Re: [win-pv-devel] Next signed release - support for readonly disks?

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: win-pv-devel [mailto:win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> Behalf Of Chris McClymont
> Sent: 07 December 2017 08:34
> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [win-pv-devel] Next signed release - support for readonly disks?
> 
> I just got around to testing the patches that Owen sent to the mailing
> list on October 18th. They were a group of 5 and were all acked by
> Paul except for 5/5.
> 
> [PATCH 4/5] Rationalize SCSIOP_* handlers
> in particular is what implements the readonly fixes in the SCSI system.
> 
> I built the xenvbd driver with these 5 patches on top of master and
> tested with Windows Server 2012. It had the desired effect of showing
> a readonly disk as such in the Disk Management panel, and also when
> trying to copy files into the drive it shows an error dialog with "The
> disk is write-protected".
> 
> Can these patches be pushed to the git remote?

I thought I had pushed them. Thanks for spotting that! It is done now.

Cheers,

  Paul

> 
> Regards,
> Chris McClymont
> 
> 
> On Wed, Oct 18, 2017 at 8:38 PM, Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> wrote:
> >> -----Original Message-----
> >> From: win-pv-devel [mailto:win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx]
> On
> >> Behalf Of Chris McClymont
> >> Sent: 18 October 2017 00:40
> >> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> >> Subject: Re: [win-pv-devel] Next signed release - support for readonly
> disks?
> >>
> >> > In my experience an NTFS filesystem requires a disk to be read/write
> >> otherwise it will not function... certainly this is true of a system disk. 
> >> Are
> you
> >> using a different filesystem? TBH I think it's quite reasonable for Windows
> to
> >> assume that a non-removable medium calling itself is a disk is read/write.
> >>
> >> Readonly disks appear to behave as expected for me using Windows
> >> Server 2012 with the GPLPV drivers signed by EJB Digital, tested using
> >> both VFAT and NTFS. In the Disk Management UI, the disk appears as
> >> Read Only where it normally says Online. For some reason, the option
> >> to add a drive letter is not there, but I can mount them using
> >> diskpart. Files can be read but trying to paste a file into the
> >> mounted readonly disk results in an error dialog:
> >> "The disk is write-protected. ... Remove the write-protection or use
> >> another disk."  Try Again / Skip / Cancel
> >>
> >> I believe this is achieved by setting the Write Protected flag in the
> >> SCSI parameters in response to the Sense command.
> >> It looks like it is set here in the GPLPV code:
> >> http://xenbits.xensource.com/ext/win-
> >>
> pvdrivers/file/2d392ecdd366/xenvbd_common/common_miniport.h#l497
> >
> > Interesting, thanks for the detail.
> >
> >>
> >> These disks have "EJECTSUPPORTED" and also "SURPRISEREMOVALOK" as
> >> capabilities (In both GPLPV and this project) so I think they are
> >> classified as removable.
> >>
> >
> > It's a bit of a strange distinction but I believe that's different from
> removable media and I was wondering whether Windows will cope with non-
> removable media being read-only. From what you say above though, it
> appears it does.
> >
> >> > This fix was unintended - and it does seem possible to boot with read-
> only
> >> non-boot disks attached. It's not a fully tested setup, and the frontend
> offers
> >> no protection against writes to read only disks, so the results are
> undefined
> >> Yeah, my testing shows that writes appear to work, but after
> >> refreshing the disk or folder the written files disappear.
> >>
> >> Thanks Paul and Owen, I will either keep using the GPLPV drivers or
> >> look into feasibility of patching in the SCSI level write protection.
> >>
> >
> > I'm sure one of us can look at patching xenvbd accordingly but, as I said, 
> > it
> may be a little while before we do a signed release of the 9.0 drivers.
> >
> > Cheers,
> >
> >   Paul
> >
> >> Regards,
> >> Chris McClymont
> >>
> >>
> >> On Tue, Oct 17, 2017 at 1:46 AM, Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> >> wrote:
> >> >> -----Original Message-----
> >> >> From: win-pv-devel [mailto:win-pv-devel-
> bounces@xxxxxxxxxxxxxxxxxxxx]
> >> On
> >> >> Behalf Of Chris McClymont
> >> >> Sent: 14 October 2017 02:19
> >> >> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> >> >> Subject: [win-pv-devel] Next signed release - support for readonly
> disks?
> >> >>
> >> >> Hi everyone,
> >> >>
> >> >> Support for readonly disks was fixed in xenvbd commit
> >> >> 3bb41b49ff66433ab5ebb5d36d24946f40390d7c. When is this likely to
> make
> >> >> it into a signed release?
> >> >>
> >> >>
> >> >> I'm working on Windows templates for Xen and would love to use the
> >> >> newer Xen Project drivers signed by the Linux Foundation, rather than
> >> >> the EJB Digital or others floating around. But I have a requirement to
> >> >> support readonly disks, which don't work in the 8.2.0 release.
> >> >> Readonly disks appear in device manage only when emulated, and
> >> >> disappear (even with Show Hidden Devices) after the PV drivers are
> >> >> installed.
> >> >>
> >> >> The commit I mentioned is somewhere between 8.2.0 and master.
> >> >> Previously, pdo.c would set ScsiStatus to SCSI_ABORT if
> >> >> (DiskInfo->DiskInfo & VDISK_READONLY). Now, pdo.c is called target.c
> >> >> and the commit removes the readonly limitation.
> >> >>
> >> >
> >> > Hi Chris,
> >> >
> >> > Owen may have more to say, but I assume this was an unintended
> >> consequence of the patch.
> >> >
> >> > In my experience an NTFS filesystem requires a disk to be read/write
> >> otherwise it will not function... certainly this is true of a system disk. 
> >> Are
> you
> >> using a different filesystem? TBH I think it's quite reasonable for Windows
> to
> >> assume that a non-removable medium calling itself is a disk is read/write.
> >> >
> >> >> I'm wondering a few things:
> >> >>   1) When is this commit likely to make it into a signed release
> >> >
> >> > It's not currently a back-port candidate and there is no firm timeline 
> >> > for
> >> releasing 9.0 drivers.
> >> >
> >> >>   2) Is there a roadmap? I.e. How is it decided when to make releases
> >> >> and which features/fixes to include
> >> >
> >> > Because the Xen Project does not have dedicated infrastructure for
> testing
> >> the PV drivers, we generally rely on the testing done by Citrix XenServer
> and
> >> therefore releases tend to be aligned with updates made to the Citrix
> >> branded variant of the drivers.
> >> >
> >> >>   3) How can I search this mailing list? It doesn't seem to be
> >> >> included on http://xen.markmail.org/search/
> >> >>
> >> >
> >> > You can see the mailing list archives at
> >> https://lists.xenproject.org/archives/html/win-pv-devel. As for searching
> via
> >> markmail... I have requested that the list be added in the past, but I'll
> have
> >> another go.
> >> >
> >> > Cheers,
> >> >
> >> >   Paul
> >> >
> >> >> Thanks,
> >> >> Chris McClymont
> >> >>
> >> >> _______________________________________________
> >> >> win-pv-devel mailing list
> >> >> win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> >> >> https://lists.xenproject.org/cgi-bin/mailman/listinfo/win-pv-devel
> >>
> >> _______________________________________________
> >> win-pv-devel mailing list
> >> win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> >> https://lists.xenproject.org/cgi-bin/mailman/listinfo/win-pv-devel
> 
> _______________________________________________
> win-pv-devel mailing list
> win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> https://lists.xenproject.org/mailman/listinfo/win-pv-devel
_______________________________________________
win-pv-devel mailing list
win-pv-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/win-pv-devel