zfs fails to boot up with error 22

[Volodymyr Kostyrko]

Hello.

Just pushed updates to one of dev servers and found out it's unable to 
boot right now. During boot situation resembles what was shown 
previously at:

https://lists.freebsd.org/pipermail/freebsd-fs/2013-September/018246.html

1. Gmirror grabs partitions for two devices (swap/boot)
2. ZFS fails to mount root with error 22.
3. random: unblocking device
4. ZFS retries mount and fails again, exits to debug prompt.

Setting vfs.mountroot.timeout to 300 just makes kernel output another 
error each ~12 seconds. There is a problem with a code, it decreases 
value by one second for each full timeout period.

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=208882

^^^ Here's where I got those tunables.

My kernel configuration is rather minimal and is very close to MINIMAL. 
Removing geom_mirror fixes the problem. Starting geom_mirror later works 
without any issues.

Machine has UFS root due to rather nasty Cisco firmware that only allows 
one single device to be available during boot.

-- 
Sphinx of black quartz judge my vow.