1816 lines · c
1// SPDX-License-Identifier: GPL-2.02 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; they20 * exist to provide a stable identifier for the whole lifetime of a snapshot21 * tree.22 */23 24void 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 34int bch2_snapshot_tree_validate(struct bch_fs *c, struct bkey_s_c k,35 enum bch_validate_flags flags)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)),41 c, snapshot_tree_pos_bad,42 "bad pos");43fsck_err:44 return ret;45}46 47int 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 58struct 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 77static 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 94static bool __bch2_snapshot_is_ancestor_early(struct snapshot_table *t, u32 id, u32 ancestor)95{96 while (id && id < ancestor) {97 const struct snapshot_t *s = __snapshot_t(t, id);98 id = s ? s->parent : 0;99 }100 return id == ancestor;101}102 103static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)104{105 rcu_read_lock();106 bool ret = __bch2_snapshot_is_ancestor_early(rcu_dereference(c->snapshots), id, ancestor);107 rcu_read_unlock();108 109 return ret;110}111 112static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor)113{114 const struct snapshot_t *s = __snapshot_t(t, id);115 if (!s)116 return 0;117 118 if (s->skip[2] <= ancestor)119 return s->skip[2];120 if (s->skip[1] <= ancestor)121 return s->skip[1];122 if (s->skip[0] <= ancestor)123 return s->skip[0];124 return s->parent;125}126 127static bool test_ancestor_bitmap(struct snapshot_table *t, u32 id, u32 ancestor)128{129 const struct snapshot_t *s = __snapshot_t(t, id);130 if (!s)131 return false;132 133 return test_bit(ancestor - id - 1, s->is_ancestor);134}135 136bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)137{138 bool ret;139 140 rcu_read_lock();141 struct snapshot_table *t = rcu_dereference(c->snapshots);142 143 if (unlikely(c->recovery_pass_done < BCH_RECOVERY_PASS_check_snapshots)) {144 ret = __bch2_snapshot_is_ancestor_early(t, id, ancestor);145 goto out;146 }147 148 while (id && id < ancestor - IS_ANCESTOR_BITMAP)149 id = get_ancestor_below(t, id, ancestor);150 151 ret = id && id < ancestor152 ? test_ancestor_bitmap(t, id, ancestor)153 : id == ancestor;154 155 EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor));156out:157 rcu_read_unlock();158 159 return ret;160}161 162static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id)163{164 size_t idx = U32_MAX - id;165 struct snapshot_table *new, *old;166 167 size_t new_bytes = kmalloc_size_roundup(struct_size(new, s, idx + 1));168 size_t new_size = (new_bytes - sizeof(*new)) / sizeof(new->s[0]);169 170 if (unlikely(new_bytes > INT_MAX))171 return NULL;172 173 new = kvzalloc(new_bytes, GFP_KERNEL);174 if (!new)175 return NULL;176 177 new->nr = new_size;178 179 old = rcu_dereference_protected(c->snapshots, true);180 if (old)181 memcpy(new->s, old->s, sizeof(old->s[0]) * old->nr);182 183 rcu_assign_pointer(c->snapshots, new);184 kvfree_rcu(old, rcu);185 186 return &rcu_dereference_protected(c->snapshots,187 lockdep_is_held(&c->snapshot_table_lock))->s[idx];188}189 190static inline struct snapshot_t *snapshot_t_mut(struct bch_fs *c, u32 id)191{192 size_t idx = U32_MAX - id;193 struct snapshot_table *table =194 rcu_dereference_protected(c->snapshots,195 lockdep_is_held(&c->snapshot_table_lock));196 197 lockdep_assert_held(&c->snapshot_table_lock);198 199 if (likely(table && idx < table->nr))200 return &table->s[idx];201 202 return __snapshot_t_mut(c, id);203}204 205void bch2_snapshot_to_text(struct printbuf *out, struct bch_fs *c,206 struct bkey_s_c k)207{208 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(k);209 210 prt_printf(out, "is_subvol %llu deleted %llu parent %10u children %10u %10u subvol %u tree %u",211 BCH_SNAPSHOT_SUBVOL(s.v),212 BCH_SNAPSHOT_DELETED(s.v),213 le32_to_cpu(s.v->parent),214 le32_to_cpu(s.v->children[0]),215 le32_to_cpu(s.v->children[1]),216 le32_to_cpu(s.v->subvol),217 le32_to_cpu(s.v->tree));218 219 if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, depth))220 prt_printf(out, " depth %u skiplist %u %u %u",221 le32_to_cpu(s.v->depth),222 le32_to_cpu(s.v->skip[0]),223 le32_to_cpu(s.v->skip[1]),224 le32_to_cpu(s.v->skip[2]));225}226 227int bch2_snapshot_validate(struct bch_fs *c, struct bkey_s_c k,228 enum bch_validate_flags flags)229{230 struct bkey_s_c_snapshot s;231 u32 i, id;232 int ret = 0;233 234 bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) ||235 bkey_lt(k.k->p, POS(0, 1)),236 c, snapshot_pos_bad,237 "bad pos");238 239 s = bkey_s_c_to_snapshot(k);240 241 id = le32_to_cpu(s.v->parent);242 bkey_fsck_err_on(id && id <= k.k->p.offset,243 c, snapshot_parent_bad,244 "bad parent node (%u <= %llu)",245 id, k.k->p.offset);246 247 bkey_fsck_err_on(le32_to_cpu(s.v->children[0]) < le32_to_cpu(s.v->children[1]),248 c, snapshot_children_not_normalized,249 "children not normalized");250 251 bkey_fsck_err_on(s.v->children[0] && s.v->children[0] == s.v->children[1],252 c, snapshot_child_duplicate,253 "duplicate child nodes");254 255 for (i = 0; i < 2; i++) {256 id = le32_to_cpu(s.v->children[i]);257 258 bkey_fsck_err_on(id >= k.k->p.offset,259 c, snapshot_child_bad,260 "bad child node (%u >= %llu)",261 id, k.k->p.offset);262 }263 264 if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, skip)) {265 bkey_fsck_err_on(le32_to_cpu(s.v->skip[0]) > le32_to_cpu(s.v->skip[1]) ||266 le32_to_cpu(s.v->skip[1]) > le32_to_cpu(s.v->skip[2]),267 c, snapshot_skiplist_not_normalized,268 "skiplist not normalized");269 270 for (i = 0; i < ARRAY_SIZE(s.v->skip); i++) {271 id = le32_to_cpu(s.v->skip[i]);272 273 bkey_fsck_err_on(id && id < le32_to_cpu(s.v->parent),274 c, snapshot_skiplist_bad,275 "bad skiplist node %u", id);276 }277 }278fsck_err:279 return ret;280}281 282static void __set_is_ancestor_bitmap(struct bch_fs *c, u32 id)283{284 struct snapshot_t *t = snapshot_t_mut(c, id);285 u32 parent = id;286 287 while ((parent = bch2_snapshot_parent_early(c, parent)) &&288 parent - id - 1 < IS_ANCESTOR_BITMAP)289 __set_bit(parent - id - 1, t->is_ancestor);290}291 292static void set_is_ancestor_bitmap(struct bch_fs *c, u32 id)293{294 mutex_lock(&c->snapshot_table_lock);295 __set_is_ancestor_bitmap(c, id);296 mutex_unlock(&c->snapshot_table_lock);297}298 299static int __bch2_mark_snapshot(struct btree_trans *trans,300 enum btree_id btree, unsigned level,301 struct bkey_s_c old, struct bkey_s_c new,302 enum btree_iter_update_trigger_flags flags)303{304 struct bch_fs *c = trans->c;305 struct snapshot_t *t;306 u32 id = new.k->p.offset;307 int ret = 0;308 309 mutex_lock(&c->snapshot_table_lock);310 311 t = snapshot_t_mut(c, id);312 if (!t) {313 ret = -BCH_ERR_ENOMEM_mark_snapshot;314 goto err;315 }316 317 if (new.k->type == KEY_TYPE_snapshot) {318 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(new);319 320 t->parent = le32_to_cpu(s.v->parent);321 t->children[0] = le32_to_cpu(s.v->children[0]);322 t->children[1] = le32_to_cpu(s.v->children[1]);323 t->subvol = BCH_SNAPSHOT_SUBVOL(s.v) ? le32_to_cpu(s.v->subvol) : 0;324 t->tree = le32_to_cpu(s.v->tree);325 326 if (bkey_val_bytes(s.k) > offsetof(struct bch_snapshot, depth)) {327 t->depth = le32_to_cpu(s.v->depth);328 t->skip[0] = le32_to_cpu(s.v->skip[0]);329 t->skip[1] = le32_to_cpu(s.v->skip[1]);330 t->skip[2] = le32_to_cpu(s.v->skip[2]);331 } else {332 t->depth = 0;333 t->skip[0] = 0;334 t->skip[1] = 0;335 t->skip[2] = 0;336 }337 338 __set_is_ancestor_bitmap(c, id);339 340 if (BCH_SNAPSHOT_DELETED(s.v)) {341 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);342 if (c->curr_recovery_pass > BCH_RECOVERY_PASS_delete_dead_snapshots)343 bch2_delete_dead_snapshots_async(c);344 }345 } else {346 memset(t, 0, sizeof(*t));347 }348err:349 mutex_unlock(&c->snapshot_table_lock);350 return ret;351}352 353int bch2_mark_snapshot(struct btree_trans *trans,354 enum btree_id btree, unsigned level,355 struct bkey_s_c old, struct bkey_s new,356 enum btree_iter_update_trigger_flags flags)357{358 return __bch2_mark_snapshot(trans, btree, level, old, new.s_c, flags);359}360 361int bch2_snapshot_lookup(struct btree_trans *trans, u32 id,362 struct bch_snapshot *s)363{364 return bch2_bkey_get_val_typed(trans, BTREE_ID_snapshots, POS(0, id),365 BTREE_ITER_with_updates, snapshot, s);366}367 368static int bch2_snapshot_live(struct btree_trans *trans, u32 id)369{370 struct bch_snapshot v;371 int ret;372 373 if (!id)374 return 0;375 376 ret = bch2_snapshot_lookup(trans, id, &v);377 if (bch2_err_matches(ret, ENOENT))378 bch_err(trans->c, "snapshot node %u not found", id);379 if (ret)380 return ret;381 382 return !BCH_SNAPSHOT_DELETED(&v);383}384 385/*386 * If @k is a snapshot with just one live child, it's part of a linear chain,387 * which we consider to be an equivalence class: and then after snapshot388 * deletion cleanup, there should only be a single key at a given position in389 * this equivalence class.390 *391 * This sets the equivalence class of @k to be the child's equivalence class, if392 * it's part of such a linear chain: this correctly sets equivalence classes on393 * startup if we run leaf to root (i.e. in natural key order).394 */395static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k)396{397 struct bch_fs *c = trans->c;398 unsigned i, nr_live = 0, live_idx = 0;399 struct bkey_s_c_snapshot snap;400 u32 id = k.k->p.offset, child[2];401 402 if (k.k->type != KEY_TYPE_snapshot)403 return 0;404 405 snap = bkey_s_c_to_snapshot(k);406 407 child[0] = le32_to_cpu(snap.v->children[0]);408 child[1] = le32_to_cpu(snap.v->children[1]);409 410 for (i = 0; i < 2; i++) {411 int ret = bch2_snapshot_live(trans, child[i]);412 413 if (ret < 0)414 return ret;415 416 if (ret)417 live_idx = i;418 nr_live += ret;419 }420 421 mutex_lock(&c->snapshot_table_lock);422 423 snapshot_t_mut(c, id)->equiv = nr_live == 1424 ? snapshot_t_mut(c, child[live_idx])->equiv425 : id;426 427 mutex_unlock(&c->snapshot_table_lock);428 429 return 0;430}431 432/* fsck: */433 434static u32 bch2_snapshot_child(struct bch_fs *c, u32 id, unsigned child)435{436 return snapshot_t(c, id)->children[child];437}438 439static u32 bch2_snapshot_left_child(struct bch_fs *c, u32 id)440{441 return bch2_snapshot_child(c, id, 0);442}443 444static u32 bch2_snapshot_right_child(struct bch_fs *c, u32 id)445{446 return bch2_snapshot_child(c, id, 1);447}448 449static u32 bch2_snapshot_tree_next(struct bch_fs *c, u32 id)450{451 u32 n, parent;452 453 n = bch2_snapshot_left_child(c, id);454 if (n)455 return n;456 457 while ((parent = bch2_snapshot_parent(c, id))) {458 n = bch2_snapshot_right_child(c, parent);459 if (n && n != id)460 return n;461 id = parent;462 }463 464 return 0;465}466 467static u32 bch2_snapshot_tree_oldest_subvol(struct bch_fs *c, u32 snapshot_root)468{469 u32 id = snapshot_root;470 u32 subvol = 0, s;471 472 rcu_read_lock();473 while (id) {474 s = snapshot_t(c, id)->subvol;475 476 if (s && (!subvol || s < subvol))477 subvol = s;478 479 id = bch2_snapshot_tree_next(c, id);480 }481 rcu_read_unlock();482 483 return subvol;484}485 486static int bch2_snapshot_tree_master_subvol(struct btree_trans *trans,487 u32 snapshot_root, u32 *subvol_id)488{489 struct bch_fs *c = trans->c;490 struct btree_iter iter;491 struct bkey_s_c k;492 bool found = false;493 int ret;494 495 for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN,496 0, k, ret) {497 if (k.k->type != KEY_TYPE_subvolume)498 continue;499 500 struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);501 if (!bch2_snapshot_is_ancestor(c, le32_to_cpu(s.v->snapshot), snapshot_root))502 continue;503 if (!BCH_SUBVOLUME_SNAP(s.v)) {504 *subvol_id = s.k->p.offset;505 found = true;506 break;507 }508 }509 510 bch2_trans_iter_exit(trans, &iter);511 512 if (!ret && !found) {513 struct bkey_i_subvolume *u;514 515 *subvol_id = bch2_snapshot_tree_oldest_subvol(c, snapshot_root);516 517 u = bch2_bkey_get_mut_typed(trans, &iter,518 BTREE_ID_subvolumes, POS(0, *subvol_id),519 0, subvolume);520 ret = PTR_ERR_OR_ZERO(u);521 if (ret)522 return ret;523 524 SET_BCH_SUBVOLUME_SNAP(&u->v, false);525 }526 527 return