[PATCH] xen-blkfront: handle backend CLOSED without CLOSING

[PATCH] xen-blkfront: handle backend CLOSED without CLOSING

[David Vrabel]

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.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: stable@vger.kernel.org
---
Cc: Jens Axboe <axboe@kernel.dk>
---
 drivers/block/xen-blkfront.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 8dcfb54..0471d63 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1904,13 +1904,16 @@ 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);
 		break;
-- 
1.7.2.5