Re: [Qemu-block] [Qemu-devel] [PATCH] iscsi: Fix divide-by-zero regression on raw SG devices

[Eric Blake]

On 09/07/2016 06:48 AM, Holger Schranz wrote:
> Hello Eric, Kevin,
> 
> unfortunately it was not possible for me to get the git tree at this
> time. I have insert the changes by hand, which was into this mail below
> in block/iscsi.c in the distribution from qemu.org for 2.7 (was this o.k.)?

Probably good enough, as it at least got you further (doesn't feel quite
as clean as testing git directly, but since the patch should be
backportable as-is to the 2.7 code, it matches what downstream distros
will be doing).

> 
> After installing and start with virsh create, the following problem occur:
> 
> internal error: process exited while connecting to monitor:
> qemu-system-x86_64: block.c:1022:
> bdrv_open_common: Assertion `is_power_of_2(bs->bl.request_alignment)'
> failed.
> 
> We will send you the backtrace later on.

Ah, I already know where the backtrace would point to. The patch is
setting bl.request_alignment to 0, which is not a power of two, so the
assertion in block.c should also exempt SG devices from reporting a
preferred request_alignment. v2 coming up.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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