Re: [PATCH 1/1] scsi: add Synology to 1024 sector blacklist

[Paolo Bonzini <pbonzini@redhat.com>]

On 13/01/2016 10:33, Nicholas A. Bellinger wrote:
>>> This results in IO errors when
>>> handling large IOs. This patch just has us use the old 1024 default
>>> sectors for this target by adding it to the scsi blacklist. We do
>>> not have good contacs with this vendors, so I have not been able to
>>> try and fix on their side.
>>
>> IIRC I saw similar problems a
>> couple years ago with LIO because iscsit_map_iovec maps everything a
>> page at a time and produced too large an iovec for the underlying
>> storage.  I'm afraid you're going to get this for pretty much every user
>> of LIO.
> 
> Two points here.
> 
> We've been exposing backend dev->dev_attrib.hw_max_sectors settings for
> block limits EVPD for FILEIO based on iov limits, and IBLOCK based on
> queue_max_hw_sectors() for some time now.
> 
> So initiators that honor block limits EVPD will work as expected.

What I was describing is more like the backend request_queue's
queue_max_segments influencing the backend's hw_max_sectors.  Is that
covered as well?

Paolo