[PATCH 00/29] fs: require filesystems to explicitly opt-in to nfsd export support

[Jeff Layton]

In recent years, a number of filesystems that can't present stable
filehandles have grown struct export_operations. They've mostly done
this for local use-cases (enabling open_by_handle_at() and the like).
Unfortunately, having export_operations is generally sufficient to make
a filesystem be considered exportable via nfsd, but that requires that
the server present stable filehandles.

This patchset declares a new EXPORT_OP_STABLE_HANDLES flag, adds it to
all of the filesystems that have stable filehandles, and then adds a
check in nfsd to ensure that that flag is set for any filesystem to
which it has been presented a handle. When a filesystem doesn't have
this flag, it will treat the filehandle as stale.

Signed-off-by: Jeff Layton <jlayton at kernel.org>
---
Jeff Layton (29):
      exportfs: add new EXPORT_OP_STABLE_HANDLES flag
      tmpfs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      ext4: add EXPORT_OP_STABLE_HANDLES flag to export operations
      ext2: add EXPORT_OP_STABLE_HANDLES flag to export operations
      erofs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      efs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      xfs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      ceph: add EXPORT_OP_STABLE_HANDLES flag to export operations
      btrfs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      befs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      ufs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      udf: add EXPORT_OP_STABLE_HANDLES flag to export operations
      affs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      squashfs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      smb/client: add EXPORT_OP_STABLE_HANDLES flag to export operations
      ovl: add EXPORT_OP_STABLE_HANDLES flag to export operations
      orangefs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      ocfs2: add EXPORT_OP_STABLE_HANDLES flag to export operations
      ntfs3: add EXPORT_OP_STABLE_HANDLES flag to export operations
      nilfs2: add EXPORT_OP_STABLE_HANDLES flag to export operations
      nfs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      jfs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      jffs2: add EXPORT_OP_STABLE_HANDLES flag to export operations
      isofs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      gfs2: add EXPORT_OP_STABLE_HANDLES flag to export operations
      fuse: add EXPORT_OP_STABLE_HANDLES flag to export operations
      fat: add EXPORT_OP_STABLE_HANDLES flag to export operations
      f2fs: add EXPORT_OP_STABLE_HANDLES flag to export operations
      nfsd: only allow filesystems that set EXPORT_OP_STABLE_HANDLES

 fs/affs/namei.c          |  1 +
 fs/befs/linuxvfs.c       |  1 +
 fs/btrfs/export.c        |  1 +
 fs/ceph/export.c         |  1 +
 fs/efs/super.c           |  1 +
 fs/erofs/super.c         |  1 +
 fs/ext2/super.c          |  1 +
 fs/ext4/super.c          |  1 +
 fs/f2fs/super.c          |  1 +
 fs/fat/nfs.c             |  2 ++
 fs/fuse/inode.c          |  2 ++
 fs/gfs2/export.c         |  1 +
 fs/isofs/export.c        |  1 +
 fs/jffs2/super.c         |  1 +
 fs/jfs/super.c           |  1 +
 fs/nfs/export.c          |  3 ++-
 fs/nfsd/nfsfh.c          |  4 ++++
 fs/nilfs2/namei.c        |  1 +
 fs/ntfs3/super.c         |  1 +
 fs/ocfs2/export.c        |  1 +
 fs/orangefs/super.c      |  1 +
 fs/overlayfs/export.c    |  2 ++
 fs/smb/client/export.c   |  1 +
 fs/squashfs/export.c     |  3 ++-
 fs/udf/namei.c           |  1 +
 fs/ufs/super.c           |  1 +
 fs/xfs/xfs_export.c      |  1 +
 include/linux/exportfs.h | 16 +++++++++-------
 mm/shmem.c               |  1 +
 29 files changed, 45 insertions(+), 9 deletions(-)
---
base-commit: c537e12daeecaecdcd322c56a5f70659d2de7bde
change-id: 20260114-exportfs-nfsd-12515072e9a9

Best regards,
-- 
Jeff Layton <jlayton at kernel.org>