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nfsd: implement server-stats-get netlink handler

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Implement nfsd_nl_server_stats_get_dumpit() which exposes the
NFS server statistics currently available via /proc/net/rpc/nfsd
through the nfsd generic netlink family.

The handler uses a dump operation to stream statistics across one
or more netlink messages. The reply is divided into sections that
are emitted in order:

  - scalar stats (reply cache, filehandle, IO, network, RPC),
    emitted once in the first message, then

  - per-version procedure counts (proc2/3/4-ops) and the NFSv4
    per-operation counts (proc4ops-ops), using the per-netns
    vs_count arrays.

cb->args[0] tracks the current section and cb->args[1] the entry
index within it, so a section that does not fit in the current
message is closed and resumed in the next one. This matters because
the first dump message is allocated at NLMSG_GOODSIZE (a single page
on most architectures) regardless of the client's receive buffer;
packing every counter into one message would overflow it and fail
the dump with -EMSGSIZE. Userspace merges the attributes from every
message.

This allows nfsstat to retrieve server statistics via netlink
with a procfs fallback for older kernels.

Assisted-by: LLM
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260717-exportd-netlink-v7-3-b7ce17b83b60@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>
This commit is contained in:
Jeff Layton 2026-07-17 07:08:55 -04:00 committed by Chuck Lever
parent c1cd844217
commit 36ed32f46e
5 changed files with 369 additions and 0 deletions
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105
Documentation/netlink/specs/nfsd.yaml
View File

@ -330,6 +330,86 @@ attribute-sets:
of which client holds the state. Intended for use after
all clients have been unexported from a given path,
enabling the underlying filesystem to be unmounted.
-
name: server-proc-entry
attributes:
-
name: op
type: u32
-
name: count
type: u64
-
name: pad
type: pad
-
name: server-stats
attributes:
-
name: rc-hits
type: u64
-
name: rc-misses
type: u64
-
name: rc-nocache
type: u64
-
name: pad
type: pad
-
name: fh-stale
type: u64
-
name: io-read
type: u64
-
name: io-write
type: u64
-
name: netcnt
type: u32
-
name: netudpcnt
type: u32
-
name: nettcpcnt
type: u32
-
name: nettcpconn
type: u32
-
name: rpccnt
type: u32
-
name: rpcbadfmt
type: u32
-
name: rpcbadauth
type: u32
-
name: rpcbadclnt
type: u32
-
name: proc2-ops
type: nest
nested-attributes: server-proc-entry
multi-attr: true
-
name: proc3-ops
type: nest
nested-attributes: server-proc-entry
multi-attr: true
-
name: proc4-ops
type: nest
nested-attributes: server-proc-entry
multi-attr: true
-
name: proc4ops-ops
type: nest
nested-attributes: server-proc-entry
multi-attr: true
operations:
list:
@ -516,6 +596,31 @@ operations:
request:
attributes:
- path
-
name: server-stats-get
doc: dump NFS server statistics
attribute-set: server-stats
dump:
reply:
attributes:
- rc-hits
- rc-misses
- rc-nocache
- fh-stale
- io-read
- io-write
- netcnt
- netudpcnt
- nettcpcnt
- nettcpconn
- rpccnt
- rpcbadfmt
- rpcbadauth
- rpcbadclnt
- proc2-ops
- proc3-ops
- proc4-ops
- proc4ops-ops
mcast-groups:
list:

5
fs/nfsd/netlink.c
View File

@ -225,6 +225,11 @@ static const struct genl_split_ops nfsd_nl_ops[] = {
.maxattr = NFSD_A_UNLOCK_EXPORT_PATH,
.flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
},
{
.cmd = NFSD_CMD_SERVER_STATS_GET,
.dumpit = nfsd_nl_server_stats_get_dumpit,
.flags = GENL_CMD_CAP_DUMP,
},
};
static const struct genl_multicast_group nfsd_nl_mcgrps[] = {

