gptzfsboot: "ZFS: i/o error - all block copies unavailable" after crash (r297629)

[Marcin Cieslak]

On Sat, 30 Apr 2016, Marcin Cieslak wrote:

> (original report: https://lists.freebsd.org/pipermail/freebsd-virtualization/2016-April/004362.html)
> 
> I am running r298620 as dom0 under Xen, for debugging
> some Xen-related crashes.

(...)
> After a crash, the bootblocks complain on boot
> 
> ZFS: i/o error - all block copies unavailable
> ZFS: i/o error - all block copies unavailable
> ZFS: i/o error - all block copies unavailable
> 
> Can't find /boot/zfsloader
> 
> FreeBSD/x86 boot
> Default: zroot:/boot/kernel/kernel
> boot:
> ZFS: i/o error - all block copies unavailable
> 

After bisecting with /usr/src/lib/libstand and /usr/src/sys/boot
it looks that it was r297629 that broke this:

------------------------------------------------------------------------
r297629 | allanjude | 2016-04-06 23:21:44 +0000 (Wed, 06 Apr 2016) | 13 lines

Fix GELIBoot support for GELI sector size is > 512

Add support for 4k sector GELI encrypted partitions to the bootloader
This is the default created by the installer

Because the IV is different for each sector, and the XTS tweak carries forward you can not decrypt a partial sector if the starting offset is not 0

Make boot2 and the loader read in 4k aligned chunks

Reviewed by:    ed, oshogbo
Sponsored by:   ScaleEngine Inc.
Differential Revision:  https://reviews.freebsd.org/D5820

------------------------------------------------------------------------

I am not using geli, and my sectors are 512 bytes.

Marcin