2_btree_iter_peek(iter);
2283 }
2284
2285 /**
2286  * bch2_btree_iter_peek_prev() - returns first key less than or equal to
2287  * iterator's current position
2288  * @iter:       iterator to peek from
2289  *
2290  * Returns:     key if found, or an error extractable with bkey_err().
2291  */
2292 struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
2293 {
2294         struct btree_trans *trans = iter->trans;
2295         struct bpos search_key = iter->pos;
2296         struct bkey_s_c k;
2297         struct bkey saved_k;
2298         const struct bch_val *saved_v;
2299         btree_path_idx_t saved_path = 0;
2300         int ret;
2301
2302         EBUG_ON(btree_iter_path(trans, iter)->cached ||
2303                 btree_iter_path(trans, iter)->level);
2304
2305         if (iter->flags & BTREE_ITER_WITH_JOURNAL)
2306                 return bkey_s_c_err(-EIO);
2307
2308         bch2_btree_iter_verify(iter);
2309         bch2_btree_iter_verify_entry_exit(iter);
2310
2311         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2312                 search_key.snapshot = U32_MAX;
2313
2314         while (1) {
2315                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2316                                                 iter->flags & BTREE_ITER_INTENT,
2317                                                 btree_iter_ip_allocated(iter));
2318
2319                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2320                 if (unlikely(ret)) {
2321                         /* ensure that iter->k is consistent with iter->pos: */
2322                         bch2_btree_iter_set_pos(iter, iter->pos);
2323                         k = bkey_s_c_err(ret);
2324                         goto out_no_locked;
2325                 }
2326
2327                 struct btree_path *path = btree_iter_path(trans, iter);
2328
2329                 k = btree_path_level_peek(trans, path, &path->l[0], &iter->k);
2330                 if (!k.k ||
2331                     ((iter->flags & BTREE_ITER_IS_EXTENTS)
2332                      ? bpos_ge(bkey_start_pos(k.k), search_key)
2333                      : bpos_gt(k.k->p, search_key)))
2334                         k = btree_path_level_prev(trans, path, &path->l[0], &iter->k);
2335
2336                 if (unlikely((iter->flags & BTREE_ITER_WITH_UPDATES) &&
2337                              trans->nr_updates))
2338                         bch2_btree_trans_peek_prev_updates(trans, iter, &k);
2339
2340                 if (likely(k.k)) {
2341                         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) {
2342                                 if (k.k->p.snapshot == iter->snapshot)
2343                                         goto got_key;
2344
2345                                 /*
2346                                  * If we have a saved candidate, and we're no
2347                                  * longer at the same _key_ (not pos), return
2348                                  * that candidate
2349                                  */
2350                                 if (saved_path && !bkey_eq(k.k->p, saved_k.p)) {
2351                                         bch2_path_put_nokeep(trans, iter->path,
2352                                                       iter->flags & BTREE_ITER_INTENT);
2353                                         iter->path = saved_path;
2354                                         saved_path = 0;
2355                                         iter->k = saved_k;
2356                                         k.v     = saved_v;
2357                                         goto got_key;
2358                                 }
2359
2360                                 if (bch2_snapshot_is_ancestor(trans->c,
2361                                                               iter->snapshot,
2362                                                               k.k->p.snapshot)) {
2363                                         if (saved_path)
2364                                                 bch2_path_put_nokeep(trans, saved_path,
2365                                                       iter->flags & BTREE_ITER_INTENT);
2366                                         saved_path = btree_path_clone(trans, iter->path,
2367                                                                 iter->flags & BTREE_ITER_INTENT);
2368                                         path = btree_iter_path(trans, iter);
2369                                         saved_k = *k.k;
2370                                         saved_v = k.v;
2371                                 }
2372
2373                                 search_key = bpos_predecessor(k.k->p);
2374                                 continue;
2375                         }
2376 got_key:
2377                         if (bkey_whiteout(k.k) &&
2378                             !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2379                                 search_key = bkey_predecessor(iter, k.k->p);
2380                                 if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2381                                         search_key.snapshot = U32_MAX;
2382                                 continue;
2383                         }
2384
2385                         btree_path_set_should_be_locked(path);
2386                         break;
2387                 } else if (likely(!bpos_eq(path->l[0].b->data->min_key, POS_MIN))) {
2388                         /* Advance to previous leaf node: */
2389                         search_key = bpos_predecessor(path->l[0].b->data->min_key);
2390                 } else {
2391                         /* Start of btree: */
2392                         bch2_btree_iter_set_pos(iter, POS_MIN);
2393                         k = bkey_s_c_null;
2394                         goto out_no_locked;
2395                 }
2396         }
2397
2398         EBUG_ON(bkey_gt(bkey_start_pos(k.k), iter->pos));
2399
2400         /* Extents can straddle iter->pos: */
2401         if (bkey_lt(k.k->p, iter->pos))
2402                 iter->pos = k.k->p;
2403
2404         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2405                 iter->pos.snapshot = iter->snapshot;
2406 out_no_locked:
2407         if (saved_path)
2408                 bch2_path_put_nokeep(trans, saved_path, iter->flags & BTREE_ITER_INTENT);
2409
2410         bch2_btree_iter_verify_entry_exit(iter);
2411         bch2_btree_iter_verify(iter);
2412
2413         return k;
2414 }
2415
2416 /**
2417  * bch2_btree_iter_prev() - returns first key less than iterator's current
2418  * position
2419  * @iter:       iterator to peek from
2420  *
2421  * Returns:     key if found, or an error extractable with bkey_err().
