- return mtd->_write_user_prot_reg(mtd, to, len, retlen, buf);
+ ret = mtd->_write_user_prot_reg(mtd, to, len, retlen, buf);
+ if (ret)
+ return ret;
+
+ /*
+ * If no data could be written at all, we are out of memory and
+ * must return -ENOSPC.
+ */
+ return (*retlen) ? 0 : -ENOSPC;