bcachefs: Fix interior update path btree_path uses

Since the btree_paths array is now about to become growable, we have to
be careful not to refer to paths by pointer across contexts where they
may be reallocated.

This fixes the remaining btree_interior_update() paths - split and
merge.

Signed-off-by: Kent Overstreet <[e-mail]>

fs/bcachefs/btree_trans_commit.c

···
 
 		if (!same_leaf_as_next(trans, i)) {
 			if (u64s_delta <= 0) {
-				ret = bch2_foreground_maybe_merge(trans, trans->paths + i->path,
+				ret = bch2_foreground_maybe_merge(trans, i->path,
 							i->level, flags);
 				if (unlikely(ret))
 					return ret;
···
 	struct bch_fs *c = trans->c;
 
 	switch (ret) {
-	case -BCH_ERR_btree_insert_btree_node_full: {
-		struct btree_path *path = trans->paths + i->path;
-
-		ret = bch2_btree_split_leaf(trans, path, flags);
+	case -BCH_ERR_btree_insert_btree_node_full:
+		ret = bch2_btree_split_leaf(trans, i->path, flags);
 		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
-			trace_and_count(c, trans_restart_btree_node_split, trans, trace_ip, path);
+			trace_and_count(c, trans_restart_btree_node_split, trans,
+					trace_ip, trans->paths + i->path);
 		break;
-	}
 	case -BCH_ERR_btree_insert_need_mark_replicas:
 		ret = drop_locks_do(trans,
 			bch2_replicas_delta_list_mark(c, trans->fs_usage_deltas));

fs/bcachefs/btree_update_interior.c

···
 #include <linux/random.h>
 
 static int bch2_btree_insert_node(struct btree_update *, struct btree_trans *,
-				  struct btree_path *, struct btree *,
+				  btree_path_idx_t, struct btree *,
 				  struct keylist *, unsigned);
 static void bch2_btree_update_add_new_node(struct btree_update *, struct btree *);
 
···
  */
 static void btree_split_insert_keys(struct btree_update *as,
 				    struct btree_trans *trans,
-				    struct btree_path *path,
+				    btree_path_idx_t path_idx,
 				    struct btree *b,
 				    struct keylist *keys)
 {
+	struct btree_path *path = trans->paths + path_idx;
+
 	if (!bch2_keylist_empty(keys) &&
 	    bpos_le(bch2_keylist_front(keys)->k.p, b->data->max_key)) {
 		struct btree_node_iter node_iter;
···
 }
 
 static int btree_split(struct btree_update *as, struct btree_trans *trans,
-		       struct btree_path *path, struct btree *b,
+		       btree_path_idx_t path, struct btree *b,
 		       struct keylist *keys, unsigned flags)
 {
 	struct bch_fs *c = as->c;
-	struct btree *parent = btree_node_parent(path, b);
+	struct btree *parent = btree_node_parent(trans->paths + path, b);
 	struct btree *n1, *n2 = NULL, *n3 = NULL;
 	btree_path_idx_t path1 = 0, path2 = 0;
 	u64 start_time = local_clock();
 	int ret = 0;
 
 	BUG_ON(!parent && (b != btree_node_root(c, b)));
-	BUG_ON(parent && !btree_node_intent_locked(path, b->c.level + 1));
+	BUG_ON(parent && !btree_node_intent_locked(trans->paths + path, b->c.level + 1));
 
 	bch2_btree_interior_update_will_free_node(as, b);
 
···
 		six_unlock_write(&n2->c.lock);
 		six_unlock_write(&n1->c.lock);
 
-		path1 = get_unlocked_mut_path(trans, path->btree_id, n1->c.level, n1->key.k.p);
+		path1 = get_unlocked_mut_path(trans, as->btree_id, n1->c.level, n1->key.k.p);
 		six_lock_increment(&n1->c.lock, SIX_LOCK_intent);
 		mark_btree_node_locked(trans, trans->paths + path1, n1->c.level, BTREE_NODE_INTENT_LOCKED);
 		bch2_btree_path_level_init(trans, trans->paths + path1, n1);
 
-		path2 = get_unlocked_mut_path(trans, path->btree_id, n2->c.level, n2->key.k.p);
+		path2 = get_unlocked_mut_path(trans, as->btree_id, n2->c.level, n2->key.k.p);
 		six_lock_increment(&n2->c.lock, SIX_LOCK_intent);
 		mark_btree_node_locked(trans, trans->paths + path2, n2->c.level, BTREE_NODE_INTENT_LOCKED);
 		bch2_btree_path_level_init(trans, trans->paths + path2, n2);
···
 		bch2_btree_update_add_new_node(as, n1);
 		six_unlock_write(&n1->c.lock);
 
