1 // SPDX-License-Identifier: GPL-2.0 2 3 #include "bcachefs.h" 4 #include "bkey_buf.h" 5 #include "btree_key_cache.h" 6 #include "btree_update.h" 7 #include "buckets.h" 8 #include "errcode.h" 9 #include "error.h" 10 #include "fs.h" 11 #include "recovery_passes.h" 12 #include "snapshot.h" 13 14 #include <linux/random.h> 15 16 /* 17 * Snapshot trees: 18 * 19 * Keys in BTREE_ID_snapshot_trees identify a whole tree of snapshot nodes; they 20 * exist to provide a stable identifier for the whole lifetime of a snapshot 21 * tree. 22 */ 23 24 void bch2_snapshot_tree_to_text(struct printbuf *out, struct bch_fs *c, 25 struct bkey_s_c k) 26 { 27 struct bkey_s_c_snapshot_tree t = bkey_s_c_to_snapshot_tree(k); 28 29 prt_printf(out, "subvol %u root snapshot %u", 30 le32_to_cpu(t.v->master_subvol), 31 le32_to_cpu(t.v->root_snapshot)); 32 } 33 34 int bch2_snapshot_tree_invalid(struct bch_fs *c, struct bkey_s_c k, 35 enum bch_validate_flags flags, 36 struct printbuf *err) 37 { 38 int ret = 0; 39 40 bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) || 41 bkey_lt(k.k->p, POS(0, 1)), c, err, 42 snapshot_tree_pos_bad, 43 "bad pos"); 44 fsck_err: 45 return ret; 46 } 47 48 int bch2_snapshot_tree_lookup(struct btree_trans *trans, u32 id, 49 struct bch_snapshot_tree *s) 50 { 51 int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_snapshot_trees, POS(0, id), 52 BTREE_ITER_with_updates, snapshot_tree, s); 53 54 if (bch2_err_matches(ret, ENOENT)) 55 ret = -BCH_ERR_ENOENT_snapshot_tree; 56 return ret; 57 } 58 59 struct bkey_i_snapshot_tree * 60 __bch2_snapshot_tree_create(struct btree_trans *trans) 61 { 62 struct btree_iter iter; 63 int ret = bch2_bkey_get_empty_slot(trans, &iter, 64 BTREE_ID_snapshot_trees, POS(0, U32_MAX)); 65 struct bkey_i_snapshot_tree *s_t; 66 67 if (ret == -BCH_ERR_ENOSPC_btree_slot) 68 ret = -BCH_ERR_ENOSPC_snapshot_tree; 69 if (ret) 70 return ERR_PTR(ret); 71 72 s_t = bch2_bkey_alloc(trans, &iter, 0, snapshot_tree); 73 ret = PTR_ERR_OR_ZERO(s_t); 74 bch2_trans_iter_exit(trans, &iter); 75 return ret ? ERR_PTR(ret) : s_t; 76 } 77 78 static int bch2_snapshot_tree_create(struct btree_trans *trans, 79 u32 root_id, u32 subvol_id, u32 *tree_id) 80 { 81 struct bkey_i_snapshot_tree *n_tree = 82 __bch2_snapshot_tree_create(trans); 83 84 if (IS_ERR(n_tree)) 85 return PTR_ERR(n_tree); 86 87 n_tree->v.master_subvol = cpu_to_le32(subvol_id); 88 n_tree->v.root_snapshot = cpu_to_le32(root_id); 89 *tree_id = n_tree->k.p.offset; 90 return 0; 91 } 92 93 /* Snapshot nodes: */ 94 95 static bool __bch2_snapshot_is_ancestor_early(struct snapshot_table *t, u32 id, u32 ancestor) 96 { 97 while (id && id < ancestor) { 98 const struct snapshot_t *s = __snapshot_t(t, id); 99 id = s ? s->parent : 0; 100 } 101 return id == ancestor; 102 } 103 104 static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor) 105 { 106 rcu_read_lock(); 107 bool ret = __bch2_snapshot_is_ancestor_early(rcu_dereference(c->snapshots), id, ancestor); 108 rcu_read_unlock(); 109 110 return ret; 111 } 112 113 static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor) 114 { 115 const struct snapshot_t *s = __snapshot_t(t, id); 116 if (!s) 117 return 0; 118 119 if (s->skip[2] <= ancestor) 120 return s->skip[2]; 121 if (s->skip[1] <= ancestor) 122 return s->skip[1]; 123 if (s->skip[0] <= ancestor) 124 return s->skip[0]; 125 return s->parent; 126 } 127 128 static bool test_ancestor_bitmap(struct snapshot_table *t, u32 id, u32 ancestor) 129 { 130 const struct snapshot_t *s = __snapshot_t(t, id); 131 if (!s) 132 return false; 133 134 return test_bit(ancestor - id - 1, s->is_ancestor); 135 } 136 137 bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor) 138 { 139 bool ret; 140 141 rcu_read_lock(); 142 struct snapshot_table *t = rcu_dereference(c->snapshots); 143 144 if (unlikely(c->recovery_pass_done < BCH_RECOVERY_PASS_check_snapshots)) { 145 ret = __bch2_snapshot_is_ancestor_early(t, id, ancestor); 146 goto out; 147 } 148 149 while (id && id < ancestor - IS_ANCESTOR_BITMAP) 150 id = get_ancestor_below(t, id, ancestor); 151 152 ret = id && id < ancestor 153 ? test_ancestor_bitmap(t, id, ancestor) 154 : id == ancestor; 155 156 EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor)); 157 out: 158 rcu_read_unlock(); 159 160 return ret; 161 } 162 163 static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id) 164 { 165 size_t idx = U32_MAX - id; 166 struct snapshot_table *new, *old; 167 168 size_t new_bytes = kmalloc_size_roundup(struct_size(new, s, idx + 1)); 169 size_t new_size = (new_bytes - sizeof(*new)) / sizeof(new->s[0]); 170 171 new = kvzalloc(new_bytes, GFP_KERNEL); 172 if (!new) 173 return NULL; 174 175 new->nr = new_size; 176 177 old = rcu_dereference_protected(c->snapshots, true); 178 if (old) 179 memcpy(new->s, old->s, sizeof(old->s[0]) * old->nr); 180 181 rcu_assign_pointer(c->snapshots, new); 182 kvfree_rcu(old, rcu); 183 184 return &rcu_dereference_protected(c->snapshots, 185 lockdep_is_held(&c->snapshot_table_lock))->s[idx]; 186 } 187 188 static inline struct snapshot_t *snapshot_t_mut(struct bch_fs *c, u32 id) 189 { 190 size_t idx = U32_MAX - id; 191 struct snapshot_table *table = 192 rcu_dereference_protected(c->snapshots, 193 lockdep_is_held(&c->snapshot_table_lock)); 194 195 lockdep_assert_held(&c->snapshot_table_lock); 196 197 if (likely(table && idx < table->nr)) 198 return &table->s[idx]; 199 200 return __snapshot_t_mut(c, id); 201 } 202 203 void bch2_snapshot_to_text(struct printbuf *out, struct bch_fs *c, 204 struct bkey_s_c k) 205 { 206 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(k); 207 208 prt_printf(out, "is_subvol %llu deleted %llu parent %10u children %10u %10u subvol %u tree %u", 209 BCH_SNAPSHOT_SUBVOL(s.v), 210 BCH_SNAPSHOT_DELETED(s.v), 211 le32_to_cpu(s.v->parent), 212 le32_to_cpu(s.v->children[0]), 213 le32_to_cpu(s.v->children[1]), 214 le32_to_cpu(s.v->subvol), 215 le32_to_cpu(s.v->tree)); 216 217 if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, depth)) 218 prt_printf(out, " depth %u skiplist %u %u %u", 219 le32_to_cpu(s.v->depth), 220 le32_to_cpu(s.v->skip[0]), 221 le32_to_cpu(s.v->skip[1]), 222 le32_to_cpu(s.v->skip[2])); 223 } 224 225 int bch2_snapshot_invalid(struct bch_fs *c, struct bkey_s_c k, 226 enum bch_validate_flags flags, 227 struct printbuf *err) 228 { 229 struct bkey_s_c_snapshot s; 230 u32 i, id; 231 int ret = 0; 232 233 bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) || 234 bkey_lt(k.k->p, POS(0, 1)), c, err, 235 snapshot_pos_bad, 236 "bad pos"); 237 238 s = bkey_s_c_to_snapshot(k); 239 240 id = le32_to_cpu(s.v->parent); 241 bkey_fsck_err_on(id && id <= k.k->p.offset, c, err, 242 snapshot_parent_bad, 243 "bad parent node (%u <= %llu)", 244 id, k.k->p.offset); 245 246 bkey_fsck_err_on(le32_to_cpu(s.v->children[0]) < le32_to_cpu(s.v->children[1]), c, err, 247 snapshot_children_not_normalized, 248 "children not normalized"); 249 250 bkey_fsck_err_on(s.v->children[0] && s.v->children[0] == s.v->children[1], c, err, 251 snapshot_child_duplicate, 252 "duplicate child nodes"); 253 254 for (i = 0; i < 2; i++) { 255 id = le32_to_cpu(s.v->children[i]); 256 257 bkey_fsck_err_on(id >= k.k->p.offset, c, err, 258 snapshot_child_bad, 259 "bad child node (%u >= %llu)", 260 id, k.k->p.offset); 261 } 262 263 if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, skip)) { 264 bkey_fsck_err_on(le32_to_cpu(s.v->skip[0]) > le32_to_cpu(s.v->skip[1]) || 265 le32_to_cpu(s.v->skip[1]) > le32_to_cpu(s.v->skip[2]), c, err, 266 snapshot_skiplist_not_normalized, 267 "skiplist not normalized"); 268 269 for (i = 0; i < ARRAY_SIZE(s.v->skip); i++) { 270 id = le32_to_cpu(s.v->skip[i]); 271 272 bkey_fsck_err_on(id && id < le32_to_cpu(s.v->parent), c, err, 273 snapshot_skiplist_bad, 274 "bad skiplist node %u", id); 275 } 276 } 277 fsck_err: 278 return ret; 279 } 280 281 static void __set_is_ancestor_bitmap(struct bch_fs *c, u32 id) 282 { 283 struct snapshot_t *t = snapshot_t_mut(c, id); 284 u32 parent = id; 285 286 while ((parent = bch2_snapshot_parent_early(c, parent)) && 287 parent - id - 1 < IS_ANCESTOR_BITMAP) 288 __set_bit(parent - id - 1, t->is_ancestor); 289 } 290 291 static void set_is_ancestor_bitmap(struct bch_fs *c, u32 id) 292 { 293 mutex_lock(&c->snapshot_table_lock); 294 __set_is_ancestor_bitmap(c, id); 295 mutex_unlock(&c->snapshot_table_lock); 296 } 297 298 static int __bch2_mark_snapshot(struct btree_trans *trans, 299 enum btree_id btree, unsigned level, 300 struct bkey_s_c old, struct bkey_s_c new, 301 enum btree_iter_update_trigger_flags flags) 302 { 303 struct bch_fs *c = trans->c; 304 struct snapshot_t *t; 305 u32 id = new.k->p.offset; 306 int ret = 0; 307 308 mutex_lock(&c->snapshot_table_lock); 309 310 t = snapshot_t_mut(c, id); 311 if (!t) { 312 ret = -BCH_ERR_ENOMEM_mark_snapshot; 313 goto err; 314 } 315 316 if (new.k->type == KEY_TYPE_snapshot) { 317 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(new); 318 319 t->parent = le32_to_cpu(s.v->parent); 320 t->children[0] = le32_to_cpu(s.v->children[0]); 321 t->children[1] = le32_to_cpu(s.v->children[1]); 322 t->subvol = BCH_SNAPSHOT_SUBVOL(s.v) ? le32_to_cpu(s.v->subvol) : 0; 323 t->tree = le32_to_cpu(s.v->tree); 324 325 if (bkey_val_bytes(s.k) > offsetof(struct bch_snapshot, depth)) { 326 t->depth = le32_to_cpu(s.v->depth); 327 t->skip[0] = le32_to_cpu(s.v->skip[0]); 328 t->skip[1] = le32_to_cpu(s.v->skip[1]); 329 t->skip[2] = le32_to_cpu(s.v->skip[2]); 330 } else { 331 t->depth = 0; 332 t->skip[0] = 0; 333 t->skip[1] = 0; 334 t->skip[2] = 0; 335 } 336 337 __set_is_ancestor_bitmap(c, id); 338 339 if (BCH_SNAPSHOT_DELETED(s.v)) { 340 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags); 341 if (c->curr_recovery_pass > BCH_RECOVERY_PASS_delete_dead_snapshots) 342 bch2_delete_dead_snapshots_async(c); 343 } 344 } else { 345 memset(t, 0, sizeof(*t)); 346 } 347 err: 348 mutex_unlock(&c->snapshot_table_lock); 349 return ret; 350 } 351 352 int bch2_mark_snapshot(struct btree_trans *trans, 353 enum btree_id btree, unsigned level, 354 struct bkey_s_c old, struct bkey_s new, 355 enum btree_iter_update_trigger_flags flags) 356 { 357 return __bch2_mark_snapshot(trans, btree, level, old, new.s_c, flags); 358 } 359 360 int bch2_snapshot_lookup(struct btree_trans *trans, u32 id, 361 struct bch_snapshot *s) 362 { 363 return bch2_bkey_get_val_typed(trans, BTREE_ID_snapshots, POS(0, id), 364 BTREE_ITER_with_updates, snapshot, s); 365 } 366 367 static int bch2_snapshot_live(struct btree_trans *trans, u32 id) 368 { 369 struct bch_snapshot v; 370 int ret; 371 372 if (!id) 373 return 0; 374 375 ret = bch2_snapshot_lookup(trans, id, &v); 376 if (bch2_err_matches(ret, ENOENT)) 377 bch_err(trans->c, "snapshot node %u not found", id); 378 if (ret) 379 return ret; 380 381 return !BCH_SNAPSHOT_DELETED(&v); 382 } 383 384 /* 385 * If @k is a snapshot with just one live child, it's part of a linear chain, 386 * which we consider to be an equivalence class: and then after snapshot 387 * deletion cleanup, there should only be a single key at a given position in 388 * this equivalence class. 389 * 390 * This sets the equivalence class of @k to be the child's equivalence class, if 391 * it's part of such a linear chain: this correctly sets equivalence classes on 392 * startup if we run leaf to root (i.e. in natural key order). 393 */ 394 static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k) 395 { 396 struct bch_fs *c = trans->c; 397 unsigned i, nr_live = 0, live_idx = 0; 398 struct bkey_s_c_snapshot snap; 399 u32 id = k.k->p.offset, child[2]; 400 401 if (k.k->type != KEY_TYPE_snapshot) 402 return 0; 403 404 snap = bkey_s_c_to_snapshot(k); 405 406 child[0] = le32_to_cpu(snap.v->children[0]); 407 child[1] = le32_to_cpu(snap.v->children[1]); 408 409 for (i = 0; i < 2; i++) { 410 int ret = bch2_snapshot_live(trans, child[i]); 411 412 if (ret < 0) 413 return ret; 414 415 if (ret) 416 live_idx = i; 417 nr_live += ret; 418 } 419 420 mutex_lock(&c->snapshot_table_lock); 421 422 snapshot_t_mut(c, id)->equiv = nr_live == 1 423 ? snapshot_t_mut(c, child[live_idx])->equiv 424 : id; 425 426 mutex_unlock(&c->snapshot_table_lock); 427 428 return 0; 429 } 430 431 /* fsck: */ 432 433 static u32 bch2_snapshot_child(struct bch_fs *c, u32 id, unsigned child) 434 { 435 return snapshot_t(c, id)->children[child]; 436 } 437 438 static u32 bch2_snapshot_left_child(struct bch_fs *c, u32 id) 439 { 440 return bch2_snapshot_child(c, id, 0); 441 } 442 443 static u32 bch2_snapshot_right_child(struct bch_fs *c, u32 id) 444 { 445 return bch2_snapshot_child(c, id, 1); 446 } 447 448 static u32 bch2_snapshot_tree_next(struct bch_fs *c, u32 id) 449 { 450 u32 n, parent; 451 452 n = bch2_snapshot_left_child(c, id); 453 if (n) 454 return n; 455 456 while ((parent = bch2_snapshot_parent(c, id))) { 457 n = bch2_snapshot_right_child(c, parent); 458 if (n && n != id) 459 return n; 460 id = parent; 461 } 462 463 return 0; 464 } 465 466 static u32 bch2_snapshot_tree_oldest_subvol(struct bch_fs *c, u32 snapshot_root) 467 { 468 u32 id = snapshot_root; 469 u32 subvol = 0, s; 470 471 while (id) { 472 s = snapshot_t(c, id)->subvol; 473 474 if (s && (!subvol || s < subvol)) 475 subvol = s; 476 477 id = bch2_snapshot_tree_next(c, id); 478 } 479 480 return subvol; 481 } 482 483 static int bch2_snapshot_tree_master_subvol(struct btree_trans *trans, 484 u32 snapshot_root, u32 *subvol_id) 485 { 486 struct bch_fs *c = trans->c; 487 struct btree_iter iter; 488 struct bkey_s_c k; 489 bool found = false; 490 int ret; 491 492 for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN, 493 0, k, ret) { 494 if (k.k->type != KEY_TYPE_subvolume) 495 continue; 496 497 struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k); 498 if (!bch2_snapshot_is_ancestor(c, le32_to_cpu(s.v->snapshot), snapshot_root)) 499 continue; 500 if (!BCH_SUBVOLUME_SNAP(s.v)) { 501 *subvol_id = s.k->p.offset; 502 found = true; 503 break; 504 } 505 } 506 507 bch2_trans_iter_exit(trans, &iter); 508 509 if (!ret && !found) { 510 struct bkey_i_subvolume *u; 511 512 *subvol_id = bch2_snapshot_tree_oldest_subvol(c, snapshot_root); 513 514 u = bch2_bkey_get_mut_typed(trans, &iter, 515 BTREE_ID_subvolumes, POS(0, *subvol_id), 516 0, subvolume); 517 ret = PTR_ERR_OR_ZERO(u); 518 if (ret) 519 return ret; 520 521 SET_BCH_SUBVOLUME_SNAP(&u->v, false); 522 } 523 524 return ret; 525 } 526 527 static int check_snapshot_tree(struct btree_trans *trans, 528 struct btree_iter *iter, 529 struct bkey_s_c k) 530 { 531 struct bch_fs *c = trans->c; 532 struct bkey_s_c_snapshot_tree st; 533 struct bch_snapshot s; 534 struct bch_subvolume subvol; 535 struct printbuf buf = PRINTBUF; 536 u32 root_id; 537 int ret; 538 539 if (k.k->type != KEY_TYPE_snapshot_tree) 540 return 0; 541 542 st = bkey_s_c_to_snapshot_tree(k); 543 root_id = le32_to_cpu(st.v->root_snapshot); 544 545 ret = bch2_snapshot_lookup(trans, root_id, &s); 546 if (ret && !bch2_err_matches(ret, ENOENT)) 547 goto err; 548 549 if (fsck_err_on(ret || 550 root_id != bch2_snapshot_root(c, root_id) || 551 st.k->p.offset != le32_to_cpu(s.tree), 552 c, snapshot_tree_to_missing_snapshot, 553 "snapshot tree points to missing/incorrect snapshot:\n %s", 554 (bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) { 555 ret = bch2_btree_delete_at(trans, iter, 0); 556 goto err; 557 } 558 559 ret = bch2_subvolume_get(trans, le32_to_cpu(st.v->master_subvol), 560 false, 0, &subvol); 561 if (ret && !bch2_err_matches(ret, ENOENT)) 562 goto err; 563 564 if (fsck_err_on(ret, 565 c, snapshot_tree_to_missing_subvol, 566 "snapshot tree points to missing subvolume:\n %s", 567 (printbuf_reset(&buf), 568 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) || 569 fsck_err_on(!bch2_snapshot_is_ancestor(c, 570 le32_to_cpu(subvol.snapshot), 571 root_id), 572 c, snapshot_tree_to_wrong_subvol, 573 "snapshot tree points to subvolume that does not point to snapshot in this tree:\n %s", 574 (printbuf_reset(&buf), 575 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) || 576 fsck_err_on(BCH_SUBVOLUME_SNAP(&subvol), 577 c, snapshot_tree_to_snapshot_subvol, 578 "snapshot tree points to snapshot subvolume:\n %s", 579 (printbuf_reset(&buf), 580 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) { 581 struct bkey_i_snapshot_tree *u; 582 u32 subvol_id; 583 584 ret = bch2_snapshot_tree_master_subvol(trans, root_id, &subvol_id); 585 bch_err_fn(c, ret); 586 587 if (bch2_err_matches(ret, ENOENT)) { /* nothing to be done here */ 588 ret = 0; 589 goto err; 590 } 591 592 if (ret) 593 goto err; 594 595 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot_tree); 596 ret = PTR_ERR_OR_ZERO(u); 597 if (ret) 598 goto err; 599 600 u->v.master_subvol = cpu_to_le32(subvol_id); 601 st = snapshot_tree_i_to_s_c(u); 602 } 603 err: 604 fsck_err: 605 printbuf_exit(&buf); 606 return ret; 607 } 608 609 /* 610 * For each snapshot_tree, make sure it points to the root of a snapshot tree 611 * and that snapshot entry points back to it, or delete it. 612 * 613 * And, make sure it points to a subvolume within that snapshot tree, or correct 614 * it to point to the oldest subvolume within that snapshot tree. 615 */ 616 int bch2_check_snapshot_trees(struct bch_fs *c) 617 { 618 int ret = bch2_trans_run(c, 619 for_each_btree_key_commit(trans, iter, 620 BTREE_ID_snapshot_trees, POS_MIN, 621 BTREE_ITER_prefetch, k, 622 NULL, NULL, BCH_TRANS_COMMIT_no_enospc, 623 check_snapshot_tree(trans, &iter, k))); 624 bch_err_fn(c, ret); 625 return ret; 626 } 627 628 /* 629 * Look up snapshot tree for @tree_id and find root, 630 * make sure @snap_id is a descendent: 631 */ 632 static int snapshot_tree_ptr_good(struct btree_trans *trans, 633 u32 snap_id, u32 tree_id) 634 { 635 struct bch_snapshot_tree s_t; 636 int ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t); 637 638 if (bch2_err_matches(ret, ENOENT)) 639 return 0; 640 if (ret) 641 return ret; 642 643 return bch2_snapshot_is_ancestor_early(trans->c, snap_id, le32_to_cpu(s_t.root_snapshot)); 644 } 645 646 u32 bch2_snapshot_skiplist_get(struct bch_fs *c, u32 id) 647 { 648 const struct snapshot_t *s; 649 650 if (!id) 651 return 0; 652 653 rcu_read_lock(); 654 s = snapshot_t(c, id); 655 if (s->parent) 656 id = bch2_snapshot_nth_parent(c, id, get_random_u32_below(s->depth)); 657 rcu_read_unlock(); 658 659 return id; 660 } 661 662 static int snapshot_skiplist_good(struct btree_trans *trans, u32 id, struct bch_snapshot s) 663 { 664 unsigned i; 665 666 for (i = 0; i < 3; i++) 667 if (!s.parent) { 668 if (s.skip[i]) 669 return false; 670 } else { 671 if (!bch2_snapshot_is_ancestor_early(trans->c, id, le32_to_cpu(s.skip[i]))) 672 return false; 673 } 674 675 return true; 676 } 677 678 /* 679 * snapshot_tree pointer was incorrect: look up root snapshot node, make sure 680 * its snapshot_tree pointer is correct (allocate new one if necessary), then 681 * update this node's pointer to root node's pointer: 682 */ 683 static int snapshot_tree_ptr_repair(struct btree_trans *trans, 684 struct btree_iter *iter, 685 struct bkey_s_c k, 686 struct bch_snapshot *s) 687 { 688 struct bch_fs *c = trans->c; 689 struct btree_iter root_iter; 690 struct bch_snapshot_tree s_t; 691 struct bkey_s_c_snapshot root; 692 struct bkey_i_snapshot *u; 693 u32 root_id = bch2_snapshot_root(c, k.k->p.offset), tree_id; 694 int ret; 695 696 root = bch2_bkey_get_iter_typed(trans, &root_iter, 697 BTREE_ID_snapshots, POS(0, root_id), 698 BTREE_ITER_with_updates, snapshot); 699 ret = bkey_err(root); 700 if (ret) 701 goto err; 702 703 tree_id = le32_to_cpu(root.v->tree); 704 705 ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t); 706 if (ret && !bch2_err_matches(ret, ENOENT)) 707 return ret; 708 709 if (ret || le32_to_cpu(s_t.root_snapshot) != root_id) { 710 u = bch2_bkey_make_mut_typed(trans, &root_iter, &root.s_c, 0, snapshot); 711 ret = PTR_ERR_OR_ZERO(u) ?: 712 bch2_snapshot_tree_create(trans, root_id, 713 bch2_snapshot_tree_oldest_subvol(c, root_id), 714 &tree_id); 715 if (ret) 716 goto err; 717 718 u->v.tree = cpu_to_le32(tree_id); 719 if (k.k->p.offset == root_id) 720 *s = u->v; 721 } 722 723 if (k.k->p.offset != root_id) { 