2422  */
2423 struct bkey_s_c bch2_btree_iter_prev(struct btree_iter *iter)
2424 {
2425         if (!bch2_btree_iter_rewind(iter))
2426                 return bkey_s_c_null;
2427
2428         return bch2_btree_iter_peek_prev(iter);
2429 }
2430
2431 struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
2432 {
2433         struct btree_trans *trans = iter->trans;
2434         struct bpos search_key;
2435         struct bkey_s_c k;
2436         int ret;
2437
2438         bch2_btree_iter_verify(iter);
2439         bch2_btree_iter_verify_entry_exit(iter);
2440         EBUG_ON(btree_iter_path(trans, iter)->level && (iter->flags & BTREE_ITER_WITH_KEY_CACHE));
2441
2442         /* extents can't span inode numbers: */
2443         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
2444             unlikely(iter->pos.offset == KEY_OFFSET_MAX)) {
2445                 if (iter->pos.inode == KEY_INODE_MAX)
2446                         return bkey_s_c_null;
2447
2448                 bch2_btree_iter_set_pos(iter, bpos_nosnap_successor(iter->pos));
2449         }
2450
2451         search_key = btree_iter_search_key(iter);
2452         iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2453                                         iter->flags & BTREE_ITER_INTENT,
2454                                         btree_iter_ip_allocated(iter));
2455
2456         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2457         if (unlikely(ret)) {
2458                 k = bkey_s_c_err(ret);
2459                 goto out_no_locked;
2460         }
2461
2462         if ((iter->flags & BTREE_ITER_CACHED) ||
2463             !(iter->flags & (BTREE_ITER_IS_EXTENTS|BTREE_ITER_FILTER_SNAPSHOTS))) {
2464                 k = bkey_s_c_null;
2465
2466                 if (unlikely((iter->flags & BTREE_ITER_WITH_UPDATES) &&
2467                              trans->nr_updates)) {
2468                         bch2_btree_trans_peek_slot_updates(trans, iter, &k);
2469                         if (k.k)
2470                                 goto out;
2471                 }
2472
2473                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL) &&
2474                     (k = btree_trans_peek_slot_journal(trans, iter)).k)
2475                         goto out;
2476
2477                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2478                     (k = btree_trans_peek_key_cache(iter, iter->pos)).k) {
2479                         if (!bkey_err(k))
2480                                 iter->k = *k.k;
2481                         /* We're not returning a key from iter->path: */
2482                         goto out_no_locked;
2483                 }
2484
2485                 k = bch2_btree_path_peek_slot(trans->paths + iter->path, &iter->k);
2486                 if (unlikely(!k.k))
2487                         goto out_no_locked;
2488         } else {
2489                 struct bpos next;
2490                 struct bpos end = iter->pos;
2491
2492                 if (iter->flags & BTREE_ITER_IS_EXTENTS)
2493                         end.offset = U64_MAX;
2494
2495                 EBUG_ON(btree_iter_path(trans, iter)->level);
2496
2497                 if (iter->flags & BTREE_ITER_INTENT) {
2498                         struct btree_iter iter2;
2499
2500                         bch2_trans_copy_iter(&iter2, iter);
2501                         k = bch2_btree_iter_peek_upto(&iter2, end);
2502
2503                         if (k.k && !bkey_err(k)) {
2504                                 iter->k = iter2.k;
2505                                 k.k = &iter->k;
2506                         }
2507                         bch2_trans_iter_exit(trans, &iter2);
2508                 } else {
2509                         struct bpos pos = iter->pos;
2510
2511                         k = bch2_btree_iter_peek_upto(iter, end);
2512                         if (unlikely(bkey_err(k)))
2513                                 bch2_btree_iter_set_pos(iter, pos);
2514                         else
2515                                 iter->pos = pos;
2516                 }
2517
2518                 if (unlikely(bkey_err(k)))
2519                         goto out_no_locked;
2520
2521                 next = k.k ? bkey_start_pos(k.k) : POS_MAX;
