xen/blkback: Prefix 'vbd' with 'xen' in structs and functions.

[ This is an ancient bug and it's too old to know who to blame. But
what I know is that it probably has nothing to do with changing the prefix from vbd_ to xen_ so my blame scripts are likely wrong. - dan ]

Hello Konrad Rzeszutek Wilk,

This is a semi-automatic email about new static checker warnings.

The patch 3d814731ba67: "xen/blkback: Prefix 'vbd' with 'xen' in structs and functions." from May 12, 2011, leads to the following Smatch complaint:

    drivers/block/xen-blkback/xenbus.c:510 xen_vbd_create()
    error: we previously assumed 'vbd->bdev->bd_disk' could be null (see line 507)

drivers/block/xen-blkback/xenbus.c
506 vbd->bdev = bdev;

   507		if (vbd->bdev->bd_disk == NULL) {
                    ^^^^^^^^^^^^^^^^^^

If vbd->bdev->bd_disk is NULL then we are toasted.

508 pr_warn("xen_vbd_create: device %08x doesn't exist\n",
509 vbd->pdevice);
510 xen_vbd_free(vbd);

The disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE); call in blkdev_put() will Oops.

511 return -ENOENT;
512 }

regards,
dan carpenter