Revert all GetObjectNInfo related PRs (#6398)

* Revert "Encrypted reader wrapped in NewGetObjectReader should be closed (#6383)"

This reverts commit 53a0bbeb5b.

* Revert "Change SelectAPI to use new GetObjectNInfo API (#6373)"

This reverts commit 5b05df215a.

* Revert "Implement GetObjectNInfo object layer call (#6290)"

This reverts commit e6d740ce09.

cmd/object-api-utils.go

@@ -20,12 +20,10 @@ import (
 	"context"
 	"encoding/hex"
 	"fmt"
-	"io"
 	"math/rand"
 	"path"
 	"runtime"
 	"strings"
-	"sync"
 	"time"
 	"unicode/utf8"
 
@@ -304,56 +302,3 @@ type byBucketName []BucketInfo
 func (d byBucketName) Len() int           { return len(d) }
 func (d byBucketName) Swap(i, j int)      { d[i], d[j] = d[j], d[i] }
 func (d byBucketName) Less(i, j int) bool { return d[i].Name < d[j].Name }
-
-// GetObjectReader is a type that wraps a reader with a lock to
-// provide a ReadCloser interface that unlocks on Close()
-type GetObjectReader struct {
-	lock RWLocker
-	pr   io.Reader
-
-	// register any clean up actions (happens before unlocking)
-	cleanUp func()
-
-	once sync.Once
-}
-
-// NewGetObjectReader creates a new GetObjectReader. The cleanUp
-// action is called on Close() before the lock is unlocked.
-func NewGetObjectReader(reader io.Reader, lock RWLocker, cleanUp func()) io.ReadCloser {
-	return &GetObjectReader{
-		lock:    lock,
-		pr:      reader,
-		cleanUp: cleanUp,
-	}
-}
-
-// Close - calls the cleanup action if provided, and *then* unlocks
-// the object. Calling Close multiple times is safe.
-func (g *GetObjectReader) Close() error {
-	// sync.Once is used here to ensure that Close() is
-	// idempotent.
-	g.once.Do(func() {
-		// Unlocking is defer-red - this ensures that
-		// unlocking happens even if cleanUp panics.
-		defer func() {
-			if g.lock != nil {
-				g.lock.RUnlock()
-			}
-		}()
-		if g.cleanUp != nil {
-			g.cleanUp()
-		}
-	})
-	return nil
-}
-
-// Read - to implement Reader interface.
-func (g *GetObjectReader) Read(p []byte) (n int, err error) {
-	n, err = g.pr.Read(p)
-	if err != nil {
-		// Calling code may not Close() in case of error, so
-		// we ensure it.
-		g.Close()
-	}
-	return
-}