[PATCH v6 0/6] nfsd/sunrpc: convert nfsstat server-side interfaces to use netlink

This version fixes a few problems that Chuck and Sashiko pointed
out in review.

The nfsstat tool currently scrapes /proc/net/rpc/nfsd for server
statistics. This procfs interface has several limitations: the
counters are global (not network-namespace-aware), the format is
fragile to parse, and it cannot be extended without breaking
existing parsers.

This series adds per-network-namespace procedure call counts to
the sunrpc layer and exposes them through a new netlink handler
in the nfsd generic netlink family, allowing nfsstat to retrieve
server statistics via netlink with a procfs fallback for older
kernels. The nfs-utils patch for that part is already merged.

Additionally, this version adds tracking of callback operation counts.

Signed-off-by: Jeff Layton <[email protected]>
---
Changes in v6:
- Emit the entire server-stats object in a single netlink dump message
- Count CB_SEQUENCE on v4.1+ callbacks, for parity with the forechannel SEQUENCE count
- Fix a use-after-free in nfsd4_run_cb() by snapshotting the opcode, net, and minorversion
- Link to v5: https://lore.kernel.org/r/20260618-exportd-netlink-v5-0-e9aef947af3d-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org

Changes in v5:
- Add NFSv4 callback call counts to nfsstat upcall
- Link to v4: https://lore.kernel.org/r/20260616-exportd-netlink-v4-0-03505aee3883-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org

Changes in v4:
- Ensure error is returned when nla_put_*() calls fail
- Link to v3: https://lore.kernel.org/r/20260609-exportd-netlink-v3-0-aa5508a5bb1d-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org

Changes in v3:
- Only increment per-net stats for the "primary" program
- Link to v2: https://lore.kernel.org/r/20260525-exportd-netlink-v2-0-40003fed450c-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org

---
Jeff Layton (6):
      sunrpc: add per-netns per-procedure call counts to svc_stat
      sunrpc: use per-net counts in svc_seq_show()
      nfsd: implement server-stats-get netlink handler
      sunrpc: remove unused svc_version vs_count field
      nfsd: count NFSv4 callback operations per netns
      nfsd: export NFSv4 callback op stats via netlink

 Documentation/netlink/specs/nfsd.yaml | 111 +++++++++++++++++
 fs/lockd/svc4proc.c                   |   4 -
 fs/lockd/svcproc.c                    |   7 --
 fs/nfs/callback_xdr.c                 |   6 -
 fs/nfsd/localio.c                     |   3 -
 fs/nfsd/netlink.c                     |   5 +
 fs/nfsd/netlink.h                     |   2 +
 fs/nfsd/netns.h                       |  12 +-
 fs/nfsd/nfs2acl.c                     |   3 -
 fs/nfsd/nfs3acl.c                     |   3 -
 fs/nfsd/nfs3proc.c                    |   3 -
 fs/nfsd/nfs4callback.c                |  22 +++-
 fs/nfsd/nfs4proc.c                    |   3 -
 fs/nfsd/nfs4state.c                   |   2 -
 fs/nfsd/nfsctl.c                      | 222 +++++++++++++++++++++++++++++++++-
 fs/nfsd/nfsproc.c                     |   3 -
 fs/nfsd/stats.c                       |   2 +-
 fs/nfsd/stats.h                       |   5 +-
 include/linux/sunrpc/stats.h          |   6 +
 include/linux/sunrpc/svc.h            |   1 -
 include/uapi/linux/nfsd_netlink.h     |  36 ++++++
 net/sunrpc/stats.c                    |   2 +-
 net/sunrpc/svc.c                      |  63 +++++++++-
 23 files changed, 479 insertions(+), 47 deletions(-)
---
base-commit: 6f90c7618528b5ca5887f8c6057f26dcc7a27a99
change-id: 20260316-exportd-netlink-1c9fb52536e3

Best regards,
-- 
Jeff Layton <[email protected]>