virtiofs: add a mount option to enable dax

Add a mount option to allow using dax with virtio_fs.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 3e8cebf..8c7021f 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -7,5 +7,7 @@
 obj-$(CONFIG_CUSE) += cuse.o
 obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
 
-fuse-objs := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o
-virtiofs-y += virtio_fs.o
+fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o
+fuse-$(CONFIG_FUSE_DAX) += dax.o
+
+virtiofs-y := virtio_fs.o