Occasionally when importing a pool with encrypted datasets it in we see this failure.
Interestingly though we can't reproduce this on demand. Any ideas on what it is I've likely done that causes dn_nlevels to be wrong ? panic[cpu1]/thread=ffffff04e01c7180: assertion failed: dn->dn_nlevels > level (0x0 > 0x0), file: ../../common/fs/zfs/dbuf.c, line: 1567 ffffff001ee15660 genunix:assfail3+b9 () ffffff001ee15700 zfs:dbuf_hold_impl+33a () ffffff001ee15740 zfs:dbuf_hold+2b () ffffff001ee157d0 zfs:dnode_hold_impl+bd () ffffff001ee15800 zfs:dnode_hold+2b () ffffff001ee15880 zfs:dmu_buf_hold+45 () ffffff001ee15950 zfs:zap_lockdir+60 () ffffff001ee159f0 zfs:zap_lookup_norm+56 () ffffff001ee15a50 zfs:zap_lookup+2d () ffffff001ee15ac0 zfs:dsl_pool_open+94 () ffffff001ee15b80 zfs:spa_load+574 () ffffff001ee15be0 zfs:spa_tryimport+99 () ffffff001ee15c30 zfs:zfs_ioc_pool_tryimport+3c () ffffff001ee15cb0 zfs:zfsdev_ioctl+162 () ffffff001ee15cf0 genunix:cdev_ioctl+48 () ffffff001ee15d30 specfs:spec_ioctl+86 () ffffff001ee15db0 genunix:fop_ioctl+7b () ffffff001ee15ec0 genunix:ioctl+174 () ffffff001ee15f10 unix:brand_sys_syscall32+197 () -- Darren J Moffat
