Hi!

As I mentioned in the v1 cover letter, I've been working on implementing the
FUSE_LOOKUP_HANDLE operation.  As I also mentioned, this is being done in
the scope of a wider project, which is to be able to restart FUSE servers
without the need to unmount the file systems.  For context, here are the
links again: [0] [1].

This v2 tries to address (most of) the comments from Amir to v1[2].  I don't
think I'm addressing them all, but since a few weeks have already passed, I
decided it's time to send a new version anyway.

Here's what changed since v1:

- Handle assertion gracefully in create_new_entry() (Amir)
- Don't truncate handle in fuse_iget() if size is too large (Amir)
- Move NFS-related changes to a different patch (Amir)
  In fact, I ended-up moving all the NFS-related code to a different file
- Handle compat (still WIP)
- Fix out_argvar handling: variable length arguments are not always the last
  arg now, so a new patch is handling this
- Re-implemented NFS-related changes
  Still only lightly tested, and as Amir hinted, it should probably include
  an extra init flag to select between old vs new NFS handles format
- The usual bug fixes found during more testing

[0] https://lore.kernel.org/all/8734afp0ct.fsf@igalia.com
[1] https://lore.kernel.org/all/CAJfpegvNZ6Z7uhuTdQ6quBaTOYNkAP8W_4yUY4L2JRAEKxEwOQ@mail.gmail.com
[2] https://lore.kernel.org/all/20251120105535.13374-1-luis@igalia.com

Cheers,
--
Luis

Luis Henriques (6):
  fuse: store index of the variable length argument
  fuse: move fuse_entry_out structs out of the stack
  fuse: initial infrastructure for FUSE_LOOKUP_HANDLE support
  fuse: implementation of the FUSE_LOOKUP_HANDLE operation
  fuse: factor out NFS export related code
  fuse: implementation of export_operations with FUSE_LOOKUP_HANDLE

 fs/fuse/Makefile          |   2 +-
 fs/fuse/cuse.c            |   1 +
 fs/fuse/dev.c             |  20 ++-
 fs/fuse/dir.c             | 216 ++++++++++++++++++--------
 fs/fuse/export.c          | 318 ++++++++++++++++++++++++++++++++++++++
 fs/fuse/file.c            |   1 +
 fs/fuse/fuse_i.h          |  53 ++++++-
 fs/fuse/inode.c           | 230 +++++++++------------------
 fs/fuse/ioctl.c           |   1 +
 fs/fuse/readdir.c         |  10 +-
 fs/fuse/virtio_fs.c       |   6 +-
 fs/fuse/xattr.c           |   2 +
 include/linux/exportfs.h  |   7 +
 include/uapi/linux/fuse.h |  16 +-
 14 files changed, 645 insertions(+), 238 deletions(-)
 create mode 100644 fs/fuse/export.c