In the HSM archive cases of ll_ioc_copy_{start,end}() we depend on search_inode_for_lustre() to get the data version. search_inode_for_lustre() does a MDS_GETATTR using the FID and returns a only partially initialized inode. The CT will later open and fstat the file so we have extra 3 RPCs (getattr, enqueue for layout for data version, enqueue for stat). If the CT would open the file to be archived before the the start ioctl and close it after the end ioctl then we could skip the extra 3 RPCs and just send 1 open.