block: cancel jobs when a device is ready to go away

We do not want jobs to keep a device busy for a possibly very long
time, and management could become confused because they thought a
device was not even there anymore.  So, cancel long-running jobs
as soon as their device is going to disappear.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

blockdev.c

@@ -64,6 +64,9 @@ void blockdev_mark_auto_del(BlockDriverState *bs)
 {
     DriveInfo *dinfo = drive_get_by_blockdev(bs);
 
+    if (bs->job) {
+        block_job_cancel(bs->job);
+    }
     if (dinfo) {
         dinfo->auto_del = 1;
     }