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 bkey_invalid_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 bkey_invalid_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 unsigned 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 unsigned 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 u32 tree_id; 904 int ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id); 905 if (ret) 906 return ret; 907 908 struct bkey_i_snapshot *snapshot = bch2_trans_kmalloc(trans, sizeof(*snapshot)); 909 ret = PTR_ERR_OR_ZERO(snapshot); 910 if (ret) 911 return ret; 912 913 bkey_snapshot_init(&snapshot->k_i); 914 snapshot->k.p = POS(0, id); 915 snapshot->v.tree = cpu_to_le32(tree_id); 916 snapshot->v.btime.lo = cpu_to_le64(bch2_current_time(c)); 917 918 return bch2_btree_insert_trans(trans, BTREE_ID_snapshots, &snapshot->k_i, 0) ?: 919 bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, 920 bkey_s_c_null, bkey_i_to_s(&snapshot->k_i), 0) ?: 921 bch2_snapshot_set_equiv(trans, bkey_i_to_s_c(&snapshot->k_i)); 922 } 923 924 /* Figure out which snapshot nodes belong in the same tree: */ 925 struct snapshot_tree_reconstruct { 926 enum btree_id btree; 927 struct bpos cur_pos; 928 snapshot_id_list cur_ids; 929 DARRAY(snapshot_id_list) trees; 930 }; 931 932 static void snapshot_tree_reconstruct_exit(struct snapshot_tree_reconstruct *r) 933 { 934 darray_for_each(r->trees, i) 935 darray_exit(i); 936 darray_exit(&r->trees); 937 darray_exit(&r->cur_ids); 938 } 939 940 static inline bool same_snapshot(struct snapshot_tree_reconstruct *r, struct bpos pos) 941 { 942 return r->btree == BTREE_ID_inodes 943 ? r->cur_pos.offset == pos.offset 944 : r->cur_pos.inode == pos.inode; 945 } 946 947 static inline bool snapshot_id_lists_have_common(snapshot_id_list *l, snapshot_id_list *r) 948 { 949 darray_for_each(*l, i) 950 if (snapshot_list_has_id(r, *i)) 951 return true; 952 return false; 953 } 954 955 static void snapshot_id_list_to_text(struct printbuf *out, snapshot_id_list *s) 956 { 957 bool first = true; 958 darray_for_each(*s, i) { 959 if (!first) 960 prt_char(out, ' '); 961 first = false; 962 prt_printf(out, "%u", *i); 963 } 964 } 965 966 static int snapshot_tree_reconstruct_next(struct bch_fs *c, struct snapshot_tree_reconstruct *r) 967 { 968 if (r->cur_ids.nr) { 969 darray_for_each(r->trees, i) 970 if (snapshot_id_lists_have_common(i, &r->cur_ids)) { 971 int ret = snapshot_list_merge(c, i, &r->cur_ids); 972 if (ret) 973 return ret; 974 goto out; 975 } 976 darray_push(&r->trees, r->cur_ids); 977 darray_init(&r->cur_ids); 978 } 979 out: 980 r->cur_ids.nr = 0; 981 return 0; 982 } 983 984 static int get_snapshot_trees(struct bch_fs *c, struct snapshot_tree_reconstruct *r, struct bpos pos) 985 { 986 if (!same_snapshot(r, pos)) 987 snapshot_tree_reconstruct_next(c, r); 988 r->cur_pos = pos; 989 return snapshot_list_add_nodup(c, &r->cur_ids, pos.snapshot); 990 } 991 992 int bch2_reconstruct_snapshots(struct bch_fs *c) 993 { 994 struct btree_trans *trans = bch2_trans_get(c); 995 struct printbuf buf = PRINTBUF; 996 struct snapshot_tree_reconstruct r = {}; 997 int ret = 0; 998 999 for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) { 1000 if (btree_type_has_snapshots(btree)) { 1001 r.btree = btree; 1002 1003 ret = for_each_btree_key(trans, iter, btree, POS_MIN, 1004 BTREE_ITER_ALL_SNAPSHOTS|BTREE_ITER_PREFETCH, k, ({ 1005 get_snapshot_trees(c, &r, k.k->p); 1006 })); 1007 if (ret) 1008 goto err; 1009 1010 snapshot_tree_reconstruct_next(c, &r); 1011 } 1012 } 1013 1014 darray_for_each(r.trees, t) { 1015 printbuf_reset(&buf); 1016 