samba: run lsof and fuser after shutdown

The clients are pretty regularly reporting busy on unmount when
samba runs above them. This will hopefully give us some info about why.

Signed-off-by: Greg Farnum <greg@inktank.com>

teuthology/task/samba.py

@@ -199,5 +199,21 @@ def task(ctx, config):
                         'sudo', 'killall', '-9', 'smbd',
                         ],
                     )
+
+                remote.run(
+                    args=[
+                        'sudo',
+                        'lsof',
+                        backend,
+                        ],
+                    )
+                remote.run(
+                    args=[
+                        'sudo',
+                        'fuser',
+                        '-M',
+                        backend,
+                        ],
+                    )
             except:
                 pass