2522
2523                 if (bkey_lt(iter->pos, next)) {
2524                         bkey_init(&iter->k);
2525                         iter->k.p = iter->pos;
2526
2527                         if (iter->flags & BTREE_ITER_IS_EXTENTS) {
2528                                 bch2_key_resize(&iter->k,
2529                                                 min_t(u64, KEY_SIZE_MAX,
2530                                                       (next.inode == iter->pos.inode
2531                                                        ? next.offset
2532                                                        : KEY_OFFSET_MAX) -
2533                                                       iter->pos.offset));
2534                                 EBUG_ON(!iter->k.size);
2535                         }
2536
2537                         k = (struct bkey_s_c) { &iter->k, NULL };
2538                 }
2539         }
2540 out:
2541         btree_path_set_should_be_locked(btree_iter_path(trans, iter));
2542 out_no_locked:
2543         bch2_btree_iter_verify_entry_exit(iter);
2544         bch2_btree_iter_verify(iter);
2545         ret = bch2_btree_iter_verify_ret(iter, k);
2546         if (unlikely(ret))
2547                 return bkey_s_c_err(ret);
2548
2549         return k;
2550 }
2551
2552 struct bkey_s_c bch2_btree_iter_next_slot(struct btree_iter *iter)
2553 {
2554         if (!bch2_btree_iter_advance(iter))
2555                 return bkey_s_c_null;
2556
2557         return bch2_btree_iter_peek_slot(iter);
2558 }
2559
2560 struct bkey_s_c bch2_btree_iter_prev_slot(struct btree_iter *iter)
2561 {
2562         if (!bch2_btree_iter_rewind(iter))
2563                 return bkey_s_c_null;
2564
2565         return bch2_btree_iter_peek_slot(iter);
2566 }
2567
2568 struct bkey_s_c bch2_btree_iter_peek_and_restart_outlined(struct btree_iter *iter)
2569 {
2570         struct bkey_s_c k;
2571
2572         while (btree_trans_too_many_iters(iter->trans) ||
2573                (k = bch2_btree_iter_peek_type(iter, iter->flags),
2574                 bch2_err_matches(bkey_err(k), BCH_ERR_transaction_restart)))
2575                 bch2_trans_begin(iter->trans);
2576
2577         return k;
2578 }
2579
2580 /* new transactional stuff: */
2581
2582 #ifdef CONFIG_BCACHEFS_DEBUG
2583 static void btree_trans_verify_sorted_refs(struct btree_trans *trans)
2584 {
2585         struct btree_path *path;
2586         unsigned i;
2587
2588         BUG_ON(trans->nr_sorted != bitmap_weight(trans->paths_allocated, trans->nr_paths) - 1);
2589
2590         trans_for_each_path(trans, path, i) {
2591                 BUG_ON(path->sorted_idx >= trans->nr_sorted);
2592                 BUG_ON(trans->sorted[path->sorted_idx] != i);
2593         }
2594
2595         for (i = 0; i < trans->nr_sorted; i++) {
2596                 unsigned idx = trans->sorted[i];
2597
2598                 BUG_ON(!test_bit(idx, trans->paths_allocated));
2599                 BUG_ON(trans->paths[idx].sorted_idx != i);
2600         }
2601 }
2602
2603 static void btree_trans_verify_sorted(struct btree_trans *trans)
2604 {
2605         struct btree_path *path, *prev = NULL;
2606         struct trans_for_each_path_inorder_iter iter;
2607
2608         if (!bch2_debug_check_iterators)
2609                 return;
2610
2611         trans_for_each_path_inorder(trans, path, iter) {
2612                 if (prev && btree_path_cmp(prev, path) > 0) {
2613                         __bch2_dump_trans_paths_updates(trans, true);
2614                         panic("trans paths out of order!\n");
2615                 }
2616                 prev = path;
2617         }
2618 }
2619 #else
2620 static inline void btree_trans_verify_sorted_refs(struct btree_trans *trans) {}
2621 static inline void btree_trans_verify_sorted(struct btree_trans *trans) {}
2622 #endif
2623
2624 void __bch2_btree_trans_sort_paths(struct btree_trans *trans)
2625 {
2626         int i, l = 0, r = trans->nr_sorted, inc = 1;
2627         bool swapped;
2628
2629         btree_trans_verify_sorted_refs(trans);
2630
2631         if (trans->paths_sorted)
2632                 goto out;
2633
2634         /*
2635          * Cocktail shaker sort: this is efficient because iterators will be
2636          * mostly sorted.
