[PATCH] device-mapper multipath: Flush workqueue when destroying

The multipath destructor must flush its workqueue.  Otherwise items that
reference the destroyed object could remain.

From: "goggin, edward" <egoggin@emc.com>
Signed-off-by: Lars Marowsky-Bree <lmb@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/dm-mpath.c

@@ -752,6 +752,8 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 static void multipath_dtr(struct dm_target *ti)
 {
 	struct multipath *m = (struct multipath *) ti->private;
+
+	flush_workqueue(kmultipathd);
 	free_multipath(m);
 }