ceph: add get_name() NFS export callback

Use the newly introduced LOOKUPNAME MDS request to connect child
inode to its parent directory.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>
diff --git a/fs/ceph/strings.c b/fs/ceph/strings.c
index 4440f44..51cc23e 100644
--- a/fs/ceph/strings.c
+++ b/fs/ceph/strings.c
@@ -54,6 +54,7 @@
 	case CEPH_MDS_OP_LOOKUPHASH:  return "lookuphash";
 	case CEPH_MDS_OP_LOOKUPPARENT:  return "lookupparent";
 	case CEPH_MDS_OP_LOOKUPINO:  return "lookupino";
+	case CEPH_MDS_OP_LOOKUPNAME:  return "lookupname";
 	case CEPH_MDS_OP_GETATTR:  return "getattr";
 	case CEPH_MDS_OP_SETXATTR: return "setxattr";
 	case CEPH_MDS_OP_SETATTR: return "setattr";