[PATCH 00/14] nfsd/sunrpc: add support for netlink upcalls for mountd/exportd

[Jeff Layton]

mountd/exportd use the sunrpc cache mechanism for some of its internal
caches that are populated by userland. These currently use some very
antiquated interfaces in /proc to handle upcalls and downcalls. While it
has worked well for decades and is relatively stable, it has some
problems:

Most notably, it's very difficult to extend to add support for new
export options. There is also the matter of requiring /proc which is not
always desirable in a container.

This patchset adds new netlink-based interfaces for handling the sunrpc
cache upcalls. The basic idea is to add a new "cache_notify" operation
to struct cache_detail. That causes the kernel to send a notification to
userland which then fetches any outstanding cache_requests and then
responds to them via netlink.

There is also a companion patchset for nfs-utils that adds the necessary
support for these interfaces to mountd/exportd and exportfs.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
Jeff Layton (14):
      nfsd: move struct nfsd_genl_rqstp to nfsctl.c
      sunrpc: rename sunrpc_cache_pipe_upcall() to sunrpc_cache_upcall()
      sunrpc: rename sunrpc_cache_pipe_upcall_timeout()
      sunrpc: rename cache_pipe_upcall() to cache_do_upcall()
      sunrpc: add a cache_notify callback
      sunrpc: add helpers to count and snapshot pending cache requests
      sunrpc: add a generic netlink family for cache upcalls
      sunrpc: add netlink upcall for the auth.unix.ip cache
      sunrpc: add netlink upcall for the auth.unix.gid cache
      nfsd: add new netlink spec for svc_export upcall
      nfsd: add netlink upcall for the svc_export cache
      nfsd: add netlink upcall for the nfsd.fh cache
      sunrpc: add SUNRPC_CMD_CACHE_FLUSH netlink command
      nfsd: add NFSD_CMD_CACHE_FLUSH netlink command

 Documentation/netlink/specs/nfsd.yaml         | 239 +++++++++
 Documentation/netlink/specs/sunrpc_cache.yaml | 149 ++++++
 fs/nfs/dns_resolve.c                          |   2 +-
 fs/nfsd/export.c                              | 707 +++++++++++++++++++++++++-
 fs/nfsd/netlink.c                             | 109 +++-
 fs/nfsd/netlink.h                             |  18 +
 fs/nfsd/nfs4idmap.c                           |   4 +-
 fs/nfsd/nfsctl.c                              |  75 +++
 fs/nfsd/nfsd.h                                |  17 +-
 include/linux/sunrpc/cache.h                  |  12 +-
 include/uapi/linux/nfsd_netlink.h             | 133 +++++
 include/uapi/linux/sunrpc_netlink.h           |  84 +++
 net/sunrpc/Makefile                           |   2 +-
 net/sunrpc/auth_gss/svcauth_gss.c             |   2 +-
 net/sunrpc/cache.c                            |  76 ++-
 net/sunrpc/netlink.c                          | 144 ++++++
 net/sunrpc/netlink.h                          |  38 ++
 net/sunrpc/sunrpc_syms.c                      |  10 +
 net/sunrpc/svcauth_unix.c                     | 506 +++++++++++++++++-
 19 files changed, 2287 insertions(+), 40 deletions(-)
---
base-commit: e344b49528c8ef457ee714bb65e2da4c121132c2
change-id: 20260316-exportd-netlink-1c9fb52536e3

Best regards,
-- 
Jeff Layton <jlayton@xxxxxxxxxx>