ceph: support file lock on directory

Link: http://tracker.ceph.com/issues/24028
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 1a78dd6..036ac0f 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1486,6 +1486,8 @@ const struct file_operations ceph_dir_fops = {
 	.release = ceph_release,
 	.unlocked_ioctl = ceph_ioctl,
 	.fsync = ceph_fsync,
+	.lock = ceph_lock,
+	.flock = ceph_flock,
 };
 
 const struct file_operations ceph_snapdir_fops = {