The patch uses the value from the field 'stored' if it is available.
In Ceph 14.2.2 the storage calculation changed to a per pool basis. This
introduced an additional field 'stored' that holds the amount of data
that has been written to the pool. While the field 'used' now has the
data after replication for the pool.
The new calculation will be used only if all OSDs are running with the
on-disk format introduced by Ceph 14.2.2.
Signed-off-by: Alwin Antreich <a.antreich@proxmox.com>