How To: Shrink (Reduce) a ReiserFS formatted LVM partition
1. Umount the part it ion you want to shrink
umount /opt
2. Resize the ReiserFS filesystem on the affected partition
resize_reiserfs –s -1G /dev/vgroot/lvopt
3. Shrink the LV part it ion
lvreduce –L -1GB /dev/vgroot/lvopt
4. Mount the part it ion again
Mount /dev/vgroot/lvopt /opt
5. done :-)