Using e2label

To label a device
e2label /dev/mapper/vg_mp3-lv_mp3 MP3Data

To show the label
blkid
findfs LABEL=MP3Data
e2label /dev/mapper/vg_mp3-lv

To mount a labeled device
mount -t ext4 LABEL=MP3Data /mp3_data

On fstab

LABEL=MP3Data   /mp3_data       ext4    defaults    0 0