Simplify fs codebase, split them into separate files and more commenting

pkg/storage/donut/erasure/erasure.go

@@ -7,6 +7,7 @@ import (
 	"github.com/minio-io/minio/pkg/storage/donut/erasure/erasure1"
 )
 
+// EncoderTechnique - encoder matrix type
 type EncoderTechnique int
 
 const (

pkg/storage/donut/erasure/erasure1/erasure.go

@@ -25,6 +25,7 @@ import (
 	"strconv"
 )
 
+// Version - format version
 const (
 	Version = uint32(1)
 )
@@ -102,7 +103,7 @@ func Write(target io.Writer, key string, part uint8, length uint32, k, m uint8,
 	return nil
 }
 
-// Read an erasure block
+// ReadHeader - read an erasure block
 func ReadHeader(reader io.Reader) (dataHeader DataHeader, err error) {
 	versionArray := make([]byte, 4)
 	if err := binary.Read(reader, binary.LittleEndian, versionArray); err != nil {

pkg/storage/donut/fragment/fragment1/fragment.go

@@ -146,7 +146,7 @@ func Write(target io.Writer, reader io.Reader, length uint64) error {
 	return nil
 }
 
-// Reads a donut fragment
+// Read - reads a donut fragment
 func Read(reader io.Reader) (io.Reader, error) {
 	header, err := ReadHeader(reader)
 	if err != nil {
@@ -185,7 +185,7 @@ func Read(reader io.Reader) (io.Reader, error) {
 	return bytes.NewBuffer(data), nil
 }
 
-// Reads the header of a donut
+// ReadHeader - reads the header of a donut
 func ReadHeader(reader io.Reader) (header DonutFrameHeader, err error) {
 	headerSlice := make([]byte, 32)
 	headerLength, err := reader.Read(headerSlice)