ret;528}529 530static int check_snapshot_tree(struct btree_trans *trans,531 struct btree_iter *iter,532 struct bkey_s_c k)533{534 struct bch_fs *c = trans->c;535 struct bkey_s_c_snapshot_tree st;536 struct bch_snapshot s;537 struct bch_subvolume subvol;538 struct printbuf buf = PRINTBUF;539 u32 root_id;540 int ret;541 542 if (k.k->type != KEY_TYPE_snapshot_tree)543 return 0;544 545 st = bkey_s_c_to_snapshot_tree(k);546 root_id = le32_to_cpu(st.v->root_snapshot);547 548 ret = bch2_snapshot_lookup(trans, root_id, &s);549 if (ret && !bch2_err_matches(ret, ENOENT))550 goto err;551 552 if (fsck_err_on(ret ||553 root_id != bch2_snapshot_root(c, root_id) ||554 st.k->p.offset != le32_to_cpu(s.tree),555 trans, snapshot_tree_to_missing_snapshot,556 "snapshot tree points to missing/incorrect snapshot:\n %s",557 (bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {558 ret = bch2_btree_delete_at(trans, iter, 0);559 goto err;560 }561 562 ret = bch2_subvolume_get(trans, le32_to_cpu(st.v->master_subvol),563 false, 0, &subvol);564 if (ret && !bch2_err_matches(ret, ENOENT))565 goto err;566 567 if (fsck_err_on(ret,568 trans, snapshot_tree_to_missing_subvol,569 "snapshot tree points to missing subvolume:\n %s",570 (printbuf_reset(&buf),571 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||572 fsck_err_on(!bch2_snapshot_is_ancestor(c,573 le32_to_cpu(subvol.snapshot),574 root_id),575 trans, snapshot_tree_to_wrong_subvol,576 "snapshot tree points to subvolume that does not point to snapshot in this tree:\n %s",577 (printbuf_reset(&buf),578 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||579 fsck_err_on(BCH_SUBVOLUME_SNAP(&subvol),580 trans, snapshot_tree_to_snapshot_subvol,581 "snapshot tree points to snapshot subvolume:\n %s",582 (printbuf_reset(&buf),583 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {584 struct bkey_i_snapshot_tree *u;585 u32 subvol_id;586 587 ret = bch2_snapshot_tree_master_subvol(trans, root_id, &subvol_id);588 bch_err_fn(c, ret);589 590 if (bch2_err_matches(ret, ENOENT)) { /* nothing to be done here */591 ret = 0;592 goto err;593 }594 595 if (ret)596 goto err;597 598 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot_tree);599 ret = PTR_ERR_OR_ZERO(u);600 if (ret)601 goto err;602 603 u->v.master_subvol = cpu_to_le32(subvol_id);604 st = snapshot_tree_i_to_s_c(u);605 }606err:607fsck_err:608 printbuf_exit(&buf);609 return ret;610}611 612/*613 * For each snapshot_tree, make sure it points to the root of a snapshot tree614 * and that snapshot entry points back to it, or delete it.615 *616 * And, make sure it points to a subvolume within that snapshot tree, or correct617 * it to point to the oldest subvolume within that snapshot tree.618 */619int bch2_check_snapshot_trees(struct bch_fs *c)620{621 int ret = bch2_trans_run(c,622 for_each_btree_key_commit(trans, iter,623 BTREE_ID_snapshot_trees, POS_MIN,624 BTREE_ITER_prefetch, k,625 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,626 check_snapshot_tree(trans, &iter, k)));627 bch_err_fn(c, ret);628 return ret;629}630 631/*632 * Look up snapshot tree for @tree_id and find root,633 * make sure @snap_id is a descendent:634 */635static int snapshot_tree_ptr_good(struct btree_trans *trans,636 u32 snap_id, u32 tree_id)637{638 struct bch_snapshot_tree s_t;639 int ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);640 641 if (bch2_err_matches(ret, ENOENT))642 return 0;643 if (ret)644 return ret;645 646 return bch2_snapshot_is_ancestor_early(trans->c, snap_id, le32_to_cpu(s_t.root_snapshot));647}648 649u32 bch2_snapshot_skiplist_get(struct bch_fs *c, u32 id)650{651 const struct snapshot_t *s;652 653 if (!id)654 return 0;655 656 rcu_read_lock();657 s = snapshot_t(c, id);658 if (s->parent)659 id = bch2_snapshot_nth_parent(c, id, get_random_u32_below(s->depth));660 rcu_read_unlock();661 662 return id;663}664 665static int snapshot_skiplist_good(struct btree_trans *trans, u32 id, struct bch_snapshot s)666{667 unsigned i;668 669 for (i = 0; i < 3; i++)670 if (!s.parent) {671 if (s.skip[i])672 return false;673 } else {674 if (!bch2_snapshot_is_ancestor_early(trans->c, id, le32_to_cpu(s.skip[i])))675 return false;676 }677 678 return true;679}680 681/*682 * snapshot_tree pointer was incorrect: look up root snapshot node, make sure683 * its snapshot_tree pointer is correct (allocate new one if necessary), then684 * update this node's pointer to root node's pointer:685 */686static int snapshot_tree_ptr_repair(struct btree_trans *trans,687 struct btree_iter *iter,688 struct bkey_s_c k,689 struct bch_snapshot *s)690{691 struct bch_fs *c = trans->c;692 struct btree_iter root_iter;693 struct bch_snapshot_tree s_t;694 struct bkey_s_c_snapshot root;695 struct bkey_i_snapshot *u;696 u32 root_id = bch2_snapshot_root(c, k.k->p.offset), tree_id;697 int ret;698 699 root = bch2_bkey_get_iter_typed(trans, &root_iter,700 BTREE_ID_snapshots, POS(0, root_id),701 BTREE_ITER_with_updates, snapshot);702 ret = bkey_err(root);703 if (ret)704 goto err;705 706 tree_id = le32_to_cpu(root.v->tree);707 708 ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);709 if (ret && !bch2_err_matches(ret, ENOENT))710 return ret;711 712 if (ret || le32_to_cpu(s_t.root_snapshot) != root_id) {713 u = bch2_bkey_make_mut_typed(trans, &root_iter, &root.s_c, 0, snapshot);714 ret = PTR_ERR_OR_ZERO(u) ?:715 bch2_snapshot_tree_create(trans, root_id,716 bch2_snapshot_tree_oldest_subvol(c, root_id),717 &tree_id);718 if (ret)719 goto err;720 721 u->v.tree = cpu_to_le32(tree_id);722 if (k.k->p.offset == root_id)723 *s = u->v;724 }725 726 if (k.k->p.offset != root_id) {727 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);728 ret = PTR_ERR_OR_ZERO(u);729 if (ret)730 goto err;731 732 u->v.tree = cpu_to_le32(tree_id);733 *s = u->v;734 }735err:736 bch2_trans_iter_exit(trans, &root_iter);737 return ret;738}739 740static int check_snapshot(struct btree_trans *trans,741 struct btree_iter *iter,742 struct bkey_s_c k)743{744 struct bch_fs *c = trans->c;745 struct bch_snapshot s;746 struct bch_subvolume subvol;747 struct bch_snapshot