// SPDX-License-Identifier: GPL-2.0 #include "bcachefs.h" #include "bkey_buf.h" #include "btree_key_cache.h" #include "btree_update.h" #include "buckets.h" #include "errcode.h" #include "error.h" #include "fs.h" #include "recovery_passes.h" #include "snapshot.h" #include /* * Snapshot trees: * * Keys in BTREE_ID_snapshot_trees identify a whole tree of snapshot nodes; they * exist to provide a stable identifier for the whole lifetime of a snapshot * tree. */ void bch2_snapshot_tree_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k) { struct bkey_s_c_snapshot_tree t = bkey_s_c_to_snapshot_tree(k); prt_printf(out, "subvol %u root snapshot %u", le32_to_cpu(t.v->master_subvol), le32_to_cpu(t.v->root_snapshot)); } int bch2_snapshot_tree_invalid(struct bch_fs *c, struct bkey_s_c k, enum bkey_invalid_flags flags, struct printbuf *err) { int ret = 0; bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) || bkey_lt(k.k->p, POS(0, 1)), c, err, snapshot_tree_pos_bad, "bad pos"); fsck_err: return ret; } int bch2_snapshot_tree_lookup(struct btree_trans *trans, u32 id, struct bch_snapshot_tree *s) { int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_snapshot_trees, POS(0, id), BTREE_ITER_with_updates, snapshot_tree, s); if (bch2_err_matches(ret, ENOENT)) ret = -BCH_ERR_ENOENT_snapshot_tree; return ret; } struct bkey_i_snapshot_tree * __bch2_snapshot_tree_create(struct btree_trans *trans) { struct btree_iter iter; int ret = bch2_bkey_get_empty_slot(trans, &iter, BTREE_ID_snapshot_trees, POS(0, U32_MAX)); struct bkey_i_snapshot_tree *s_t; if (ret == -BCH_ERR_ENOSPC_btree_slot) ret = -BCH_ERR_ENOSPC_snapshot_tree; if (ret) return ERR_PTR(ret); s_t = bch2_bkey_alloc(trans, &iter, 0, snapshot_tree); ret = PTR_ERR_OR_ZERO(s_t); bch2_trans_iter_exit(trans, &iter); return ret ? ERR_PTR(ret) : s_t; } static int bch2_snapshot_tree_create(struct btree_trans *trans, u32 root_id, u32 subvol_id, u32 *tree_id) { struct bkey_i_snapshot_tree *n_tree = __bch2_snapshot_tree_create(trans); if (IS_ERR(n_tree)) return PTR_ERR(n_tree); n_tree->v.master_subvol = cpu_to_le32(subvol_id); n_tree->v.root_snapshot = cpu_to_le32(root_id); *tree_id = n_tree->k.p.offset; return 0; } /* Snapshot nodes: */ static bool __bch2_snapshot_is_ancestor_early(struct snapshot_table *t, u32 id, u32 ancestor) { while (id && id < ancestor) { const struct snapshot_t *s = __snapshot_t(t, id); id = s ? s->parent : 0; } return id == ancestor; } static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor) { rcu_read_lock(); bool ret = __bch2_snapshot_is_ancestor_early(rcu_dereference(c->snapshots), id, ancestor); rcu_read_unlock(); return ret; } static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor) { const struct snapshot_t *s = __snapshot_t(t, id); if (!s) return 0; if (s->skip[2] <= ancestor) return s->skip[2]; if (s->skip[1] <= ancestor) return s->skip[1]; if (s->skip[0] <= ancestor) return s->skip[0]; return s->parent; } static bool test_ancestor_bitmap(struct snapshot_table *t, u32 id, u32 ancestor) { const struct snapshot_t *s = __snapshot_t(t, id); if (!s) return false; return test_bit(ancestor - id - 1, s->is_ancestor); } bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor) { bool ret; rcu_read_lock(); struct snapshot_table *t = rcu_dereference(c->snapshots); if (unlikely(c->recovery_pass_done < BCH_RECOVERY_PASS_check_snapshots)) { ret = __bch2_snapshot_is_ancestor_early(t, id, ancestor); goto out; } while (id && id < ancestor - IS_ANCESTOR_BITMAP) id = get_ancestor_below(t, id, ancestor); ret = id && id < ancestor ? test_ancestor_bitmap(t, id, ancestor) : id == ancestor; EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor)); out: rcu_read_unlock(); return ret; } static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id) { size_t idx = U32_MAX - id; struct snapshot_table *new, *old; size_t new_bytes = kmalloc_size_roundup(struct_size(new, s, idx + 1)); size_t new_size = (new_bytes - sizeof(*new)) / sizeof(new->s[0]); new = kvzalloc(new_bytes, GFP_KERNEL); if (!new) return NULL; new->nr = new_size; old = rcu_dereference_protected(c->snapshots, true); if (old) memcpy(new->s, old->s, sizeof(old->s[0]) * old->nr); rcu_assign_pointer(c->snapshots, new); kvfree_rcu(old, rcu); return &rcu_dereference_protected(c->snapshots, lockdep_is_held(&c->snapshot_table_lock))->s[idx]; } static inline struct snapshot_t *snapshot_t_mut(struct bch_fs *c, u32 id) { size_t idx = U32_MAX - id; struct snapshot_table *table = rcu_dereference_protected(c->snapshots, lockdep_is_held(&c->snapshot_table_lock)); lockdep_assert_held(&c->snapshot_table_lock); if (likely(table && idx < table->nr)) return &table->s[idx]; return __snapshot_t_mut(c, id); } void bch2_snapshot_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k) { struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(k); prt_printf(out, "is_subvol %llu deleted %llu parent %10u children %10u %10u subvol %u tree %u", BCH_SNAPSHOT_SUBVOL(s.v), BCH_SNAPSHOT_DELETED(s.v), le32_to_cpu(s.v->parent), le32_to_cpu(s.v->children[0]), le32_to_cpu(s.v->children[1]), le32_to_cpu(s.v->subvol), le32_to_cpu(s.v->tree)); if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, depth)) prt_printf(out, " depth %u skiplist %u %u %u", le32_to_cpu(s.v->depth), le32_to_cpu(s.v->skip[0]), le32_to_cpu(s.v->skip[1]), le32_to_cpu(s.v->skip[2])); } int bch2_snapshot_invalid(struct bch_fs *c, struct bkey_s_c k, enum bkey_invalid_flags flags, struct printbuf *err) { struct bkey_s_c_snapshot s; u32 i, id; int ret = 0; bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) || bkey_lt(k.k->p, POS(0, 1)), c, err, snapshot_pos_bad, "bad pos"); s = bkey_s_c_to_snapshot(k); id = le32_to_cpu(s.v->parent); bkey_fsck_err_on(id && id <= k.k->p.offset, c, err, snapshot_parent_bad, "bad parent node (%u <= %llu)", id, k.k->p.offset); bkey_fsck_err_on(le32_to_cpu(s.v->children[0]) < le32_to_cpu(s.v->children[1]), c, err, snapshot_children_not_normalized, "children not normalized"); bkey_fsck_err_on(s.v->children[0] && s.v->children[0] == s.v->children[1], c, err, snapshot_child_duplicate, "duplicate child nodes"); for (i = 0; i < 2; i++) { id = le32_to_cpu(s.v->children[i]); bkey_fsck_err_on(id >= k.k->p.offset, c, err, snapshot_child_bad, "bad child node (%u >= %llu)", id, k.k->p.offset); } if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, skip)) { bkey_fsck_err_on(le32_to_cpu(s.v->skip[0]) > le32_to_cpu(s.v->skip[1]) || le32_to_cpu(s.v->skip[1]) > le32_to_cpu(s.v->skip[2]), c, err, snapshot_skiplist_not_normalized, "skiplist not normalized"); for (i = 0; i < ARRAY_SIZE(s.v->skip); i++) { id = le32_to_cpu(s.v->skip[i]); bkey_fsck_err_on(id && id < le32_to_cpu(s.v->parent), c, err, snapshot_skiplist_bad, "bad skiplist node %u", id); } } fsck_err: return ret; } static void __set_is_ancestor_bitmap(struct bch_fs *c, u32 id) { struct snapshot_t *t = snapshot_t_mut(c, id); u32 parent = id; while ((parent = bch2_snapshot_parent_early(c, parent)) && parent - id - 1 < IS_ANCESTOR_BITMAP) __set_bit(parent - id - 1, t->is_ancestor); } static void set_is_ancestor_bitmap(struct bch_fs *c, u32 id) { mutex_lock(&c->snapshot_table_lock); __set_is_ancestor_bitmap(c, id); mutex_unlock(&c->snapshot_table_lock); } static int __bch2_mark_snapshot(struct btree_trans *trans, enum btree_id btree, unsigned level, struct bkey_s_c old, struct bkey_s_c new, unsigned flags) { struct bch_fs *c = trans->c; struct snapshot_t *t; u32 id = new.k->p.offset; int ret = 0; mutex_lock(&c->snapshot_table_lock); t = snapshot_t_mut(c, id); if (!t) { ret = -BCH_ERR_ENOMEM_mark_snapshot; goto err; } if (new.k->type == KEY_TYPE_snapshot) { struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(new); t->parent = le32_to_cpu(s.v->parent); t->children[0] = le32_to_cpu(s.v->children[0]); t->children[1] = le32_to_cpu(s.v->children[1]); t->subvol = BCH_SNAPSHOT_SUBVOL(s.v) ? le32_to_cpu(s.v->subvol) : 0; t->tree = le32_to_cpu(s.v->tree); if (bkey_val_bytes(s.k) > offsetof(struct bch_snapshot, depth)) { t->depth = le32_to_cpu(s.v->depth); t->skip[0] = le32_to_cpu(s.v->skip[0]); t->skip[1] = le32_to_cpu(s.v->skip[1]); t->skip[2] = le32_to_cpu(s.v->skip[2]); } else { t->depth = 0; t->skip[0] = 0; t->skip[1] = 0; t->skip[2] = 0; } __set_is_ancestor_bitmap(c, id); if (BCH_SNAPSHOT_DELETED(s.v)) { set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags); if (c->curr_recovery_pass > BCH_RECOVERY_PASS_delete_dead_snapshots) bch2_delete_dead_snapshots_async(c); } } else { memset(t, 0, sizeof(*t)); } err: mutex_unlock(&c->snapshot_table_lock); return ret; } int bch2_mark_snapshot(struct btree_trans *trans, enum btree_id btree, unsigned level, struct bkey_s_c old, struct bkey_s new, unsigned flags) { return __bch2_mark_snapshot(trans, btree, level, old, new.s_c, flags); } int bch2_snapshot_lookup(struct btree_trans *trans, u32 id, struct bch_snapshot *s) { return bch2_bkey_get_val_typed(trans, BTREE_ID_snapshots, POS(0, id), BTREE_ITER_with_updates, snapshot, s); } static int bch2_snapshot_live(struct btree_trans *trans, u32 id) { struct bch_snapshot v; int ret; if (!id) return 0; ret = bch2_snapshot_lookup(trans, id, &v); if (bch2_err_matches(ret, ENOENT)) bch_err(trans->c, "snapshot node %u not found", id); if (ret) return ret; return !BCH_SNAPSHOT_DELETED(&v); } /* * If @k is a snapshot with just one live child, it's part of a linear chain, * which we consider to be an equivalence class: and then after snapshot * deletion cleanup, there should only be a single key at a given position in * this equivalence class. * * This sets the equivalence class of @k to be the child's equivalence class, if * it's part of such a linear chain: this correctly sets equivalence classes on * startup if we run leaf to root (i.e. in natural key order). */ static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k) { struct bch_fs *c = trans->c; unsigned i, nr_live = 0, live_idx = 0; struct bkey_s_c_snapshot snap; u32 id = k.k->p.offset, child[2]; if (k.k->type != KEY_TYPE_snapshot) return 0; snap = bkey_s_c_to_snapshot(k); child[0] = le32_to_cpu(snap.v->children[0]); child[1] = le32_to_cpu(snap.v->children[1]); for (i = 0; i < 2; i++) { int ret = bch2_snapshot_live(trans, child[i]); if (ret < 0) return ret; if (ret) live_idx = i; nr_live += ret; } mutex_lock(&c->snapshot_table_lock); snapshot_t_mut(c, id)->equiv = nr_live == 1 ? snapshot_t_mut(c, child[live_idx])->equiv : id; mutex_unlock(&c->snapshot_table_lock); return 0; } /* fsck: */ static u32 bch2_snapshot_child(struct bch_fs *c, u32 id, unsigned child) { return snapshot_t(c, id)->children[child]; } static u32 bch2_snapshot_left_child(struct bch_fs *c, u32 id) { return bch2_snapshot_child(c, id, 0); } static u32 bch2_snapshot_right_child(struct bch_fs *c, u32 id) { return bch2_snapshot_child(c, id, 1); } static u32 bch2_snapshot_tree_next(struct bch_fs *c, u32 id) { u32 n, parent; n = bch2_snapshot_left_child(c, id); if (n) return n; while ((parent = bch2_snapshot_parent(c, id))) { n = bch2_snapshot_right_child(c, parent); if (n && n != id) return n; id = parent; } return 0; } static u32 bch2_snapshot_tree_oldest_subvol(struct bch_fs *c, u32 snapshot_root) { u32 id = snapshot_root; u32 subvol = 0, s; while (id) { s = snapshot_t(c, id)->subvol; if (s && (!subvol || s < subvol)) subvol = s; id = bch2_snapshot_tree_next(c, id); } return subvol; } static int bch2_snapshot_tree_master_subvol(struct btree_trans *trans, u32 snapshot_root, u32 *subvol_id) { struct bch_fs *c = trans->c; struct btree_iter iter; struct bkey_s_c k; bool found = false; int ret; for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN, 0, k, ret) { if (k.k->type != KEY_TYPE_subvolume) continue; struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k); if (!bch2_snapshot_is_ancestor(c, le32_to_cpu(s.v->snapshot), snapshot_root)) continue; if (!BCH_SUBVOLUME_SNAP(s.v)) { *subvol_id = s.k->p.offset; found = true; break; } } bch2_trans_iter_exit(trans, &iter); if (!ret && !found) { struct bkey_i_subvolume *u; *subvol_id = bch2_snapshot_tree_oldest_subvol(c, snapshot_root); u = bch2_bkey_get_mut_typed(trans, &iter, BTREE_ID_subvolumes, POS(0, *subvol_id), 0, subvolume); ret = PTR_ERR_OR_ZERO(u); if (ret) return ret; SET_BCH_SUBVOLUME_SNAP(&u->v, false); } return ret; } static int check_snapshot_tree(struct btree_trans *trans, struct btree_iter *iter, struct bkey_s_c k) { struct bch_fs *c = trans->c; struct bkey_s_c_snapshot_tree st; struct bch_snapshot s; struct bch_subvolume subvol; struct printbuf buf = PRINTBUF; u32 root_id; int ret; if (k.k->type != KEY_TYPE_snapshot_tree) return 0; st = bkey_s_c_to_snapshot_tree(k); root_id = le32_to_cpu(st.v->root_snapshot); ret = bch2_snapshot_lookup(trans, root_id, &s); if (ret && !bch2_err_matches(ret, ENOENT)) goto err; if (fsck_err_on(ret || root_id != bch2_snapshot_root(c, root_id) || st.k->p.offset != le32_to_cpu(s.tree), c, snapshot_tree_to_missing_snapshot, "snapshot tree points to missing/incorrect snapshot:\n %s", (bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) { ret = bch2_btree_delete_at(trans, iter, 0); goto err; } ret = bch2_subvolume_get(trans, le32_to_cpu(st.v->master_subvol), false, 0, &subvol); if (ret && !bch2_err_matches(ret, ENOENT)) goto err; if (fsck_err_on(ret, c, snapshot_tree_to_missing_subvol, "snapshot tree points to missing subvolume:\n %s", (printbuf_reset(&buf), bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) || fsck_err_on(!bch2_snapshot_is_ancestor(c, le32_to_cpu(subvol.snapshot), root_id), c, snapshot_tree_to_wrong_subvol, "snapshot tree points to subvolume that does not point to snapshot in this tree:\n %s", (printbuf_reset(&buf), bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) || fsck_err_on(BCH_SUBVOLUME_SNAP(&subvol), c, snapshot_tree_to_snapshot_subvol, "snapshot tree points to snapshot subvolume:\n %s", (printbuf_reset(&buf), bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) { struct bkey_i_snapshot_tree *u; u32 subvol_id; ret = bch2_snapshot_tree_master_subvol(trans, root_id, &subvol_id); bch_err_fn(c, ret); if (bch2_err_matches(ret, ENOENT)) { /* nothing to be done here */ ret = 0; goto err; } if (ret) goto err; u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot_tree); ret = PTR_ERR_OR_ZERO(u); if (ret) goto err; u->v.master_subvol = cpu_to_le32(subvol_id); st = snapshot_tree_i_to_s_c(u); } err: fsck_err: printbuf_exit(&buf); return ret; } /* * For each snapshot_tree, make sure it points to the root of a snapshot tree * and that snapshot entry points back to it, or delete it. * * And, make sure it points to a subvolume within that snapshot tree, or correct * it to point to the oldest subvolume within that snapshot tree. */ int bch2_check_snapshot_trees(struct bch_fs *c) { int ret = bch2_trans_run(c, for_each_btree_key_commit(trans, iter, BTREE_ID_snapshot_trees, POS_MIN, BTREE_ITER_prefetch, k, NULL, NULL, BCH_TRANS_COMMIT_no_enospc, check_snapshot_tree(trans, &iter, k))); bch_err_fn(c, ret); return ret; } /* * Look up snapshot tree for @tree_id and find root, * make sure @snap_id is a descendent: */ static int snapshot_tree_ptr_good(struct btree_trans *trans, u32 snap_id, u32 tree_id) { struct bch_snapshot_tree s_t; int ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t); if (bch2_err_matches(ret, ENOENT)) return 0; if (ret) return ret; return bch2_snapshot_is_ancestor_early(trans->c, snap_id, le32_to_cpu(s_t.root_snapshot)); } u32 bch2_snapshot_skiplist_get(struct bch_fs *c, u32 id) { const struct snapshot_t *s; if (!id) return 0; rcu_read_lock(); s = snapshot_t(c, id); if (s->parent) id = bch2_snapshot_nth_parent(c, id, get_random_u32_below(s->depth)); rcu_read_unlock(); return id; } static int snapshot_skiplist_good(struct btree_trans *trans, u32 id, struct bch_snapshot s) { unsigned i; for (i = 0; i < 3; i++) if (!s.parent) { if (s.skip[i]) return false; } else { if (!bch2_snapshot_is_ancestor_early(trans->c, id, le32_to_cpu(s.skip[i]))) return false; } return true; } /* * snapshot_tree pointer was incorrect: look up root snapshot node, make sure * its snapshot_tree pointer is correct (allocate new one if necessary), then * update this node's pointer to root node's pointer: */ static int snapshot_tree_ptr_repair(struct btree_trans *trans, struct btree_iter *iter, struct bkey_s_c k, struct bch_snapshot *s) { struct bch_fs *c = trans->c; struct btree_iter root_iter; struct bch_snapshot_tree s_t; struct bkey_s_c_snapshot root; struct bkey_i_snapshot *u; u32 root_id = bch2_snapshot_root(c, k.k->p.offset), tree_id; int ret; root = bch2_bkey_get_iter_typed(trans, &root_iter, BTREE_ID_snapshots, POS(0, root_id), BTREE_ITER_with_updates, snapshot); ret = bkey_err(root); if (ret) goto err; tree_id = le32_to_cpu(root.v->tree); ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t); if (ret && !bch2_err_matches(ret, ENOENT)) return ret; if (ret || le32_to_cpu(s_t.root_snapshot) != root_id) { u = bch2_bkey_make_mut_typed(trans, &root_iter, &root.s_c, 0, snapshot); ret = PTR_ERR_OR_ZERO(u) ?: bch2_snapshot_tree_create(trans, root_id, bch2_snapshot_tree_oldest_subvol(c, root_id), &tree_id); if (ret) goto err; u->v.tree = cpu_to_le32(tree_id); if (k.k->p.offset == root_id) *s = u->v; } if (k.k->p.offset != root_id) { u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot); ret = PTR_ERR_OR_ZERO(u); if (ret) goto err; u->v.tree = cpu_to_le32(tree_id); *s = u->v; } err: bch2_trans_iter_exit(trans, &root_iter); return ret; } static int check_snapshot(struct btree_trans *trans, struct btree_iter *iter, struct bkey_s_c k) { struct bch_fs *c = trans->c; struct bch_snapshot s; struct bch_subvolume subvol; struct bch_snapshot v; struct bkey_i_snapshot *u; u32 parent_id = bch2_snapshot_parent_early(c, k.k->p.offset); u32 real_depth; struct printbuf buf = PRINTBUF; u32 i, id; int ret = 0; if (k.k->type != KEY_TYPE_snapshot) return 0; memset(&s, 0, sizeof(s)); memcpy(&s, k.v, min(sizeof(s), bkey_val_bytes(k.k))); id = le32_to_cpu(s.parent); if (id) { ret = bch2_snapshot_lookup(trans, id, &v); if (bch2_err_matches(ret, ENOENT)) bch_err(c, "snapshot with nonexistent parent:\n %s", (bch2_bkey_val_to_text(&buf, c, k), buf.buf)); if (ret) goto err; if (le32_to_cpu(v.children[0]) != k.k->p.offset && le32_to_cpu(v.children[1]) != k.k->p.offset) { bch_err(c, "snapshot parent %u missing pointer to child %llu", id, k.k->p.offset); ret = -EINVAL; goto err; } } for (i = 0; i < 2 && s.children[i]; i++) { id = le32_to_cpu(s.children[i]); ret = bch2_snapshot_lookup(trans, id, &v); if (bch2_err_matches(ret, ENOENT)) bch_err(c, "snapshot node %llu has nonexistent child %u", k.k->p.offset, id); if (ret) goto err; if (le32_to_cpu(v.parent) != k.k->p.offset) { bch_err(c, "snapshot child %u has wrong parent (got %u should be %llu)", id, le32_to_cpu(v.parent), k.k->p.offset); ret = -EINVAL; goto err; } } bool should_have_subvol = BCH_SNAPSHOT_SUBVOL(&s) && !BCH_SNAPSHOT_DELETED(&s); if (should_have_subvol) { id = le32_to_cpu(s.subvol); ret = bch2_subvolume_get(trans, id, 0, false, &subvol); if (bch2_err_matches(ret, ENOENT)) bch_err(c, "snapshot points to nonexistent subvolume:\n %s", (bch2_bkey_val_to_text(&buf, c, k), buf.buf)); if (ret) goto err; if (BCH_SNAPSHOT_SUBVOL(&s) != (le32_to_cpu(subvol.snapshot) == k.k->p.offset)) { bch_err(c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL", k.k->p.offset); ret = -EINVAL; goto err; } } else { if (fsck_err_on(s.subvol, c, snapshot_should_not_have_subvol, "snapshot should not point to subvol:\n %s", (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) { u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot); ret = PTR_ERR_OR_ZERO(u); if (ret) goto err; u->v.subvol = 0; s = u->v; } } ret = snapshot_tree_ptr_good(trans, k.k->p.offset, le32_to_cpu(s.tree)); if (ret < 0) goto err; if (fsck_err_on(!ret, c, snapshot_to_bad_snapshot_tree, "snapshot points to missing/incorrect tree:\n %s", (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) { ret = snapshot_tree_ptr_repair(trans, iter, k, &s); if (ret) goto err; } ret = 0; real_depth = bch2_snapshot_depth(c, parent_id); if (fsck_err_on(le32_to_cpu(s.depth) != real_depth, c, snapshot_bad_depth, "snapshot with incorrect depth field, should be %u:\n %s", real_depth, (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) { u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot); ret = PTR_ERR_OR_ZERO(u); if (ret) goto err; u->v.depth = cpu_to_le32(real_depth); s = u->v; } ret = snapshot_skiplist_good(trans, k.k->p.offset, s); if (ret < 0) goto err; if (fsck_err_on(!ret, c, snapshot_bad_skiplist, "snapshot with bad skiplist field:\n %s", (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) { u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot); ret = PTR_ERR_OR_ZERO(u); if (ret) goto err; for (i = 0; i < ARRAY_SIZE(u->v.skip); i++) u->v.skip[i] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent_id)); bubble_sort(u->v.skip, ARRAY_SIZE(u->v.skip), cmp_le32); s = u->v; } ret = 0; err: fsck_err: printbuf_exit(&buf); return ret; } int bch2_check_snapshots(struct bch_fs *c) { /* * We iterate backwards as checking/fixing the depth field requires that * the parent's depth already be correct: */ int ret = bch2_trans_run(c, for_each_btree_key_reverse_commit(trans, iter, BTREE_ID_snapshots, POS_MAX, BTREE_ITER_prefetch, k, NULL, NULL, BCH_TRANS_COMMIT_no_enospc, check_snapshot(trans, &iter, k))); bch_err_fn(c, ret); return ret; } static int check_snapshot_exists(struct btree_trans *trans, u32 id) { struct bch_fs *c = trans->c; if (bch2_snapshot_equiv(c, id)) return 0; u32 tree_id; int ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id); if (ret) return ret; struct bkey_i_snapshot *snapshot = bch2_trans_kmalloc(trans, sizeof(*snapshot)); ret = PTR_ERR_OR_ZERO(snapshot); if (ret) return ret; bkey_snapshot_init(&snapshot->k_i); snapshot->k.p = POS(0, id); snapshot->v.tree = cpu_to_le32(tree_id); snapshot->v.btime.lo = cpu_to_le64(bch2_current_time(c)); return bch2_btree_insert_trans(trans, BTREE_ID_snapshots, &snapshot->k_i, 0) ?: bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, bkey_i_to_s(&snapshot->k_i), 0) ?: bch2_snapshot_set_equiv(trans, bkey_i_to_s_c(&snapshot->k_i)); } /* Figure out which snapshot nodes belong in the same tree: */ struct snapshot_tree_reconstruct { enum btree_id btree; struct bpos cur_pos; snapshot_id_list cur_ids; DARRAY(snapshot_id_list) trees; }; static void snapshot_tree_reconstruct_exit(struct snapshot_tree_reconstruct *r) { darray_for_each(r->trees, i) darray_exit(i); darray_exit(&r->trees); darray_exit(&r->cur_ids); } static