2
fs/nfsd/netlink.h
View File

@ -42,6 +42,8 @@ int nfsd_nl_cache_flush_doit(struct sk_buff *skb, struct genl_info *info);
int nfsd_nl_unlock_ip_doit(struct sk_buff *skb, struct genl_info *info);
int nfsd_nl_unlock_filesystem_doit(struct sk_buff *skb, struct genl_info *info);
int nfsd_nl_unlock_export_doit(struct sk_buff *skb, struct genl_info *info);
int nfsd_nl_server_stats_get_dumpit(struct sk_buff *skb,
struct netlink_callback *cb);
enum {
NFSD_NLGRP_NONE,

222
fs/nfsd/nfsctl.c
View File

@ -2331,6 +2331,228 @@ int nfsd_nl_cache_flush_doit(struct sk_buff *skb, struct genl_info *info)
return 0;
}
/* Emit a single server-proc-entry nest: { op, count }. */
static int nfsd_nl_put_proc_entry(struct sk_buff *skb, int attr,
u32 op, u64 count)
{
struct nlattr *nest;
nest = nla_nest_start(skb, attr);
if (!nest)
return -EMSGSIZE;
if (nla_put_u32(skb, NFSD_A_SERVER_PROC_ENTRY_OP, op) ||
nla_put_u64_64bit(skb, NFSD_A_SERVER_PROC_ENTRY_COUNT,
count, NFSD_A_SERVER_PROC_ENTRY_PAD)) {
nla_nest_cancel(skb, nest);
return -EMSGSIZE;
}
nla_nest_end(skb, nest);
return 0;
}
/* Emit the scalar server-stats counters. Only ever called on a fresh skb. */
static int nfsd_nl_server_stats_scalars(struct sk_buff *skb,
struct nfsd_net *nn,
struct svc_stat *statp)
{
if (nla_put_u64_64bit(skb, NFSD_A_SERVER_STATS_RC_HITS,
percpu_counter_sum_positive(&nn->counter[NFSD_STATS_RC_HITS]),
NFSD_A_SERVER_STATS_PAD) ||
nla_put_u64_64bit(skb, NFSD_A_SERVER_STATS_RC_MISSES,
percpu_counter_sum_positive(&nn->counter[NFSD_STATS_RC_MISSES]),
NFSD_A_SERVER_STATS_PAD) ||
nla_put_u64_64bit(skb, NFSD_A_SERVER_STATS_RC_NOCACHE,
percpu_counter_sum_positive(&nn->counter[NFSD_STATS_RC_NOCACHE]),
NFSD_A_SERVER_STATS_PAD))
return -EMSGSIZE;
if (nla_put_u64_64bit(skb, NFSD_A_SERVER_STATS_FH_STALE,
percpu_counter_sum_positive(&nn->counter[NFSD_STATS_FH_STALE]),
NFSD_A_SERVER_STATS_PAD))
return -EMSGSIZE;
if (nla_put_u64_64bit(skb, NFSD_A_SERVER_STATS_IO_READ,
percpu_counter_sum_positive(&nn->counter[NFSD_STATS_IO_READ]),
NFSD_A_SERVER_STATS_PAD) ||
nla_put_u64_64bit(skb, NFSD_A_SERVER_STATS_IO_WRITE,
percpu_counter_sum_positive(&nn->counter[NFSD_STATS_IO_WRITE]),
NFSD_A_SERVER_STATS_PAD))
return -EMSGSIZE;
if (nla_put_u32(skb, NFSD_A_SERVER_STATS_NETCNT, statp->netcnt) ||
nla_put_u32(skb, NFSD_A_SERVER_STATS_NETUDPCNT, statp->netudpcnt) ||
nla_put_u32(skb, NFSD_A_SERVER_STATS_NETTCPCNT, statp->nettcpcnt) ||
nla_put_u32(skb, NFSD_A_SERVER_STATS_NETTCPCONN, statp->nettcpconn))
return -EMSGSIZE;
if (nla_put_u32(skb, NFSD_A_SERVER_STATS_RPCCNT, statp->rpccnt) ||
nla_put_u32(skb, NFSD_A_SERVER_STATS_RPCBADFMT, statp->rpcbadfmt) ||
nla_put_u32(skb, NFSD_A_SERVER_STATS_RPCBADAUTH, statp->rpcbadauth) ||
nla_put_u32(skb, NFSD_A_SERVER_STATS_RPCBADCLNT, statp->rpcbadclnt))
return -EMSGSIZE;
return 0;
}
/*
* Emit per-version procedure counts for one NFS version, resuming at *idx.
* Returns 0 when the version has been fully emitted (or is not present), or
* -EMSGSIZE when @skb filled up, leaving *idx at the entry still to emit.
*/
static int nfsd_nl_server_stats_proc(struct sk_buff *skb,
struct svc_stat *statp,
struct svc_program *prog,
unsigned int ver, int attr, int *idx)
{
unsigned long __percpu *counts;
unsigned int nproc;
if (!statp->vs_count || ver >= prog->pg_nvers ||
!prog->pg_vers[ver] || !statp->vs_count[ver])
return 0;
counts = statp->vs_count[ver];
nproc = prog->pg_vers[ver]->vs_nproc;
