On Tue, Sep 19, 2023 at 3:28 PM Jan Kara <jack@xxxxxxx> wrote: > Inotify event is fixed length so > fsid+fhandle is completely out of the realm of "easy extension". (Not quite true, it's variable-length. But that's not relevant if we're talking about adding an optional feature.) If I were to implement this, I'd add a mask bit called, say, IN_FILE_HANDLE. If that bit is enabled on a watch, the (variable-length) inotify_event would be followed by another (variable-length) struct that looks just like fanotify_event_info_fid, containining fsid and file_handle (of course, only if the same bit is also set in inotify_event.mask, which would give the kernel a way to omit it if it's not available for a certain file). This is a backwards-compatible extension because it's opt-in. Only applications which support it will set the IN_FILE_HANDLE bit. Old applications don't set this bit and never see this trailing struct. Max