v;748 struct bkey_i_snapshot *u;749 u32 parent_id = bch2_snapshot_parent_early(c, k.k->p.offset);750 u32 real_depth;751 struct printbuf buf = PRINTBUF;752 u32 i, id;753 int ret = 0;754 755 if (k.k->type != KEY_TYPE_snapshot)756 return 0;757 758 memset(&s, 0, sizeof(s));759 memcpy(&s, k.v, min(sizeof(s), bkey_val_bytes(k.k)));760 761 id = le32_to_cpu(s.parent);762 if (id) {763 ret = bch2_snapshot_lookup(trans, id, &v);764 if (bch2_err_matches(ret, ENOENT))765 bch_err(c, "snapshot with nonexistent parent:\n %s",766 (bch2_bkey_val_to_text(&buf, c, k), buf.buf));767 if (ret)768 goto err;769 770 if (le32_to_cpu(v.children[0]) != k.k->p.offset &&771 le32_to_cpu(v.children[1]) != k.k->p.offset) {772 bch_err(c, "snapshot parent %u missing pointer to child %llu",773 id, k.k->p.offset);774 ret = -EINVAL;775 goto err;776 }777 }778 779 for (i = 0; i < 2 && s.children[i]; i++) {780 id = le32_to_cpu(s.children[i]);781 782 ret = bch2_snapshot_lookup(trans, id, &v);783 if (bch2_err_matches(ret, ENOENT))784 bch_err(c, "snapshot node %llu has nonexistent child %u",785 k.k->p.offset, id);786 if (ret)787 goto err;788 789 if (le32_to_cpu(v.parent) != k.k->p.offset) {790 bch_err(c, "snapshot child %u has wrong parent (got %u should be %llu)",791 id, le32_to_cpu(v.parent), k.k->p.offset);792 ret = -EINVAL;793 goto err;794 }795 }796 797 bool should_have_subvol = BCH_SNAPSHOT_SUBVOL(&s) &&798 !BCH_SNAPSHOT_DELETED(&s);799 800 if (should_have_subvol) {801 id = le32_to_cpu(s.subvol);802 ret = bch2_subvolume_get(trans, id, 0, false, &subvol);803 if (bch2_err_matches(ret, ENOENT))804 bch_err(c, "snapshot points to nonexistent subvolume:\n %s",805 (bch2_bkey_val_to_text(&buf, c, k), buf.buf));806 if (ret)807 goto err;808 809 if (BCH_SNAPSHOT_SUBVOL(&s) != (le32_to_cpu(subvol.snapshot) == k.k->p.offset)) {810 bch_err(c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL",811 k.k->p.offset);812 ret = -EINVAL;813 goto err;814 }815 } else {816 if (fsck_err_on(s.subvol,817 trans, snapshot_should_not_have_subvol,818 "snapshot should not point to subvol:\n %s",819 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {820 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);821 ret = PTR_ERR_OR_ZERO(u);822 if (ret)823 goto err;824 825 u->v.subvol = 0;826 s = u->v;827 }828 }829 830 ret = snapshot_tree_ptr_good(trans, k.k->p.offset, le32_to_cpu(s.tree));831 if (ret < 0)832 goto err;833 834 if (fsck_err_on(!ret,835 trans, snapshot_to_bad_snapshot_tree,836 "snapshot points to missing/incorrect tree:\n %s",837 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {838 ret = snapshot_tree_ptr_repair(trans, iter, k, &s);839 if (ret)840 goto err;841 }842 ret = 0;843 844 real_depth = bch2_snapshot_depth(c, parent_id);845 846 if (fsck_err_on(le32_to_cpu(s.depth) != real_depth,847 trans, snapshot_bad_depth,848 "snapshot with incorrect depth field, should be %u:\n %s",849 real_depth, (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {850 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);851 ret = PTR_ERR_OR_ZERO(u);852 if (ret)853 goto err;854 855 u->v.depth = cpu_to_le32(real_depth);856 s = u->v;857 }858 859 ret = snapshot_skiplist_good(trans, k.k->p.offset, s);860 if (ret < 0)861 goto err;862 863 if (fsck_err_on(!ret,864 trans, snapshot_bad_skiplist,865 "snapshot with bad skiplist field:\n %s",866 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {867 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);868 ret = PTR_ERR_OR_ZERO(u);869 if (ret)870 goto err;871 872 for (i = 0; i < ARRAY_SIZE(u->v.skip); i++)873 u->v.skip[i] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent_id));874 875 bubble_sort(u->v.skip, ARRAY_SIZE(u->v.skip), cmp_le32);876 s = u->v;877 }878 ret = 0;879err:880fsck_err:881 printbuf_exit(&buf);882 return ret;883}884 885int bch2_check_snapshots(struct bch_fs *c)886{887 /*888 * We iterate backwards as checking/fixing the depth field requires that889 * the parent's depth already be correct:890 */891 int ret = bch2_trans_run(c,892 for_each_btree_key_reverse_commit(trans, iter,893 BTREE_ID_snapshots, POS_MAX,894 BTREE_ITER_prefetch, k,895 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,896 check_snapshot(trans, &iter, k)));897 bch_err_fn(c, ret);898 return ret;899}900 901static int check_snapshot_exists(struct btree_trans *trans, u32 id)902{903 struct bch_fs *c = trans->c;904 905 if (bch2_snapshot_equiv(c, id))906 return 0;907 908 /* Do we need to reconstruct the snapshot_tree entry as well? */909 struct btree_iter iter;910 struct bkey_s_c k;911 int ret = 0;912 u32 tree_id = 0;913 914 for_each_btree_key_norestart(trans, iter, BTREE_ID_snapshot_trees, POS_MIN,915 0, k, ret) {916 if (le32_to_cpu(bkey_s_c_to_snapshot_tree(k).v->root_snapshot) == id) {917 tree_id = k.k->p.offset;918 break;919 }920 }921 bch2_trans_iter_exit(trans, &iter);922 923 if (ret)924 return ret;925 926 if (!tree_id) {927 ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id);928 if (ret)929 return ret;930 }931 932 struct bkey_i_snapshot *snapshot = bch2_trans_kmalloc(trans, sizeof(*snapshot));933 ret = PTR_ERR_OR_ZERO(snapshot);934 if (ret)935 return ret;936 937 bkey_snapshot_init(&snapshot->k_i);938 snapshot->k.p = POS(0, id);939 snapshot->v.tree = cpu_to_le32(tree_id);940 snapshot->v.btime.lo = cpu_to_le64(bch2_current_time(c));941 942 for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN,943 0, k, ret) {944 if (le32_to_cpu(bkey_s_c_to_subvolume(k).v->snapshot) == id) {945 snapshot->v.subvol = cpu_to_le32(k.k->p.offset);946 SET_BCH_SNAPSHOT_SUBVOL(&snapshot->v, true);947 break;948 }949 }950 bch2_trans_iter_exit(trans, &iter);951 952 return bch2_btree_insert_trans(trans, BTREE_ID_snapshots, &snapshot->k_i, 0) ?:953 bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,954 bkey_s_c_null, bkey_i_to_s(&snapshot->k_i), 0) ?:955 bch2_snapshot_set_equiv(trans, bkey_i_to_s_c(&snapshot->k_i));956}957 958/* Figure out which snapshot nodes belong in the same tree: */959struct snapshot_tree_reconstruct {960 enum btree_id btree;961 struct bpos cur_pos;962 snapshot_id_list