for (; *idx < nproc; (*idx)++) {
unsigned long count = 0;
int cpu;
for_each_possible_cpu(cpu)
count += per_cpu(counts[*idx], cpu);
if (!count)
continue;
if (nfsd_nl_put_proc_entry(skb, attr, *idx, count))
return -EMSGSIZE;
}
return 0;
}
#ifdef CONFIG_NFSD_V4
/*
* Emit NFSv4 per-operation counts, resuming at *idx. Same return convention
* as nfsd_nl_server_stats_proc().
*/
static int nfsd_nl_server_stats_nfs4ops(struct sk_buff *skb,
struct nfsd_net *nn, int *idx)
{
for (; *idx <= LAST_NFS4_OP; (*idx)++) {
u64 cnt = percpu_counter_sum_positive(
&nn->counter[NFSD_STATS_NFS4_OP(*idx)]);
if (!cnt)
continue;
if (nfsd_nl_put_proc_entry(skb, NFSD_A_SERVER_STATS_PROC4OPS_OPS,
*idx, cnt))
return -EMSGSIZE;
}
return 0;
}
#endif
/* Sections of the server-stats dump, emitted in order across messages. */
enum {
NFSD_SERVER_STATS_SCALARS = 0,
NFSD_SERVER_STATS_PROC2,
NFSD_SERVER_STATS_PROC3,
NFSD_SERVER_STATS_PROC4,
NFSD_SERVER_STATS_PROC4OPS,
NFSD_SERVER_STATS_DONE,
};
/**
* nfsd_nl_server_stats_get_dumpit - dump NFS server statistics
* @skb: reply buffer
* @cb: netlink metadata and command arguments
*
* The server-stats object is emitted across one or more netlink messages.
* cb->args[0] tracks the current section and cb->args[1] the entry index
* within it, so a section that does not fit in the current message is resumed
* in the next one. The scalar counters are small and emitted once, in the
* first message; userspace merges the attributes from every message.
*
* Returns the size of the reply or a negative errno.
*/
int nfsd_nl_server_stats_get_dumpit(struct sk_buff *skb,
struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
struct svc_stat *statp = &nn->nfsd_svcstats;
struct svc_program *prog = statp->program;
int section = cb->args[0];
int idx = cb->args[1];
void *hdr;
if (section >= NFSD_SERVER_STATS_DONE)
return 0;
hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, &nfsd_nl_family,
NLM_F_MULTI, NFSD_CMD_SERVER_STATS_GET);
if (!hdr)
return -ENOBUFS;
/* Scalar stats fit easily and are emitted in the first message. */
if (section == NFSD_SERVER_STATS_SCALARS) {
if (nfsd_nl_server_stats_scalars(skb, nn, statp))
goto err_cancel;
section = NFSD_SERVER_STATS_PROC2;
idx = 0;
}
/*
* Emit as many of the remaining sections as fit. A section returning
* -EMSGSIZE means the message is full: close it and resume from the
* same section/index on the next call with a fresh skb. Each entry is
* small enough to fit in a fresh skb, so forward progress is assured.
*/
while (section < NFSD_SERVER_STATS_DONE) {
int ret = 0;
switch (section) {
case NFSD_SERVER_STATS_PROC2:
ret = nfsd_nl_server_stats_proc(skb, statp, prog, 2,
NFSD_A_SERVER_STATS_PROC2_OPS, &idx);
break;
case NFSD_SERVER_STATS_PROC3:
ret = nfsd_nl_server_stats_proc(skb, statp, prog, 3,
NFSD_A_SERVER_STATS_PROC3_OPS, &idx);
break;
case NFSD_SERVER_STATS_PROC4:
ret = nfsd_nl_server_stats_proc(skb, statp, prog, 4,
NFSD_A_SERVER_STATS_PROC4_OPS, &idx);
break;
#ifdef CONFIG_NFSD_V4
case NFSD_SERVER_STATS_PROC4OPS:
ret = nfsd_nl_server_stats_nfs4ops(skb, nn, &idx);
break;
#endif
}
if (ret == -EMSGSIZE)
goto out;
if (ret)
goto err_cancel;
section++;
idx = 0;
}
out:
genlmsg_end(skb, hdr);
cb->args[0] = section;
cb->args[1] = idx;
return skb->len;
err_cancel:
genlmsg_cancel(skb, hdr);
return -EMSGSIZE;
}
int nfsd_cache_notify(struct cache_detail *cd, struct cache_head *h, u32 cache_type)
{
struct genlmsghdr *hdr;

