commit c1005322ff02110a4df7f0033368ea015062b583 upstream.

Call writecache_flush() on REQ_FUA in writecache_map().

Cc: stable@vger.kernel.org # 4.18+
Signed-off-by: NMaged Mokhtar <mmokhtar@petasan.org>
Acked-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>