inline bool same_snapshot(struct snapshot_tree_reconstruct *r, struct bpos pos) { return r->btree == BTREE_ID_inodes ? r->cur_pos.offset == pos.offset : r->cur_pos.inode == pos.inode; } static inline bool snapshot_id_lists_have_common(snapshot_id_list *l, snapshot_id_list *r) { darray_for_each(*l, i) if (snapshot_list_has_id(r, *i)) return true; return false; } static void snapshot_id_list_to_text(struct printbuf *out, snapshot_id_list *s) { bool first = true; darray_for_each(*s, i) { if (!first) prt_char(out, ' '); first = false; prt_printf(out, "%u", *i); } } static int snapshot_tree_reconstruct_next(struct bch_fs *c, struct snapshot_tree_reconstruct *r) { if (r->cur_ids.nr) { darray_for_each(r->trees, i) if (snapshot_id_lists_have_common(i, &r->cur_ids)) { int ret = snapshot_list_merge(c, i, &r->cur_ids); if (ret) return ret; goto out; } darray_push(&r->trees, r->cur_ids); darray_init(&r->cur_ids); } out: r->cur_ids.nr = 0; return 0; } static int get_snapshot_trees(struct bch_fs *c, struct snapshot_tree_reconstruct *r, struct bpos pos) { if (!same_snapshot(r, pos)) snapshot_tree_reconstruct_next(c, r); r->cur_pos = pos; return snapshot_list_add_nodup(c, &r->cur_ids, pos.snapshot); } int bch2_reconstruct_snapshots(struct bch_fs *c) { struct btree_trans *trans = bch2_trans_get(c); struct printbuf buf = PRINTBUF; struct snapshot_tree_reconstruct r = {}; int ret = 0; for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) { if (btree_type_has_snapshots(btree)) { r.btree = btree; ret = for_each_btree_key(trans, iter, btree, POS_MIN, BTREE_ITER_all_snapshots|BTREE_ITER_prefetch, k, ({ get_snapshot_trees(c, &r, k.k->p); })); if (ret) goto err; snapshot_tree_reconstruct_next(c, &r); } } darray_for_each(r.trees, t) { printbuf_reset(&buf); snapshot_id_list_to_text(&buf, t); darray_for_each(*t, id) { if (fsck_err_on(!bch2_snapshot_equiv(c, *id), c, snapshot_node_missing, "snapshot node %u from tree %s missing, recreate?", *id, buf.buf)) { if (t->nr > 1) { bch_err(c, "cannot reconstruct snapshot trees with multiple nodes"); ret = -BCH_ERR_fsck_repair_unimplemented; goto err; } ret = commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc, check_snapshot_exists(trans, *id)); if (ret) goto err; } } } fsck_err: err: bch2_trans_put(trans); snapshot_tree_reconstruct_exit(&r); printbuf_exit(&buf); bch_err_fn(c, ret); return ret; } /* * Mark a snapshot as deleted, for future cleanup: */ int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id) { struct btree_iter iter; struct bkey_i_snapshot *s; int ret = 0; s = bch2_bkey_get_mut_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id), 0, snapshot); ret = PTR_ERR_OR_ZERO(s); if (unlikely(ret)) { bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c, "missing snapshot %u", id); return ret; } /* already deleted? */ if (BCH_SNAPSHOT_DELETED(&s->v)) goto err; SET_BCH_SNAPSHOT_DELETED(&s->v, true); SET_BCH_SNAPSHOT_SUBVOL(&s->v, false); s->v.subvol = 0; err: bch2_trans_iter_exit(trans, &iter); return ret; } static inline void normalize_snapshot_child_pointers(struct bch_snapshot *s) { if (le32_to_cpu(s->children[0]) < le32_to_cpu(s->children[1])) swap(s->children[0], s->children[1]); } static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id) { struct bch_fs *c = trans->c; struct btree_iter iter, p_iter = (struct btree_iter) { NULL }; struct btree_iter c_iter = (struct btree_iter) { NULL }; struct btree_iter tree_iter = (struct btree_iter) { NULL }; struct bkey_s_c_snapshot s; u32 parent_id, child_id; unsigned i; int ret = 0; s = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id), BTREE_ITER_intent, snapshot); ret = bkey_err(s); bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, "missing snapshot %u", id); if (ret) goto err; BUG_ON(s.v->children[1]); parent_id = le32_to_cpu(s.v->parent); child_id = le32_to_cpu(s.v->children[0]); if (parent_id) { struct bkey_i_snapshot *parent; parent = bch2_bkey_get_mut_typed(trans, &p_iter, BTREE_ID_snapshots, POS(0, parent_id), 0, snapshot); ret = PTR_ERR_OR_ZERO(parent); bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, "missing snapshot %u", parent_id); if (unlikely(ret)) goto err; /* find entry in parent->children for node being deleted */ for (i = 0; i < 2; i++) if (le32_to_cpu(parent->v.children[i]) == id) break; if (bch2_fs_inconsistent_on(i == 2, c, "snapshot %u missing child pointer to %u", parent_id, id)) goto err; parent->v.children[i] = cpu_to_le32(child_id); normalize_snapshot_child_pointers(&parent->v); } if (child_id) { struct bkey_i_snapshot *child; child = bch2_bkey_get_mut_typed(trans, &c_iter, BTREE_ID_snapshots, POS(0, child_id), 0, snapshot); ret = PTR_ERR_OR_ZERO(child); bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, "missing snapshot %u", child_id); if (unlikely(ret)) goto err; child->v.parent = cpu_to_le32(parent_id); if (!child->v.parent) { child->v.skip[0] = 0; child->v.skip[1] = 0; child->v.skip[2] = 0; } } if (!parent_id) { /* * We're deleting the root of a snapshot tree: update the * snapshot_tree entry to point to the new root, or delete it if * this is the last snapshot ID in this tree: */ struct bkey_i_snapshot_tree *s_t; BUG_ON(s.v->children[1]); s_t = bch2_bkey_get_mut_typed(trans, &tree_iter, BTREE_ID_snapshot_trees, POS(0, le32_to_cpu(s.v->tree)), 0, snapshot_tree); ret = PTR_ERR_OR_ZERO(s_t); if (ret) goto err; if (s.v->children[0]) { s_t->v.root_snapshot = s.v->children[0]; } else { s_t->k.type = KEY_TYPE_deleted; set_bkey_val_u64s(&s_t->k, 0); } } ret = bch2_btree_delete_at(trans, &iter, 0); err: bch2_trans_iter_exit(trans, &tree_iter); bch2_trans_iter_exit(trans, &p_iter); bch2_trans_iter_exit(trans, &c_iter); bch2_trans_iter_exit(trans, &iter); return