snapshot_id_list_to_text(&buf, t); 1017 1018 darray_for_each(*t, id) { 1019 if (fsck_err_on(!bch2_snapshot_equiv(c, *id), 1020 c, snapshot_node_missing, 1021 "snapshot node %u from tree %s missing", *id, buf.buf)) { 1022 if (t->nr > 1) { 1023 bch_err(c, "cannot reconstruct snapshot trees with multiple nodes"); 1024 ret = -BCH_ERR_fsck_repair_unimplemented; 1025 goto err; 1026 } 1027 1028 ret = commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc, 1029 check_snapshot_exists(trans, *id)); 1030 if (ret) 1031 goto err; 1032 } 1033 } 1034 } 1035 fsck_err: 1036 err: 1037 bch2_trans_put(trans); 1038 snapshot_tree_reconstruct_exit(&r); 1039 printbuf_exit(&buf); 1040 bch_err_fn(c, ret); 1041 return ret; 1042 } 1043 1044 /* 1045 * Mark a snapshot as deleted, for future cleanup: 1046 */ 1047 int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id) 1048 { 1049 struct btree_iter iter; 1050 struct bkey_i_snapshot *s; 1051 int ret = 0; 1052 1053 s = bch2_bkey_get_mut_typed(trans, &iter, 1054 BTREE_ID_snapshots, POS(0, id), 1055 0, snapshot); 1056 ret = PTR_ERR_OR_ZERO(s); 1057 if (unlikely(ret)) { 1058 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), 1059 trans->c, "missing snapshot %u", id); 1060 return ret; 1061 } 1062 1063 /* already deleted? */ 1064 if (BCH_SNAPSHOT_DELETED(&s->v)) 1065 goto err; 1066 1067 SET_BCH_SNAPSHOT_DELETED(&s->v, true); 1068 SET_BCH_SNAPSHOT_SUBVOL(&s->v, false); 1069 s->v.subvol = 0; 1070 err: 1071 bch2_trans_iter_exit(trans, &iter); 1072 return ret; 1073 } 1074 1075 static inline void normalize_snapshot_child_pointers(struct bch_snapshot *s) 1076 { 1077 if (le32_to_cpu(s->children[0]) < le32_to_cpu(s->children[1])) 1078 swap(s->children[0], s->children[1]); 1079 } 1080 1081 static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id) 1082 { 1083 struct bch_fs *c = trans->c; 1084 struct btree_iter iter, p_iter = (struct btree_iter) { NULL }; 1085 struct btree_iter c_iter = (struct btree_iter) { NULL }; 1086 struct btree_iter tree_iter = (struct btree_iter) { NULL }; 1087 struct bkey_s_c_snapshot s; 1088 u32 parent_id, child_id; 1089 unsigned i; 1090 int ret = 0; 1091 1092 s = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id), 1093 BTREE_ITER_INTENT, snapshot); 1094 ret = bkey_err(s); 1095 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, 1096 "missing snapshot %u", id); 1097 1098 if (ret) 1099 goto err; 1100 1101 BUG_ON(s.v->children[1]); 1102 1103 parent_id = le32_to_cpu(s.v->parent); 1104 child_id = le32_to_cpu(s.v->children[0]); 1105 1106 if (parent_id) { 1107 struct bkey_i_snapshot *parent; 1108 1109 parent = bch2_bkey_get_mut_typed(trans, &p_iter, 1110 BTREE_ID_snapshots, POS(0, parent_id), 1111 0, snapshot); 1112 ret = PTR_ERR_OR_ZERO(parent); 1113 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, 1114 "missing snapshot %u", parent_id); 1115 if (unlikely(ret)) 1116 goto err; 1117 1118 /* find entry in parent->children for node being deleted */ 1119 for (i = 0; i < 2; i++) 1120 if (le32_to_cpu(parent->v.children[i]) == id) 1121 break; 1122 1123 if (bch2_fs_inconsistent_on(i == 2, c, 1124 "snapshot %u missing child pointer to %u", 1125 parent_id, id)) 1126 goto err; 1127 1128 parent->v.children[i] = cpu_to_le32(child_id); 1129 1130 normalize_snapshot_child_pointers(&parent->v); 1131 } 1132 1133 if (child_id) { 1134 struct bkey_i_snapshot *child; 1135 1136 child = bch2_bkey_get_mut_typed(trans, &c_iter, 1137 BTREE_ID_snapshots, POS(0, child_id), 1138 0, snapshot); 1139 ret = PTR_ERR_OR_ZERO(child); 1140 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, 1141 "missing snapshot %u", child_id); 1142 if (unlikely(ret)) 1143 goto err; 1144 1145 child->v.parent = cpu_to_le32(parent_id); 1146 1147 if (!child->v.parent) { 1148 child->v.skip[0] = 0; 1149 child->v.skip[1] = 0; 1150 child->v.skip[2] = 0; 1151 } 1152 } 1153 1154 if (!parent_id) { 1155 /* 1156 * We're deleting the root of a snapshot tree: update the 1157 * snapshot_tree entry to point to the new root, or delete it if 1158 * this is the last snapshot ID in this tree: 1159 */ 1160 struct bkey_i_snapshot_tree *s_t; 1161 1162 BUG_ON(s.v->children[1]); 1163 1164 s_t = bch2_bkey_get_mut_typed(trans, &tree_iter, 1165 BTREE_ID_snapshot_trees, POS(0, le32_to_cpu(s.v->tree)), 1166 0, snapshot_tree); 1167 ret = PTR_ERR_OR_ZERO(s_t); 1168 if (ret) 1169 goto err; 1170 1171 if (s.v->children[0]) { 1172 s_t->v.root_snapshot = s.v->children[0]; 1173 } else { 1174 s_t->k.type = KEY_TYPE_deleted; 1175 set_bkey_val_u64s(&s_t->k, 0); 1176 } 1177 } 1178 1179 ret = bch2_btree_delete_at(trans, &iter, 0); 1180 err: 1181 bch2_trans_iter_exit(trans, &tree_iter); 1182 bch2_trans_iter_exit(trans, &p_iter); 1183 bch2_trans_iter_exit(trans, &c_iter); 1184 bch2_trans_iter_exit(trans, &iter); 1185 return ret; 1186 } 1187 1188 static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree, 1189 u32 *new_snapids, 1190 u32 *snapshot_subvols, 1191 unsigned nr_snapids) 1192 { 1193 struct bch_fs *c = trans->c; 1194 struct btree_iter iter; 1195 struct bkey_i_snapshot *n; 1196 struct bkey_s_c k; 1197 unsigned i, j; 1198 u32 depth = bch2_snapshot_depth(c, parent); 1199 int ret; 1200 1201 bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots, 1202 POS_MIN, BTREE_ITER_INTENT); 1203 k = bch2_btree_iter_peek(&iter); 1204 ret = bkey_err(k); 1205 if (ret) 1206 goto err; 1207 1208 for (i = 0; i < nr_snapids; i++) { 1209 k = bch2_btree_iter_prev_slot(&iter); 1210 ret = bkey_err(k); 1211 if (ret) 1212 goto err; 1213 1214 if (!k.k || !k.k->p.offset) { 1215 ret = -BCH_ERR_ENOSPC_snapshot_create; 1216 goto err; 1217 } 1218 1219 n = bch2_bkey_alloc(trans, &iter, 0, snapshot); 1220 ret = PTR_ERR_OR_ZERO(n); 1221 if (ret) 1222 goto err; 1223 1224 n->v.flags = 0; 1225 n->v.parent = cpu_to_le32(parent); 1226 n->v.subvol = cpu_to_le32(snapshot_subvols[i]); 1227 n->v.tree = cpu_to_le32(tree); 1228 n->v.depth = cpu_to_le32(depth); 1229 n->v.btime.lo = cpu_to_le64(bch2_current_time(c)); 1230 n->v.btime.hi = 0; 1231 1232 for (j = 0; j < ARRAY_SIZE(n->v.skip); j++) 1233 n->v.skip[j] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent)); 1234 1235 bubble_sort(n->v.skip, ARRAY_SIZE(n->v.skip), cmp_le32); 1236 SET_BCH_SNAPSHOT_SUBVOL(&n->v, true); 1237 1238 ret = __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, 1239 bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0); 1240 if (ret) 1241 goto err; 1242 1243 new_snapids[i] = iter.pos.offset; 1244 1245 mutex_lock(&c->snapshot_table_lock); 1246 snapshot_t_mut(c, new_snapids[i])->equiv = new_snapids[i]; 1247 mutex_unlock(&c->snapshot_table_lock); 1248 } 1249 err: 1250 bch2_trans_iter_exit(trans, &iter); 1251 return ret; 1252 } 1253 1254 /* 1255 * Create new snapshot IDs as children of an existing snapshot ID: 1256 */ 1257 static int bch2_snapshot_node_create_children(struct btree_trans *trans, u32 parent, 1258 u32 *new_snapids, 1259 u32 *snapshot_subvols, 1260 unsigned nr_snapids) 1261 { 1262 struct btree_iter iter; 1263 struct bkey_i_snapshot *n_parent; 1264 int ret = 0; 1265 1266 n_parent = bch2_bkey_get_mut_typed(trans, &iter, 1267 BTREE_ID_snapshots, POS(0, parent), 1268 0, snapshot); 1269 ret = PTR_ERR_OR_ZERO(n_parent); 1270 if (unlikely(ret)) { 