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-rw-r--r--libbcachefs/snapshot.c886
1 files changed, 886 insertions, 0 deletions
diff --git a/libbcachefs/snapshot.c b/libbcachefs/snapshot.c
new file mode 100644
index 00000000..82425917
--- /dev/null
+++ b/libbcachefs/snapshot.c
@@ -0,0 +1,886 @@
+// 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;
+}
+
+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)
+ kvfree_rcu(old);
+
+ 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;
+}
+
+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));
+}
generated by cgit v1.2.3 (git 2.46.0) at 2025-07-01 08:01:43 +0000