Here are my partitions:
[awake@desktop ~]$ sudo df -h
Filesystem Size Used Avail Use% Mounted on
rootfs 36G 2.5G 33G 8% /
udev 495M 0 495M 0% /dev
tmpfs 502M 260K 502M 1% /dev/shm
tmpfs 502M 748K 501M 1% /run
/dev/mapper/vg_desktop-lv_root
36G 2.5G 33G 8% /
tmpfs 502M 0 502M 0% /sys/fs/cgroup
tmpfs 502M 0 502M 0% /media
/dev/sda1 485M 50M 410M 11% /boot
/dev/mapper/vg_desktop-lv_home
36G 20G 15G 59% /home
/dev/mapper/vg_desktop-lv_root
36G 2.5G 33G 8% /tmp
/dev/mapper/vg_desktop-lv_root
36G 2.5G 33G 8% /var/tmp
/dev/mapper/vg_desktop-lv_home
36G 20G 15G 59% /home
/dev/sdb5 932G 637G 295G 69% /media/Новый том
So I have no any free space. How to send a part of / partitions size to /home in encrypted lvm without data loosing?