A don't understand there is space from lvm root partition

edit

a have: Linux 4.3.3-303.fc23.x8664 #1 SMP Tue Jan 19 18:31:55 UTC 2016 x8664 x8664 x8664 GNU/Linux

# sudo df -Th
Filesystem              Type      Size  Used Avail Use% Mounted on
devtmpfs                devtmpfs  5.9G     0  5.9G   0% /dev
tmpfs                   tmpfs     5.9G  8.0K  5.9G   1% /dev/shm
tmpfs                   tmpfs     5.9G  964K  5.9G   1% /run
tmpfs                   tmpfs     5.9G     0  5.9G   0% /sys/fs/cgroup
**/dev/mapper/fedora-root xfs        50G   49G  2.0G  97% /**
tmpfs                   tmpfs     5.9G   36K  5.9G   1% /tmp
/dev/sda1               ext4      477M  153M  295M  35% /boot
/dev/mapper/fedora-home xfs        55G  7.9G   47G  15% /home
tmpfs                   tmpfs     1.2G     0  1.2G   0% /run/user/0
//10.10.1.22/Z          cifs       71T   71T  786G  99% /mnt/logger

I dont undestand where is my 50gb of root space

#sudo du -sh *
0       bin
151M    boot
184K    conf
16K     conf.rar
8.0K    dev
22M     etc
7.9G    home
0       lib
0       lib64
0       media
72K     MegaSAS.log
70T     mnt
8.0K    monit
367M    opt
du: cannot access ‘proc/19049/task/19049/fd/3’: No such file or directory
du: cannot access ‘proc/19049/task/19049/fdinfo/3’: No such file or directory
du: cannot access ‘proc/19049/fd/3’: No such file or directory
du: cannot access ‘proc/19049/fdinfo/3’: No such file or directory
0       proc
1.3G    root
964K    run
0       sbin
0       srv
1.4M    stalker_db.sql
0       sys
36K     tmp
5.6G    usr
6.6G    var



# sudo du -h -x --max-depth=1 /

22M     /etc
1.3G    /root
6.6G    /var
5.6G    /usr
0       /media
0       /mnt
373M    /opt
0       /srv
184K    /conf
14G     /

I can't undertasand where is 36G of root partition may someone to help me find the lost space thank you