fix backup goroutine leak (#15410)

Signed-off-by: deepthi <deepthi@planetscale.com>

go/vt/mysqlctl/builtinbackupengine.go

@@ -848,6 +848,16 @@ func (be *BuiltinBackupEngine) backupFile(ctx context.Context, params BackupPara
  var reader io.Reader = br
  var writer io.Writer = bw
 
+ defer func() {
+ // Close the backupPipe to finish writing on destination.
+ if err := bw.Close(); err != nil {
+ createAndCopyErr = errors.Join(createAndCopyErr, vterrors.Wrapf(err, "cannot flush destination: %v", name))
+ }
+
+ if err := br.Close(); err != nil {
+ createAndCopyErr = errors.Join(createAndCopyErr, vterrors.Wrap(err, "failed to close the source reader"))
+ }
+ }()
  // Create the gzip compression pipe, if necessary.
  if backupStorageCompress {
  var compressor io.WriteCloser
@@ -891,16 +901,7 @@ func (be *BuiltinBackupEngine) backupFile(ctx context.Context, params BackupPara
  }
 
  if err := createAndCopy(); err != nil {
- return err
- }
-
- // Close the backupPipe to finish writing on destination.
- if err = bw.Close(); err != nil {
- return vterrors.Wrapf(err, "cannot flush destination: %v", name)
- }
-
- if err := br.Close(); err != nil {
- return vterrors.Wrap(err, "failed to close the source reader")
+ return errors.Join(finalErr, err)
  }
 
  // Save the hash.