ceph: stop using current_kernel_time()

ceph_mdsc_create_request() is one of the last callers of the
deprecated current_kernel_time() as well as timespec_trunc().

This changes it to use the timespec64 based interfaces instead,
though we still need to convert the result until we are ready to
change over req->r_stamp.

The output of the two functions, ktime_get_coarse_real_ts64() and
current_kernel_time() is the same coarse-granular timestamp,
the only difference here is that ktime_get_coarse_real_ts64()
doesn't overflow in 2038.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: N"Yan, Zheng" <zyan@redhat.com>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

fs/ceph/mds_client.c

@@ -1779,6 +1779,7 @@ struct ceph_mds_request *
 ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
 {
 	struct ceph_mds_request *req = kzalloc(sizeof(*req), GFP_NOFS);
+	struct timespec64 ts;
 
 	if (!req)
 		return ERR_PTR(-ENOMEM);
@@ -1797,7 +1798,9 @@ ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
 	init_completion(&req->r_safe_completion);
 	INIT_LIST_HEAD(&req->r_unsafe_item);
 
-	req->r_stamp = timespec_trunc(current_kernel_time(), mdsc->fsc->sb->s_time_gran);
+	ktime_get_coarse_real_ts64(&ts);
+	req->r_stamp = timespec64_to_timespec(timespec64_trunc(ts,
+						mdsc->fsc->sb->s_time_gran));
 
 	req->r_op = op;
 	req->r_direct_mode = mode;