bcachefs: Fix for iterator not being traverse at commit timebcachefs-v4.19-backport-2022-hotfix

Custumer system is hitting a BUG_ON() at btree_update_leaf +692: btree
iterator is not uptodate, meaning we dropped locks somewhere.

A proper backported fix is not possible, but we can re-traverse the
iterator, ensuring it is uptodate before calling bch2_trans_commit().

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

1 files changed, 23 insertions, 11 deletions

diff --git a/fs/bcachefs/btree_update_leaf.c b/fs/bcachefs/btree_update_leaf.c
index e7816afe4a08..3723e845d5e3 100644
--- a/fs/bcachefs/btree_update_leaf.c
+++ b/fs/bcachefs/btree_update_leaf.c
@@ -695,17 +695,20 @@ static inline int btree_iter_pos_cmp(const struct btree_iter *l,
 		 bkey_cmp(l->pos, r->pos);
 }
 
-static void bch2_trans_update2(struct btree_trans *trans,
-			       struct btree_iter *iter,
-			       struct bkey_i *insert)
+static int bch2_trans_update2(struct btree_trans *trans,
+			      struct btree_iter *iter,
+			      struct bkey_i *insert)
 {
 	struct btree_insert_entry *i, n = (struct btree_insert_entry) {
 		.iter = iter, .k = insert
 	};
+	int ret;
 
 	btree_insert_entry_checks(trans, n.iter, n.k);
 
-	BUG_ON(iter->uptodate > BTREE_ITER_NEED_PEEK);
+	ret = bch2_btree_iter_traverse(iter);
+	if (ret)
+		return ret;
 
 	EBUG_ON(trans->nr_updates2 >= BTREE_ITER_MAX);
 
@@ -714,7 +717,7 @@ static void bch2_trans_update2(struct btree_trans *trans,
 	trans_for_each_update2(trans, i) {
 		if (btree_iter_pos_cmp(n.iter, i->iter) == 0) {
 			*i = n;
-			return;
+			return 0;
 		}
 
 		if (btree_iter_pos_cmp(n.iter, i->iter) <= 0)
@@ -723,6 +726,7 @@ static void bch2_trans_update2(struct btree_trans *trans,
 
 	array_insert_item(trans->updates2, trans->nr_updates2,
 			  i - trans->updates2, n);
+	return 0;
 }
 
 static int extent_update_to_keys(struct btree_trans *trans,
@@ -743,9 +747,9 @@ static int extent_update_to_keys(struct btree_trans *trans,
 
 	iter->flags |= BTREE_ITER_INTENT;
 	__bch2_btree_iter_set_pos(iter, insert->k.p, false);
-	bch2_trans_update2(trans, iter, insert);
+	ret = bch2_trans_update2(trans, iter, insert);
 	bch2_trans_iter_put(trans, iter);
-	return 0;
+	return ret;
 }
 
 static int extent_handle_overwrites(struct btree_trans *trans,
@@ -775,8 +779,10 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 			bch2_cut_back(start, update);
 
 			__bch2_btree_iter_set_pos(update_iter, update->k.p, false);
-			bch2_trans_update2(trans, update_iter, update);
+			ret = bch2_trans_update2(trans, update_iter, update);
 			bch2_trans_iter_put(trans, update_iter);
+			if (ret)
+				goto err;
 		}
 
 		if (bkey_cmp(k.k->p, end) > 0) {
@@ -790,8 +796,10 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 			bch2_cut_front(end, update);
 
 			__bch2_btree_iter_set_pos(update_iter, update->k.p, false);
-			bch2_trans_update2(trans, update_iter, update);
+			ret = bch2_trans_update2(trans, update_iter, update);
 			bch2_trans_iter_put(trans, update_iter);
+			if (ret)
+				goto err;
 		} else {
 			update_iter = bch2_trans_copy_iter(trans, iter);
 
@@ -805,8 +813,10 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 			update->k.size = 0;
 
 			__bch2_btree_iter_set_pos(update_iter, update->k.p, false);
-			bch2_trans_update2(trans, update_iter, update);
+			ret = bch2_trans_update2(trans, update_iter, update);
 			bch2_trans_iter_put(trans, update_iter);
+			if (ret)
+				goto err;
 		}
 
 		k = bch2_btree_iter_next_with_updates(iter);
@@ -914,7 +924,9 @@ int __bch2_trans_commit(struct btree_trans *trans)
 			if (ret)
 				goto out;
 		} else {
-			bch2_trans_update2(trans, i->iter, i->k);
+			ret = bch2_trans_update2(trans, i->iter, i->k);
+			if (ret)
+				goto out;
 		}
 	}