-		path1 = get_unlocked_mut_path(trans, path->btree_id, n1->c.level, n1->key.k.p);
+		path1 = get_unlocked_mut_path(trans, as->btree_id, n1->c.level, n1->key.k.p);
 		six_lock_increment(&n1->c.lock, SIX_LOCK_intent);
 		mark_btree_node_locked(trans, trans->paths + path1, n1->c.level, BTREE_NODE_INTENT_LOCKED);
 		bch2_btree_path_level_init(trans, trans->paths + path1, n1);
···
 		if (ret)
 			goto err;
 	} else if (n3) {
-		bch2_btree_set_root(as, trans, path, n3);
+		bch2_btree_set_root(as, trans, trans->paths + path, n3);
 	} else {
 		/* Root filled up but didn't need to be split */
-		bch2_btree_set_root(as, trans, path, n1);
+		bch2_btree_set_root(as, trans, trans->paths + path, n1);
 	}
 
 	if (n3) {
···
 	 * node after another thread has locked and updated the new node, thus
 	 * seeing stale data:
 	 */
-	bch2_btree_node_free_inmem(trans, path, b);
+	bch2_btree_node_free_inmem(trans, trans->paths + path, b);
 
 	if (n3)
-		bch2_trans_node_add(trans, path, n3);
+		bch2_trans_node_add(trans, trans->paths + path, n3);
 	if (n2)
 		bch2_trans_node_add(trans, trans->paths + path2, n2);
 	bch2_trans_node_add(trans, trans->paths + path1, n1);
···
  *
  * @as:			btree_update object
  * @trans:		btree_trans object
- * @path:		path that points to current node
+ * @path_idx:		path that points to current node
  * @b:			node to insert keys into
  * @keys:		list of keys to insert
  * @flags:		transaction commit flags
···
  * for leaf nodes -- inserts into interior nodes have to be atomic.
  */
 static int bch2_btree_insert_node(struct btree_update *as, struct btree_trans *trans,
-				  struct btree_path *path, struct btree *b,
+				  btree_path_idx_t path_idx, struct btree *b,
 				  struct keylist *keys, unsigned flags)
 {
 	struct bch_fs *c = as->c;
+	struct btree_path *path = trans->paths + path_idx;
 	int old_u64s = le16_to_cpu(btree_bset_last(b)->u64s);
 	int old_live_u64s = b->nr.live_u64s;
 	int live_u64s_added, u64s_added;
···
 		return btree_trans_restart(trans, BCH_ERR_transaction_restart_split_race);
 	}
 
-	return btree_split(as, trans, path, b, keys, flags);
+	return btree_split(as, trans, path_idx, b, keys, flags);
 }
 
 int bch2_btree_split_leaf(struct btree_trans *trans,
-			  struct btree_path *path,
+			  btree_path_idx_t path,
 			  unsigned flags)
 {
-	struct btree *b = path_l(path)->b;
+	/* btree_split & merge may both cause paths array to be reallocated */
+
+	struct btree *b = path_l(trans->paths + path)->b;
 	struct btree_update *as;
 	unsigned l;
 	int ret = 0;
 
-	as = bch2_btree_update_start(trans, path, path->level,
+	as = bch2_btree_update_start(trans, trans->paths + path,
+				     trans->paths[path].level,
 				     true, flags);
 	if (IS_ERR(as))
 		return PTR_ERR(as);
···
 
 	bch2_btree_update_done(as, trans);
 
-	for (l = path->level + 1; btree_node_intent_locked(path, l) && !ret; l++)
+	for (l = trans->paths[path].level + 1;
+	     btree_node_intent_locked(&trans->paths[path], l) && !ret;
+	     l++)
 		ret = bch2_foreground_maybe_merge(trans, path, l, flags);
 
 	return ret;
 }
 
 int __bch2_foreground_maybe_merge(struct btree_trans *trans,
-				  struct btree_path *path,
+				  btree_path_idx_t path,
 				  unsigned level,
 				  unsigned flags,
 				  enum btree_node_sibling sib)
···
 	struct btree *b, *m, *n, *prev, *next, *parent;
 	struct bpos sib_pos;
 	size_t sib_u64s;
+	enum btree_id btree = trans->paths[path].btree_id;
 	btree_path_idx_t sib_path = 0, new_path = 0;
 	u64 start_time = local_clock();
 	int ret = 0;
 
-	BUG_ON(!path->should_be_locked);
-	BUG_ON(!btree_node_locked(path, level));
+	BUG_ON(!trans->paths[path].should_be_locked);
+	BUG_ON(!btree_node_locked(&trans->paths[path], level));
 
