Re: [Xen-devel] [PATCH] blkfront: don't change to closing if we're busy

[Andrew Jones <drjones@xxxxxxxxxx>]

----- Original Message -----
> On Fri, Feb 17, 2012 at 07:50:11AM -0500, Andrew Jones wrote:
> > 
> > 
> > ----- Original Message -----
> > > On Thu, Feb 16, 2012 at 01:17:09PM +0100, Andrew Jones wrote:
> > > > We just reported to xenbus that we can't close yet, because
> > > > blkfront is still in use. So we shouldn't then immediately
> > > > state that we are closing.
> > > 
> > > What happens if the user uses --force to unplug the device?
> > > Will that still work?
> > 
> > With RHEL5 tooling I get the same results. That is, the device
> > is forcibly detached, and then any task in the guest that still
> > attempts to use (or even just unmount) the device hangs.
> > 
> > I don't know anything about xl, but afaict block-detach
> > doesn't take a 'force' option?
> 
> konrad@phenom:~/ssd/linux$ xm block-detach
> xend [ERROR] Config file does not exist: /etc/xen/xend-config.sxp
> Error: 'xm block-detach' requires between 2 and 3 arguments.
> 
> Usage: xm block-detach <Domain> <DevId> [-f|--force]
> 
> Destroy a domain's virtual block device.

That's 'xm', not 'xl'. I tested RHEL5's 'xm' with the force option
and, as I said above, I got the same results before and after this
patch. I believe the problem (the non-force case) may exist with
latest 'xm' too (not just RHEL5's), but I didn't really check, since
I know 'xl' is the tool that truly matters for upstream now. As I
said before, the problem shouldn't exist with 'xl' though, since it
bails on state != 4, and afaict it doesn't have a force option.
Anyway, I don't think this patch would break that path even if it
did.

I'm actually going to send a v2 of this patch in a few minutes. I'm
just finishing it up now.

Drew

> 
> 
> > 
> > Drew
> > 
> > > > 
> > > > Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
> > > > ---
> > > >  drivers/block/xen-blkfront.c |    1 -
> > > >  1 files changed, 0 insertions(+), 1 deletions(-)
> > > > 
> > > > diff --git a/drivers/block/xen-blkfront.c
> > > > b/drivers/block/xen-blkfront.c
> > > > index 5d45688..b53cae4 100644
> > > > --- a/drivers/block/xen-blkfront.c
> > > > +++ b/drivers/block/xen-blkfront.c
> > > > @@ -1134,7 +1134,6 @@ blkfront_closing(struct blkfront_info
> > > > *info)
> > > >         if (bdev->bd_openers) {
> > > >                 xenbus_dev_error(xbdev, -EBUSY,
> > > >                                  "Device in use; refusing to close");
> > > > -               xenbus_switch_state(xbdev, XenbusStateClosing);
> > > >         } else {
> > > >                 xlvbd_release_gendisk(info);
> > > >                 xenbus_frontend_closed(xbdev);
> > > > --
> > > > 1.7.7.5
> > > > 
> > > > 
> > > > _______________________________________________
> > > > Xen-devel mailing list
> > > > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > > > http://lists.xensource.com/xen-devel
> > > 
> 

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