[PATCH v4 0/4] nfsd/sunrpc: convert nfsstat server-side interfaces to use netlink

This version just fixes an error handling bug that Sashiko noticed.

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.

Patch 1 adds per-netns per-procedure percpu call count arrays to
struct svc_stat, allocated alongside the nfsd_net lifecycle.

Patch 2 switches svc_seq_show() to read from the per-netns
counters, making /proc/net/rpc/nfsd namespace-aware. Note that this
is a behavior change, but I think it's a desirable one.

Patch 3 implements the server-stats-get netlink dump handler,
streaming reply-cache, filehandle, IO, network, and RPC
statistics plus per-version and per-operation procedure counts.

Patch 4 removes the now-unused global svc_version vs_count
percpu arrays from nfsd, lockd, and the NFS client callback
service.

I'll also be sending an nfs-utils patch to convert nfsstat to use the
new interfaces.

Signed-off-by: Jeff Layton <[email protected]>
---
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 (4):
      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

 Documentation/netlink/specs/nfsd.yaml | 105 +++++++++++++++++
 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/nfs2acl.c                     |   3 -
 fs/nfsd/nfs3acl.c                     |   3 -
 fs/nfsd/nfs3proc.c                    |   3 -
 fs/nfsd/nfs4proc.c                    |   3 -
 fs/nfsd/nfsctl.c                      | 214 +++++++++++++++++++++++++++++++++-
 fs/nfsd/nfsproc.c                     |   3 -
 include/linux/sunrpc/stats.h          |   6 +
 include/linux/sunrpc/svc.h            |   1 -
 include/uapi/linux/nfsd_netlink.h     |  35 ++++++
 net/sunrpc/stats.c                    |  56 ++++++++-
 net/sunrpc/svc.c                      |   9 +-
 18 files changed, 428 insertions(+), 40 deletions(-)
---
base-commit: c13952992d5459add7732eb4876eebfeec03af58
change-id: 20260316-exportd-netlink-1c9fb52536e3

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