@@ -658,7 +658,11 @@ struct cache_set {
/*
* A btree node on disk could have too many bsets for an iterator to fit
- * on the stack - have to dynamically allocate them
+ * on the stack - have to dynamically allocate them.
+ * bch_cache_set_alloc() will make sure the pool can allocate iterators
+ * equipped with enough room that can host
+ * (sb.bucket_size / sb.block_size)
+ * btree_iter_sets, which is more than static MAX_BSETS.
*/
mempool_t fill_iter;
@@ -207,6 +207,11 @@ void bch_btree_node_read_done(struct btree *b)
struct bset *i = btree_bset_first(b);
struct btree_iter *iter;
+ /*
+ * c->fill_iter can allocate an iterator with more memory space
+ * than static MAX_BSETS.
+ * See the comment arount cache_set->fill_iter.
+ */
iter = mempool_alloc(&b->c->fill_iter, GFP_NOIO);
iter->size = b->c->sb.bucket_size / b->c->sb.block_size;
iter->used = 0;