e2e: report an error if writing persistent data fails

Use `dd` to sync the data, do not wait for unmounting to flush
outstanding I/O (and ignore failed writes).

See-also: https://tracker.ceph.com/issues/73997?#note-27
Co-authored-by: Patrick Donnelly <pdonnell@ibm.com>
Signed-off-by: Niels de Vos <ndevos@ibm.com>

Author: nixpanic

e2e/utils.go

@@ -808,7 +808,12 @@ func checkDataPersist(pvcPath, appPath string, f *framework.Framework) error {
 	// write data to PVC
 	filePath := app.Spec.Containers[0].VolumeMounts[0].MountPath + "/test"
 
-	_, stdErr, err := execCommandInPod(f, fmt.Sprintf("echo %s > %s", data, filePath), app.Namespace, &opt)
+	_, stdErr, err := execCommandInPod(
+		f,
+		fmt.Sprintf("echo -n '%s' | dd of=%s conv=fsync", data, filePath),
+		app.Namespace,
+		&opt,
+	)
 	if err != nil {
 		return fmt.Errorf("failed to exec command in pod: %w", err)
 	}