2637          */
2638         do {
2639                 swapped = false;
2640
2641                 for (i = inc > 0 ? l : r - 2;
2642                      i + 1 < r && i >= l;
2643                      i += inc) {
2644                         if (btree_path_cmp(trans->paths + trans->sorted[i],
2645                                            trans->paths + trans->sorted[i + 1]) > 0) {
2646                                 swap(trans->sorted[i], trans->sorted[i + 1]);
2647                                 trans->paths[trans->sorted[i]].sorted_idx = i;
2648                                 trans->paths[trans->sorted[i + 1]].sorted_idx = i + 1;
2649                                 swapped = true;
2650                         }
2651                 }
2652
2653                 if (inc > 0)
2654                         --r;
2655                 else
2656                         l++;
2657                 inc = -inc;
2658         } while (swapped);
2659
2660         trans->paths_sorted = true;
2661 out:
2662         btree_trans_verify_sorted(trans);
2663 }
2664
2665 static inline void btree_path_list_remove(struct btree_trans *trans,
2666                                           struct btree_path *path)
2667 {
2668         EBUG_ON(path->sorted_idx >= trans->nr_sorted);
2669 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2670         trans->nr_sorted--;
2671         memmove_u64s_down_small(trans->sorted + path->sorted_idx,
2672                                 trans->sorted + path->sorted_idx + 1,
2673                                 DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx,
2674                                              sizeof(u64) / sizeof(btree_path_idx_t)));
2675 #else
2676         array_remove_item(trans->sorted, trans->nr_sorted, path->sorted_idx);
2677 #endif
2678         for (unsigned i = path->sorted_idx; i < trans->nr_sorted; i++)
2679                 trans->paths[trans->sorted[i]].sorted_idx = i;
2680 }
2681
2682 static inline void btree_path_list_add(struct btree_trans *trans,
2683                                        btree_path_idx_t pos,
2684                                        btree_path_idx_t path_idx)
2685 {
2686         struct btree_path *path = trans->paths + path_idx;
2687
2688         path->sorted_idx = pos ? trans->paths[pos].sorted_idx + 1 : trans->nr_sorted;
2689
2690 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2691         memmove_u64s_up_small(trans->sorted + path->sorted_idx + 1,
2692                               trans->sorted + path->sorted_idx,
2693                               DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx,
2694                                            sizeof(u64) / sizeof(btree_path_idx_t)));
2695         trans->nr_sorted++;
2696         trans->sorted[path->sorted_idx] = path_idx;
2697 #else
2698         array_insert_item(trans->sorted, trans->nr_sorted, path->sorted_idx, path_idx);
2699 #endif
2700
2701         for (unsigned i = path->sorted_idx; i < trans->nr_sorted; i++)
2702                 trans->paths[trans->sorted[i]].sorted_idx = i;
2703
2704         btree_trans_verify_sorted_refs(trans);
2705 }
2706
2707 void bch2_trans_iter_exit(struct btree_trans *trans, struct btree_iter *iter)
2708 {
2709         if (iter->update_path)
2710                 bch2_path_put_nokeep(trans, iter->update_path,
2711                               iter->flags & BTREE_ITER_INTENT);
2712         if (iter->path)
2713                 bch2_path_put(trans, iter->path,
2714                               iter->flags & BTREE_ITER_INTENT);
2715         if (iter->key_cache_path)
2716                 bch2_path_put(trans, iter->key_cache_path,
2717                               iter->flags & BTREE_ITER_INTENT);
2718         iter->path              = 0;
2719         iter->update_path       = 0;
2720         iter->key_cache_path    = 0;
2721         iter->trans             = NULL;
2722 }
2723
2724 void bch2_trans_iter_init_outlined(struct btree_trans *trans,
2725                           struct btree_iter *iter,
2726                           enum btree_id btree_id, struct bpos pos,
2727                           unsigned flags)
2728 {
2729         bch2_trans_iter_init_common(trans, iter, btree_id, pos, 0, 0,
2730                                bch2_btree_iter_flags(trans, btree_id, flags),
2731                                _RET_IP_);
2732 }
2733
2734 void bch2_trans_node_iter_init(struct btree_trans *trans,
2735                                struct btree_iter *iter,
2736                                enum btree_id btree_id,
2737                                struct bpos pos,
2738                                unsigned locks_want,
2739                                unsigned depth,
2740                                unsigned flags)
2741 {
2742         flags |= BTREE_ITER_NOT_EXTENTS;
2743         flags |= __BTREE_ITER_ALL_SNAPSHOTS;
2744         flags |= BTREE_ITER_ALL_SNAPSHOTS;
2745
2746         bch2_trans_iter_init_common(trans, iter, btree_id, pos, locks_want, depth,
2747                                __bch2_btree_iter_flags(trans, btree_id, flags),
2748                                _RET_IP_);
2749
2750         iter->min_depth = depth;
2751
2752         struct btree_path *path = btree_iter_path(trans, iter);
2753         BUG_ON(path->locks_want  < min(locks_want, BTREE_MAX_DEPTH));
2754         BUG_ON(path->level      != depth);
2755         BUG_ON(iter->min_depth  != depth);