ret; } static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree, u32 *new_snapids, u32 *snapshot_subvols, unsigned nr_snapids) { struct bch_fs *c = trans->c; struct btree_iter iter; struct bkey_i_snapshot *n; struct bkey_s_c k; unsigned i, j; u32 depth = bch2_snapshot_depth(c, parent); int ret; bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots, POS_MIN, BTREE_ITER_intent); k = bch2_btree_iter_peek(&iter); ret = bkey_err(k); if (ret) goto err; for (i = 0; i < nr_snapids; i++) { k = bch2_btree_iter_prev_slot(&iter); ret = bkey_err(k); if (ret) goto err; if (!k.k || !k.k->p.offset) { ret = -BCH_ERR_ENOSPC_snapshot_create; goto err; } n = bch2_bkey_alloc(trans, &iter, 0, snapshot); ret = PTR_ERR_OR_ZERO(n); if (ret) goto err; n->v.flags = 0; n->v.parent = cpu_to_le32(parent); n->v.subvol = cpu_to_le32(snapshot_subvols[i]); n->v.tree = cpu_to_le32(tree); n->v.depth = cpu_to_le32(depth); n->v.btime.lo = cpu_to_le64(bch2_current_time(c)); n->v.btime.hi = 0; for (j = 0; j < ARRAY_SIZE(n->v.skip); j++) n->v.skip[j] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent)); bubble_sort(n->v.skip, ARRAY_SIZE(n->v.skip), cmp_le32); SET_BCH_SNAPSHOT_SUBVOL(&n->v, true); ret = __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0); if (ret) goto err; new_snapids[i] = iter.pos.offset; mutex_lock(&c->snapshot_table_lock); snapshot_t_mut(c, new_snapids[i])->equiv = new_snapids[i]; mutex_unlock(&c->snapshot_table_lock); } err: bch2_trans_iter_exit(trans, &iter); return ret; } /* * Create new snapshot IDs as children of an existing snapshot ID: */ static int bch2_snapshot_node_create_children(struct btree_trans *trans, u32 parent, u32 *new_snapids, u32 *snapshot_subvols, unsigned nr_snapids) { struct btree_iter iter; struct bkey_i_snapshot *n_parent; int ret = 0; n_parent = bch2_bkey_get_mut_typed(trans, &iter, BTREE_ID_snapshots, POS(0, parent), 0, snapshot); ret = PTR_ERR_OR_ZERO(n_parent); if (unlikely(ret)) { if (bch2_err_matches(ret, ENOENT)) bch_err(trans->c, "snapshot %u not found", parent); return ret; } if (n_parent->v.children[0] || n_parent->v.children[1]) { bch_err(trans->c, "Trying to add child snapshot nodes to parent that already has children"); ret = -EINVAL; goto err; } ret = create_snapids(trans, parent, le32_to_cpu(n_parent->v.tree), new_snapids, snapshot_subvols, nr_snapids); if (ret) goto err; n_parent->v.children[0] = cpu_to_le32(new_snapids[0]); n_parent->v.children[1] = cpu_to_le32(new_snapids[1]); n_parent->v.subvol = 0; SET_BCH_SNAPSHOT_SUBVOL(&n_parent->v, false); err: bch2_trans_iter_exit(trans, &iter); return ret; } /* * Create a snapshot node that is the root of a new tree: */ static int bch2_snapshot_node_create_tree(struct btree_trans *trans, u32 *new_snapids, u32 *snapshot_subvols, unsigned nr_snapids) { struct bkey_i_snapshot_tree *n_tree; int ret; n_tree = __bch2_snapshot_tree_create(trans); ret = PTR_ERR_OR_ZERO(n_tree) ?: create_snapids(trans, 0, n_tree->k.p.offset, new_snapids, snapshot_subvols, nr_snapids); if (ret) return ret; n_tree->v.master_subvol = cpu_to_le32(snapshot_subvols[0]); n_tree->v.root_snapshot = cpu_to_le32(new_snapids[0]); return 0; } int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent, u32 *new_snapids, u32 *snapshot_subvols, unsigned nr_snapids) { BUG_ON((parent == 0) != (nr_snapids == 1)); BUG_ON((parent != 0) != (nr_snapids == 2)); return parent ? bch2_snapshot_node_create_children(trans, parent, new_snapids, snapshot_subvols, nr_snapids) : bch2_snapshot_node_create_tree(trans, new_snapids, snapshot_subvols, nr_snapids); } /* * If we have an unlinked inode in an internal snapshot node, and the inode * really has been deleted in all child snapshots, how does this get cleaned up? * * first there is the problem of how keys that have been overwritten in all * child snapshots get deleted (unimplemented?), but inodes may perhaps be * special? * * also: unlinked inode in internal snapshot appears to not be getting deleted * correctly if inode doesn't exist in leaf snapshots * * solution: * * for a key in an interior snapshot node that needs work to be done that * requires it to be mutated: iterate over all descendent leaf nodes and copy * that key to snapshot leaf nodes, where we can mutate it */ static int snapshot_delete_key(struct btree_trans *trans, struct btree_iter *iter, struct bkey_s_c k, snapshot_id_list *deleted, snapshot_id_list *equiv_seen, struct bpos *last_pos) { struct bch_fs *c = trans->c; u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot); if (!bkey_eq(k.k->p, *last_pos)) equiv_seen->nr = 0; *last_pos = k.k->p; if (snapshot_list_has_id(deleted, k.k->p.snapshot) || snapshot_list_has_id(equiv_seen, equiv)) { return bch2_btree_delete_at(trans, iter, BTREE_UPDATE_internal_snapshot_node); } else { return snapshot_list_add(c, equiv_seen, equiv); } } static int move_key_to_correct_snapshot(struct btree_trans *trans, struct btree_iter *iter, struct bkey_s_c k) { struct bch_fs *c = trans->c; u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot); /* * When we have a linear chain of snapshot nodes, we consider * those to form an equivalence class: we're going to collapse * them all down to a single node, and keep the leaf-most node - * which has the same id as the equivalence class id. * * If there are multiple keys in different snapshots at the same * position, we're only going to keep the one in the newest * snapshot - the rest have been overwritten and are redundant, * and for the key we're going to keep we need to move it to the * equivalance class ID if it's not there already. */ if (equiv != k.k->p.snapshot) { struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k); struct btree_iter new_iter; int ret; ret = PTR_ERR_OR_ZERO(new); if (ret) return ret; new->k.p.snapshot = equiv; bch2_trans_iter_init(trans, &new_iter, iter->btree_id, new->k.p, BTREE_ITER_all_snapshots| BTREE_ITER_cached| BTREE_ITER_intent); ret = bch2_btree_iter_traverse(&new_iter) ?: bch2_trans_update(trans, &new_iter, new, BTREE_UPDATE_internal_snapshot_node) ?: bch2_btree_delete_at(trans, iter, BTREE_UPDATE_internal_snapshot_node); bch2_trans_iter_exit(trans, &new_iter); if (ret) return ret; } return 0; } static int bch2_snapshot_needs_delete(struct btree_trans *trans, struct bkey_s_c k) { struct bkey_s_c_snapshot snap; u32 children[2]; int ret; if (k.k->type != KEY_TYPE_snapshot) return 0; snap = bkey_s_c_to_snapshot(k); if (BCH_SNAPSHOT_DELETED(snap.v) || BCH_SNAPSHOT_SUBVOL(snap.v)) return 0; children[0] = le32_to_cpu(snap.v->children[0]); children[1] = le32_to_cpu(snap.v->children[1]); ret = bch2_snapshot_live(trans, children[0]) ?: bch2_snapshot_live(trans, children[1]); if (ret < 0) return ret; return !ret; } /* * For a given snapshot, if it doesn't have a subvolume that points to it, and * it doesn't have child snapshot nodes - it's now redundant and we can mark it * as deleted. */ static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct bkey_s_c k) { int ret = bch2_snapshot_needs_delete(trans, k); return ret <= 0 ? ret : bch2_snapshot_node_set_deleted(trans, k.k->p.offset); } static inline u32 bch2_snapshot_nth_parent_skip(struct bch_fs *c, u32 id, u32 n, snapshot_id_list *skip) { rcu_read_lock(); while (snapshot_list_has_id(skip, id)) id = __bch2_snapshot_parent(c, id); while (n--) { do { id = __bch2_snapshot_parent(c, id); } while (snapshot_list_has_id(skip, id)); } rcu_read_unlock(); return id; } static int bch2_fix_child_of_deleted_snapshot(struct btree_trans *trans, struct btree_iter *iter, struct bkey_s_c k, snapshot_id_list *deleted) { struct bch_fs *c = trans->c; u32 nr_deleted_ancestors = 0; struct bkey_i_snapshot *s; int ret; if (k.k->type != KEY_TYPE_snapshot) return 0; if (snapshot_list_has_id(deleted, k.k->p.offset)) return 0; s = bch2_bkey_make_mut_noupdate_typed(trans, k, snapshot); ret = PTR_ERR_OR_ZERO(s); if (ret) return ret; darray_for_each(*deleted, i) nr_deleted_ancestors += bch2_snapshot_is_ancestor(c, s->k.p.offset, *i); if (!nr_deleted_ancestors) return 0; le32_add_cpu(&s->v.depth, -nr_deleted_ancestors); if (!s->v.depth) { s->v.skip[0] = 0; s->v.skip[1] = 0; s->v.skip[2] = 0; } else { u32 depth = le32_to_cpu(s->v.depth); u32 parent = bch2_snapshot_parent(c, s->k.p.offset); for (unsigned j = 0; j < ARRAY_SIZE(s->v.skip); j++) { u32 id = le32_to_cpu(s->v.skip[j]); if (snapshot_list_has_id(deleted, id)) { id = bch2_snapshot_nth_parent_skip(c, parent, depth > 1 ? get_random_u32_below(depth - 1) : 0, deleted); s->v.skip[j] = cpu_to_le32(id); } } bubble_sort(s->v.skip, ARRAY_SIZE(s->v.skip), cmp_le32); } return bch2_trans_update(trans, iter, &s->k_i, 0); } int bch2_delete_dead_snapshots(struct bch_fs *c) { struct btree_trans *trans; snapshot_id_list deleted = { 0 }; snapshot_id_list deleted_interior = { 0 }; u32 id; int ret = 0; if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags)) return 0; if (!test_bit(BCH_FS_started, &c->flags)) { ret = bch2_fs_read_write_early(c); bch_err_msg(c, ret, "deleting dead snapshots: error going rw"); if (ret) return ret; } trans = bch2_trans_get(c); /* * For every snapshot node: If we have no live children and it's not * pointed to by a subvolume, delete it: */ ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, POS_MIN, 0, k, NULL, NULL, 0, bch2_delete_redundant_snapshot(trans, k)); bch_err_msg(c, ret, "deleting redundant snapshots"); if (ret) goto err; ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, POS_MIN, 0, k, bch2_snapshot_set_equiv(trans, k)); bch_err_msg(c, ret, "in bch2_snapshots_set_equiv"); if (ret) goto err; ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, POS_MIN, 0, k, ({ if (k.k->type != KEY_TYPE_snapshot) continue; BCH_SNAPSHOT_DELETED(bkey_s_c_to_snapshot(k).v) ? snapshot_list_add(c, &deleted, k.k->p.offset) : 0; })); bch_err_msg(c, ret, "walking snapshots"); if (ret) goto err; for (id = 0; id < BTREE_ID_NR; id++) { struct bpos last_pos = POS_MIN; snapshot_id_list equiv_seen = { 0 }; struct disk_reservation res = { 0 }; if (!btree_type_has_snapshots(id)) continue; /* * deleted inodes btree is maintained by a trigger on the inodes * btree - no work for us to do here, and it's not safe to scan * it because we'll see out of date keys due to the btree write * buffer: */ if (id == BTREE_ID_deleted_inodes) continue; ret = for_each_btree_key_commit(trans, iter, id, POS_MIN, BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k, &res, NULL, BCH_TRANS_COMMIT_no_enospc, snapshot_delete_key(trans, &iter, k, &deleted, &equiv_seen, &last_pos)) ?: for_each_btree_key_commit(trans, iter, id, POS_MIN, BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k, &res, NULL, BCH_TRANS_COMMIT_no_enospc, move_key_to_correct_snapshot(trans, &iter, k)); bch2_disk_reservation_put(c, &res); darray_exit(&equiv_seen); bch_err_msg(c, ret, "deleting keys from dying snapshots"); if (ret) goto err; } bch2_trans_unlock(trans); down_write(&c->snapshot_create_lock); ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots, POS_MIN, 0, k, ({ u32 snapshot = k.k->p.offset; u32 equiv = bch2_snapshot_equiv(c, snapshot); equiv != snapshot ? snapshot_list_add(c, &deleted_interior, snapshot) : 0; })); bch_err_msg(c, ret, "walking snapshots"); if (ret) goto