724 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot); 725 ret = PTR_ERR_OR_ZERO(u); 726 if (ret) 727 goto err; 728 729 u->v.tree = cpu_to_le32(tree_id); 730 *s = u->v; 731 } 732 err: 733 bch2_trans_iter_exit(trans, &root_iter); 734 return ret; 735 } 736 737 static int check_snapshot(struct btree_trans *trans, 738 struct btree_iter *iter, 739 struct bkey_s_c k) 740 { 741 struct bch_fs *c = trans->c; 742 struct bch_snapshot s; 743 struct bch_subvolume subvol; 744 struct bch_snapshot v; 745 struct bkey_i_snapshot *u; 746 u32 parent_id = bch2_snapshot_parent_early(c, k.k->p.offset); 747 u32 real_depth; 748 struct printbuf buf = PRINTBUF; 749 u32 i, id; 750 int ret = 0; 751 752 if (k.k->type != KEY_TYPE_snapshot) 753 return 0; 754 755 memset(&s, 0, sizeof(s)); 756 memcpy(&s, k.v, min(sizeof(s), bkey_val_bytes(k.k))); 757 758 id = le32_to_cpu(s.parent); 759 if (id) { 760 ret = bch2_snapshot_lookup(trans, id, &v); 761 if (bch2_err_matches(ret, ENOENT)) 762 bch_err(c, "snapshot with nonexistent parent:\n %s", 763 (bch2_bkey_val_to_text(&buf, c, k), buf.buf)); 764 if (ret) 765 goto err; 766 767 if (le32_to_cpu(v.children[0]) != k.k->p.offset && 768 le32_to_cpu(v.children[1]) != k.k->p.offset) { 769 bch_err(c, "snapshot parent %u missing pointer to child %llu", 770 id, k.k->p.offset); 771 ret = -EINVAL; 772 goto err; 773 } 774 } 775 776 for (i = 0; i < 2 && s.children[i]; i++) { 777 id = le32_to_cpu(s.children[i]); 778 779 ret = bch2_snapshot_lookup(trans, id, &v); 780 if (bch2_err_matches(ret, ENOENT)) 781 bch_err(c, "snapshot node %llu has nonexistent child %u", 782 k.k->p.offset, id); 783 if (ret) 784 goto err; 785 786 if (le32_to_cpu(v.parent) != k.k->p.offset) { 787 bch_err(c, "snapshot child %u has wrong parent (got %u should be %llu)", 788 id, le32_to_cpu(v.parent), k.k->p.offset); 789 ret = -EINVAL; 790 goto err; 791 } 792 } 793 794 bool should_have_subvol = BCH_SNAPSHOT_SUBVOL(&s) && 795 !BCH_SNAPSHOT_DELETED(&s); 796 797 if (should_have_subvol) { 798 id = le32_to_cpu(s.subvol); 799 ret = bch2_subvolume_get(trans, id, 0, false, &subvol); 800 if (bch2_err_matches(ret, ENOENT)) 801 bch_err(c, "snapshot points to nonexistent subvolume:\n %s", 802 (bch2_bkey_val_to_text(&buf, c, k), buf.buf)); 803 if (ret) 804 goto err; 805 806 if (BCH_SNAPSHOT_SUBVOL(&s) != (le32_to_cpu(subvol.snapshot) == k.k->p.offset)) { 807 bch_err(c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL", 808 k.k->p.offset); 809 ret = -EINVAL; 810 goto err; 811 } 812 } else { 813 if (fsck_err_on(s.subvol, 814 c, snapshot_should_not_have_subvol, 815 "snapshot should not point to subvol:\n %s", 816 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) { 817 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot); 818 ret = PTR_ERR_OR_ZERO(u); 819 if (ret) 820 goto err; 821 822 u->v.subvol = 0; 823 s = u->v; 824 } 825 } 826 827 ret = snapshot_tree_ptr_good(trans, k.k->p.offset, le32_to_cpu(s.tree)); 828 if (ret < 0) 829 goto err; 830 831 if (fsck_err_on(!ret, c, snapshot_to_bad_snapshot_tree, 832 "snapshot points to missing/incorrect tree:\n %s", 833 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) { 834 ret = snapshot_tree_ptr_repair(trans, iter, k, &s); 835 if (ret) 836 goto err; 837 } 838 ret = 0; 839 840 real_depth = bch2_snapshot_depth(c, parent_id); 841 842 if (fsck_err_on(le32_to_cpu(s.depth) != real_depth, 843 c, snapshot_bad_depth, 844 "snapshot with incorrect depth field, should be %u:\n %s", 845 real_depth, (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) { 846 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot); 847 ret = PTR_ERR_OR_ZERO(u); 848 if (ret) 849 goto err; 850 851 u->v.depth = cpu_to_le32(real_depth); 852 s = u->v; 853 } 854 855 ret = snapshot_skiplist_good(trans, k.k->p.offset, s); 856 if (ret < 0) 857 goto err; 858 859 if (fsck_err_on(!ret, c, snapshot_bad_skiplist, 860 "snapshot with bad skiplist field:\n %s", 861 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) { 862 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot); 863 ret = PTR_ERR_OR_ZERO(u); 864 if (ret) 865 goto err; 866 867 for (i = 0; i < ARRAY_SIZE(u->v.skip); i++) 868 u->v.skip[i] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent_id)); 869 870 bubble_sort(u->v.skip, ARRAY_SIZE(u->v.skip), cmp_le32); 871 s = u->v; 872 } 873 ret = 0; 874 err: 875 fsck_err: 876 printbuf_exit(&buf); 877 return ret; 878 } 879 880 int bch2_check_snapshots(struct bch_fs *c) 881 { 882 /* 883 * We iterate backwards as checking/fixing the depth field requires that 884 * the parent's depth already be correct: 885 */ 886 int ret = bch2_trans_run(c, 887 for_each_btree_key_reverse_commit(trans, iter, 888 BTREE_ID_snapshots, POS_MAX, 889 BTREE_ITER_prefetch, k, 890 NULL, NULL, BCH_TRANS_COMMIT_no_enospc, 891 check_snapshot(trans, &iter, k))); 892 bch_err_fn(c, ret); 893 return ret; 894 } 895 896 static int check_snapshot_exists(struct btree_trans *trans, u32 id) 897 { 898 struct bch_fs *c = trans->c; 899 900 if (bch2_snapshot_equiv(c, id)) 901 return 0; 902 903 /* 0 is an invalid tree ID */ 904 u32 tree_id = 0; 905 int ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id); 906 if (ret) 907 return ret; 908 909 struct bkey_i_snapshot *snapshot = bch2_trans_kmalloc(trans, sizeof(*snapshot)); 910 ret = PTR_ERR_OR_ZERO(snapshot); 911 if (ret) 912 return ret; 913 914 bkey_snapshot_init(&snapshot->k_i); 915 snapshot->k.p = POS(0, id); 916 snapshot->v.tree = cpu_to_le32(tree_id); 917 snapshot->v.btime.lo = cpu_to_le64(bch2_current_time(c)); 918 919 return bch2_btree_insert_trans(trans, BTREE_ID_snapshots, &snapshot->k_i, 0) ?: 920 bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, 921 bkey_s_c_null, bkey_i_to_s(&snapshot->k_i), 0) ?: 922 bch2_snapshot_set_equiv(trans, bkey_i_to_s_c(&snapshot->k_i)); 923 } 924 925 /* Figure out which snapshot nodes belong in the same tree: */ 926 struct snapshot_tree_reconstruct { 927 enum btree_id btree; 928 struct bpos cur_pos; 929 snapshot_id_list cur_ids; 930 DARRAY(snapshot_id_list) trees; 931 }; 932 933 static void snapshot_tree_reconstruct_exit(struct snapshot_tree_reconstruct *r) 934 { 935 darray_for_each(r->trees, i) 936 darray_exit(i); 937 darray_exit(&r->trees); 938 darray_exit(&r->cur_ids); 939 } 940 941 static inline bool same_snapshot(struct snapshot_tree_reconstruct *r, struct bpos pos) 942 { 943 return r->btree == BTREE_ID_inodes 944 ? r->cur_pos.offset == pos.offset 945 : r->cur_pos.inode == pos.inode; 946 } 947 948 static inline bool snapshot_id_lists_have_common(snapshot_id_list *l, snapshot_id_list *r) 949 { 950 darray_for_each(*l, i) 951 if (snapshot_list_has_id(r, *i)) 952 return true; 953 return false; 954 } 955 956 static void