[PATCH 0/2] scsi: hyper-v storvsc changes by Ubuntu

James Bottomley James.Bottomley at HansenPartnership.com
Thu May 22 14:38:16 UTC 2014


On Thu, 2014-05-22 at 10:49 +0000, KY Srinivasan wrote:
> 
> 
> > -----Original Message-----
> > From: Andy Whitcroft [mailto:apw at canonical.com]
> > Sent: Wednesday, May 21, 2014 7:25 AM
> > To: Ian Abbott
> > Cc: linux-scsi at vger.kernel.org; devel at linuxdriverproject.org; KY Srinivasan;
> > Haiyang Zhang; James E.J. Bottomley; Tim Gardner
> > Subject: Re: [PATCH 0/2] scsi: hyper-v storvsc changes by Ubuntu
> > 
> > On 16 May 2014 16:39, Ian Abbott <abbotti at mev.co.uk> wrote:
> > > These changes to the Microsoft Hyper-V storage driver in Ubuntu
> > > Saucy's
> > > 3.13 kernel look useful for the mainline kernel, especially as they
> > > enable 'TRIM' support.
> > >
> > > Andy Whitcroft (2):
> > >   scsi: hyper-v storvsc switch up to SPC-3
> > >   scsi: hyper-v storvsc -- host takes MAINTENANCE_IN commands badly --
> > >     elide them
> > >
> > >  drivers/scsi/storvsc_drv.c | 10 ++++++++++
> > >  1 file changed, 10 insertions(+)
> > 
> > 
> > The back story here is a little complex.  The main issue is that the Hyper-V
> > drives claim to be SPC-2, and yet implement the SPC-3 extensions for TRIM.
> > We did attempt to upstream quirks to allow these features to be negotiated
> > specifically for the Hyper-V virtual drives (minimum regression potential) but
> > these were NAKd, and it was suggested that just overriding the Hyper-V
> > drives to SPC-3 unconditionally was more appropriate.  The first of the
> > patches here does does this.  This has been sitting in our tree for some time
> > as it was not clear that this would be entirely safe, though the SPC-3 bits are
> > in theory at least mostly detected.  That said this change has been in Ubuntu
> > for a full cycle now and does not seem to have caused any issues.  If KY is
> > happy we should likely submit it formally.  The second fix I believed was
> > already being submitted to mainline.
> > 
> > KY?
> 
> The Windows guys are not currently comfortable claiming conformance to
> SPC-3, as they have not done
> the necessary testing. This will change hopefully soon.

Any bounds on the value of "soon" are we talking weeks or months?  I
think trim is a feature, which means no huge rush to get this in, but it
is nice to respond in a timely fashion to a request from a distribution
to enable a useful feature.

James




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