Почему я не могу размонтировать раздел и почему он занят

Я случайно удалил всю папку «Документы» . Я хочу использовать extundelete, чтобы восстановить его. Как девственница Ubuntu, я потратил час, чтобы правильно написать команду:

sudo extundelete / dev / sda6 --restore-directory home / ladislav / Dokumenty

ladislav@Ladislav:~$ sudo extundelete /dev/sda6 --restore-directory home/ladislav/Dokumenty
WARNING: Extended attributes are not restored.
WARNING: EXT3_FEATURE_INCOMPAT_RECOVER is set.

Как я могу это исправить?

The partition should be unmounted to undelete any files without further data loss
If the partition is not currently mounted, this message indicates 
it was improperly unmounted, and you should run fsck before continuing.
If you decide to continue, extundelete may overwrite some of the deleted
files and make recovering those files impossible.  You should unmount the
file system and check it with fsck before using extundelete.

Когда я пытаюсь разобрать его, ответ занят ...

ladislav@Ladislav:~$ sudo umount /dev/sda6
umount: /: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))


Would you like to continue? (y/n) 
y
Loading filesystem metadata ... 344 groups loaded.
Loading journal descriptors ... 30498 descriptors loaded.
Searching for recoverable inodes in directory home/ladislav/Dokumenty ... 
3300 recoverable inodes found.
Looking through the directory structure for deleted files ... 
3300 recoverable inodes still lost.
No files were undeleted.

Что я делаю не так? (Кроме того, не хранить резервную копию моих данных?)