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SubjectRe: [PATCH 2/6] xen-blkfront: handle backend CLOSED without CLOSING
On Mon, Oct 01, 2012 at 06:19:19PM +0100, David Vrabel wrote:
> On 25/09/12 18:53, David Vrabel wrote:
> > On 21/09/12 17:04, David Vrabel wrote:
> >> From: David Vrabel <david.vrabel@citrix.com>
> >>
> >> Backend drivers shouldn't transistion to CLOSED unless the frontend is
> >> CLOSED. If a backend does transition to CLOSED too soon then the
> >> frontend may not see the CLOSING state and will not properly shutdown.
> >>
> >> So, treat an unexpected backend CLOSED state the same as CLOSING.
> >
> > Didn't handle the frontend block device being mounted. Updated patch here.
>
> Konrad, can you ack this updated patch if you're happy with it.

Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Or should I just carry it in my for-jens-3.7 bug-fixes queue and ask
Jen to pull it once rc0 is out?
>
> Thanks.
>
> David
>
> > 8<---------------------------------
> > xen-blkfront: handle backend CLOSED without CLOSING
> >
> > Backend drivers shouldn't transistion to CLOSED unless the frontend is
> > CLOSED. If a backend does transition to CLOSED too soon then the
> > frontend may not see the CLOSING state and will not properly shutdown.
> >
> > So, treat an unexpected backend CLOSED state the same as CLOSING.
> >
> > If the backend is CLOSED then the frontend can't talk to it so go to
> > CLOSED immediately without waiting for the block device to be closed
> > or unmounted.
> >
> > Signed-off-by: David Vrabel <david.vrabel@citrix.com>
> > ---
> > drivers/block/xen-blkfront.c | 13 +++++++++----
> > 1 files changed, 9 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> > index 2c2d2e5..c1f5f38 100644
> > --- a/drivers/block/xen-blkfront.c
> > +++ b/drivers/block/xen-blkfront.c
> > @@ -1143,7 +1143,8 @@ static int blkfront_resume(struct xenbus_device *dev)
> > }
> >
> > static void
> > -blkfront_closing(struct blkfront_info *info)
> > +blkfront_closing(struct blkfront_info *info,
> > + enum xenbus_state backend_state)
> > {
> > struct xenbus_device *xbdev = info->xbdev;
> > struct block_device *bdev = NULL;
> > @@ -1167,7 +1168,8 @@ blkfront_closing(struct blkfront_info *info)
> >
> > mutex_lock(&bdev->bd_mutex);
> >
> > - if (bdev->bd_openers) {
> > + /* If the backend is already CLOSED, close now. */
> > + if (bdev->bd_openers && backend_state != XenbusStateClosed) {
> > xenbus_dev_error(xbdev, -EBUSY,
> > "Device in use; refusing to close");
> > xenbus_switch_state(xbdev, XenbusStateClosing);
> > @@ -1340,15 +1342,18 @@ static void blkback_changed(struct xenbus_device *dev,
> > case XenbusStateReconfiguring:
> > case XenbusStateReconfigured:
> > case XenbusStateUnknown:
> > - case XenbusStateClosed:
> > break;
> >
> > case XenbusStateConnected:
> > blkfront_connect(info);
> > break;
> >
> > + case XenbusStateClosed:
> > + if (dev->state == XenbusStateClosed)
> > + break;
> > + /* Missed the backend's Closing state -- fallthrough */
> > case XenbusStateClosing:
> > - blkfront_closing(info);
> > + blkfront_closing(info, backend_state);
> > break;
> > }
> > }


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