Update reed+solomon (#9562)

Only create encoder when strictly needed.

cmd/xl-v1-metadata.go

@@ -139,6 +139,25 @@ func (e ErasureInfo) GetChecksumInfo(partNumber int) (ckSum ChecksumInfo) {
 	return ChecksumInfo{}
 }
 
+// ShardFileSize - returns final erasure size from original size.
+func (e ErasureInfo) ShardFileSize(totalLength int64) int64 {
+	if totalLength == 0 {
+		return 0
+	}
+	if totalLength == -1 {
+		return -1
+	}
+	numShards := totalLength / e.BlockSize
+	lastBlockSize := totalLength % e.BlockSize
+	lastShardSize := ceilFrac(lastBlockSize, int64(e.DataBlocks))
+	return numShards*e.ShardSize() + lastShardSize
+}
+
+// ShardSize - returns actual shared size from erasure blockSize.
+func (e ErasureInfo) ShardSize() int64 {
+	return ceilFrac(e.BlockSize, int64(e.DataBlocks))
+}
+
 // statInfo - carries stat information of the object.
 type statInfo struct {
 	Size    int64     `json:"size"`    // Size of the object `xl.json`.