35
include/uapi/linux/nfsd_netlink.h
View File

@ -225,6 +225,40 @@ enum {
NFSD_A_UNLOCK_EXPORT_MAX = (__NFSD_A_UNLOCK_EXPORT_MAX - 1)
};
enum {
NFSD_A_SERVER_PROC_ENTRY_OP = 1,
NFSD_A_SERVER_PROC_ENTRY_COUNT,
NFSD_A_SERVER_PROC_ENTRY_PAD,
__NFSD_A_SERVER_PROC_ENTRY_MAX,
NFSD_A_SERVER_PROC_ENTRY_MAX = (__NFSD_A_SERVER_PROC_ENTRY_MAX - 1)
};
enum {
NFSD_A_SERVER_STATS_RC_HITS = 1,
NFSD_A_SERVER_STATS_RC_MISSES,
NFSD_A_SERVER_STATS_RC_NOCACHE,
NFSD_A_SERVER_STATS_PAD,
NFSD_A_SERVER_STATS_FH_STALE,
NFSD_A_SERVER_STATS_IO_READ,
NFSD_A_SERVER_STATS_IO_WRITE,
NFSD_A_SERVER_STATS_NETCNT,
NFSD_A_SERVER_STATS_NETUDPCNT,
NFSD_A_SERVER_STATS_NETTCPCNT,
NFSD_A_SERVER_STATS_NETTCPCONN,
NFSD_A_SERVER_STATS_RPCCNT,
NFSD_A_SERVER_STATS_RPCBADFMT,
NFSD_A_SERVER_STATS_RPCBADAUTH,
NFSD_A_SERVER_STATS_RPCBADCLNT,
NFSD_A_SERVER_STATS_PROC2_OPS,
NFSD_A_SERVER_STATS_PROC3_OPS,
NFSD_A_SERVER_STATS_PROC4_OPS,
NFSD_A_SERVER_STATS_PROC4OPS_OPS,
__NFSD_A_SERVER_STATS_MAX,
NFSD_A_SERVER_STATS_MAX = (__NFSD_A_SERVER_STATS_MAX - 1)
};
enum {
NFSD_CMD_RPC_STATUS_GET = 1,
NFSD_CMD_THREADS_SET,
@ -244,6 +278,7 @@ enum {
NFSD_CMD_UNLOCK_IP,
NFSD_CMD_UNLOCK_FILESYSTEM,
NFSD_CMD_UNLOCK_EXPORT,
NFSD_CMD_SERVER_STATS_GET,
__NFSD_CMD_MAX,
NFSD_CMD_MAX = (__NFSD_CMD_MAX - 1)