-	b = path->l[level].b;
+	b = trans->paths[path].l[level].b;
 
 	if ((sib == btree_prev_sib && bpos_eq(b->data->min_key, POS_MIN)) ||
 	    (sib == btree_next_sib && bpos_eq(b->data->max_key, SPOS_MAX))) {
···
 		? bpos_predecessor(b->data->min_key)
 		: bpos_successor(b->data->max_key);
 
-	sib_path = bch2_path_get(trans, path->btree_id, sib_pos,
+	sib_path = bch2_path_get(trans, btree, sib_pos,
 				 U8_MAX, level, BTREE_ITER_INTENT, _THIS_IP_);
 	ret = bch2_btree_path_traverse(trans, sib_path, false);
 	if (ret)
···
 
 	m = trans->paths[sib_path].l[level].b;
 
-	if (btree_node_parent(path, b) !=
+	if (btree_node_parent(trans->paths + path, b) !=
 	    btree_node_parent(trans->paths + sib_path, m)) {
 		b->sib_u64s[sib] = U16_MAX;
 		goto out;
···
 	if (b->sib_u64s[sib] > c->btree_foreground_merge_threshold)
 		goto out;
 
-	parent = btree_node_parent(path, b);
-	as = bch2_btree_update_start(trans, path, level, false,
+	parent = btree_node_parent(trans->paths + path, b);
+	as = bch2_btree_update_start(trans, trans->paths + path, level, false,
 				     BCH_TRANS_COMMIT_no_enospc|flags);
 	ret = PTR_ERR_OR_ZERO(as);
 	if (ret)
···
 	bch2_btree_update_add_new_node(as, n);
 	six_unlock_write(&n->c.lock);
 
-	new_path = get_unlocked_mut_path(trans, path->btree_id, n->c.level, n->key.k.p);
+	new_path = get_unlocked_mut_path(trans, btree, n->c.level, n->key.k.p);
 	six_lock_increment(&n->c.lock, SIX_LOCK_intent);
 	mark_btree_node_locked(trans, trans->paths + new_path, n->c.level, BTREE_NODE_INTENT_LOCKED);
 	bch2_btree_path_level_init(trans, trans->paths + new_path, n);
···
 	bch2_btree_update_get_open_buckets(as, n);
 	bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
 
-	bch2_btree_node_free_inmem(trans, path, b);
+	bch2_btree_node_free_inmem(trans, trans->paths + path, b);
 	bch2_btree_node_free_inmem(trans, trans->paths + sib_path, m);
 
-	bch2_trans_node_add(trans, path, n);
+	bch2_trans_node_add(trans, trans->paths + path, n);
 
 	bch2_trans_verify_paths(trans);
 
···
 
 	if (parent) {
 		bch2_keylist_add(&as->parent_keys, &n->key);
-		ret = bch2_btree_insert_node(as, trans, btree_iter_path(trans, iter),
+		ret = bch2_btree_insert_node(as, trans, iter->path,
 					     parent, &as->parent_keys, flags);
 		if (ret)
 			goto err;

fs/bcachefs/btree_update_interior.h

···
 						  struct btree *,
 						  struct bkey_format);
 
-int bch2_btree_split_leaf(struct btree_trans *, struct btree_path *, unsigned);
+int bch2_btree_split_leaf(struct btree_trans *, btree_path_idx_t, unsigned);
 
-int __bch2_foreground_maybe_merge(struct btree_trans *, struct btree_path *,
+int __bch2_foreground_maybe_merge(struct btree_trans *, btree_path_idx_t,
 				  unsigned, unsigned, enum btree_node_sibling);
 
 static inline int bch2_foreground_maybe_merge_sibling(struct btree_trans *trans,
-					struct btree_path *path,
+					btree_path_idx_t path_idx,
 					unsigned level, unsigned flags,
 					enum btree_node_sibling sib)
 {
+	struct btree_path *path = trans->paths + path_idx;
 	struct btree *b;
 
 	EBUG_ON(!btree_node_locked(path, level));
···
 	if (b->sib_u64s[sib] > trans->c->btree_foreground_merge_threshold)
 		return 0;
 
-	return __bch2_foreground_maybe_merge(trans, path, level, flags, sib);
+	return __bch2_foreground_maybe_merge(trans, path_idx, level, flags, sib);
 }
 
 static inline int bch2_foreground_maybe_merge(struct btree_trans *trans,
-					      struct btree_path *path,
+					      btree_path_idx_t path,
 					      unsigned level,
 					      unsigned flags)
 {