2756 }
2757
2758 void bch2_trans_copy_iter(struct btree_iter *dst, struct btree_iter *src)
2759 {
2760         struct btree_trans *trans = src->trans;
2761
2762         *dst = *src;
2763         if (src->path)
2764                 __btree_path_get(trans->paths + src->path, src->flags & BTREE_ITER_INTENT);
2765         if (src->update_path)
2766                 __btree_path_get(trans->paths + src->update_path, src->flags & BTREE_ITER_INTENT);
2767         dst->key_cache_path = 0;
2768 }
2769
2770 void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
2771 {
2772         struct bch_fs *c = trans->c;
2773         unsigned new_top = trans->mem_top + size;
2774         unsigned old_bytes = trans->mem_bytes;
2775         unsigned new_bytes = roundup_pow_of_two(new_top);
2776         int ret;
2777         void *new_mem;
2778         void *p;
2779
2780         WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);
2781
2782         struct btree_transaction_stats *s = btree_trans_stats(trans);
2783         s->max_mem = max(s->max_mem, new_bytes);
2784
2785         new_mem = krealloc(trans->mem, new_bytes, GFP_NOWAIT|__GFP_NOWARN);
2786         if (unlikely(!new_mem)) {
2787                 bch2_trans_unlock(trans);
2788
2789                 new_mem = krealloc(trans->mem, new_bytes, GFP_KERNEL);
2790                 if (!new_mem && new_bytes <= BTREE_TRANS_MEM_MAX) {
2791                         new_mem = mempool_alloc(&c->btree_trans_mem_pool, GFP_KERNEL);
2792                         new_bytes = BTREE_TRANS_MEM_MAX;
2793                         kfree(trans->mem);
2794                 }
2795
2796                 if (!new_mem)
2797                         return ERR_PTR(-BCH_ERR_ENOMEM_trans_kmalloc);
2798
2799                 trans->mem = new_mem;
2800                 trans->mem_bytes = new_bytes;
2801
2802                 ret = bch2_trans_relock(trans);
2803                 if (ret)
2804                         return ERR_PTR(ret);
2805         }
2806
2807         trans->mem = new_mem;
2808         trans->mem_bytes = new_bytes;
2809
2810         if (old_bytes) {
2811                 trace_and_count(c, trans_restart_mem_realloced, trans, _RET_IP_, new_bytes);
2812                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_mem_realloced));
2813         }
2814
2815         p = trans->mem + trans->mem_top;
2816         trans->mem_top += size;
2817         memset(p, 0, size);
2818         return p;
2819 }
2820
2821 #include "sb-members.h"
2822
2823 static inline void check_srcu_held_too_long(struct btree_trans *trans)
2824 {
2825         if (trans->srcu_held && time_after(jiffies, trans->srcu_lock_time + HZ * 10)) {
2826                 struct printbuf buf = PRINTBUF;
2827
2828                 prt_str(&buf, "btree node read time:\n");
2829                 bch2_time_stats_to_text(&buf, &trans->c->times[BCH_TIME_btree_node_read]);
2830
2831                 prt_str(&buf, "btree node read_done time:\n");
2832                 bch2_time_stats_to_text(&buf, &trans->c->times[BCH_TIME_btree_node_read_done]);
2833
2834                 for_each_member_device(trans->c, ca) {
2835                         prt_printf(&buf, "device %u read time:\n", ca->dev_idx);
2836                         bch2_time_stats_to_text(&buf, &ca->io_latency[READ]);
2837                 }
2838
2839                 struct btree_transaction_stats *s = btree_trans_stats(trans);
2840                 prt_str(&buf, "transaction duration:\n");
2841                 bch2_time_stats_to_text(&buf, &s->duration);
2842
2843                 WARN(trans->srcu_held && time_after(jiffies, trans->srcu_lock_time + HZ * 10),
2844                      "btree trans held srcu lock (delaying memory reclaim) for %lu seconds",
2845                      (jiffies - trans->srcu_lock_time) / HZ);
2846                 bch2_print_string_as_lines(KERN_ERR, buf.buf);
2847                 printbuf_exit(&buf);
2848         }
2849 }
2850
2851 void bch2_trans_srcu_unlock(struct btree_trans *trans)
2852 {
2853         if (trans->srcu_held) {
2854                 struct bch_fs *c = trans->c;
2855                 struct btree_path *path;
2856                 unsigned i;
2857
2858                 trans_for_each_path(trans, path, i)
2859                         if (path->cached && !btree_node_locked(path, 0))
2860                                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_srcu_reset);
2861
2862                 check_srcu_held_too_long(trans);
2863                 srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
2864                 trans->srcu_held = false;
2865         }
2866 }
2867
2868 static void bch2_trans_srcu_lock(struct btree_trans *trans)
2869 {
2870         if (!trans->srcu_held) {
2871                 trans->srcu_idx = srcu_read_lock(&trans->c->btree_trans_barrier);
2872                 trans->srcu_lock_time   = jiffies;
2873                 trans->srcu_held = true;
2874         }
2875 }
2876
2877 /**
2878  * bch2_trans_begin() - reset a transaction after a interrupted attempt
2879  * @trans: transaction to reset
2880  *
2881  * Returns:     current restart counter, to be used with trans_was_restarted()
2882  *
2883  * While iterating over nodes or updating nodes a attempt to lock a btree node
2884  * may return BCH_ERR_transaction_restart when the trylock fails. When this
2885  * occurs bch2_trans_begin() should be called and the transaction retried.
