[PATCH v2] drivers/block/xen-blkback: preq.dev is used without initialized

[Chen Gang <gang.chen@asianux.com>]

  if call xen_vbd_translate failed, the preq.dev will be not initialized.
  so use blkif->vbd.pdevice instead (still better to print relative info).

additional information:
  before commit 01c681d4c70d64cb72142a2823f27c4146a02e63, the value printed
  here was bogus, as it was the guest provided value from req->u.rw.handle
  rather than the actual device.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Acked-by: Jan Beulich <JBeulich@suse.com>
---
 drivers/block/xen-blkback/blkback.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index de1f319..6d1cc3d 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -904,7 +904,8 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
 		pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n",
 			 operation == READ ? "read" : "write",
 			 preq.sector_number,
-			 preq.sector_number + preq.nr_sects, preq.dev);
+			 preq.sector_number + preq.nr_sects,
+			 blkif->vbd.pdevice);
 		goto fail_response;
 	}
 
-- 
1.7.7.6