Hey, Some filesystems like kernfs and pidfs support file handles as a convenience to enable the use of name_to_handle_at(2) and open_by_handle_at(2) but don't want to and cannot be reliably exported. Add a flag that allows them to mark their export operations accordingly and make NFS check for its presence. @Amir, I'll reorder the patches such that this series comes prior to the pidfs file handle series. Doing it that way will mean that there's never a state where pidfs supports file handles while also being exportable. It's probably not a big deal but it's definitely cleaner. It also means the last patch in this series to mark pidfs as non-exportable can be dropped. Instead pidfs export operations will be marked as non-exportable in the patch that they are added in. Thanks! Christian --- Christian Brauner (4): exportfs: add flag to indicate local file handles kernfs: restrict to local file handles ovl: restrict to exportable file handles pidfs: restrict to local file handles fs/kernfs/mount.c | 1 + fs/nfsd/export.c | 8 +++++++- fs/overlayfs/util.c | 7 ++++++- fs/pidfs.c | 1 + include/linux/exportfs.h | 1 + 5 files changed, 16 insertions(+), 2 deletions(-) --- base-commit: 74e20c5946ab3f8ad959ea34f63f21e157d3ebae change-id: 20241201-work-exportfs-cd49bee773c5