Updated mountroot
Added a timer event source that triggers 1 second after module load, then repeatedly every 0.1 second if needed. Previous method was working reliably in a VM, or using USB drives on bare metal.
Current method is working fine on bare metal as well as in a VM, booted from zpool on internal SSD.
Tested with two zvols - Mavericks Recovery and Mavericks 10.9.2. Updated Mavericks 10.9.2 -> 10.9.3 without issues, but did copy kernel cache into booter partition manually between reboot.