On Sat, Apr 29, 2023 at 8:26 PM Amir Goldstein [off-list ref] wrote:

On Sat, Apr 29, 2023 at 5:45 PM Chuck Lever [off-list ref] wrote:

quoted

On Thu, Apr 27, 2023 at 11:13:33AM -0400, Jeff Layton wrote:

quoted

On Tue, 2023-04-25 at 16:01 +0300, Amir Goldstein wrote:

quoted

Jan,

Following up on the FAN_REPORT_ANY_FID proposal [1], here is a shot at an
alternative proposal to seamlessly support more filesystems.

While fanotify relaxes the requirements for filesystems to support
reporting fid to require only the ->encode_fh() operation, there are
currently no new filesystems that meet the relaxed requirements.

I will shortly post patches that allow overlayfs to meet the new
requirements with default overlay configurations.

The overlay and vfs/fanotify patch sets are completely independent.
The are both available on my github branch [2] and there is a simple
LTP test variant that tests reporting fid from overlayfs [3], which
also demonstrates the minor UAPI change of name_to_handle_at(2) for
requesting a non-decodeable file handle by userspace.

Thanks,
Amir.

[1] https://lore.kernel.org/linux-fsdevel/20230417162721.ouzs33oh6mb7vtft@quack3/ (local)
[2] https://github.com/amir73il/linux/commits/exportfs_encode_fid
[3] https://github.com/amir73il/ltp/commits/exportfs_encode_fid

Amir Goldstein (4):
  exportfs: change connectable argument to bit flags
  exportfs: add explicit flag to request non-decodeable file handles
  exportfs: allow exporting non-decodeable file handles to userspace
  fanotify: support reporting non-decodeable file handles

 Documentation/filesystems/nfs/exporting.rst |  4 +--
 fs/exportfs/expfs.c                         | 29 ++++++++++++++++++---
 fs/fhandle.c                                | 20 ++++++++------
 fs/nfsd/nfsfh.c                             |  5 ++--
 fs/notify/fanotify/fanotify.c               |  4 +--
 fs/notify/fanotify/fanotify_user.c          |  6 ++---
 fs/notify/fdinfo.c                          |  2 +-
 include/linux/exportfs.h                    | 18 ++++++++++---
 include/uapi/linux/fcntl.h                  |  5 ++++
 9 files changed, 67 insertions(+), 26 deletions(-)

This set looks fairly benign to me, so ACK on the general concept.

Me also (modulo previous review comments), so

  Acked-by: Chuck Lever [off-list ref]

I assume either Amir or Jeff will take these when they are ready.
If I'm wrong, please do let me know and I can take them via the
NFSD tree.

With your and Jeff's ACKs I think it would be best if Jan takes
these changes through the fsnotify tree, because they are only
meant to improve fanotify at this point.

quoted

quoted

I am starting to dislike how the AT_* flags are turning into a bunch of
flags that only have meanings on certain syscalls. I don't see a cleaner
way to handle it though.

With all the various proposals of file_handle_v2, I still think that the
AT_HANDLE_FID is the cleanest in terms of API simplicity.

Just trying to document file_handle_v2 and backward compat with
file_handle_v1 gives me a headache and documenting AT_HANDLE_FID
is a no brainer.

To prove my point, here is the man page draft for AT_HANDLE_FID:

https://github.com/amir73il/man-pages/commit/da7e8dc4749ced85ba692073a42724f2bbe5fe3b

Thanks,
Amir.