Make sure to drain body upon an error (#7197)

Also cleanup redundant code and use it at a common place

cmd/utils.go

@@ -34,7 +34,6 @@ import (
 	"path/filepath"
 	"reflect"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/minio/minio/cmd/logger"
@@ -467,35 +466,6 @@ func isNetworkOrHostDown(err error) bool {
 	return false
 }
 
-var b512pool = sync.Pool{
-	New: func() interface{} {
-		buf := make([]byte, 512)
-		return &buf
-	},
-}
-
-// CloseResponse close non nil response with any response Body.
-// convenient wrapper to drain any remaining data on response body.
-//
-// Subsequently this allows golang http RoundTripper
-// to re-use the same connection for future requests.
-func CloseResponse(respBody io.ReadCloser) {
-	// Callers should close resp.Body when done reading from it.
-	// If resp.Body is not closed, the Client's underlying RoundTripper
-	// (typically Transport) may not be able to re-use a persistent TCP
-	// connection to the server for a subsequent "keep-alive" request.
-	if respBody != nil {
-		// Drain any remaining Body and then close the connection.
-		// Without this closing connection would disallow re-using
-		// the same connection for future uses.
-		//  - http://stackoverflow.com/a/17961593/4465767
-		bufp := b512pool.Get().(*[]byte)
-		defer b512pool.Put(bufp)
-		io.CopyBuffer(ioutil.Discard, respBody, *bufp)
-		respBody.Close()
-	}
-}
-
 // Used for registering with rest handlers (have a look at registerStorageRESTHandlers for usage example)
 // If it is passed ["aaaa", "bbbb"], it returns ["aaaa", "{aaaa:.*}", "bbbb", "{bbbb:.*}"]
 func restQueries(keys ...string) []string {