The comparisons used in add_vol() shouldn't be identical.  Pretty sure
the following is correct but it is completely untested.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Acked-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>