2886  */
2887 u32 bch2_trans_begin(struct btree_trans *trans)
2888 {
2889         struct btree_path *path;
2890         unsigned i;
2891         u64 now;
2892
2893         bch2_trans_reset_updates(trans);
2894
2895         trans->restart_count++;
2896         trans->mem_top                  = 0;
2897         trans->journal_entries          = NULL;
2898
2899         trans_for_each_path(trans, path, i) {
2900                 path->should_be_locked = false;
2901
2902                 /*
2903                  * If the transaction wasn't restarted, we're presuming to be
2904                  * doing something new: dont keep iterators excpt the ones that
2905                  * are in use - except for the subvolumes btree:
2906                  */
2907                 if (!trans->restarted && path->btree_id != BTREE_ID_subvolumes)
2908                         path->preserve = false;
2909
2910                 /*
2911                  * XXX: we probably shouldn't be doing this if the transaction
2912                  * was restarted, but currently we still overflow transaction
2913                  * iterators if we do that
2914                  */
2915                 if (!path->ref && !path->preserve)
2916                         __bch2_path_free(trans, i);
2917                 else
2918                         path->preserve = false;
2919         }
2920
2921         now = local_clock();
2922
2923         if (!IS_ENABLED(CONFIG_BCACHEFS_NO_LATENCY_ACCT) &&
2924             time_after64(now, trans->last_begin_time + 10))
2925                 __bch2_time_stats_update(&btree_trans_stats(trans)->duration,
2926                                          trans->last_begin_time, now);
2927
2928         if (!trans->restarted &&
2929             (need_resched() ||
2930              time_after64(now, trans->last_begin_time + BTREE_TRANS_MAX_LOCK_HOLD_TIME_NS))) {
2931                 drop_locks_do(trans, (cond_resched(), 0));
2932                 now = local_clock();
2933         }
2934         trans->last_begin_time = now;
2935
2936         if (unlikely(trans->srcu_held &&
2937                      time_after(jiffies, trans->srcu_lock_time + msecs_to_jiffies(10))))
2938                 bch2_trans_srcu_unlock(trans);
2939
2940         trans->last_begin_ip = _RET_IP_;
2941         if (trans->restarted) {
2942                 bch2_btree_path_traverse_all(trans);
2943                 trans->notrace_relock_fail = false;
2944         }
2945
2946         return trans->restart_count;
2947 }
2948
2949 const char *bch2_btree_transaction_fns[BCH_TRANSACTIONS_NR] = { "(unknown)" };
2950
2951 unsigned bch2_trans_get_fn_idx(const char *fn)
2952 {
2953         for (unsigned i = 0; i < ARRAY_SIZE(bch2_btree_transaction_fns); i++)
2954                 if (!bch2_btree_transaction_fns[i] ||
2955                     bch2_btree_transaction_fns[i] == fn) {
2956                         bch2_btree_transaction_fns[i] = fn;
2957                         return i;
2958                 }
2959
2960         pr_warn_once("BCH_TRANSACTIONS_NR not big enough!");
2961         return 0;
2962 }
2963
2964 struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx)
2965         __acquires(&c->btree_trans_barrier)
2966 {
2967         struct btree_trans *trans;
2968
2969         if (IS_ENABLED(__KERNEL__)) {
2970                 trans = this_cpu_xchg(c->btree_trans_bufs->trans, NULL);
2971                 if (trans) {
2972                         memset(trans, 0, offsetof(struct btree_trans, list));
2973                         goto got_trans;
2974                 }
2975         }
2976
2977         trans = mempool_alloc(&c->btree_trans_pool, GFP_NOFS);
2978         memset(trans, 0, sizeof(*trans));
2979         closure_init_stack(&trans->ref);
2980
2981         seqmutex_lock(&c->btree_trans_lock);
2982         if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG)) {
2983                 struct btree_trans *pos;
2984                 pid_t pid = current->pid;
2985
2986                 trans->locking_wait.task = current;
2987
2988                 list_for_each_entry(pos, &c->btree_trans_list, list) {
2989                         struct task_struct *pos_task = READ_ONCE(pos->locking_wait.task);
2990                         /*
2991                          * We'd much prefer to be stricter here and completely
2992                          * disallow multiple btree_trans in the same thread -
2993                          * but the data move path calls bch2_write when we
2994                          * already have a btree_trans initialized.
2995                          */
2996                         BUG_ON(pos_task &&
2997                                pid == pos_task->pid &&
2998                                bch2_trans_locked(pos));
2999
3000                         if (pos_task && pid < pos_task->pid) {
3001                                 list_add_tail(&trans->list, &pos->list);
3002                                 goto list_add_done;
3003                         }
3004                 }
3005         }
3006         list_add_tail(&trans->list, &c->btree_trans_list);
3007 list_add_done:
3008         seqmutex_unlock(&c->btree_trans_lock);
3009 got_trans:
3010         trans->c                = c;
3011         trans->last_begin_time  = local_clock();
3012         trans->fn_idx           = fn_idx;
3013         trans->locking_wait.task = current;
3014         trans->journal_replay_not_finished =
3015                 unlikely(!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags)) &&
