Re: [PATCH] scsi: storvsc: make INQUIRY response SPC-compliant

[Vitaly Kuznetsov]

KY Srinivasan <kys@xxxxxxxxxxxxx> writes:

>> -----Original Message-----
>> From: Christoph Hellwig [mailto:hch@xxxxxxxxxxxxx]
>> Sent: Friday, July 3, 2015 9:19 AM
>> To: Vitaly Kuznetsov
>> Cc: linux-scsi@xxxxxxxxxxxxxxx; Long Li; KY Srinivasan; Haiyang Zhang; James
>> E.J. Bottomley; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
>> Subject: Re: [PATCH] scsi: storvsc: make INQUIRY response SPC-compliant
>> 
>> On Wed, Jul 01, 2015 at 11:04:08AM +0200, Vitaly Kuznetsov wrote:
>> > SPC-2/3/4 specs state that "The standard INQUIRY data (see table ...)
>> > shall contain at least 36 bytes". Hyper-V host doesn't always honor this
>> > requirement, e.g. when there is no physical device present at a particular
>> > LUN host sets Peripheral qualifier to 011b and Additional length to 0
>> > (thus making the reply 5-bytes long). Upper level SCSI stack complains
>> > with 'INQUIRY result too short (5), using 36'. Fix the issue by mangling
>> > Additional length field in host's reply at the driver level.
>> 
>> This looks like a big mess, and usage of phys_to_virt is not generally
>> safe to start with.
>> 
>> If HyperV really is that broken the warning seems correct, but if you
>> really have to get rid of it we could add a blist flag to not issue
>> the warning in the core code instead of hacking around it in the driver.
>
> Agreed. We have fixed this issue in win10 and I am trying to get the fix backported.

In case this is fixed in future Hyper-V versions introducing new blist
flags looks like an overkill, let's leave things as they are.

Thanks,

-- 
  Vitaly
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