snapshot_id_list_to_text(struct printbuf *out, snapshot_id_list *s) 957 { 958 bool first = true; 959 darray_for_each(*s, i) { 960 if (!first) 961 prt_char(out, ' '); 962 first = false; 963 prt_printf(out, "%u", *i); 964 } 965 } 966 967 static int snapshot_tree_reconstruct_next(struct bch_fs *c, struct snapshot_tree_reconstruct *r) 968 { 969 if (r->cur_ids.nr) { 970 darray_for_each(r->trees, i) 971 if (snapshot_id_lists_have_common(i, &r->cur_ids)) { 972 int ret = snapshot_list_merge(c, i, &r->cur_ids); 973 if (ret) 974 return ret; 975 goto out; 976 } 977 darray_push(&r->trees, r->cur_ids); 978 darray_init(&r->cur_ids); 979 } 980 out: 981 r->cur_ids.nr = 0; 982 return 0; 983 } 984 985 static int get_snapshot_trees(struct bch_fs *c, struct snapshot_tree_reconstruct *r, struct bpos pos) 986 { 987 if (!same_snapshot(r, pos)) 988 snapshot_tree_reconstruct_next(c, r); 989 r->cur_pos = pos; 990 return snapshot_list_add_nodup(c, &r->cur_ids, pos.snapshot); 991 } 992 993 int bch2_reconstruct_snapshots(struct bch_fs *c) 994 { 995 struct btree_trans *trans = bch2_trans_get(c); 996 struct printbuf buf = PRINTBUF; 997 struct snapshot_tree_reconstruct r = {}; 998 int ret = 0; 999 1000 for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) { 1001 if (btree_type_has_snapshots(btree)) { 1002 r.btree = btree; 1003 1004 ret = for_each_btree_key(trans, iter, btree, POS_MIN, 1005 BTREE_ITER_all_snapshots|BTREE_ITER_prefetch, k, ({ 1006 get_snapshot_trees(c, &r, k.k->p); 1007 })); 1008 if (ret) 1009 goto err; 1010 1011 snapshot_tree_reconstruct_next(c, &r); 1012 } 1013 } 1014 1015 darray_for_each(r.trees, t) { 1016 printbuf_reset(&buf); 1017 snapshot_id_list_to_text(&buf, t); 1018 1019 darray_for_each(*t, id) { 1020 if (fsck_err_on(!bch2_snapshot_equiv(c, *id), 1021 c, snapshot_node_missing, 1022 "snapshot node %u from tree %s missing, recreate?", *id, buf.buf)) { 1023 if (t->nr > 1) { 1024 bch_err(c, "cannot reconstruct snapshot trees with multiple nodes"); 1025 ret = -BCH_ERR_fsck_repair_unimplemented; 1026 goto err; 1027 } 1028 1029 ret = commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc, 1030 check_snapshot_exists(trans, *id)); 1031 if (ret) 1032 goto err; 1033 } 1034 } 1035 } 1036 fsck_err: 1037 err: 1038 bch2_trans_put(trans); 1039 snapshot_tree_reconstruct_exit(&r); 1040 printbuf_exit(&buf); 1041 bch_err_fn(c, ret); 1042 return ret; 1043 } 1044 1045 /* 1046 * Mark a snapshot as deleted, for future cleanup: 1047 */ 1048 int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id) 1049 { 1050 struct btree_iter iter; 1051 struct bkey_i_snapshot *s; 1052 int ret = 0; 1053 1054 s = bch2_bkey_get_mut_typed(trans, &iter, 1055 BTREE_ID_snapshots, POS(0, id), 1056 0, snapshot); 1057 ret = PTR_ERR_OR_ZERO(s); 1058 if (unlikely(ret)) { 1059 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), 1060 trans->c, "missing snapshot %u", id); 1061 return ret; 1062 } 1063 1064 /* already deleted? */ 1065 if (BCH_SNAPSHOT_DELETED(&s->v)) 1066 goto err; 1067 1068 SET_BCH_SNAPSHOT_DELETED(&s->v, true); 1069 SET_BCH_SNAPSHOT_SUBVOL(&s->v, false); 1070 s->v.subvol = 0; 1071 err: 1072 bch2_trans_iter_exit(trans, &iter); 1073 return ret; 1074 } 1075 1076 static inline void normalize_snapshot_child_pointers(struct bch_snapshot *s) 1077 { 1078 if (le32_to_cpu(s->children[0]) < le32_to_cpu(s->children[1])) 1079 swap(s->children[0], s->children[1]); 1080 } 1081 1082 static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id) 1083 { 1084 struct bch_fs *c = trans->c; 1085 struct btree_iter iter, p_iter = (struct btree_iter) { NULL }; 1086 struct btree_iter c_iter = (struct btree_iter) { NULL }; 1087 struct btree_iter tree_iter = (struct btree_iter) { NULL }; 1088 struct bkey_s_c_snapshot s; 1089 u32 parent_id, child_id; 1090 unsigned i; 1091 int ret = 0; 1092 1093 s = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id), 1094 BTREE_ITER_intent, snapshot); 1095 ret = bkey_err(s); 1096 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, 1097 "missing snapshot %u", id); 1098 1099 if (ret) 1100 goto err; 1101 1102 BUG_ON(s.v->children[1]); 1103 1104 parent_id = le32_to_cpu(s.v->parent); 1105 child_id = le32_to_cpu(s.v->children[0]); 1106 1107 if (parent_id) { 1108 struct bkey_i_snapshot *parent; 1109 1110 parent = bch2_bkey_get_mut_typed(trans, &p_iter, 1111 BTREE_ID_snapshots, POS(0, parent_id), 1112 0, snapshot); 1113 ret = PTR_ERR_OR_ZERO(parent); 1114 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, 1115 "missing snapshot %u", parent_id); 1116 if (unlikely(ret)) 1117 goto err; 1118 1119 /* find entry in parent->children for node being deleted */ 1120 for (i = 0; i < 2; i++) 1121 if (le32_to_cpu(parent->v.children[i]) == id) 1122 break; 1123 1124 if (bch2_fs_inconsistent_on(i == 2, c, 1125 "snapshot %u missing child pointer to %u", 1126 parent_id, id)) 1127 goto err; 1128 1129 parent->v.children[i] = cpu_to_le32(child_id); 1130 1131 normalize_snapshot_child_pointers(&parent->v); 1132 } 1133 1134 if (child_id) { 1135 struct bkey_i_snapshot *child; 1136 1137 child = bch2_bkey_get_mut_typed(trans, &c_iter, 1138 BTREE_ID_snapshots, POS(0, child_id), 1139 0, snapshot); 1140 ret = PTR_ERR_OR_ZERO(child); 1141 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, 1142 "missing snapshot %u", child_id); 1143 if (unlikely(ret)) 1144 goto err; 1145 1146 child->v.parent = cpu_to_le32(parent_id); 1147 1148 if (!child->v.parent) { 1149 child->v.skip[0] = 0; 1150 child->v.skip[1] = 0; 1151 child->v.skip[2] = 0; 1152 } 1153 } 1154 1155 if (!parent_id) { 1156 /* 1157 * We're deleting the root of a snapshot tree: update the 1158 * snapshot_tree entry to point to the new root, or delete it if 1159 * this is the last snapshot ID in this tree: 1160 */ 1161 struct bkey_i_snapshot_tree *s_t; 1162 1163 BUG_ON(s.v->children[1]); 1164 1165 s_t = bch2_bkey_get_mut_typed(trans, &tree_iter, 1166 BTREE_ID_snapshot_trees, POS(0, le32_to_cpu(s.v->tree)), 1167 0, snapshot_tree); 1168 ret = PTR_ERR_OR_ZERO(s_t); 1169 if (ret) 1170 goto err; 1171 1172 if (s.v->children[0]) { 1173 s_t->v.root_snapshot = s.v->children[0]; 1174 } else { 1175 s_t->k.type = KEY_TYPE_deleted; 1176 set_bkey_val_u64s(&s_t->k, 0); 1177 } 1178 } 1179 1180 ret = bch2_btree_delete_at(trans, &iter, 0); 1181 err: 1182 bch2_trans_iter_exit(trans, &tree_iter); 1183 bch2_trans_iter_exit(trans, &p_iter); 1184 bch2_trans_iter_exit(trans, &c_iter); 1185 bch2_trans_iter_exit(trans, &iter); 1186 return ret; 1187 } 1188 1189 static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree, 1190 u32 *new_snapids, 1191 u32 *snapshot_subvols, 1192 unsigned nr_snapids) 1193 { 1194 struct bch_fs *c = trans->c; 1195 struct btree_iter iter; 1196 struct bkey_i_snapshot *n; 1197 struct bkey_s_c k; 1198 unsigned i, j; 1199 u32 depth = bch2_snapshot_depth(c, parent); 1200 int ret; 1201 1202 bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots, 1203 POS_MIN, BTREE_ITER_intent); 1204 k = bch2_btree_iter_peek(&iter); 1205 ret = bkey_err(k); 1206 if (ret) 1207 goto err; 1208 1209 for (i = 0; i < nr_snapids; i++) { 1210 k = bch2_btree_iter_prev_slot(&iter); 1211 ret = bkey_err(k); 1212 if (ret) 1213 goto err; 1214 1215 if (!k.k || !k.k->p.offset) { 1216 ret = -BCH_ERR_ENOSPC_snapshot_create; 1217 goto err; 1218 } 1219 1220 n = bch2_bkey_alloc(trans, &iter, 0, snapshot); 1221 ret = PTR_ERR_OR_ZERO(n); 1222 if (ret) 1223 goto err; 1224 1225 n->v.flags = 0; 1226 n->v.parent = cpu_to_le32(parent); 1227 n->v.subvol = cpu_to_le32(snapshot_subvols[i]); 1228 n->v.tree = cpu_to_le32(tree); 1229 n->v.depth = cpu_to_le32(depth); 1230 n->v.btime.lo = cpu_to_le64(bch2_current_time(c)); 1231 n->v.btime.hi = 0; 1232 1233 for (j = 0; j < ARRAY_SIZE(n->v.skip); j++) 1234 n->v.skip[j] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent)); 1235 1236 bubble_sort(n->v.skip, ARRAY_SIZE(n->v.skip), cmp_le32); 1237 SET_BCH_SNAPSHOT_SUBVOL(&n->v, true); 1238 1239 ret = __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, 1240 bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0); 1241 if (ret) 1242 goto err; 1243 1244 new_snapids[i] = iter.pos.offset; 1245 1246 mutex_lock(&c->snapshot_table_lock); 1247 snapshot_t_mut(c, new_snapids[i])->equiv = new_snapids[i]; 1248 mutex_unlock(&c->snapshot_table_lock); 1249 } 1250 err: 1251 bch2_trans_iter_exit(trans, &iter); 1252 return ret; 1253 } 1254 1255 /* 1256 * Create new snapshot IDs as children of an existing snapshot ID: 1257 */ 1258 static int bch2_snapshot_node_create_children(struct btree_trans *trans, u32 parent, 1259 u32 *new_snapids, 1260 u32 *snapshot_subvols, 1261 unsigned nr_snapids) 1262 { 1263 struct btree_iter iter; 1264 struct bkey_i_snapshot *n_parent; 1265 int ret = 0; 1266 1267 n_parent = bch2_bkey_get_mut_typed(trans, &iter, 1268 BTREE_ID_snapshots, POS(0, parent), 1269 0, snapshot); 1270 ret = PTR_ERR_OR_ZERO(n_parent); 1271 if (unlikely(ret)) { 1272 if (bch2_err_matches(ret, ENOENT)) 1273 bch_err(trans->c, "snapshot %u not found", parent); 1274 return ret; 1275 } 1276 1277 if (n_parent->v.children[0] || n_parent->v.children[1]) { 1278 bch_err(trans->c, "Trying to add child snapshot nodes to parent that already has children"); 1279 ret = -EINVAL; 1280 goto err; 1281 } 1282 1283 ret = create_snapids(trans, parent, le32_to_cpu(n_parent->v.tree), 1284 new_snapids, snapshot_subvols, nr_snapids); 1285 if (ret) 1286 goto err; 1287 1288 n_parent->v.children[0] = cpu_to_le32(new_snapids[0]); 1289 n_parent->v.children[1] = cpu_to_le32(new_snapids[1]); 1290 n_parent->v.subvol = 0; 1291 SET_BCH_SNAPSHOT_SUBVOL(&n_parent->v, false); 1292 err: 1293 bch2_trans_iter_exit(trans, &iter); 1294 return ret; 1295 } 1296 1297 /* 1298 * Create a snapshot node that is the root of a new tree: 1299 */ 1300 static int bch2_snapshot_node_create_tree(struct btree_trans *trans, 1301 u32 *new_snapids, 1302 u32 *snapshot_subvols, 1303 unsigned nr_snapids) 1304 { 1305 struct bkey_i_snapshot_tree *n_tree; 1306 int ret; 1307 1308 n_tree = __bch2_snapshot_tree_create(trans); 1309 ret = PTR_ERR_OR_ZERO(n_tree) ?: 1310 create_snapids(trans, 0, n_tree->k.p.offset, 1311 new_snapids, snapshot_subvols, nr_snapids); 1312 if (ret) 1313 return ret; 1314 1315 n_tree->v.master_subvol = cpu_to_le32(snapshot_subvols[0]); 1316 n_tree->v.root_snapshot = cpu_to_le32(new_snapids[0]); 1317 return 0; 1318 } 1319 1320 int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent, 1321 u32 *new_snapids, 1322 u32 *snapshot_subvols, 1323 unsigned nr_snapids) 1324 { 1325 BUG_ON((parent == 0) != (nr_snapids == 1)); 1326 BUG_ON((parent != 0) != (nr_snapids == 2)); 1327 1328 return parent 1329 ? bch2_snapshot_node_create_children(trans, parent, 1330 new_snapids, snapshot_subvols, nr_snapids) 1331 : bch2_snapshot_node_create_tree(trans, 1332 new_snapids, snapshot_subvols, nr_snapids); 1333 1334 } 1335 1336 /* 1337 * If we have an unlinked inode in an internal snapshot node, and the inode 1338 * really has been deleted in all child snapshots, how does this get cleaned up? 1339 * 1340 * first there is the problem of how keys that have been overwritten in all 1341 * child snapshots get deleted (unimplemented?), but inodes may perhaps be 1342 * special? 1343 * 1344 * also: unlinked inode in internal snapshot appears to not be getting deleted 1345 * correctly if inode doesn't exist in leaf snapshots 1346 * 1347 * solution: 1348 * 1349 * for a key in an interior snapshot node that needs work to be done that 1350 * requires it to be mutated: iterate over all descendent leaf nodes and copy 1351 * that key to snapshot leaf nodes, where we can mutate it 1352 */ 1353 1354 static int snapshot_delete_key(struct btree_trans *trans, 1355 struct btree_iter *iter, 1356 struct bkey_s_c k, 1357 snapshot_id_list *deleted, 1358 snapshot_id_list *equiv_seen, 1359 struct bpos *last_pos) 1360 { 1361 struct bch_fs *c = trans->c; 1362 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot); 1363 1364 if (!bkey_eq(k.k->p, *last_pos)) 1365 equiv_seen->nr = 0; 1366 *last_pos = k.k->p; 1367 1368 if (snapshot_list_has_id(deleted, k.k->p.snapshot) || 1369 snapshot_list_has_id(equiv_seen, equiv)) { 1370 return bch2_btree_delete_at(trans, iter, 1371 BTREE_UPDATE_internal_snapshot_node); 1372 } else { 1373 return snapshot_list_add(c, equiv_seen, equiv); 1374 } 1375 } 1376 1377 static int move_key_to_correct_snapshot(struct btree_trans *trans, 1378 struct btree_iter *iter, 1379 struct bkey_s_c k) 1380 { 1381 struct bch_fs *c = trans->c; 1382 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot); 1383 1384 /* 1385 * When we have a linear chain of snapshot nodes, we consider 1386 * those to form an equivalence class: we're going to collapse 1387 * them all down to a single node, and keep the leaf-most node - 1388 * which has the same id as the equivalence class id. 1389 * 1390 * If there are multiple keys in different snapshots at the same 1391 * position, we're only going to keep the one in the newest 1392 * snapshot - the rest have been overwritten and are redundant, 1393 * and for the key we're going to keep we need to move it to the 1394 * equivalance class ID if it's not there already. 