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