diff options
author | Kent Overstreet <kent.overstreet@linux.dev> | 2023-08-16 16:54:33 -0400 |
---|---|---|
committer | Kent Overstreet <kent.overstreet@linux.dev> | 2023-10-22 17:10:11 -0400 |
commit | 8e877caaad818595ecb6754355cea2058fd9848e (patch) | |
tree | 8097f33fb97c9de8ff0bd7dcf334b756f902bcd4 /fs/bcachefs/snapshot.c | |
parent | e5570df295fc951546fec782bc087f72a47277e0 (diff) |
bcachefs: Split out snapshot.c
subvolume.c has gotten a bit large, this splits out a separate file just
for managing snapshot trees - BTREE_ID_snapshots.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/snapshot.c')
-rw-r--r-- | fs/bcachefs/snapshot.c | 1358 |
1 files changed, 1358 insertions, 0 deletions
diff --git a/fs/bcachefs/snapshot.c b/fs/bcachefs/snapshot.c new file mode 100644 index 000000000000..ad7991ad87a9 --- /dev/null +++ b/fs/bcachefs/snapshot.c @@ -0,0 +1,1358 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "bcachefs.h" +#include "btree_key_cache.h" +#include "btree_update.h" +#include "errcode.h" +#include "error.h" +#include "fs.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_invalid(const struct bch_fs *c, struct bkey_s_c k, + enum bkey_invalid_flags flags, + struct printbuf *err) +{ + if (bkey_gt(k.k->p, POS(0, U32_MAX)) || + bkey_lt(k.k->p, POS(0, 1))) { + prt_printf(err, "bad pos"); + return -BCH_ERR_invalid_bkey; + } + + return 0; +} + +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 inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor) +{ + const struct snapshot_t *s = __snapshot_t(t, id); + + 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; +} + +bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor) +{ + struct snapshot_table *t; + bool ret; + + EBUG_ON(c->curr_recovery_pass <= BCH_RECOVERY_PASS_check_snapshots); + + rcu_read_lock(); + t = rcu_dereference(c->snapshots); + + while (id && id < ancestor - IS_ANCESTOR_BITMAP) + id = get_ancestor_below(t, id, ancestor); + + ret = id && id < ancestor + ? test_bit(ancestor - id - 1, __snapshot_t(t, id)->is_ancestor) + : id == ancestor; + rcu_read_unlock(); + + return ret; +} + +static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor) +{ + struct snapshot_table *t; + + rcu_read_lock(); + t = rcu_dereference(c->snapshots); + + while (id && id < ancestor) + id = __snapshot_t(t, id)->parent; + rcu_read_unlock(); + + return id == ancestor; +} + +struct snapshot_t_free_rcu { + struct rcu_head rcu; + struct snapshot_table *t; +}; + +static void snapshot_t_free_rcu(struct rcu_head *rcu) +{ + struct snapshot_t_free_rcu *free_rcu = + container_of(rcu, struct snapshot_t_free_rcu, rcu); + + kvfree(free_rcu->t); + kfree(free_rcu); +} + +static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id) +{ + size_t idx = U32_MAX - id; + size_t new_size; + struct snapshot_table *new, *old; + + new_size = max(16UL, roundup_pow_of_two(idx + 1)); + + new = kvzalloc(struct_size(new, s, new_size), GFP_KERNEL); + if (!new) + return NULL; + + old = rcu_dereference_protected(c->snapshots, true); + if (old) + memcpy(new->s, + rcu_dereference_protected(c->snapshots, true)->s, + sizeof(new->s[0]) * c->snapshot_table_size); + + rcu_assign_pointer(c->snapshots, new); + c->snapshot_table_size = new_size; + if (old) { + struct snapshot_t_free_rcu *rcu = + kmalloc(sizeof(*rcu), GFP_KERNEL|__GFP_NOFAIL); + + rcu->t = old; + call_rcu(&rcu->rcu, snapshot_t_free_rcu); + } + + return &rcu_dereference_protected(c->snapshots, true)->s[idx]; +} + +static inline struct snapshot_t *snapshot_t_mut(struct bch_fs *c, u32 id) +{ + size_t idx = U32_MAX - id; + + lockdep_assert_held(&c->snapshot_table_lock); + + if (likely(idx < c->snapshot_table_size)) + return &rcu_dereference_protected(c->snapshots, true)->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(const 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; + + if (bkey_gt(k.k->p, POS(0, U32_MAX)) || + bkey_lt(k.k->p, POS(0, 1))) { + prt_printf(err, "bad pos"); + return -BCH_ERR_invalid_bkey; + } + + s = bkey_s_c_to_snapshot(k); + + id = le32_to_cpu(s.v->parent); + if (id && id <= k.k->p.offset) { + prt_printf(err, "bad parent node (%u <= %llu)", + id, k.k->p.offset); + return -BCH_ERR_invalid_bkey; + } + + if (le32_to_cpu(s.v->children[0]) < le32_to_cpu(s.v->children[1])) { + prt_printf(err, "children not normalized"); + return -BCH_ERR_invalid_bkey; + } + + if (s.v->children[0] && + s.v->children[0] == s.v->children[1]) { + prt_printf(err, "duplicate