+ * We need to take into account alignment here to ensure that
+ * we don't modify the free list if we fail to have an exact
+ * block. If we don't have an exact match, and every oher
+ * attempt allocation attempt fails, we'll end up cancelling
+ * a dirty transaction and shutting down.
+ *
+ * For an exact allocation, alignment must be 1,
+ * however we need to take cluster alignment into account when
+ * fixing up the freelist. Use the minalignslop field to
+ * indicate that extra blocks might be required for alignment,
+ * but not to use them in the actual exact allocation.