s3: fix s3 concurrent uploader will overwrite error (pingcap#48163)

close pingcap#48164

br/pkg/storage/s3.go

@@ -958,9 +958,10 @@ func (rs *S3Storage) Create(ctx context.Context, name string, option *WriterOpti
 		s3Writer.wg.Add(1)
 		go func() {
 			_, err := up.UploadWithContext(ctx, upParams)
-			err1 := rd.Close()
+			// like a channel we only let sender close the pipe in happy path
 			if err != nil {
-				log.Warn("upload to s3 failed", zap.String("filename", name), zap.Error(err), zap.Error(err1))
+				log.Warn("upload to s3 failed", zap.String("filename", name), zap.Error(err))
+				_ = rd.CloseWithError(err)
 			}
 			s3Writer.err = err
 			s3Writer.wg.Done()

br/pkg/storage/s3_test.go

@@ -484,6 +484,24 @@ func TestWriteNoError(t *testing.T) {
 	require.NoError(t, err)
 }
 
+func TestMultiUploadErrorNotOverwritten(t *testing.T) {
+	s := createS3Suite(t)
+	ctx := aws.BackgroundContext()
+
+	s.s3.EXPECT().
+		CreateMultipartUploadWithContext(ctx, gomock.Any(), gomock.Any()).
+		Return(nil, errors.New("mock error"))
+
+	w, err := s.storage.Create(ctx, "file", &WriterOption{Concurrency: 2})
+	require.NoError(t, err)
+	// data should be larger than 5MB to trigger CreateMultipartUploadWithContext path
+	data := make([]byte, 5*1024*1024+6716)
+	n, err := w.Write(ctx, data)
+	require.NoError(t, err)
+	require.Equal(t, 5*1024*1024+6716, n)
+	require.ErrorContains(t, w.Close(ctx), "mock error")
+}
+
 // TestReadNoError ensures the ReadFile API issues a GetObject request and correctly
 // read the entire body.
 func TestReadNoError(t *testing.T) {