1271 if (bch2_err_matches(ret, ENOENT)) 1272 bch_err(trans->c, "snapshot %u not found", parent); 1273 return ret; 1274 } 1275 1276 if (n_parent->v.children[0] || n_parent->v.children[1]) { 1277 bch_err(trans->c, "Trying to add child snapshot nodes to parent that already has children"); 1278 ret = -EINVAL; 1279 goto err; 1280 } 1281 1282 ret = create_snapids(trans, parent, le32_to_cpu(n_parent->v.tree), 1283 new_snapids, snapshot_subvols, nr_snapids); 1284 if (ret) 1285 goto err; 1286 1287 n_parent->v.children[0] = cpu_to_le32(new_snapids[0]); 1288 n_parent->v.children[1] = cpu_to_le32(new_snapids[1]); 1289 n_parent->v.subvol = 0; 1290 SET_BCH_SNAPSHOT_SUBVOL(&n_parent->v, false); 1291 err: 1292 bch2_trans_iter_exit(trans, &iter); 1293 return ret; 1294 } 1295 1296 /* 1297 * Create a snapshot node that is the root of a new tree: 1298 */ 1299 static int bch2_snapshot_node_create_tree(struct btree_trans *trans, 1300 u32 *new_snapids, 1301 u32 *snapshot_subvols, 1302 unsigned nr_snapids) 1303 { 1304 struct bkey_i_snapshot_tree *n_tree; 1305 int ret; 1306 1307 n_tree = __bch2_snapshot_tree_create(trans); 1308 ret = PTR_ERR_OR_ZERO(n_tree) ?: 1309 create_snapids(trans, 0, n_tree->k.p.offset, 1310 new_snapids, snapshot_subvols, nr_snapids); 1311 if (ret) 1312 return ret; 1313 1314 n_tree->v.master_subvol = cpu_to_le32(snapshot_subvols[0]); 1315 n_tree->v.root_snapshot = cpu_to_le32(new_snapids[0]); 1316 return 0; 1317 } 1318 1319 int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent, 1320 u32 *new_snapids, 1321 u32 *snapshot_subvols, 1322 unsigned nr_snapids) 1323 { 1324 BUG_ON((parent == 0) != (nr_snapids == 1)); 1325 BUG_ON((parent != 0) != (nr_snapids == 2)); 1326 1327 return parent 1328 ? bch2_snapshot_node_create_children(trans, parent, 1329 new_snapids, snapshot_subvols, nr_snapids) 1330 : bch2_snapshot_node_create_tree(trans, 1331 new_snapids, snapshot_subvols, nr_snapids); 1332 1333 } 1334 1335 /* 1336 * If we have an unlinked inode in an internal snapshot node, and the inode 1337 * really has been deleted in all child snapshots, how does this get cleaned up? 1338 * 1339 * first there is the problem of how keys that have been overwritten in all 1340 * child snapshots get deleted (unimplemented?), but inodes may perhaps be 1341 * special? 1342 * 1343 * also: unlinked inode in internal snapshot appears to not be getting deleted 1344 * correctly if inode doesn't exist in leaf snapshots 1345 * 1346 * solution: 1347 * 1348 * for a key in an interior snapshot node that needs work to be done that 1349 * requires it to be mutated: iterate over all descendent leaf nodes and copy 1350 * that key to snapshot leaf nodes, where we can mutate it 1351 */ 1352 1353 static int snapshot_delete_key(struct btree_trans *trans, 1354 struct btree_iter *iter, 1355 struct bkey_s_c k, 1356 snapshot_id_list *deleted, 1357 snapshot_id_list *equiv_seen, 1358 struct bpos *last_pos) 1359 { 1360 struct bch_fs *c = trans->c; 1361 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot); 1362 1363 if (!bkey_eq(k.k->p, *last_pos)) 1364 equiv_seen->nr = 0; 1365 *last_pos = k.k->p; 1366 1367 if (snapshot_list_has_id(deleted, k.k->p.snapshot) || 1368 snapshot_list_has_id(equiv_seen, equiv)) { 1369 return bch2_btree_delete_at(trans, iter, 1370 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE); 1371 } else { 1372 return snapshot_list_add(c, equiv_seen, equiv); 1373 } 1374 } 1375 1376 static int move_key_to_correct_snapshot(struct btree_trans *trans, 1377 struct btree_iter *iter, 1378 struct bkey_s_c k) 1379 { 1380 struct bch_fs *c = trans->c; 1381 