Read disk io information from /proc/diskstats.
This will allow the user who provides partition container hints to get partition-specific io (blkio provides io for the container, but at the disk device level).
This computes the space usage for mounted partitions. It takes in a list of mounted partitions from containerHints
and computes the device's disk usage(so each mount must be a separate partition). This is useful for users who
mount partitions on containers and store most of the container's persistent data on those partitions.
