255             self.first_cluster = fs.allocate_cluster(None)?;  in ensure_len()
424         let mut first_free: Option<(Cluster, u64)> = None;  in find_free_entries()
441                 return Ok(None);  in find_free_entries()
542         let f: FATFile = self.find_entry(name, Some(false), None, fs)?.to_file()?;  in open_file()
548         let d: FATDir = self.find_entry(name, Some(true), None, fs)?.to_dir()?;  in open_dir()
578                         None,  in create_file()
616                 let first_cluster: Cluster = fs.allocate_cluster(None)?;  in create_dir()
744             None => return Err(SystemError::ENOSPC),
747             FATDirEntryOffsetIter::new(fs.clone(), start_loc, num_entries, None).collect();
797         let e: FATDirEntry = self.find_entry(name, None, None, fs.clone())?;  in remove()
853         return self.find_entry(name, None, None, fs);  in get_dir_entry()
866             self.check_existence(old_name, None, fs.clone())?  in rename()
875             self.check_existence(new_name, None, fs.clone())?  in rename()
1230             dir.root_offset = None;  in to_dir_entry()
1273             dir.root_offset = None;  in to_dir_entry_with_long_name()
1419                 return Ok((self.current_cluster, self.offset, None));  in get_dir_entry()
1433                         return Ok((self.current_cluster, self.offset, None));  in get_dir_entry()
1441                 return Ok((self.current_cluster, self.offset, None));  in get_dir_entry()
1555                     return Ok((self.current_cluster, self.offset, None));  in get_dir_entry()
1574                 return None;  in next()
1640                 None => {  in short_name()
1704                 None => {
1867             None => {  in new()
1965             None
1985             None
2239                 return None;  in next()
2321             return None;  in next()