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot); 1382 1383 /* 1384 * When we have a linear chain of snapshot nodes, we consider 1385 * those to form an equivalence class: we're going to collapse 1386 * them all down to a single node, and keep the leaf-most node - 1387 * which has the same id as the equivalence class id. 1388 * 1389 * If there are multiple keys in different snapshots at the same 1390 * position, we're only going to keep the one in the newest 1391 * snapshot - the rest have been overwritten and are redundant, 1392 * and for the key we're going to keep we need to move it to the 1393 * equivalance class ID if it's not there already. 1394 */ 1395 if (equiv != k.k->p.snapshot) { 1396 struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k); 1397 struct btree_iter new_iter; 1398 int ret; 1399 1400 ret = PTR_ERR_OR_ZERO(new); 1401 if (ret) 1402 return ret; 1403 1404 new->k.p.snapshot = equiv; 1405 1406 bch2_trans_iter_init(trans, &new_iter, iter->btree_id, new->k.p, 1407 BTREE_ITER_ALL_SNAPSHOTS| 1408 BTREE_ITER_CACHED| 1409 BTREE_ITER_INTENT); 1410 1411 ret = bch2_btree_iter_traverse(&new_iter) ?: 1412 bch2_trans_update(trans, &new_iter, new, 1413 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?: 1414 bch2_btree_delete_at(trans, iter, 1415 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE); 1416 bch2_trans_iter_exit(trans, &new_iter); 1417 if (ret) 1418 return ret; 1419 } 1420 1421 return 0; 1422 } 1423 1424 static int bch2_snapshot_needs_delete(struct btree_trans *trans, struct bkey_s_c k) 1425 { 1426 struct bkey_s_c_snapshot snap; 1427 u32 children[2]; 1428 int ret; 1429 1430 if (k.k->type != KEY_TYPE_snapshot) 1431 return 0; 1432 1433 snap = bkey_s_c_to_snapshot(k); 1434 if (BCH_SNAPSHOT_DELETED(snap.v) || 1435 BCH_SNAPSHOT_SUBVOL(snap.v)) 1436 return 0; 1437 1438 children[0] = le32_to_cpu(snap.v->children[0]); 1439 children[1] = le32_to_cpu(snap.v->children[1]); 1440 1441 ret = bch2_snapshot_live(trans, children[0]) ?: 1442 bch2_snapshot_live(trans, children[1]); 1443 if (ret < 0) 1444 return ret; 1445 return !ret; 1446 } 1447 1448 /* 1449 * For a given snapshot, if it doesn't have a subvolume that points to it, and 1450 * it doesn't have child snapshot nodes - it's now redundant and we can mark it 1451 * as deleted. 1452 */ 1453 static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct bkey_s_c k) 1454 { 1455 int ret = bch2_snapshot_needs_delete(trans, k); 1456 1457 return ret <= 0 1458 ? ret 1459 : bch2_snapshot_node_set_deleted(trans, k.k->p.offset); 1460 } 1461 1462 static inline u32 bch2_snapshot_nth_parent_skip(struct bch_fs *c, u32 id, u32 n, 1463 snapshot_id_list *skip) 1464 { 1465 rcu_read_lock(); 1466 while (snapshot_list_has_id(skip, id)) 1467 id = __bch2_snapshot_parent(c, id); 1468 1469 while (n--) { 1470 do { 1471 id = __bch2_snapshot_parent(c, id); 1472 } while (snapshot_list_has_id(skip, id)); 1473 } 1474 rcu_read_unlock(); 1475 1476 return id; 1477 } 1478 1479 static int bch2_fix_child_of_deleted_snapshot(struct btree_trans *trans, 1480 struct btree_iter *iter, struct bkey_s_c k, 1481 snapshot_id_list *deleted) 1482 { 1483 struct bch_fs *c = trans->c; 1484 u32 nr_deleted_ancestors = 0; 1485 struct bkey_i_snapshot *s; 1486 int ret; 1487 1488 if (k.k->type != KEY_TYPE_snapshot) 1489 return 0; 1490 1491 if (snapshot_list_has_id(deleted, k.k->p.offset)) 1492 return 0; 1493 1494 s = bch2_bkey_make_mut_noupdate_typed(trans, k, snapshot); 1495 ret = PTR_ERR_OR_ZERO(s); 1496 if (ret) 1497 return ret; 1498 1499 darray_for_each(*deleted, i) 1500 nr_deleted_ancestors += bch2_snapshot_is_ancestor(c, s->k.p.offset, *i); 1501 1502 if (!nr_deleted_ancestors) 1503 return 0; 1504 1505 le32_add_cpu(&s->v.depth, -nr_deleted_ancestors); 1506 1507 if (!s->v.depth) { 1508 s->v.skip[0] = 0; 1509 s->v.skip[1] = 0; 1510 s->v.skip[2] = 0; 1511 } else { 1512 u32 depth = le32_to_cpu(s->v.depth); 1513 u32 parent = bch2_snapshot_parent(c, s->k.p.offset); 1514 1515 for (unsigned j = 0; j < ARRAY_SIZE(s->v.skip); j++) { 1516 u32 id = le32_to_cpu(s->v.skip[j]); 1517 1518 if (snapshot_list_has_id(deleted, id)) { 1519 id = bch2_snapshot_nth_parent_skip(c, 1520 parent, 1521 depth > 1 1522 ? get_random_u32_below(depth - 1) 1523 : 0, 1524 deleted); 1525 s->v.skip[j] = cpu_to_le32(id); 1526 } 1527 } 1528 1529 bubble_sort(s->v.skip, ARRAY_SIZE(s->v.skip), cmp_le32); 1530 } 1531 1532 return bch2_trans_update(trans, iter, &s->k_i, 0); 1533 } 1534 1535 int bch2_delete_dead_snapshots(struct bch_fs *c) 1536 { 1537 struct btree_trans *trans; 1538 snapshot_id_list deleted = { 0 }; 1539 snapshot_id_list deleted_interior = { 0 }; 1540 u32 id; 1541 int ret = 0; 1542 1543 if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags)) 1544 return 0; 1545 1546 if (!test_bit(BCH_FS_started, &c->flags)) { 1547 ret = bch2_fs_read_write_early(c); 1548 bch_err_msg(c, ret, "deleting dead snapshots: error going rw"); 1549 if (ret) 1550 return ret; 1551 } 1552 1553 trans = bch2_trans_get(c); 1554 1555 /* 1556 * For every snapshot node: If we have no live children and it's not 1557 * pointed to by a subvolume, delete it: 1558 */ 1559 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, 1560 POS_MIN, 0, k, 1561 NULL, NULL, 0, 1562 bch2_delete_redundant_snapshot(trans, k)); 1563 bch_err_msg(c, ret, "deleting redundant snapshots"); 1564 if (ret) 1565 goto err; 1566 1567 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1568 POS_MIN, 0, k, 1569 bch2_snapshot_set_equiv(trans, k)); 1570 bch_err_msg(c, ret, "in bch2_snapshots_set_equiv"); 1571 if (ret) 1572 goto err; 1573 1574 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1575 POS_MIN, 0, k, ({ 1576 if (k.k->type != KEY_TYPE_snapshot) 1577 continue; 1578 1579 BCH_SNAPSHOT_DELETED(bkey_s_c_to_snapshot(k).v) 1580 ? snapshot_list_add(c, &deleted, k.k->p.offset) 1581 : 0; 1582 })); 1583 bch_err_msg(c, ret, "walking snapshots"); 1584 if (ret) 1585 goto err; 1586 1587 for (id = 0; id < BTREE_ID_NR; id++) { 1588 struct bpos last_pos = POS_MIN; 1589 snapshot_id_list equiv_seen = { 0 }; 1590 struct disk_reservation res = { 0 }; 1591 1592 if (!btree_type_has_snapshots(id)) 1593 continue; 1594 1595 /* 1596 * deleted inodes btree is maintained by a trigger on the inodes 1597 * btree - no work for us to do here, and it's not safe to scan 1598 * it because we'll see out of date keys due to the btree write 1599 * buffer: 1600 */ 1601 if (id == BTREE_ID_deleted_inodes) 1602 continue; 1603 1604 ret = for_each_btree_key_commit(trans, iter, 1605 id, POS_MIN, 1606 BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k, 1607 &res, NULL, BCH_TRANS_COMMIT_no_enospc, 1608 snapshot_delete_key(trans, &iter, k, &deleted, &equiv_seen, &last_pos)) ?: 1609 for_each_btree_key_commit(trans, iter, 1610 id, POS_MIN, 1611 BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k, 1612 &res, NULL, BCH_TRANS_COMMIT_no_enospc, 1613 move_key_to_correct_snapshot(trans, &iter, k)); 1614 1615 bch2_disk_reservation_put(c, &res); 1616 darray_exit(&equiv_seen); 1617 1618 bch_err_msg(c, ret, "deleting keys from dying snapshots"); 1619 if (ret) 1620 goto err; 1621 } 1622 1623 bch2_trans_unlock(trans); 1624 down_write(&c->snapshot_create_lock); 