If device_not_write_same_capable() returns true then the iterate_devices
loop in dm_table_supports_write_same() should return false.
Reported-by: NBharata B Rao <bharata.rao@gmail.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v3.8+
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>