3016                 atomic_inc_not_zero(&c->journal_keys.ref);
3017         trans->nr_paths         = ARRAY_SIZE(trans->_paths);
3018         trans->paths_allocated  = trans->_paths_allocated;
3019         trans->sorted           = trans->_sorted;
3020         trans->paths            = trans->_paths;
3021         trans->updates          = trans->_updates;
3022
3023         *trans_paths_nr(trans->paths) = BTREE_ITER_INITIAL;
3024
3025         trans->paths_allocated[0] = 1;
3026
3027         if (fn_idx < BCH_TRANSACTIONS_NR) {
3028                 trans->fn = bch2_btree_transaction_fns[fn_idx];
3029
3030                 struct btree_transaction_stats *s = &c->btree_transaction_stats[fn_idx];
3031
3032                 if (s->max_mem) {
3033                         unsigned expected_mem_bytes = roundup_pow_of_two(s->max_mem);
3034
3035                         trans->mem = kmalloc(expected_mem_bytes, GFP_KERNEL);
3036                         if (likely(trans->mem))
3037                                 trans->mem_bytes = expected_mem_bytes;
3038                 }
3039
3040                 trans->nr_paths_max = s->nr_max_paths;
3041                 trans->journal_entries_size = s->journal_entries_size;
3042         }
3043
3044         trans->srcu_idx         = srcu_read_lock(&c->btree_trans_barrier);
3045         trans->srcu_lock_time   = jiffies;
3046         trans->srcu_held        = true;
3047         return trans;
3048 }
3049
3050 static void check_btree_paths_leaked(struct btree_trans *trans)
3051 {
3052 #ifdef CONFIG_BCACHEFS_DEBUG
3053         struct bch_fs *c = trans->c;
3054         struct btree_path *path;
3055         unsigned i;
3056
3057         trans_for_each_path(trans, path, i)
3058                 if (path->ref)
3059                         goto leaked;
3060         return;
3061 leaked:
3062         bch_err(c, "btree paths leaked from %s!", trans->fn);
3063         trans_for_each_path(trans, path, i)
3064                 if (path->ref)
3065                         printk(KERN_ERR "  btree %s %pS\n",
3066                                bch2_btree_id_str(path->btree_id),
3067                                (void *) path->ip_allocated);
3068         /* Be noisy about this: */
3069         bch2_fatal_error(c);
3070 #endif
3071 }
3072
3073 void bch2_trans_put(struct btree_trans *trans)
3074         __releases(&c->btree_trans_barrier)
3075 {
3076         struct bch_fs *c = trans->c;
3077
3078         bch2_trans_unlock(trans);
3079
3080         trans_for_each_update(trans, i)
3081                 __btree_path_put(trans->paths + i->path, true);
3082         trans->nr_updates       = 0;
3083         trans->locking_wait.task = NULL;
3084
3085         check_btree_paths_leaked(trans);
3086
3087         if (trans->srcu_held) {
3088                 check_srcu_held_too_long(trans);
3089                 srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
3090         }
3091
3092         if (trans->fs_usage_deltas) {
3093                 if (trans->fs_usage_deltas->size + sizeof(trans->fs_usage_deltas) ==
3094                     REPLICAS_DELTA_LIST_MAX)
3095                         mempool_free(trans->fs_usage_deltas,
3096                                      &c->replicas_delta_pool);
3097                 else
3098                         kfree(trans->fs_usage_deltas);
3099         }
3100
3101         if (unlikely(trans->journal_replay_not_finished))
3102                 bch2_journal_keys_put(c);
3103
3104         unsigned long *paths_allocated = trans->paths_allocated;
3105         trans->paths_allocated  = NULL;
3106         trans->paths            = NULL;
3107
3108         if (paths_allocated != trans->_paths_allocated)
3109                 kfree_rcu_mightsleep(paths_allocated);
3110
3111         if (trans->mem_bytes == BTREE_TRANS_MEM_MAX)
3112                 mempool_free(trans->mem, &c->btree_trans_mem_pool);
3113         else
3114                 kfree(trans->mem);
3115
3116         /* Userspace doesn't have a real percpu implementation: */
3117         if (IS_ENABLED(__KERNEL__))
3118                 trans = this_cpu_xchg(c->btree_trans_bufs->trans, trans);
3119
3120         if (trans) {
3121                 closure_sync(&trans->ref);
3122
3123                 seqmutex_lock(&c->btree_trans_lock);
3124                 list_del(&trans->list);
3125                 seqmutex_unlock(&c->btree_trans_lock);
3126
3127                 mempool_free(trans, &c->btree_trans_pool);
3128         }
3129 }
3130
3131 static void __maybe_unused
3132 bch2_btree_bkey_cached_common_to_text(struct printbuf *out,
3133                                       struct btree_bkey_cached_common *b)
3134 {
3135         struct six_lock_count c = six_lock_counts(&b->lock);
3136         struct task_struct *owner;
3137         pid_t pid;
3138
3139         rcu_read_lock();
3140         owner = READ_ONCE(b->lock.owner);
3141         pid = owner ? owner->pid : 0;
3142         rcu_read_unlock();
3143
3144         prt_tab(out);
3145         prt_printf(out, "%px %c l=%u %s:", b, b->cached ? 'c' : 'b',
3146                    b->level, bch2_btree_id_str(b->btree_id));
3147         bch2_bpos_to_text(out, btree_node_pos(b));
3148
3149         prt_tab(out);
3150         prt_printf(out, " locks %u:%u:%u held by pid %u",
3151                    c.n[0], c.n[1], c.n[2], pid);
3152 }
3153
3154 void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
3155 {
3156         struct btree_bkey_cached_common *b;