1625 1626 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1627 POS_MIN, 0, k, ({ 1628 u32 snapshot = k.k->p.offset; 1629 u32 equiv = bch2_snapshot_equiv(c, snapshot); 1630 1631 equiv != snapshot 1632 ? snapshot_list_add(c, &deleted_interior, snapshot) 1633 : 0; 1634 })); 1635 1636 bch_err_msg(c, ret, "walking snapshots"); 1637 if (ret) 1638 goto err_create_lock; 1639 1640 /* 1641 * Fixing children of deleted snapshots can't be done completely 1642 * atomically, if we crash between here and when we delete the interior 1643 * nodes some depth fields will be off: 1644 */ 1645 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, POS_MIN, 1646 BTREE_ITER_INTENT, k, 1647 NULL, NULL, BCH_TRANS_COMMIT_no_enospc, 1648 bch2_fix_child_of_deleted_snapshot(trans, &iter, k, &deleted_interior)); 1649 if (ret) 1650 goto err_create_lock; 1651 1652 darray_for_each(deleted, i) { 1653 ret = commit_do(trans, NULL, NULL, 0, 1654 bch2_snapshot_node_delete(trans, *i)); 1655 bch_err_msg(c, ret, "deleting snapshot %u", *i); 1656 if (ret) 1657 goto err_create_lock; 1658 } 1659 1660 darray_for_each(deleted_interior, i) { 1661 ret = commit_do(trans, NULL, NULL, 0, 1662 bch2_snapshot_node_delete(trans, *i)); 1663 bch_err_msg(c, ret, "deleting snapshot %u", *i); 1664 if (ret) 1665 goto err_create_lock; 1666 } 1667 err_create_lock: 1668 up_write(&c->snapshot_create_lock); 1669 err: 1670 darray_exit(&deleted_interior); 1671 darray_exit(&deleted); 1672 bch2_trans_put(trans); 1673 bch_err_fn(c, ret); 1674 return ret; 1675 } 1676 1677 void bch2_delete_dead_snapshots_work(struct work_struct *work) 1678 { 1679 struct bch_fs *c = container_of(work, struct bch_fs, snapshot_delete_work); 1680 1681 bch2_delete_dead_snapshots(c); 1682 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots); 1683 } 1684 1685 void bch2_delete_dead_snapshots_async(struct bch_fs *c) 1686 { 1687 if (bch2_write_ref_tryget(c, BCH_WRITE_REF_delete_dead_snapshots) && 1688 !queue_work(c->write_ref_wq, &c->snapshot_delete_work)) 1689 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots); 1690 } 1691 1692 int __bch2_key_has_snapshot_overwrites(struct btree_trans *trans, 1693 enum btree_id id, 1694 struct bpos pos) 1695 { 1696 struct bch_fs *c = trans->c; 1697 struct btree_iter iter; 1698 struct bkey_s_c k; 1699 int ret; 1700 1701 bch2_trans_iter_init(trans, &iter, id, pos, 1702 BTREE_ITER_NOT_EXTENTS| 1703 BTREE_ITER_ALL_SNAPSHOTS); 1704 while (1) { 1705 k = bch2_btree_iter_prev(&iter); 1706 ret = bkey_err(k); 1707 if (ret) 1708 break; 1709 1710 if (!k.k) 1711 break; 1712 1713 if (!bkey_eq(pos, k.k->p)) 1714 break; 1715 1716 if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) { 1717 ret = 1; 1718 break; 1719 } 1720 } 1721 bch2_trans_iter_exit(trans, &iter); 1722 1723 return ret; 1724 } 1725 1726 static u32 bch2_snapshot_smallest_child(struct bch_fs *c, u32 id) 1727 { 1728 const struct snapshot_t *s = snapshot_t(c, id); 1729 1730 return s->children[1] ?: s->children[0]; 1731 } 1732 1733 static u32 bch2_snapshot_smallest_descendent(struct bch_fs *c, u32 id) 1734 { 1735 u32 child; 1736 1737 while ((child = bch2_snapshot_smallest_child(c, id))) 1738 id = child; 1739 return id; 1740 } 1741 1742 static int bch2_propagate_key_to_snapshot_leaf(struct btree_trans *trans, 1743 enum btree_id btree, 1744 struct bkey_s_c interior_k, 1745 u32 leaf_id, struct bpos *new_min_pos) 1746 { 1747 struct btree_iter iter; 1748 struct bpos pos = interior_k.k->p; 1749 struct bkey_s_c k; 1750 struct bkey_i *new; 1751 int ret; 1752 1753 pos.snapshot = leaf_id; 1754 1755 