diff options
Diffstat (limited to 'fs/bcachefs/snapshot.c')
| -rw-r--r-- | fs/bcachefs/snapshot.c | 1815 |
1 files changed, 1815 insertions, 0 deletions
diff --git a/fs/bcachefs/snapshot.c b/fs/bcachefs/snapshot.c new file mode 100644 index 000000000000..ae57638506c3 --- /dev/null +++ b/fs/bcachefs/snapshot.c @@ -0,0 +1,1815 @@ +// 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 <linux/random.h> + +/* + * 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_validate(struct bch_fs *c, struct bkey_s_c k, + enum bch_validate_flags flags) +{ + 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, 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]); + + if (unlikely(new_bytes > INT_MAX)) + return NULL; + + 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_validate(struct bch_fs *c, struct bkey_s_c k, + enum bch_validate_flags flags) +{ + 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, 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, 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, snapshot_children_not_normalized, + "children not normalized"); + + bkey_fsck_err_on(s.v->children[0] && s.v->children[0] == s.v->children[1], + c, 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, 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, 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, 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, + enum btree_iter_update_trigger_flags 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, + enum btree_iter_update_trigger_flags 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; + + rcu_read_lock(); + while (id) { + s = snapshot_t(c, id)->subvol; + + if (s && (!subvol || s < subvol)) + subvol = s; + + id = bch2_snapshot_tree_next(c, id); + } + rcu_read_unlock(); + + 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), + trans, 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, + trans, 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), + trans, 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), + trans, 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, + trans, 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, + trans, 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, + trans, 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, + trans, 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; + + /* Do we need to reconstruct the snapshot_tree entry as well? */ + struct btree_iter iter; + struct bkey_s_c k; + int ret = 0; + u32 tree_id = 0; + + for_each_btree_key_norestart(trans, iter, BTREE_ID_snapshot_trees, POS_MIN, + 0, k, ret) { + if (le32_to_cpu(bkey_s_c_to_snapshot_tree(k).v->root_snapshot) == id) { + tree_id = k.k->p.offset; + break; + } + } + bch2_trans_iter_exit(trans, &iter); + + if (ret) + return ret; + + if (!tree_id) { + 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)); + + for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN, + 0, k, ret) { + if (le32_to_cpu(bkey_s_c_to_subvolume(k).v->snapshot) == id) { + snapshot->v.subvol = cpu_to_le32(k.k->p.offset); + SET_BCH_SNAPSHOT_SUBVOL(&snapshot->v, true); + break; + } + } + bch2_trans_iter_exit(trans, &iter); + + 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), + trans, 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; +} + +int bch2_check_key_has_snapshot(struct btree_trans *trans, + struct btree_iter *iter, + struct bkey_s_c k) +{ + struct bch_fs *c = trans->c; + struct printbuf buf = PRINTBUF; + int ret = 0; + + if (fsck_err_on(!bch2_snapshot_equiv(c, k.k->p.snapshot), + trans, bkey_in_missing_snapshot, + "key in missing snapshot %s, delete?", + (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) + ret = bch2_btree_delete_at(trans, iter, + BTREE_UPDATE_internal_snapshot_node) ?: 1; +fsck_err: + printbuf_exit(&buf); + 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 delete_dead_snapshots_process_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) +{ + int ret = bch2_check_key_has_snapshot(trans, iter, k); + if (ret) + return ret < 0 ? ret : 0; + + struct bch_fs *c = trans->c; + u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot); + if (!equiv) /* key for invalid snapshot node, but we chose not to delete */ + return 0; + + if (!bkey_eq(k.k->p, *last_pos)) + equiv_seen->nr = 0; + + if (snapshot_list_has_id(deleted, k.k->p.snapshot)) + return bch2_btree_delete_at(trans, iter, + BTREE_UPDATE_internal_snapshot_node); + + if (!bpos_eq(*last_pos, k.k->p) && + snapshot_list_has_id(equiv_seen, equiv)) + return bch2_btree_delete_at(trans, iter, + BTREE_UPDATE_internal_snapshot_node); + + *last_pos = k.k->p; + + ret = snapshot_list_add_nodup(c, equiv_seen, equiv); + if (ret) + return ret; + + /* + * 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 (we delete the others above) - 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); + int ret = PTR_ERR_OR_ZERO(new); + if (ret) + return ret; + + new->k.p.snapshot = equiv; + + struct btree_iter new_iter; + 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 }; + int ret = 0; + + if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags)) + return 0; + + 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 (unsigned btree = 0; btree < BTREE_ID_NR; btree++) { + struct bpos last_pos = POS_MIN; + snapshot_id_list equiv_seen = { 0 }; + struct disk_reservation res = { 0 }; + + if (!btree_type_has_snapshots(btree)) + continue; + + ret = for_each_btree_key_commit(trans, iter, + btree, POS_MIN, + BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k, + &res, NULL, BCH_TRANS_COMMIT_no_enospc, + delete_dead_snapshots_process_key(trans, &iter, k, &deleted, + &equiv_seen, &last_pos)); + + 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); + + set_worker_desc("bcachefs-delete-dead-snapshots/%s", c->name); + + 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 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)); +} |