Block Sub-Volume support

[aravindavk]

Add support for Block Subvols(Create a Block file and mount as loop dev)

Create

kadalu subvol create <volname>/<subvol-name> size <size> --virtblock

Example:

kadalu subvol create myvol/photos size 10G --virtblock

• Mount the Volume if not mounted.(Predictable directory say /mnt/<volname>)
• Truncate the file to the required size.
• Store info within the Volume
• Create xfs filesystem

Delete

kadalu subvol delete <volname>/<subvol-name>

Archive

kadalu subvol archive <volname>/<subvol-name>

Expand

kadalu subvol expand <volname>/<subvol-name> size <new-size>

Info

kadalu subvol info [--status] [<volname>]

Mount

Enhance the mount script to support mounting the subvol.

• Mount the Main Volume if not mounted
• Mount the block device to the requested path

mount -t kadalu <host>:/subvols/<volname>@<subvol-name> <mount-path>