[ceph-users] How to force backfill on undersized pgs ?

Hello I'm running ceph 14.2.9. During heavy backfilling due to rebalancing one OSD crashed. I want to recover the data from the lost OSD before continuing the backfilling so i out'ed the lost osd and ran "ceph osd set norebalance". But i'm noticing with the norebalance flag set the system does not backfill the undersized PG's. Only the degraded ones. So now i have plenty of undersized PG's and the system is idle. How can i recover the undersized PG's before resuming normal backfilling/rebalancing ? Regards, Kári