linux-imx

ceph: fix mksnap crash

mksnap reply only contain 'target', does not contain 'dentry'. So
it's wrong to use req->r_reply_info.head->is_dentry to detect traceless
reply.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>