3157         static char lock_types[] = { 'r', 'i', 'w' };
3158         struct task_struct *task = READ_ONCE(trans->locking_wait.task);
3159         unsigned l, idx;
3160
3161         /* before rcu_read_lock(): */
3162         bch2_printbuf_make_room(out, 4096);
3163
3164         if (!out->nr_tabstops) {
3165                 printbuf_tabstop_push(out, 16);
3166                 printbuf_tabstop_push(out, 32);
3167         }
3168
3169         prt_printf(out, "%i %s\n", task ? task->pid : 0, trans->fn);
3170
3171         /* trans->paths is rcu protected vs. freeing */
3172         rcu_read_lock();
3173         out->atomic++;
3174
3175         struct btree_path *paths = rcu_dereference(trans->paths);
3176         if (!paths)
3177                 goto out;
3178
3179         unsigned long *paths_allocated = trans_paths_allocated(paths);
3180
3181         trans_for_each_path_idx_from(paths_allocated, *trans_paths_nr(paths), idx, 1) {
3182                 struct btree_path *path = paths + idx;
3183                 if (!path->nodes_locked)
3184                         continue;
3185
3186                 prt_printf(out, "  path %u %c l=%u %s:",
3187                        idx,
3188                        path->cached ? 'c' : 'b',
3189                        path->level,
3190                        bch2_btree_id_str(path->btree_id));
3191                 bch2_bpos_to_text(out, path->pos);
3192                 prt_newline(out);
3193
3194                 for (l = 0; l < BTREE_MAX_DEPTH; l++) {
3195                         if (btree_node_locked(path, l) &&
3196                             !IS_ERR_OR_NULL(b = (void *) READ_ONCE(path->l[l].b))) {
3197                                 prt_printf(out, "    %c l=%u ",
3198                                            lock_types[btree_node_locked_type(path, l)], l);
3199                                 bch2_btree_bkey_cached_common_to_text(out, b);
3200                                 prt_newline(out);
3201                         }
3202                 }
3203         }
3204
3205         b = READ_ONCE(trans->locking);
3206         if (b) {
3207                 prt_printf(out, "  blocked for %lluus on",
3208                            div_u64(local_clock() - trans->locking_wait.start_time,
3209                                    1000));
3210                 prt_newline(out);
3211                 prt_printf(out, "    %c", lock_types[trans->locking_wait.lock_want]);
3212                 bch2_btree_bkey_cached_common_to_text(out, b);
3213                 prt_newline(out);
3214         }
3215 out:
3216         --out->atomic;
3217         rcu_read_unlock();
3218 }
3219
3220 void bch2_fs_btree_iter_exit(struct bch_fs *c)
3221 {
3222         struct btree_transaction_stats *s;
3223         struct btree_trans *trans;
3224         int cpu;
3225
3226         if (c->btree_trans_bufs)
3227                 for_each_possible_cpu(cpu) {
3228                         struct btree_trans *trans =
3229                                 per_cpu_ptr(c->btree_trans_bufs, cpu)->trans;
3230
3231                         if (trans) {
3232                                 closure_sync(&trans->ref);
3233
3234                                 seqmutex_lock(&c->btree_trans_lock);
3235                                 list_del(&trans->list);
3236                                 seqmutex_unlock(&c->btree_trans_lock);
3237                         }
3238                         kfree(trans);
3239                 }
3240         free_percpu(c->btree_trans_bufs);
3241
3242         trans = list_first_entry_or_null(&c->btree_trans_list, struct btree_trans, list);
3243         if (trans)
3244                 panic("%s leaked btree_trans\n", trans->fn);
3245
3246         for (s = c->btree_transaction_stats;
3247              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3248              s++) {
3249                 kfree(s->max_paths_text);
3250                 bch2_time_stats_exit(&s->lock_hold_times);
3251         }
3252
3253         if (c->btree_trans_barrier_initialized)
3254                 cleanup_srcu_struct(&c->btree_trans_barrier);
3255         mempool_exit(&c->btree_trans_mem_pool);
3256         mempool_exit(&c->btree_trans_pool);
3257 }
3258
3259 void bch2_fs_btree_iter_init_early(struct bch_fs *c)
3260 {
3261         struct btree_transaction_stats *s;
3262
3263         for (s = c->btree_transaction_stats;
3264              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3265              s++) {
3266                 bch2_time_stats_init(&s->duration);
3267                 bch2_time_stats_init(&s->lock_hold_times);
3268                 mutex_init(&s->lock);
3269         }
3270
3271         INIT_LIST_HEAD(&c->btree_trans_list);
3272         seqmutex_init(&c->btree_trans_lock);
3273 }
3274
3275 int bch2_fs_btree_iter_init(struct bch_fs *c)
3276 {
3277         int ret;
3278
3279         c->btree_trans_bufs = alloc_percpu(struct btree_trans_buf);
3280         if (!c->btree_trans_bufs)
3281                 return -ENOMEM;
3282
3283         ret   = mempool_init_kmalloc_pool(&c->btree_trans_pool, 1,
3284                                           sizeof(struct btree_trans)) ?:
3285                 mempool_init_kmalloc_pool(&c->btree_trans_mem_pool, 1,
3286                                           BTREE_TRANS_MEM_MAX) ?:
3287                 init_srcu_struct(&c->btree_trans_barrier);
3288         if (!ret)
3289                 c->btree_trans_barrier_initialized = true;
3290         return ret;
3291 }