cur_ids;963 DARRAY(snapshot_id_list) trees;964};965 966static void snapshot_tree_reconstruct_exit(struct snapshot_tree_reconstruct *r)967{968 darray_for_each(r->trees, i)969 darray_exit(i);970 darray_exit(&r->trees);971 darray_exit(&r->cur_ids);972}973 974static inline bool same_snapshot(struct snapshot_tree_reconstruct *r, struct bpos pos)975{976 return r->btree == BTREE_ID_inodes977 ? r->cur_pos.offset == pos.offset978 : r->cur_pos.inode == pos.inode;979}980 981static inline bool snapshot_id_lists_have_common(snapshot_id_list *l, snapshot_id_list *r)982{983 darray_for_each(*l, i)984 if (snapshot_list_has_id(r, *i))985 return true;986 return false;987}988 989static void snapshot_id_list_to_text(struct printbuf *out, snapshot_id_list *s)990{991 bool first = true;992 darray_for_each(*s, i) {993 if (!first)994 prt_char(out, ' ');995 first = false;996 prt_printf(out, "%u", *i);997 }998}999 1000static int snapshot_tree_reconstruct_next(struct bch_fs *c, struct snapshot_tree_reconstruct *r)1001{1002 if (r->cur_ids.nr) {1003 darray_for_each(r->trees, i)1004 if (snapshot_id_lists_have_common(i, &r->cur_ids)) {1005 int ret = snapshot_list_merge(c, i, &r->cur_ids);1006 if (ret)1007 return ret;1008 goto out;1009 }1010 darray_push(&r->trees, r->cur_ids);1011 darray_init(&r->cur_ids);1012 }1013out:1014 r->cur_ids.nr = 0;1015 return 0;1016}1017 1018static int get_snapshot_trees(struct bch_fs *c, struct snapshot_tree_reconstruct *r, struct bpos pos)1019{1020 if (!same_snapshot(r, pos))1021 snapshot_tree_reconstruct_next(c, r);1022 r->cur_pos = pos;1023 return snapshot_list_add_nodup(c, &r->cur_ids, pos.snapshot);1024}1025 1026int bch2_reconstruct_snapshots(struct bch_fs *c)1027{1028 struct btree_trans *trans = bch2_trans_get(c);1029 struct printbuf buf = PRINTBUF;1030 struct snapshot_tree_reconstruct r = {};1031 int ret = 0;1032 1033 for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) {1034 if (btree_type_has_snapshots(btree)) {1035 r.btree = btree;1036 1037 ret = for_each_btree_key(trans, iter, btree, POS_MIN,1038 BTREE_ITER_all_snapshots|BTREE_ITER_prefetch, k, ({1039 get_snapshot_trees(c, &r, k.k->p);1040 }));1041 if (ret)1042 goto err;1043 1044 snapshot_tree_reconstruct_next(c, &r);1045 }1046 }1047 1048 darray_for_each(r.trees, t) {1049 printbuf_reset(&buf);1050 snapshot_id_list_to_text(&buf, t);1051 1052 darray_for_each(*t, id) {1053 if (fsck_err_on(!bch2_snapshot_equiv(c, *id),1054 trans, snapshot_node_missing,1055 "snapshot node %u from tree %s missing, recreate?", *id, buf.buf)) {1056 if (t->nr > 1) {1057 bch_err(c, "cannot reconstruct snapshot trees with multiple nodes");1058 ret = -BCH_ERR_fsck_repair_unimplemented;1059 goto err;1060 }1061 1062 ret = commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,1063 check_snapshot_exists(trans, *id));1064 if (ret)1065 goto err;1066 }1067 }1068 }1069fsck_err:1070err:1071 bch2_trans_put(trans);1072 snapshot_tree_reconstruct_exit(&r);1073 printbuf_exit(&buf);1074 bch_err_fn(c, ret);1075 return ret;1076}1077 1078int bch2_check_key_has_snapshot(struct btree_trans *trans,1079 struct btree_iter *iter,1080 struct bkey_s_c k)1081{1082 struct bch_fs *c = trans->c;1083 struct printbuf buf = PRINTBUF;1084 int ret = 0;1085 1086 if (fsck_err_on(!bch2_snapshot_equiv(c, k.k->p.snapshot),1087 trans, bkey_in_missing_snapshot,1088 "key in missing snapshot %s, delete?",1089 (bch2_bkey_val_to_text(&buf, c, k), buf.buf)))1090 ret = bch2_btree_delete_at(trans, iter,1091 BTREE_UPDATE_internal_snapshot_node) ?: 1;1092fsck_err:1093 printbuf_exit(&buf);1094 return ret;1095}1096 1097/*1098 * Mark a snapshot as deleted, for future cleanup:1099 */1100int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id)1101{1102 struct btree_iter iter;1103 struct bkey_i_snapshot *s;1104 int ret = 0;1105 1106 s = bch2_bkey_get_mut_typed(trans, &iter,1107 BTREE_ID_snapshots, POS(0, id),1108 0, snapshot);1109 ret = PTR_ERR_OR_ZERO(s);1110 if (unlikely(ret)) {1111 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT),1112 trans->c, "missing snapshot %u", id);1113 return ret;1114 }1115 1116 /* already deleted? */1117 if (BCH_SNAPSHOT_DELETED(&s->v))1118 goto err;1119 1120 SET_BCH_SNAPSHOT_DELETED(&s->v, true);1121 SET_BCH_SNAPSHOT_SUBVOL(&s->v, false);1122 s->v.subvol = 0;1123err:1124 bch2_trans_iter_exit(trans, &iter);1125 return ret;1126}1127 1128static inline void normalize_snapshot_child_pointers(struct bch_snapshot *s)1129{1130 if (le32_to_cpu(s->children[0]) < le32_to_cpu(s->children[1]))1131 swap(s->children[0], s->children[1]);1132}1133 1134static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id)1135{1136 struct bch_fs *c = trans->c;1137 struct btree_iter iter, p_iter = (struct btree_iter) { NULL };1138 struct btree_iter c_iter = (struct btree_iter) { NULL };1139 struct btree_iter tree_iter = (struct btree_iter) { NULL };1140 struct bkey_s_c_snapshot s;1141 u32 parent_id, child_id;1142 unsigned i;1143 int ret = 0;1144 1145 s = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id),1146 BTREE_ITER_intent, snapshot);1147 ret = bkey_err(s);1148 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,1149 "missing snapshot %u", id);1150 1151 if (ret)1152 goto err;1153 1154 BUG_ON(s.v->children[1]);1155 1156 parent_id = le32_to_cpu(s.v->parent);1157 child_id = le32_to_cpu(s.v->children[0]);1158 1159 if (parent_id) {1160 struct bkey_i_snapshot *parent;1161 1162 parent = bch2_bkey_get_mut_typed(trans, &p_iter,1163 BTREE_ID_snapshots, POS(0, parent_id),1164 0, snapshot);1165 ret = PTR_ERR_OR_ZERO(parent);1166 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,1167 "missing snapshot %u", parent_id);1168 if (unlikely(ret))1169 goto err;1170 1171 /* find entry in parent->children for node being deleted */1172 for (i = 0; i < 2; i++)1173 if (le32_to_cpu(parent->v.children[i]) == id)1174 break;1175 1176 if (bch2_fs_inconsistent_on(i == 2, c,1177 "snapshot %u missing child pointer to %u",1178 parent_id, id))1179 goto err;1180 1181 parent->v.children[i] = cpu_to_le32(child_id);1182 1183 normalize_snapshot_child_pointers(&parent->v);1184 }1185 1186 if (child_id) {1187 struct bkey_i_snapshot *child;1188 1189 child = bch2_bkey_get_mut_typed(trans, &c_iter,1190 BTREE_ID_snapshots, POS(0, child_id),1191 0, snapshot);1192 ret = PTR_ERR_OR_ZERO(child);1193 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,1194 "missing snapshot %u", child_id);1195 if (unlikely(ret))1196 goto err;1197 1198 child->v.parent = cpu_to_le32(parent_id);1199 1200 if (!child->v.parent) {1201 child->v.skip[0] = 0;1202 child->v.skip[1] = 0;1203 child->v.skip[2] = 0;1204 }1205 }1206 1207 if (!parent_id) {1208 /*1209 * We're deleting the root of a snapshot tree: update the1210 * snapshot_tree entry to point to the new root, or delete it if1211 * this is the last snapshot ID in this tree:1212 */1213 struct bkey_i_snapshot_tree *s_t;1214 1215 BUG_ON(s.v->children[1]);1216 1217 s_t = bch2_bkey_get_mut_typed(trans, &tree_iter,1218 BTREE_ID_snapshot_trees, POS(0, le32_to_cpu(s.v->tree)),1219 0, snapshot_tree);1220 ret = PTR_ERR_OR_ZERO(s_t);1221 if (ret)1222 goto err;1223 1224 if (s.v->children[0]) {1225 s_t->v.root_snapshot = s.v->children[0];1226 } else {1227 s_t->k.type = KEY_TYPE_deleted;1228 set_bkey_val_u64s(&s_t->k, 0);1229 }1230 }1231 1232 ret = bch2_btree_delete_at(trans, &iter, 0);1233err:1234 bch2_trans_iter_exit(trans, &tree_iter);1235 bch2_trans_iter_exit(trans, &p_iter);1236 bch2_trans_iter_exit(trans, &c_iter);1237 bch2_trans_iter_exit(trans, &iter);1238 return ret;1239}1240 1241static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree,1242 u32 *new_snapids,1243 u32 *snapshot_subvols,1244 unsigned nr_snapids)1245{1246 struct bch_fs *c = trans->c;1247 struct btree_iter iter;1248 struct bkey_i_snapshot *n;1249 struct bkey_s_c k;1250 unsigned i, j;1251 u32 depth = bch2_snapshot_depth(c, parent);1252 int ret;1253 1254 bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots,1255 POS_MIN, BTREE_ITER_intent);1256 k = bch2_btree_iter_peek(&iter);1257 ret = bkey_err(k);1258 if (ret)1259 goto err;1260 1261 for (i = 0; i < nr_snapids; i++) {1262 k = bch2_btree_iter_prev_slot(&iter);1263 ret = bkey_err(k);1264 if (ret)1265 goto err;1266 1267 if (!k.k || !k.k->p.offset) {1268 ret = -BCH_ERR_ENOSPC_snapshot_create;1269 goto err;1270 }1271 1272 n = bch2_bkey_alloc(trans, &iter, 0, snapshot);1273 ret = PTR_ERR_OR_ZERO(n);1274 if (ret)1275 goto err;1276 1277 n->v.flags = 0;1278 n->v.parent = cpu_to_le32(parent);1279 n->v.subvol = cpu_to_le32(snapshot_subvols[i]);1280 n->v.tree = cpu_to_le32(tree);1281 n->v.depth = cpu_to_le32(depth);1282 n->v.btime.lo = cpu_to_le64(bch2_current_time(c));1283 n->v.btime.hi = 0;1284 1285 for (j = 0; j < ARRAY_SIZE(n->v.skip); j++)1286 n->v.skip[j] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent));1287 1288 bubble_sort(n->v.skip, ARRAY_SIZE(n->v.skip), cmp_le32);1289 SET_BCH_SNAPSHOT_SUBVOL(&n->v, true);1290 1291 ret = __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,1292 bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0);1293 if (ret)1294 goto err;1295 1296 new_snapids[i] = iter.pos.offset;1297 1298 mutex_lock(&c->snapshot_table_lock);1299 snapshot_t_mut(c, new_snapids[i])->equiv = new_snapids[i];1300 mutex_unlock(&c->snapshot_table_lock);1301 }1302err:1303 bch2_trans_iter_exit(trans, &iter);1304 return ret;1305}1306 1307/*1308 * Create new snapshot IDs as children of an existing snapshot ID:1309 */1310static int bch2_snapshot_node_create_children(struct btree_trans *trans, u32 parent,1311 u32 *new_snapids,1312 u32 *snapshot_subvols,1313 unsigned nr_snapids)1314{1315 struct btree_iter iter;1316 struct bkey_i_snapshot *n_parent;1317 int ret = 0;1318 1319 n_parent = bch2_bkey_get_mut_typed(trans, &iter,1320 BTREE_ID_snapshots, POS(0, parent),1321 0, snapshot);1322 ret = PTR_ERR_OR_ZERO(n_parent);1323 if (unlikely(ret)) {1324 if (bch2_err_matches(ret, ENOENT))1325 bch_err(trans->c, "snapshot %u not found", parent);1326 return ret;1327 }1328 1329 if (n_parent->v.children[0] || n_parent->v.children[1]) {1330 bch_err(trans->c, "Trying to add child snapshot nodes to parent that already has children");1331 ret = -EINVAL;1332 goto err;1333 }1334 1335 ret = create_snapids(trans, parent, le32_to_cpu(n_parent->v.tree),1336 new_snapids, snapshot_subvols, nr_snapids);1337 if (ret)1338 goto err;1339 1340 n_parent->v.children[0] = cpu_to_le32(new_snapids[0]);1341 n_parent->v.children[1] = cpu_to_le32(new_snapids[1]);1342 n_parent->v.subvol = 0;1343 SET_BCH_SNAPSHOT_SUBVOL(&n_parent->v, false);1344err:1345 bch2_trans_iter_exit(trans, &iter);1346 return ret;1347}1348 1349/*1350 * Create a snapshot node that is the root of a new tree:1351 */1352static int bch2_snapshot_node_create_tree(struct btree_trans *trans,1353 u32 *new_snapids,1354 u32 *snapshot_subvols,1355 unsigned nr_snapids)1356{1357 struct bkey_i_snapshot_tree *n_tree;1358 int ret;1359 1360 n_tree = __bch2_snapshot_tree_create(trans);1361 ret = PTR_ERR_OR_ZERO(n_tree) ?:1362 create_snapids(trans, 0, n_tree->k.p.offset,1363 new_snapids, snapshot_subvols, nr_snapids);1364 if (ret)1365 return ret;1366 1367 n_tree->v.master_subvol = cpu_to_le32(snapshot_subvols[0]);1368 n_tree->v.root_snapshot = cpu_to_le32(new_snapids[0]);1369 return 0;1370}1371 1372int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent,1373 u32 *new_snapids,1374 u32 *snapshot_subvols,1375 unsigned nr_snapids)1376{1377 BUG_ON((parent == 0) != (nr_snapids == 1));1378 BUG_ON((parent != 0) != (nr_snapids == 2));1379 1380 return parent1381 ? bch2_snapshot_node_create_children(trans, parent,1382 new_snapids, snapshot_subvols, nr_snapids)1383 : bch2_snapshot_node_create_tree(trans,1384 new_snapids, snapshot_subvols, nr_snapids);1385 1386}1387 1388/*1389 * If we have an unlinked inode in an internal snapshot node, and the inode1390 * really has been deleted in all child snapshots, how does this get cleaned up?1391 *1392 * first there is the problem of how keys that have been overwritten in all1393 * child snapshots get deleted (unimplemented?), but inodes may perhaps be1394 * special?1395 *1396 * also: unlinked inode in internal snapshot appears