err_create_lock; /* * Fixing children of deleted snapshots can't be done completely * atomically, if we crash between here and when we delete the interior * nodes some depth fields will be off: */ ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, POS_MIN, BTREE_ITER_intent, k, NULL, NULL, BCH_TRANS_COMMIT_no_enospc, bch2_fix_child_of_deleted_snapshot(trans, &iter, k, &deleted_interior)); if (ret) goto err_create_lock; darray_for_each(deleted, i) { ret = commit_do(trans, NULL, NULL, 0, bch2_snapshot_node_delete(trans, *i)); bch_err_msg(c, ret, "deleting snapshot %u", *i); if (ret) goto err_create_lock; } darray_for_each(deleted_interior, i) { ret = commit_do(trans, NULL, NULL, 0, bch2_snapshot_node_delete(trans, *i)); bch_err_msg(c, ret, "deleting snapshot %u", *i); if (ret) goto err_create_lock; } err_create_lock: up_write(&c->snapshot_create_lock); err: darray_exit(&deleted_interior); darray_exit(&deleted); bch2_trans_put(trans); bch_err_fn(c, ret); return ret; } void bch2_delete_dead_snapshots_work(struct work_struct *work) { struct bch_fs *c = container_of(work, struct bch_fs, snapshot_delete_work); bch2_delete_dead_snapshots(c); bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots); } void bch2_delete_dead_snapshots_async(struct bch_fs *c) { if (bch2_write_ref_tryget(c, BCH_WRITE_REF_delete_dead_snapshots) && !queue_work(c->write_ref_wq, &c->snapshot_delete_work)) bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots); } int __bch2_key_has_snapshot_overwrites(struct btree_trans *trans, enum btree_id id, struct bpos pos) { struct bch_fs *c = trans->c; struct btree_iter iter; struct bkey_s_c k; int ret; bch2_trans_iter_init(trans, &iter, id, pos, BTREE_ITER_not_extents| BTREE_ITER_all_snapshots); while (1) { k = bch2_btree_iter_prev(&iter); ret = bkey_err(k); if (ret) break; if (!k.k) break; if (!bkey_eq(pos, k.k->p)) break; if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) { ret = 1; break; } } bch2_trans_iter_exit(trans, &iter); return ret; } static u32 bch2_snapshot_smallest_child(struct bch_fs *c, u32 id) { const struct snapshot_t *s = snapshot_t(c, id); return s->children[1] ?: s->children[0]; } static u32 bch2_snapshot_smallest_descendent(struct bch_fs *c, u32 id) { u32 child; while ((child = bch2_snapshot_smallest_child(c, id))) id = child; return id; } static int bch2_propagate_key_to_snapshot_leaf(struct btree_trans *trans, enum btree_id btree, struct bkey_s_c interior_k, u32 leaf_id, struct bpos *new_min_pos) { struct btree_iter iter; struct bpos pos = interior_k.k->p; struct bkey_s_c k; struct bkey_i *new; int ret; pos.snapshot = leaf_id; bch2_trans_iter_init(trans, &iter, btree, pos, BTREE_ITER_intent); k = bch2_btree_iter_peek_slot(&iter); ret = bkey_err(k); if (ret) goto out; /* key already overwritten in this snapshot? */ if (k.k->p.snapshot != interior_k.k->p.snapshot) goto out; if (bpos_eq(*new_min_pos, POS_MIN)) { *new_min_pos = k.k->p; new_min_pos->snapshot = leaf_id; } new = bch2_bkey_make_mut_noupdate(trans, interior_k); ret = PTR_ERR_OR_ZERO(new); if (ret) goto out; new->k.p.snapshot = leaf_id; ret = bch2_trans_update(trans, &iter, new, 0); out: bch2_trans_iter_exit(trans, &iter); return ret; } int bch2_propagate_key_to_snapshot_leaves(struct btree_trans *trans, enum btree_id btree, struct bkey_s_c k, struct bpos *new_min_pos) { struct bch_fs *c = trans->c; struct bkey_buf sk; u32 restart_count = trans->restart_count; int ret = 0; bch2_bkey_buf_init(&sk); bch2_bkey_buf_reassemble(&sk, c, k); k = bkey_i_to_s_c(sk.k); *new_min_pos = POS_MIN; for (u32 id = bch2_snapshot_smallest_descendent(c, k.k->p.snapshot); id < k.k->p.snapshot; id++) { if (!bch2_snapshot_is_ancestor(c, id, k.k->p.snapshot) || !bch2_snapshot_is_leaf(c, id)) continue; again: ret = btree_trans_too_many_iters(trans) ?: bch2_propagate_key_to_snapshot_leaf(trans, btree, k, id, new_min_pos) ?: bch2_trans_commit(trans, NULL, NULL, 0); if (ret && bch2_err_matches(ret, BCH_ERR_transaction_restart)) { bch2_trans_begin(trans); goto again; } if (ret) break; } bch2_bkey_buf_exit(&sk, c); return ret ?: trans_was_restarted(trans, restart_count); } static int bch2_check_snapshot_needs_deletion(struct btree_trans *trans, struct bkey_s_c k) { struct bch_fs *c = trans->c; struct bkey_s_c_snapshot snap; int ret = 0; if (k.k->type != KEY_TYPE_snapshot) return 0; snap = bkey_s_c_to_snapshot(k); if (BCH_SNAPSHOT_DELETED(snap.v) || bch2_snapshot_equiv(c, k.k->p.offset) != k.k->p.offset || (ret = bch2_snapshot_needs_delete(trans, k)) > 0) { set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags); return 0; } return ret; } int bch2_snapshots_read(struct bch_fs *c) { int ret = bch2_trans_run(c, for_each_btree_key(trans, iter, BTREE_ID_snapshots, POS_MIN, 0, k, __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, k, 0) ?: bch2_snapshot_set_equiv(trans, k) ?: bch2_check_snapshot_needs_deletion(trans, k)) ?: for_each_btree_key(trans, iter, BTREE_ID_snapshots, POS_MIN, 0, k, (set_is_ancestor_bitmap(c, k.k->p.offset), 0))); bch_err_fn(c, ret); /* * It's important that we check if we need to reconstruct snapshots * before going RW, so we mark that pass as required in the superblock - * otherwise, we could end up deleting keys with missing snapshot nodes * instead */ BUG_ON(!test_bit(BCH_FS_new_fs, &c->flags) && test_bit(BCH_FS_may_go_rw, &c->flags)); if (bch2_err_matches(ret, EIO) || (c->sb.btrees_lost_data & BIT_ULL(BTREE_ID_snapshots))) ret = bch2_run_explicit_recovery_pass_persistent(c, BCH_RECOVERY_PASS_reconstruct_snapshots); return ret; } void bch2_fs_snapshots_exit(struct bch_fs *c) { kvfree(rcu_dereference_protected(c->snapshots, true)); }