[Virtio-fs] Issues with the virtio-fs Windows how-to (unexpected read-only file system)

[Gal Hammer]

Hello,

On Tue, 17 Nov 2020 at 11:55, Stefan Hajnoczi <stefanha at redhat.com> wrote:

> On Mon, Nov 16, 2020 at 07:59:27PM +0100, Jonas Andradas wrote:
> > On Mon, Nov 16, 2020 at 12:36 PM Jonathan Watt <jwatt at jwatt.org> wrote:
>
> CCing Gal Hammer regarding the Windows virtio-fs drivers.
>
> When you find a solution we can update the howto. Pull requests for
> making changes to the website can be sent here:
> https://gitlab.com/virtio-fs/virtio-fs.gitlab.io
>
> >
> > > Hello list,
> > >
> > > Thank you all for your work on virtio-fs. It's a very exciting step
> > > forward!
> > >
> > > Like others[1], I've encountered the issue where virtio-fs mounted file
> > > systems
> > > are unexpectedly read-only/inaccessible on Windows.
> > >
> > > I worked through the Windows how-to page[2], but the "Installing the
> > > virtio-fs
> > > service" instructions at the bottom did not work for me, as written.
> The
> > > instructions are to set the new `VirtioFsSvc` service to depend on both
> > > `WinFsp.Launcher` and `VirtioFsDrv`. However, like others, I found that
> > > the new
> > > service would not run since `VirtioFsDrv` does not appear to exist (be
> a
> > > service).
>

You can run "sc query type=driver" to locate the "VirtIO FS Driver"
(DISPLAY_NAME) and see what is the SERVICE_NAME for the driver that is
installed on your computer. It was renamed a few patches ago in order to
resolve another dependency issue.

I was able to reproduce the restart problem and I'll work to resolve it.

> I too did not manage this to work, and initially removed any dependencies,
> > thus resulting in the same behaviour you mention.
> >
> >
> > > After opening `regedit`, opening the key:
> > >
> > >   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VirtioFsSvc
> > >
> > > removing `VirtioFsDrv` from the value of `DependsOnService`, and then
> > > restarting
> > > the `VirtioFsSvc` service, the file system shared via virtio-fs
> appeared at
> > > 'Z:\' and worked as expected. However, this only works until the
> Windows
> > > VM is
> > > rebooted.
> > >
> > > On rebooting the Windows VM, the shared file system becomes read-only
> and
> > > its
> > > sub-directories cannot be opened. Manually restarting the `VirtioFsSvc`
> > > service
> > > gets the share working again (until next reboot). This seems to
> indicate
> > > that
> > > `VirtioFsSvc` is running too early, and that it really does need to
> wait
> > > for
> > > *something* else to be ready before starting.
> > >
> > > I suppose the first question is what is `VirtioFsDrv` and where is it
> > > supposed
> > >
> > to come from? Are there steps missing from the Windows how-to or has the
> > > name of
> > > this service changed?
> > >
> > >
> > I checked the Virtio FS driver, both from the Device Manager (Properties
> > and then checking the "Service" name associated with it) and also using
> the
> > "driverquery" command.  Based on this, I modified the service to depend
> > both on WinFps.Launcher and this driver ("VirtFS") by issuing the
> following
> > command:
> >
> > sc.exe config VirtioFSsvc depend= WinFsp.Launcher/VirtFS
> >
> > However, so far I have not had better results than you, as when I reboot
> I
> > still have the shared folder as read-only, and only restarting the
> service
> > manually fixes it.
> >
> > I have tried different combinations by adding all the drivers I saw which
> > could be involved (although unlikely, but just in case), resulting in
> > dependencies such as:
> >
> > sc.exe config VirtioFSsvc depend=
> > WinFsp.Launcher/VirtFS/vioscsi/viostor/VirtioSerial/WinFsp
>

This is "a bit" overkill. The service only uses the WinFsp and the virtiofs
driver.

Thanks for spotting the problem.

    Gal.


> >
> > But, still, to no avail.
>


> >
> > > -Jonathan
> > >
> > > 1. For example, the comments starting here:
> > >
> > >
> https://github.com/virtio-win/kvm-guest-drivers-windows/issues/473#issuecomment-658379853
> > >
> > > 2. https://virtio-fs.gitlab.io/howto-windows.html
> > >
>
> > _______________________________________________
> > Virtio-fs mailing list
> > Virtio-fs at redhat.com
> > https://www.redhat.com/mailman/listinfo/virtio-fs
>
>
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