ceph: Convert struct ceph_mds_request to use kuid_t and kgid_t

Hold the uid and gid for a pending ceph mds request using the types
kuid_t and kgid_t.  When a request message is finally created convert
the kuid_t and kgid_t values into uids and gids in the initial user
namespace.

Cc: Sage Weil <sage@inktank.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 9165eb8..7a3dfe0 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1658,8 +1658,8 @@
 
 	head->mdsmap_epoch = cpu_to_le32(mdsc->mdsmap->m_epoch);
 	head->op = cpu_to_le32(req->r_op);
-	head->caller_uid = cpu_to_le32(req->r_uid);
-	head->caller_gid = cpu_to_le32(req->r_gid);
+	head->caller_uid = cpu_to_le32(from_kuid(&init_user_ns, req->r_uid));
+	head->caller_gid = cpu_to_le32(from_kgid(&init_user_ns, req->r_gid));
 	head->args = req->r_args;
 
 	ceph_encode_filepath(&p, end, ino1, path1);