1395 */ 1396 if (equiv != k.k->p.snapshot) { 1397 struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k); 1398 struct btree_iter new_iter; 1399 int ret; 1400 1401 ret = PTR_ERR_OR_ZERO(new); 1402 if (ret) 1403 return ret; 1404 1405 new->k.p.snapshot = equiv; 1406 1407 bch2_trans_iter_init(trans, &new_iter, iter->btree_id, new->k.p, 1408 BTREE_ITER_all_snapshots| 1409 BTREE_ITER_cached| 1410 BTREE_ITER_intent); 1411 1412 ret = bch2_btree_iter_traverse(&new_iter) ?: 1413 bch2_trans_update(trans, &new_iter, new, 1414 BTREE_UPDATE_internal_snapshot_node) ?: 1415 bch2_btree_delete_at(trans, iter, 1416 BTREE_UPDATE_internal_snapshot_node); 1417 bch2_trans_iter_exit(trans, &new_iter); 1418 if (ret) 1419 return ret; 1420 } 1421 1422 return 0; 1423 } 1424 1425 static int bch2_snapshot_needs_delete(struct btree_trans *trans, struct bkey_s_c k) 1426 { 1427 struct bkey_s_c_snapshot snap; 1428 u32 children[2]; 1429 int ret; 1430 1431 if (k.k->type != KEY_TYPE_snapshot) 1432 return 0; 1433 1434 snap = bkey_s_c_to_snapshot(k); 1435 if (BCH_SNAPSHOT_DELETED(snap.v) || 1436 BCH_SNAPSHOT_SUBVOL(snap.v)) 1437 return 0; 1438 1439 children[0] = le32_to_cpu(snap.v->children[0]); 1440 children[1] = le32_to_cpu(snap.v->children[1]); 1441 1442 ret = bch2_snapshot_live(trans, children[0]) ?: 1443 bch2_snapshot_live(trans, children[1]); 1444 if (ret < 0) 1445 return ret; 1446 return !ret; 1447 } 1448 1449 /* 1450 * For a given snapshot, if it doesn't have a subvolume that points to it, and 1451 * it doesn't have child snapshot nodes - it's now redundant and we can mark it 1452 * as deleted. 1453 */ 1454 static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct bkey_s_c k) 1455 { 1456 int ret = bch2_snapshot_needs_delete(trans, k); 1457 1458 return ret <= 0 1459 ? ret 1460 : bch2_snapshot_node_set_deleted(trans, k.k->p.offset); 1461 } 1462 1463 static inline u32 bch2_snapshot_nth_parent_skip(struct bch_fs *c, u32 id, u32 n, 1464 snapshot_id_list *skip) 1465 { 1466 rcu_read_lock(); 1467 while (snapshot_list_has_id(skip, id)) 1468 id = __bch2_snapshot_parent(c, id); 1469 1470 while (n--) { 1471 do { 1472 id = __bch2_snapshot_parent(c, id); 1473 } while (snapshot_list_has_id(skip, id)); 1474 } 1475 rcu_read_unlock(); 1476 1477 return id; 1478 } 1479 1480 static int bch2_fix_child_of_deleted_snapshot(struct btree_trans *trans, 1481 struct btree_iter *iter, struct bkey_s_c k, 1482 snapshot_id_list *deleted) 1483 { 1484 struct bch_fs *c = trans->c; 1485 u32 nr_deleted_ancestors = 0; 1486 struct bkey_i_snapshot *s; 1487 int ret; 1488 1489 if (k.k->type != KEY_TYPE_snapshot) 1490 return 0; 1491 1492 if (snapshot_list_has_id(deleted, k.k->p.offset)) 1493 return 0; 1494 1495 s = bch2_bkey_make_mut_noupdate_typed(trans, k, snapshot); 1496 ret = PTR_ERR_OR_ZERO(s); 1497 if (ret) 1498 return ret; 1499 1500 darray_for_each(*deleted, i) 1501 nr_deleted_ancestors += bch2_snapshot_is_ancestor(c, s->k.p.offset, *i); 1502 1503 if (!nr_deleted_ancestors) 1504 return 0; 1505 1506 le32_add_cpu(&s->v.depth, -nr_deleted_ancestors); 1507 1508 if (!s->v.depth) { 1509 s->v.skip[0] = 0; 1510 s->v.skip[1] = 0; 1511 s->v.skip[2] = 0; 1512 } else { 1513 u32 depth = le32_to_cpu(s->v.depth); 1514 u32 parent = bch2_snapshot_parent(c, s->k.p.offset); 1515 1516 for (unsigned j = 0; j < ARRAY_SIZE(s->v.skip); j++) { 1517 u32 id = le32_to_cpu(s->v.skip[j]); 1518 1519 if (snapshot_list_has_id(deleted, id)) { 1520 id = bch2_snapshot_nth_parent_skip(c, 1521 parent, 1522 depth > 1 1523 ? get_random_u32_below(depth - 1) 1524 : 0, 1525 deleted); 1526 s->v.skip[j] = cpu_to_le32(id); 1527 } 1528 } 1529 1530 bubble_sort(s->v.skip, ARRAY_SIZE(s->v.skip), cmp_le32); 1531 } 1532 1533 return bch2_trans_update(trans, iter, &s->k_i, 0); 1534 } 1535 1536 int bch2_delete_dead_snapshots(struct bch_fs *c) 1537 { 1538 struct btree_trans *trans; 1539 snapshot_id_list deleted = { 0 }; 1540 snapshot_id_list deleted_interior = { 0 }; 1541 u32 id; 1542 int ret = 0; 1543 1544 if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags)) 1545 return 0; 1546 1547 if (!test_bit(BCH_FS_started, &c->flags)) { 1548 ret = bch2_fs_read_write_early(c); 1549 bch_err_msg(c, ret, "deleting dead snapshots: error going rw"); 1550 if (ret) 1551 return ret; 1552 } 1553 1554 trans = bch2_trans_get(c); 1555 1556 /* 1557 * For every snapshot node: If we have no live children and it's not 1558 * pointed to by a subvolume, delete it: 1559 */ 1560 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, 1561 POS_MIN, 0, k, 1562 NULL, NULL, 0, 1563 bch2_delete_redundant_snapshot(trans, k)); 1564 bch_err_msg(c, ret, "deleting redundant snapshots"); 1565 if (ret) 1566 goto err; 1567 1568 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1569 POS_MIN, 0, k, 1570 bch2_snapshot_set_equiv(trans, k)); 1571 bch_err_msg(c, ret, "in bch2_snapshots_set_equiv"); 1572 if (ret) 1573 goto err; 1574 1575 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1576 POS_MIN, 0, k, ({ 1577 if (k.k->type != KEY_TYPE_snapshot) 1578 continue; 1579 1580 BCH_SNAPSHOT_DELETED(bkey_s_c_to_snapshot(k).v) 1581 ? snapshot_list_add(c, &deleted, k.k->p.offset) 1582 : 0; 1583 })); 1584 bch_err_msg(c, ret, "walking snapshots"); 1585 if (ret) 1586 goto err; 1587 1588 for (id = 0; id < BTREE_ID_NR; id++) { 1589 struct bpos last_pos = POS_MIN; 1590 snapshot_id_list equiv_seen = { 0 }; 1591 struct disk_reservation res = { 0 }; 1592 1593 if (!btree_type_has_snapshots(id)) 1594 continue; 1595 1596 /* 1597 * deleted inodes btree is maintained by a trigger on the inodes 1598 * btree - no work for us to do here, and it's not safe to scan 1599 * it because we'll see out of date keys due to the btree write 1600 * buffer: 1601 */ 1602 if (id == BTREE_ID_deleted_inodes) 1603 continue; 1604 1605 ret = for_each_btree_key_commit(trans, iter, 1606 id, POS_MIN, 1607 BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k, 1608 &res, NULL, BCH_TRANS_COMMIT_no_enospc, 1609 snapshot_delete_key(trans, &iter, k, &deleted, &equiv_seen, &last_pos)) ?: 1610 for_each_btree_key_commit(trans, iter, 1611 id, POS_MIN, 1612 BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k, 1613 &res, NULL, BCH_TRANS_COMMIT_no_enospc, 1614 move_key_to_correct_snapshot(trans, &iter, k)); 1615 1616 bch2_disk_reservation_put(c, &res); 1617 darray_exit(&equiv_seen); 1618 1619 bch_err_msg(c, ret, "deleting keys from dying snapshots"); 1620 if (ret) 1621 goto err; 1622 } 1623 1624 bch2_trans_unlock(trans); 1625 down_write(&c->snapshot_create_lock); 1626 1627 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1628 POS_MIN, 0, k, ({ 1629 u32 snapshot = k.k->p.offset; 1630 u32 equiv = bch2_snapshot_equiv(c, snapshot); 1631 1632 equiv != snapshot 1633 ? snapshot_list_add(c, &deleted_interior, snapshot) 1634 : 0; 1635 })); 1636 1637 bch_err_msg(c, ret, "walking snapshots"); 1638 if (ret) 1639 goto err_create_lock; 1640 1641 /* 1642 * Fixing children of deleted snapshots can't be done completely 1643 * atomically, if we crash between here