child nodes"); + return -BCH_ERR_invalid_bkey; + } + + for (i = 0; i < 2; i++) { + id = le32_to_cpu(s.v->children[i]); + + if (id >= k.k->p.offset) { + prt_printf(err, "bad child node (%u >= %llu)", + id, k.k->p.offset); + return -BCH_ERR_invalid_bkey; + } + } + + if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, skip)) { + if (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])) { + prt_printf(err, "skiplist not normalized"); + return -BCH_ERR_invalid_bkey; + } + + for (i = 0; i < ARRAY_SIZE(s.v->skip); i++) { + id = le32_to_cpu(s.v->skip[i]); + + if (!id != !s.v->parent || + (s.v->parent && + id <= k.k->p.offset)) { + prt_printf(err, "bad skiplist node %u)", id); + return -BCH_ERR_invalid_bkey; + } + } + } + + return 0; +} + +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); + u32 parent = id; + + 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; + } + + while ((parent = bch2_snapshot_parent_early(c, parent)) && + parent - id - 1 < IS_ANCESTOR_BITMAP) + __set_bit(parent - id - 1, t->is_ancestor); + + if (BCH_SNAPSHOT_DELETED(s.v)) { + set_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags); + c->recovery_passes_explicit |= BIT_ULL(BCH_RECOVERY_PASS_delete_dead_snapshots); + } + } else { + memset(t, 0, sizeof(*t)); + } +err: + mutex_unlock(&c->snapshot_table_lock); + return ret; +} + +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); +} + +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). + */ +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; + struct bkey_s_c_subvolume s; + 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; + + 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 *s; + + *subvol_id = bch2_snapshot_tree_oldest_subvol(c, snapshot_root); + + s = bch2_bkey_get_mut_typed(trans, &iter, + BTREE_ID_subvolumes, POS(0, *subvol_id), + 0, subvolume); + ret = PTR_ERR_OR_ZERO(s); + if (ret) + return ret; + + SET_BCH_SUBVOLUME_SNAP(&s->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 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 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_early(c, + le32_to_cpu(subvol.snapshot), + root_id), c, + "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 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); + 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) +{ + struct btree_iter iter; + struct bkey_s_c k; + int ret; + + ret = bch2_trans_run(c, + for_each_btree_key_commit(&trans, iter, + BTREE_ID_snapshot_trees, POS_MIN, + BTREE_ITER_PREFETCH, k, + NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL, + check_snapshot_tree(&trans, &iter, k))); + + if (ret) + bch_err(c, "error %i checking snapshot trees", 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, struct bch_snapshot s) +{ + struct bch_snapshot a; + unsigned i; + int ret; + + for (i = 0; i < 3; i++) { + if (!s.parent != !s.skip[i]) + return false; + + if (!s.parent) + continue; + + ret = bch2_snapshot_lookup(trans, le32_to_cpu(s.skip[i]), &a); + if (bch2_err_matches(ret, ENOENT)) + return false; + if (ret) + return ret; + + if (a.tree != s.tree) + 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; + bool should_have_subvol; + u32 i, id; + int ret = 0; + + if (k.k->type != KEY_TYPE_snapshot) + return 0; + + memset(&s, 0, sizeof(s)); + memcpy(&s, k.v, 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; + } + } + + 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 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 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 (le32_to_cpu(s.depth) != real_depth && + (c->sb.version_upgrade_complete < bcachefs_metadata_version_snapshot_skiplists || + fsck_err(c, "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, s); + if (ret < 0) + goto err; + + if (!ret && + (c->sb.version_upgrade_complete < bcachefs_metadata_version_snapshot_skiplists || + fsck_err(c, "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) +{ + struct btree_iter iter; + struct bkey_s_c k; + int ret; + + /* + * We iterate backwards as checking/fixing the depth field requires that + * the parent's depth already be correct: + */ + ret = bch2_trans_run(c, + for_each_btree_key_reverse_commit(&trans, iter, + BTREE_ID_snapshots, POS_MAX, + BTREE_ITER_PREFETCH, k, + NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL, + check_snapshot(&trans, &iter, k))); + if (ret) + 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 