Add an open/unlink/mmap fallback for system that do not support
memfd (only available since 3.17, ~1y ago).
This patch may require additional SELinux policies to work for enforced
systems, but should fail gracefully in this case.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thibaut Collet <thibaut.collet@6wind.com>