I am thinking whether we will have the requirement to change OST-index in the future. If we have, then storing OST-index inside the IDIF will be trouble. Because for normal FID, OST-index is meaningless, the client can get the OST-index by checking FLD with the given FID. So as long as we can adjust the FLD correctly, then changing OST-index without breaking the system is easy.
Currently, because all the IDIF use 0-index, the OI scrub does not care about the OST-index. But if the up layer change the IDIF logic, means both LOD and OFD use the real OST-index, then OI scrub needs to the OST-index to rebuild the LMA and the /O tree. And before such conversion is completed, the system is un-accessable, it is not like OI scrub for MDT file-level backup/restore. Under the later one case, the system is still accessible during the OI scrub rebuilding the OI files. I am not sure whether OI scrub or the OSD should know the 'index' information or not.
Last patch has landed for 2.8.