On Mon, Jul 29, 2024 at 08:55:46AM +0200, Florian Weimer wrote: > It was pointed out to me that inode numbers on Linux are no longer > expected to be unique per file system, even for local file systems. I don't know if I'm parsing this correctly. Are you claiming on-disk inode numbers are not guaranteed unique per filesystem? It sounds like utter breakage, with capital 'f'. I know the 32-bit inode allocation code can result in unintentional duplicates after wrap around (see get_next_ino), but that's for in-memory stuff only(?) like pipes, so perhaps tolerable. Anyhow, the kernel recently got F_DUPFD_QUERY which tests if the *file* object is the same. While the above is not what's needed here, I guess it sets a precedent for F_DUPINODE_QUERY (or whatever other name) to be added to handily compare inode pointers. It may be worthwhile regardless of the above. (or maybe kcmp could be extended?)
