/dev/dm-x Mounted instead /dev/mapper/vg/lv

Just trying to understand was there any changes introduced to LVM2 on 14.04 in terms of mounting / FS. I am trying to figure out the reason on why / FS under LVM2 is getting mounted with block device /dev/dm-0 instead /dev/mapper/vg-name/lv despite its entry in the /etc/fstab

But i dont see the same getting applied for rest of the filesystems like /opt

Basically symlinks are being used in the /etc/fstab These symlinks are created from the UDEV rules However in mount command output i am able see /dev/mapper/vg-name/lv

Output

========
root@deadbolt:/dev/mapper# grep -i root /etc/fstab
/dev/mapper/vg00-lv_root / ext4 errors=remount-ro 0 1
root@deadbolt:/dev/mapper#

root@deadbolt:/dev/mapper# mount |grep -i root
/dev/mapper/vg00-lv_root on / type ext4 (rw,errors=remount-ro)
root@deadbolt:/dev/mapper#

root@deadbolt:/dev/mapper# df -Ph /
Filesystem Size Used Avail Use% Mounted on
/dev/dm-0 33G 1.4G 30G 5% /
root@deadbolt:/dev/mapper#

for /opt

root@deadbolt:/dev/mapper# grep -wi opt /etc/fstab
/dev/mapper/vg00-lv_opt /opt ext4 defaults 0 2
root@deadbolt:/dev/mapper#

root@deadbolt:/dev/mapper# df -Ph /
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg00-lv_opt 33G 1.4G 30G 5% /opt
root@deadbolt:/dev/mapper#