Truncate and unreserve on file replacement

dataswamp/swamp_service.go

@@ -77,6 +77,8 @@ func (s SwampFileService) SaveFile(ref swampfile.FileReference, src io.Reader, s
 		return err
 	}
 
+	ns.Usage = ns.Usage.Add(-f.Size())
+
 	written, err := io.CopyN(f, src, size)
 
 	if written < size {

infrastructure/fs/swampfile/repository.go

@@ -98,6 +98,7 @@ func (f Repository) Create(filename string, namespace_ns string) (swampfile.Swam
 	if err != nil {
 		panic(err)
 	}
+	file.Truncate(0)
 
 	bfd := FileSystemSwampFileData{filename, stat_info.Size(), stat_info.ModTime(), file}