NOTE: To extend volume size users can extend volume size by an increase, not a decrease.
1. Select the Volume you want to extend from the Volumes tab. Click Extend button 
2. Click Extend Volume after entering the new size for user Volume.
3. After the user extends the volume size. The user needs to detach and re-attach it to the Instance.
4. Then, Check for filesystem issues by SSH into Instance. Using this command:
# e2fsck -f /dev/vdd
Example of output:e2fsck 1.42.9 (28-Dec-2013)
/dev/vdd: recovering journal
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/vdd: 11/1966080 files (0.0% non-contiguous), 167453/7864320 blocks
5. To use the new Volume capacity, resize the filesystem:
# resize2fs /dev/vdd
Example of output:
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/vdd to 10485760 (4k) blocks.
The filesystem on /dev/vdd is now 10485760 blocks long.
6. Need to mount the Volume again using this command:
# mount /dev/vdd /Volume
