+ test_yaffs_umount_EBUSY //caused by having a file handle open and then trying to unmount yaffs.
+
+ test_yaffs_unmount2
+ test_yaffs_unmount2_ENODEV
+ test_yaffs_unmount2_with handle open and forced mode on
+ test_yaffs_unmount2_with handle open and forced mode off. should give EBUSY.
+ test_yaffs_unmount2_EINVAL //should be caused when the file system is alredy unmounted.