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 tree_iter = (struct btree_iter) { NULL }; + struct bkey_s_c_snapshot s; + u32 parent_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(!BCH_SNAPSHOT_DELETED(s.v)); + parent_id = le32_to_cpu(s.v->parent); + + 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); + if (unlikely(ret)) { + bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c, + "missing snapshot %u", parent_id); + goto err; + } + + for (i = 0; i < 2; i++) + if (le32_to_cpu(parent->v.children[i]) == id) + break; + + if (i == 2) + bch_err(c, "snapshot %u missing child pointer to %u", + parent_id, id); + else + parent->v.children[i] = 0; + + if (le32_to_cpu(parent->v.children[0]) < + le32_to_cpu(parent->v.children[1])) + swap(parent->v.children[0], + parent->v.children[1]); + } else { + /* + * 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, &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); + + 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; + } +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 + */ + +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); + } +} + +/* + * 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 btree_iter *iter, + 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; + + if (!ret) + return bch2_snapshot_node_set_deleted(trans, k.k->p.offset); + return 0; +} + +int bch2_delete_dead_snapshots(struct bch_fs *c) +{ + struct btree_trans trans; + struct btree_iter iter; + struct bkey_s_c k; + struct bkey_s_c_snapshot snap; + snapshot_id_list deleted = { 0 }; + u32 i, id; + int ret = 0; + + if (!test_bit(BCH_FS_STARTED, &c->flags)) { + ret = bch2_fs_read_write_early(c); + if (ret) { + bch_err(c, "error deleleting dead snapshots: error going rw: %s", bch2_err_str(ret)); + return ret; + } + } + + bch2_trans_init(&trans, c, 0, 0); + + /* + * 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, &iter, k)); + if (ret) { + bch_err(c, "error deleting redundant snapshots: %s", bch2_err_str(ret)); + goto err; + } + + for_each_btree_key2(&trans, iter, BTREE_ID_snapshots, + POS_MIN, 0, k, + bch2_snapshot_set_equiv(&trans, k)); + if (ret) { + bch_err(c, "error in bch2_snapshots_set_equiv: %s", bch2_err_str(ret)); + goto err; + } + + for_each_btree_key(&trans, iter, BTREE_ID_snapshots, + POS_MIN, 0, k, ret) { + if (k.k->type != KEY_TYPE_snapshot) + continue; + + snap = bkey_s_c_to_snapshot(k); + if (BCH_SNAPSHOT_DELETED(snap.v)) { + ret = snapshot_list_add(c, &deleted, k.k->p.offset); + if (ret) + break; + } + } + bch2_trans_iter_exit(&trans, &iter); + + if (ret) { + bch_err_msg(c, ret, "walking snapshots"); + goto err; + } + + for (id = 0; id < BTREE_ID_NR; id++) { + struct bpos last_pos = POS_MIN; + snapshot_id_list equiv_seen = { 0 }; + + if (!btree_type_has_snapshots(id)) + continue; + + ret = for_each_btree_key_commit(&trans, iter, + id, POS_MIN, + BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k, + NULL, NULL, BTREE_INSERT_NOFAIL, + snapshot_delete_key(&trans, &iter, k, &deleted, &equiv_seen, &last_pos)); + + darray_exit(&equiv_seen); + + if (ret) { + bch_err_msg(c, ret, "deleting keys from dying snapshots"); + goto err; + } + } + + for (i = 0; i < deleted.nr; i++) { + u32 node_to_delete = deleted.data[i]; + + ret = commit_do(&trans, NULL, NULL, 0, + bch2_snapshot_node_delete(&trans, node_to_delete)); + if (ret) { + bch_err_msg(c, ret, "deleting snapshot %u", node_to_delete); + goto err; + } + } + + clear_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags); +err: + darray_exit(&deleted); + bch2_trans_exit(&trans); + if (ret) + 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); + + if (test_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags)) + 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_delete_dead_snapshots_hook(struct btree_trans *trans, + struct btree_trans_commit_hook *h) +{ + struct bch_fs *c = trans->c; + + set_bit(BCH_FS_HAVE_DELETED_SNAPSHOTS, &c->flags); + + if (c->curr_recovery_pass <= BCH_RECOVERY_PASS_delete_dead_snapshots) + return 0; + + bch2_delete_dead_snapshots_async(c); + return 0; +} + +int bch2_snapshots_read(struct bch_fs *c) +{ + struct btree_iter iter; + struct bkey_s_c k; + int ret = 0; + + ret = bch2_trans_run(c, + for_each_btree_key2(&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))); + if (ret) + bch_err_fn(c, ret); + return ret; +} + +void bch2_fs_snapshots_exit(struct bch_fs *c) +{ + kfree(rcu_dereference_protected(c->snapshots, true)); +} |