The current capacity and usage numbers are insufficient to figure out
actual bytes available for a non-root user for the fs. Available is the
value used by df and the one we need to track to detect low diskspace
condition.
/storage returns {device, mountpoint, capacity, usage} for all filesystems.
In addition, it also detect and applies label for each filesystem - currently two - "root", "docker-images".
/storage/<label> returns info about the filesystem with specific label. eg. /storage/root returns info for root filesystem.
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.
