mgr/volumes: guard volume delete by waiting for pending ops

Signed-off-by: Venky Shankar <vshankar@redhat.com>

src/pybind/mgr/volumes/fs/volume.py

@@ -320,7 +320,7 @@ def delete_volume(self, volname, confirm):
             return -errno.ESHUTDOWN, "", "shutdown in progress"
 
         self.purge_queue.cancel_purge_job(volname)
-        self.connection_pool.del_fs_handle(volname)
+        self.connection_pool.del_fs_handle(volname, wait=True)
         # Tear down MDS daemons
         try:
             completion = self.mgr.remove_mds(volname)