to not be getting deleted1397 * correctly if inode doesn't exist in leaf snapshots1398 *1399 * solution:1400 *1401 * for a key in an interior snapshot node that needs work to be done that1402 * requires it to be mutated: iterate over all descendent leaf nodes and copy1403 * that key to snapshot leaf nodes, where we can mutate it1404 */1405 1406static int delete_dead_snapshots_process_key(struct btree_trans *trans,1407 struct btree_iter *iter,1408 struct bkey_s_c k,1409 snapshot_id_list *deleted,1410 snapshot_id_list *equiv_seen,1411 struct bpos *last_pos)1412{1413 int ret = bch2_check_key_has_snapshot(trans, iter, k);1414 if (ret)1415 return ret < 0 ? ret : 0;1416 1417 struct bch_fs *c = trans->c;1418 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);1419 if (!equiv) /* key for invalid snapshot node, but we chose not to delete */1420 return 0;1421 1422 if (!bkey_eq(k.k->p, *last_pos))1423 equiv_seen->nr = 0;1424 1425 if (snapshot_list_has_id(deleted, k.k->p.snapshot))1426 return bch2_btree_delete_at(trans, iter,1427 BTREE_UPDATE_internal_snapshot_node);1428 1429 if (!bpos_eq(*last_pos, k.k->p) &&1430 snapshot_list_has_id(equiv_seen, equiv))1431 return bch2_btree_delete_at(trans, iter,1432 BTREE_UPDATE_internal_snapshot_node);1433 1434 *last_pos = k.k->p;1435 1436 ret = snapshot_list_add_nodup(c, equiv_seen, equiv);1437 if (ret)1438 return ret;1439 1440 /*1441 * When we have a linear chain of snapshot nodes, we consider1442 * those to form an equivalence class: we're going to collapse1443 * them all down to a single node, and keep the leaf-most node -1444 * which has the same id as the equivalence class id.1445 *1446 * If there are multiple keys in different snapshots at the same1447 * position, we're only going to keep the one in the newest1448 * snapshot (we delete the others above) - the rest have been1449 * overwritten and are redundant, and for the key we're going to keep we1450 * need to move it to the equivalance class ID if it's not there1451 * already.1452 */1453 if (equiv != k.k->p.snapshot) {1454 struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k);1455 int ret = PTR_ERR_OR_ZERO(new);1456 if (ret)1457 return ret;1458 1459 new->k.p.snapshot = equiv;1460 1461 struct btree_iter new_iter;1462 bch2_trans_iter_init(trans, &new_iter, iter->btree_id, new->k.p,1463 BTREE_ITER_all_snapshots|1464 BTREE_ITER_cached|1465 BTREE_ITER_intent);1466 1467 ret = bch2_btree_iter_traverse(&new_iter) ?:1468 bch2_trans_update(trans, &new_iter, new,1469 BTREE_UPDATE_internal_snapshot_node) ?:1470 bch2_btree_delete_at(trans, iter,1471 BTREE_UPDATE_internal_snapshot_node);1472 bch2_trans_iter_exit(trans, &new_iter);1473 if (ret)1474 return ret;1475 }1476 1477 return 0;1478}1479 1480static int bch2_snapshot_needs_delete(struct btree_trans *trans, struct bkey_s_c k)1481{1482 struct bkey_s_c_snapshot snap;1483 u32 children[2];1484 int ret;1485 1486 if (k.k->type != KEY_TYPE_snapshot)1487 return 0;1488 1489 snap = bkey_s_c_to_snapshot(k);1490 if (BCH_SNAPSHOT_DELETED(snap.v) ||1491 BCH_SNAPSHOT_SUBVOL(snap.v))1492 return 0;1493 1494 children[0] = le32_to_cpu(snap.v->children[0]);1495 children[1] = le32_to_cpu(snap.v->children[1]);1496 1497 ret = bch2_snapshot_live(trans, children[0]) ?:1498 bch2_snapshot_live(trans, children[1]);1499 if (ret < 0)1500 return ret;1501 return !ret;1502}1503 1504/*1505 * For a given snapshot, if it doesn't have a subvolume that points to it, and1506 * it doesn't have child snapshot nodes - it's now redundant and we can mark it1507 * as deleted.1508 */1509static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct bkey_s_c k)1510{1511 int ret = bch2_snapshot_needs_delete(trans, k);1512 1513 return ret <= 01514 ? ret1515 : bch2_snapshot_node_set_deleted(trans, k.k->p.offset);1516}1517 1518static inline u32 bch2_snapshot_nth_parent_skip(struct bch_fs *c, u32 id, u32 n,1519 snapshot_id_list *skip)1520{1521 rcu_read_lock();1522 while (snapshot_list_has_id(skip, id))1523 id = __bch2_snapshot_parent(c, id);1524 1525 while (n--) {1526 do {1527 id = __bch2_snapshot_parent(c, id);1528 } while (snapshot_list_has_id(skip, id));1529 }1530 rcu_read_unlock();1531 1532 return id;1533}1534 1535static int bch2_fix_child_of_deleted_snapshot(struct btree_trans *trans,1536 struct btree_iter *iter, struct bkey_s_c k,1537 snapshot_id_list *deleted)1538{1539 struct bch_fs *c = trans->c;1540 u32 nr_deleted_ancestors = 0;1541 struct bkey_i_snapshot *s;1542 int ret;1543 1544 if (k.k->type != KEY_TYPE_snapshot)1545 return 0;1546 1547 if (snapshot_list_has_id(deleted, k.k->p.offset))1548 return 0;1549 1550 s = bch2_bkey_make_mut_noupdate_typed(trans, k, snapshot);1551 ret = PTR_ERR_OR_ZERO(s);1552 if (ret)1553 return ret;1554 1555 darray_for_each(*deleted, i)1556 nr_deleted_ancestors += bch2_snapshot_is_ancestor(c, s->k.p.offset, *i);1557 1558 if (!nr_deleted_ancestors)1559 return 0;1560 1561 le32_add_cpu(&s->v.depth, -nr_deleted_ancestors);1562 1563 if (!s->v.depth) {1564 s->v.skip[0] = 0;1565 s->v.skip[1] = 0;1566 s->v.skip[2] = 0;1567 } else {1568 u32 depth = le32_to_cpu(s->v.depth);1569 u32 parent = bch2_snapshot_parent(c, s->k.p.offset);1570 1571 for (unsigned j = 0; j < ARRAY_SIZE(s->v.skip); j++) {1572 u32 id = le32_to_cpu(s->v.skip[j]);1573 1574 if (snapshot_list_has_id(deleted, id)) {1575 id = bch2_snapshot_nth_parent_skip(c,1576 parent,1577 depth > 11578 ? get_random_u32_below(depth - 1)1579 : 0,1580 deleted);1581 s->v.skip[j] = cpu_to_le32(id);1582 }1583 }1584 1585 bubble_sort(s->v.skip, ARRAY_SIZE(s->v.skip), cmp_le32);1586 }1587 1588 return bch2_trans_update(trans, iter, &s->k_i, 0);1589}1590 1591int bch2_delete_dead_snapshots(struct bch_fs *c)1592{1593 struct btree_trans *trans;1594 snapshot_id_list deleted = { 0 };1595 snapshot_id_list deleted_interior = { 0 };1596 int ret = 0;1597 1598 if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags))1599 return 0;1600 1601 trans = bch2_trans_get(c);1602 1603 /*1604 * For every snapshot node: If we have no live children and it's not1605 * pointed to by a subvolume, delete it:1606 */1607 