and when we delete the interior 1644 * nodes some depth fields will be off: 1645 */ 1646 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, POS_MIN, 1647 BTREE_ITER_intent, k, 1648 NULL, NULL, BCH_TRANS_COMMIT_no_enospc, 1649 bch2_fix_child_of_deleted_snapshot(trans, &iter, k, &deleted_interior)); 1650 if (ret) 1651 goto err_create_lock; 1652 1653 darray_for_each(deleted, i) { 1654 ret = commit_do(trans, NULL, NULL, 0, 1655 bch2_snapshot_node_delete(trans, *i)); 1656 bch_err_msg(c, ret, "deleting snapshot %u", *i); 1657 if (ret) 1658 goto err_create_lock; 1659 } 1660 1661 darray_for_each(deleted_interior, i) { 1662 ret = commit_do(trans, NULL, NULL, 0, 1663 bch2_snapshot_node_delete(trans, *i)); 1664 bch_err_msg(c, ret, "deleting snapshot %u", *i); 1665 if (ret) 1666 goto err_create_lock; 1667 } 1668 err_create_lock: 1669 up_write(&c->snapshot_create_lock); 1670 err: 1671 darray_exit(&deleted_interior); 1672 darray_exit(&deleted); 1673 bch2_trans_put(trans); 1674 bch_err_fn(c, ret); 1675 return ret; 1676 } 1677 1678 void bch2_delete_dead_snapshots_work(struct work_struct *work) 1679 { 1680 struct bch_fs *c = container_of(work, struct bch_fs, snapshot_delete_work); 1681 1682 bch2_delete_dead_snapshots(c); 1683 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots); 1684 } 1685 1686 void bch2_delete_dead_snapshots_async(struct bch_fs *c) 1687 { 1688 if (bch2_write_ref_tryget(c, BCH_WRITE_REF_delete_dead_snapshots) && 1689 !queue_work(c->write_ref_wq, &c->snapshot_delete_work)) 1690 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots); 1691 } 1692 1693 int __bch2_key_has_snapshot_overwrites(struct btree_trans *trans, 1694 enum btree_id id, 1695 struct bpos pos) 1696 { 1697 struct bch_fs *c = trans->c; 1698 struct btree_iter iter; 1699 struct bkey_s_c k; 1700 int ret; 1701 1702 bch2_trans_iter_init(trans, &iter, id, pos, 1703 BTREE_ITER_not_extents| 1704 BTREE_ITER_all_snapshots); 1705 while (1) { 1706 k = bch2_btree_iter_prev(&iter); 1707 ret = bkey_err(k); 1708 if (ret) 1709 break; 1710 1711 if (!k.k) 1712 break; 1713 1714 if (!bkey_eq(pos, k.k->p)) 1715 break; 1716 1717 if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) { 1718 ret = 1; 1719 break; 1720 } 1721 } 1722 bch2_trans_iter_exit(trans, &iter); 1723 1724 return ret; 1725 } 1726 1727 static u32 bch2_snapshot_smallest_child(struct bch_fs *c, u32 id) 1728 { 1729 const struct snapshot_t *s = snapshot_t(c, id); 1730 1731 return s->children[1] ?: s->children[0]; 1732 } 1733 1734 static u32 bch2_snapshot_smallest_descendent(struct bch_fs *c, u32 id) 1735 { 1736 u32 child; 1737 1738 while ((child = bch2_snapshot_smallest_child(c, id))) 1739 id = child; 1740 return id; 1741 } 1742 1743 static int bch2_propagate_key_to_snapshot_leaf(struct btree_trans *trans, 1744 enum btree_id btree, 1745 struct bkey_s_c interior_k, 1746 u32 leaf_id, struct bpos *new_min_pos) 1747 { 1748 struct btree_iter iter; 1749 struct bpos pos = interior_k.k->p; 1750 struct bkey_s_c k; 1751 struct bkey_i *new; 1752 int ret; 1753 1754 pos.snapshot = leaf_id; 1755 1756 bch2_trans_iter_init(trans, &iter, btree, pos, BTREE_ITER_intent); 1757 k = bch2_btree_iter_peek_slot(&iter); 1758 ret = bkey_err(k); 1759 if (ret) 1760 goto out; 1761 1762 /* key already overwritten in this snapshot? */ 1763 if (k.k->p.snapshot != interior_k.k->p.snapshot) 1764 goto out; 1765 1766 if (bpos_eq(*new_min_pos, POS_MIN)) { 1767 *new_min_pos = k.k->p; 1768 new_min_pos->snapshot = leaf_id; 1769 } 1770 1771 new = bch2_bkey_make_mut_noupdate(trans, interior_k); 1772 ret = PTR_ERR_OR_ZERO(new); 1773 if (ret) 1774 goto out; 1775 1776 new->k.p.snapshot = leaf_id; 1777 ret = bch2_trans_update(trans, &iter, new, 0); 1778 out: 1779 bch2_trans_iter_exit(trans, &iter); 1780 return ret; 1781 } 1782 1783 int bch2_propagate_key_to_snapshot_leaves(struct btree_trans *trans, 1784 enum btree_id btree, 1785 struct bkey_s_c k, 1786 struct bpos *new_min_pos) 1787 { 1788 struct bch_fs *c = trans->c; 1789 struct bkey_buf sk; 1790 u32 restart_count = trans->restart_count; 1791 int ret = 0; 1792 1793 bch2_bkey_buf_init(&sk); 1794 bch2_bkey_buf_reassemble(&sk, c, k); 1795 k = bkey_i_to_s_c(sk.k); 1796 1797 *new_min_pos = POS_MIN; 1798 1799 for (u32 id = bch2_snapshot_smallest_descendent(c, k.k->p.snapshot); 1800 id < k.k->p.snapshot; 1801 id++) { 1802 if (!bch2_snapshot_is_ancestor(c, id, k.k->p.snapshot) || 1803 !bch2_snapshot_is_leaf(c, id)) 1804 continue; 1805 again: 1806 ret = btree_trans_too_many_iters(trans) ?: 1807 bch2_propagate_key_to_snapshot_leaf(trans, btree, k, id, new_min_pos) ?: 1808 bch2_trans_commit(trans, NULL, NULL, 0); 1809 if (ret && bch2_err_matches(ret, BCH_ERR_transaction_restart)) { 1810 bch2_trans_begin(trans); 1811 goto again; 1812 } 1813 1814 if (ret) 1815 break; 1816 } 1817 1818 bch2_bkey_buf_exit(&sk, c); 1819 1820 return ret ?: trans_was_restarted(trans, restart_count); 1821 } 1822 1823 static int bch2_check_snapshot_needs_deletion(struct btree_trans *trans, struct bkey_s_c k) 1824 { 1825 struct bch_fs *c = trans->c; 1826 struct bkey_s_c_snapshot snap; 1827 int ret = 0; 1828 1829 if (k.k->type != KEY_TYPE_snapshot) 1830 return 0; 1831 1832 snap = bkey_s_c_to_snapshot(k); 1833 if (BCH_SNAPSHOT_DELETED(snap.v) || 1834 bch2_snapshot_equiv(c, k.k->p.offset) != k.k->p.offset || 1835 (ret = bch2_snapshot_needs_delete(trans, k)) > 0) { 1836 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags); 1837 return 0; 1838 } 1839 1840 return ret; 1841 } 1842 1843 int bch2_snapshots_read(struct bch_fs *c) 1844 { 1845 int ret = bch2_trans_run(c, 1846 for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1847 POS_MIN, 0, k, 1848 __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, k, 0) ?: 1849 bch2_snapshot_set_equiv(trans, k) ?: 1850 bch2_check_snapshot_needs_deletion(trans, k)) ?: 1851 for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1852 POS_MIN, 0, k, 1853 (set_is_ancestor_bitmap(c, k.k->p.offset), 0))); 1854 bch_err_fn(c, ret); 1855 1856 /* 1857 * It's important that we check if we need to reconstruct snapshots 1858 * before going RW, so we mark that pass as required in the superblock - 1859 * otherwise, we could end up deleting keys with missing snapshot nodes 1860 * instead 1861 */ 1862 BUG_ON(!test_bit(BCH_FS_new_fs, &c->flags) && 1863 test_bit(BCH_FS_may_go_rw, &c->flags)); 1864 1865 if (bch2_err_matches(ret, EIO) || 1866 (c->sb.btrees_lost_data & BIT_ULL(BTREE_ID_snapshots))) 1867 ret = bch2_run_explicit_recovery_pass_persistent(c, BCH_RECOVERY_PASS_reconstruct_snapshots); 1868 1869 return ret; 1870 } 1871 1872 void bch2_fs_snapshots_exit(struct bch_fs *c) 1873 { 1874 kvfree(rcu_dereference_protected(c->snapshots, true)); 1875 } 1876