[ 34/77] xen/blkback: Dont trust the handle from the frontend.

[Greg Kroah-Hartman]

3.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

commit 01c681d4c70d64cb72142a2823f27c4146a02e63 upstream.

The 'handle' is the device that the request is from. For the life-time
of the ring we copy it from a request to a response so that the frontend
is not surprised by it. But we do not need it - when we start processing
I/Os we have our own 'struct phys_req' which has only most essential
information about the request. In fact the 'vbd_translate' ends up
over-writing the preq.dev with a value from the backend.

This assignment of preq.dev with the 'handle' value is superfluous
so lets not do it.

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/block/xen-blkback/blkback.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -879,7 +879,6 @@ static int dispatch_rw_block_io(struct x
 		goto fail_response;
 	}
 
-	preq.dev           = req->u.rw.handle;
 	preq.sector_number = req->u.rw.sector_number;
 	preq.nr_sects      = 0;
 


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