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots,1608 POS_MIN, 0, k,1609 NULL, NULL, 0,1610 bch2_delete_redundant_snapshot(trans, k));1611 bch_err_msg(c, ret, "deleting redundant snapshots");1612 if (ret)1613 goto err;1614 1615 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,1616 POS_MIN, 0, k,1617 bch2_snapshot_set_equiv(trans, k));1618 bch_err_msg(c, ret, "in bch2_snapshots_set_equiv");1619 if (ret)1620 goto err;1621 1622 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,1623 POS_MIN, 0, k, ({1624 if (k.k->type != KEY_TYPE_snapshot)1625 continue;1626 1627 BCH_SNAPSHOT_DELETED(bkey_s_c_to_snapshot(k).v)1628 ? snapshot_list_add(c, &deleted, k.k->p.offset)1629 : 0;1630 }));1631 bch_err_msg(c, ret, "walking snapshots");1632 if (ret)1633 goto err;1634 1635 for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) {1636 struct bpos last_pos = POS_MIN;1637 snapshot_id_list equiv_seen = { 0 };1638 struct disk_reservation res = { 0 };1639 1640 if (!btree_type_has_snapshots(btree))1641 continue;1642 1643 ret = for_each_btree_key_commit(trans, iter,1644 btree, POS_MIN,1645 BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,1646 &res, NULL, BCH_TRANS_COMMIT_no_enospc,1647 delete_dead_snapshots_process_key(trans, &iter, k, &deleted,1648 &equiv_seen, &last_pos));1649 1650 bch2_disk_reservation_put(c, &res);1651 darray_exit(&equiv_seen);1652 1653 bch_err_msg(c, ret, "deleting keys from dying snapshots");1654 if (ret)1655 goto err;1656 }1657 1658 bch2_trans_unlock(trans);1659 down_write(&c->snapshot_create_lock);1660 1661 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,1662 POS_MIN, 0, k, ({1663 u32 snapshot = k.k->p.offset;1664 u32 equiv = bch2_snapshot_equiv(c, snapshot);1665 1666 equiv != snapshot1667 ? snapshot_list_add(c, &deleted_interior, snapshot)1668 : 0;1669 }));1670 1671 bch_err_msg(c, ret, "walking snapshots");1672 if (ret)1673 goto err_create_lock;1674 1675 /*1676 * Fixing children of deleted snapshots can't be done completely1677 * atomically, if we crash between here and when we delete the interior1678 * nodes some depth fields will be off:1679 */1680 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, POS_MIN,1681 BTREE_ITER_intent, k,1682 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,1683 bch2_fix_child_of_deleted_snapshot(trans, &iter, k, &deleted_interior));1684 if (ret)1685 goto err_create_lock;1686 1687 darray_for_each(deleted, i) {1688 ret = commit_do(trans, NULL, NULL, 0,1689 bch2_snapshot_node_delete(trans, *i));1690 bch_err_msg(c, ret, "deleting snapshot %u", *i);1691 if (ret)1692 goto err_create_lock;1693 }1694 1695 darray_for_each(deleted_interior, i) {1696 ret = commit_do(trans, NULL, NULL, 0,1697 bch2_snapshot_node_delete(trans, *i));1698 bch_err_msg(c, ret, "deleting snapshot %u", *i);1699 if (ret)1700 goto err_create_lock;1701 }1702err_create_lock:1703 up_write(&c->snapshot_create_lock);1704err:1705 darray_exit(&deleted_interior);1706 darray_exit(&deleted);1707 bch2_trans_put(trans);1708 bch_err_fn(c, ret);1709 return ret;1710}1711 1712void bch2_delete_dead_snapshots_work(struct work_struct *work)1713{1714 struct bch_fs *c = container_of(work, struct bch_fs, snapshot_delete_work);1715 1716 set_worker_desc("bcachefs-delete-dead-snapshots/%s", c->name);1717 1718 bch2_delete_dead_snapshots(c);1719 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);1720}1721 1722void bch2_delete_dead_snapshots_async(struct bch_fs *c)1723{1724 if (bch2_write_ref_tryget(c, BCH_WRITE_REF_delete_dead_snapshots) &&1725 !queue_work(c->write_ref_wq, &c->snapshot_delete_work))1726 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);1727}1728 1729int __bch2_key_has_snapshot_overwrites(struct btree_trans *trans,1730 enum btree_id id,1731 struct bpos pos)1732{1733 struct bch_fs *c = trans->c;1734 struct btree_iter iter;1735 struct bkey_s_c k;1736 int ret;1737 1738 bch2_trans_iter_init(trans, &iter, id, pos,1739 BTREE_ITER_not_extents|1740 BTREE_ITER_all_snapshots);1741 while (1) {1742 k = bch2_btree_iter_prev(&iter);1743 ret = bkey_err(k);1744 if (ret)1745 break;1746 1747 if (!k.k)1748 break;1749 1750 if (!bkey_eq(pos, k.k->p))1751 break;1752 1753 if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) {1754 ret = 1;1755 break;1756 }1757 }1758 bch2_trans_iter_exit(trans, &iter);1759 1760 return ret;1761}1762 1763static int bch2_check_snapshot_needs_deletion(struct btree_trans *trans, struct bkey_s_c k)1764{1765 struct bch_fs *c = trans->c;1766 struct bkey_s_c_snapshot snap;1767 int ret = 0;1768 1769 if (k.k->type != KEY_TYPE_snapshot)1770 return 0;1771 1772 snap = bkey_s_c_to_snapshot(k);1773 if (BCH_SNAPSHOT_DELETED(snap.v) ||1774 bch2_snapshot_equiv(c, k.k->p.offset) != k.k->p.offset ||1775 (ret = bch2_snapshot_needs_delete(trans, k)) > 0) {1776 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);1777 return 0;1778 }1779 1780 return ret;1781}1782 1783int bch2_snapshots_read(struct bch_fs *c)1784{1785 int ret = bch2_trans_run(c,1786 for_each_btree_key(trans, iter, BTREE_ID_snapshots,1787 POS_MIN, 0, k,1788 __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, k, 0) ?:1789 bch2_snapshot_set_equiv(trans, k) ?:1790 bch2_check_snapshot_needs_deletion(trans, k)) ?:1791 for_each_btree_key(trans, iter, BTREE_ID_snapshots,1792 POS_MIN, 0, k,1793 (set_is_ancestor_bitmap(c, k.k->p.offset), 0)));1794 bch_err_fn(c, ret);1795 1796 /*1797 * It's important that we check if we need to reconstruct snapshots1798 * before going RW, so we mark that pass as required in the superblock -1799 * otherwise, we could end up deleting keys with missing snapshot nodes1800 * instead1801 */1802 BUG_ON(!test_bit(BCH_FS_new_fs, &c->flags) &&1803 test_bit(BCH_FS_may_go_rw, &c->flags));1804 1805 if (bch2_err_matches(ret, EIO) ||1806 (c->sb.btrees_lost_data & BIT_ULL(BTREE_ID_snapshots)))1807 ret = bch2_run_explicit_recovery_pass_persistent(c, BCH_RECOVERY_PASS_reconstruct_snapshots);1808 1809 return ret;1810}1811 1812void bch2_fs_snapshots_exit(struct bch_fs *c)1813{1814 kvfree(rcu_dereference_protected(c->snapshots, true));1815}1816