bch2_trans_iter_init(trans, &iter, btree, pos, BTREE_ITER_INTENT); 1756 k = bch2_btree_iter_peek_slot(&iter); 1757 ret = bkey_err(k); 1758 if (ret) 1759 goto out; 1760 1761 /* key already overwritten in this snapshot? */ 1762 if (k.k->p.snapshot != interior_k.k->p.snapshot) 1763 goto out; 1764 1765 if (bpos_eq(*new_min_pos, POS_MIN)) { 1766 *new_min_pos = k.k->p; 1767 new_min_pos->snapshot = leaf_id; 1768 } 1769 1770 new = bch2_bkey_make_mut_noupdate(trans, interior_k); 1771 ret = PTR_ERR_OR_ZERO(new); 1772 if (ret) 1773 goto out; 1774 1775 new->k.p.snapshot = leaf_id; 1776 ret = bch2_trans_update(trans, &iter, new, 0); 1777 out: 1778 bch2_trans_iter_exit(trans, &iter); 1779 return ret; 1780 } 1781 1782 int bch2_propagate_key_to_snapshot_leaves(struct btree_trans *trans, 1783 enum btree_id btree, 1784 struct bkey_s_c k, 1785 struct bpos *new_min_pos) 1786 { 1787 struct bch_fs *c = trans->c; 1788 struct bkey_buf sk; 1789 u32 restart_count = trans->restart_count; 1790 int ret = 0; 1791 1792 bch2_bkey_buf_init(&sk); 1793 bch2_bkey_buf_reassemble(&sk, c, k); 1794 k = bkey_i_to_s_c(sk.k); 1795 1796 *new_min_pos = POS_MIN; 1797 1798 for (u32 id = bch2_snapshot_smallest_descendent(c, k.k->p.snapshot); 1799 id < k.k->p.snapshot; 1800 id++) { 1801 if (!bch2_snapshot_is_ancestor(c, id, k.k->p.snapshot) || 1802 !bch2_snapshot_is_leaf(c, id)) 1803 continue; 1804 again: 1805 ret = btree_trans_too_many_iters(trans) ?: 1806 bch2_propagate_key_to_snapshot_leaf(trans, btree, k, id, new_min_pos) ?: 1807 bch2_trans_commit(trans, NULL, NULL, 0); 1808 if (ret && bch2_err_matches(ret, BCH_ERR_transaction_restart)) { 1809 bch2_trans_begin(trans); 1810 goto again; 1811 } 1812 1813 if (ret) 1814 break; 1815 } 1816 1817 bch2_bkey_buf_exit(&sk, c); 1818 1819 return ret ?: trans_was_restarted(trans, restart_count); 1820 } 1821 1822 static int bch2_check_snapshot_needs_deletion(struct btree_trans *trans, struct bkey_s_c k) 1823 { 1824 struct bch_fs *c = trans->c; 1825 struct bkey_s_c_snapshot snap; 1826 int ret = 0; 1827 1828 if (k.k->type != KEY_TYPE_snapshot) 1829 return 0; 1830 1831 snap = bkey_s_c_to_snapshot(k); 1832 if (BCH_SNAPSHOT_DELETED(snap.v) || 1833 bch2_snapshot_equiv(c, k.k->p.offset) != k.k->p.offset || 1834 (ret = bch2_snapshot_needs_delete(trans, k)) > 0) { 1835 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags); 1836 return 0; 1837 } 1838 1839 return ret; 1840 } 1841 1842 int bch2_snapshots_read(struct bch_fs *c) 1843 { 1844 int ret = bch2_trans_run(c, 1845 for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1846 POS_MIN, 0, k, 1847 __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, k, 0) ?: 1848 bch2_snapshot_set_equiv(trans, k) ?: 1849 bch2_check_snapshot_needs_deletion(trans, k)) ?: 1850 for_each_btree_key(trans, iter, BTREE_ID_snapshots, 1851 POS_MIN, 0, k, 1852 (set_is_ancestor_bitmap(c, k.k->p.offset), 0))); 1853 bch_err_fn(c, ret); 1854 1855 /* 1856 * It's important that we check if we need to reconstruct snapshots 1857 * before going RW, so we mark that pass as required in the superblock - 1858 * otherwise, we could end up deleting keys with missing snapshot nodes 1859 * instead 1860 */ 1861 BUG_ON(!test_bit(BCH_FS_new_fs, &c->flags) && 1862 test_bit(BCH_FS_may_go_rw, &c->flags)); 1863 1864 if (bch2_err_matches(ret, EIO) || 1865 (c->sb.btrees_lost_data & BIT_ULL(BTREE_ID_snapshots))) 1866 ret = bch2_run_explicit_recovery_pass_persistent(c, BCH_RECOVERY_PASS_reconstruct_snapshots); 1867 1868 return ret; 1869 } 1870 1871 void bch2_fs_snapshots_exit(struct bch_fs *c) 1872 { 1873 kvfree(rcu_dereference_protected(c->snapshots, true)); 1874 } 1875