[PATCH v5 5/6] nfsd: count NFSv4 callback operations per netns
From: Jeff Layton
Date: Thu Jun 18 2026 - 12:58:31 EST
The NFS server tracks per-operation call counts for the forward channel
(proc4ops) but keeps no statistics for the NFSv4 backchannel (callback)
operations it sends to clients.
Add a per-netns array of percpu counters for callback operations, indexed
by RFC 8881 callback opcode (OP_CB_GETATTR..OP_CB_OFFLOAD), and bump the
relevant counter in nfsd4_run_cb(), which is hit exactly once per callback
that is actually queued.
CB_GETATTR is sent when a GETATTR conflicts with an outstanding write
delegation, which is roughly what the dedicated wdeleg_getattr counter
tracked. The two are not identical: the old counter incremented on every
such conflict, whereas the CB_GETATTR counter only counts callbacks that
are actually queued, so concurrent conflicts that coalesce onto an
already in-flight CB_GETATTR are now counted once rather than once per
conflict. Report the procfs "wdeleg_getattr" line from the CB_GETATTR
counter and drop the now-redundant NFSD_STATS_WDELEG_GETATTR counter, its
helper, and its increment site.
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/nfsd/netns.h | 12 +++++++++++-
fs/nfsd/nfs4callback.c | 7 ++++++-
fs/nfsd/nfs4state.c | 2 --
fs/nfsd/nfsctl.c | 14 ++++++++++++++
fs/nfsd/stats.c | 2 +-
fs/nfsd/stats.h | 5 +++--
6 files changed, 35 insertions(+), 7 deletions(-)
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 03724bef10a7..37daba0d4747 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -53,11 +53,16 @@ enum {
NFSD_STATS_FIRST_NFS4_OP, /* count of individual nfsv4 operations */
NFSD_STATS_LAST_NFS4_OP = NFSD_STATS_FIRST_NFS4_OP + LAST_NFS4_OP,
#define NFSD_STATS_NFS4_OP(op) (NFSD_STATS_FIRST_NFS4_OP + (op))
- NFSD_STATS_WDELEG_GETATTR, /* count of getattr conflict with wdeleg */
#endif
NFSD_STATS_COUNTERS_NUM
};
+/*
+ * Per-netns NFSv4 callback (backchannel) per-operation counters, indexed
+ * directly by RFC 8881 callback opcode (OP_CB_GETATTR..OP_CB_OFFLOAD).
+ */
+#define NFSD_STATS_CB_OPS_NUM (OP_CB_OFFLOAD + 1)
+
/*
* Represents a nfsd "container". With respect to nfsv4 state tracking, the
* fields of interest are the *_id_hashtbls and the *_name_tree. These track
@@ -198,6 +203,11 @@ struct nfsd_net {
/* Per-netns stats counters */
struct percpu_counter counter[NFSD_STATS_COUNTERS_NUM];
+#ifdef CONFIG_NFSD_V4
+ /* Per-netns NFSv4 callback (backchannel) per-operation counters */
+ struct percpu_counter cb_counter[NFSD_STATS_CB_OPS_NUM];
+#endif
+
/* sunrpc svc stats */
struct svc_stat nfsd_svcstats;
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 71dcb448fa0a..9cbcccc26b35 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1925,8 +1925,13 @@ bool nfsd4_run_cb(struct nfsd4_callback *cb)
nfsd41_cb_inflight_begin(clp);
queued = nfsd4_queue_cb(cb);
- if (!queued)
+ if (queued) {
+ if (cb->cb_ops)
+ nfsd_stats_cb_op_inc(net_generic(clp->net, nfsd_net_id),
+ cb->cb_ops->opcode);
+ } else {
nfsd41_cb_inflight_end(clp);
+ }
return queued;
}
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index b830aed7ae39..8f8da1312231 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -9904,7 +9904,6 @@ __be32
nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
struct nfs4_delegation **pdp)
{
- struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
struct nfsd_thread_local_info *ntli = rqstp->rq_private;
struct file_lock_context *ctx;
struct nfs4_delegation *dp = NULL;
@@ -9944,7 +9943,6 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
return 0;
}
- nfsd_stats_wdeleg_getattr_inc(nn);
refcount_inc(&dp->dl_stid.sc_count);
ncf = &dp->dl_cb_fattr;
nfs4_cb_getattr(&dp->dl_cb_fattr);
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index dde026473806..9bedbe7096c3 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -2717,6 +2717,13 @@ static __net_init int nfsd_net_init(struct net *net)
if (retval)
goto out_repcache_error;
+#ifdef CONFIG_NFSD_V4
+ retval = percpu_counter_init_many(nn->cb_counter, 0, GFP_KERNEL,
+ NFSD_STATS_CB_OPS_NUM);
+ if (retval)
+ goto out_cb_counter_error;
+#endif
+
memset(&nn->nfsd_svcstats, 0, sizeof(nn->nfsd_svcstats));
nn->nfsd_svcstats.program = &nfsd_programs[0];
retval = svc_stat_alloc_counts(&nn->nfsd_svcstats);
@@ -2745,6 +2752,10 @@ static __net_init int nfsd_net_init(struct net *net)
out_svcstats_error:
svc_stat_free_counts(&nn->nfsd_svcstats);
out_proc_error:
+#ifdef CONFIG_NFSD_V4
+ percpu_counter_destroy_many(nn->cb_counter, NFSD_STATS_CB_OPS_NUM);
+out_cb_counter_error:
+#endif
percpu_counter_destroy_many(nn->counter, NFSD_STATS_COUNTERS_NUM);
out_repcache_error:
nfsd_idmap_shutdown(net);
@@ -2785,6 +2796,9 @@ static __net_exit void nfsd_net_exit(struct net *net)
nfsd_net_cb_shutdown(nn);
nfsd_proc_stat_shutdown(net);
svc_stat_free_counts(&nn->nfsd_svcstats);
+#ifdef CONFIG_NFSD_V4
+ percpu_counter_destroy_many(nn->cb_counter, NFSD_STATS_CB_OPS_NUM);
+#endif
percpu_counter_destroy_many(nn->counter, NFSD_STATS_COUNTERS_NUM);
nfsd_idmap_shutdown(net);
nfsd_export_shutdown(net);
diff --git a/fs/nfsd/stats.c b/fs/nfsd/stats.c
index f7eaf95e20fc..35d9a5571946 100644
--- a/fs/nfsd/stats.c
+++ b/fs/nfsd/stats.c
@@ -63,7 +63,7 @@ static int nfsd_show(struct seq_file *seq, void *v)
percpu_counter_sum_positive(&nn->counter[NFSD_STATS_NFS4_OP(i)]));
}
seq_printf(seq, "\nwdeleg_getattr %lld",
- percpu_counter_sum_positive(&nn->counter[NFSD_STATS_WDELEG_GETATTR]));
+ percpu_counter_sum_positive(&nn->cb_counter[OP_CB_GETATTR]));
seq_putc(seq, '\n');
#endif
diff --git a/fs/nfsd/stats.h b/fs/nfsd/stats.h
index e4efb0e4e56d..f90cd565f7cb 100644
--- a/fs/nfsd/stats.h
+++ b/fs/nfsd/stats.h
@@ -68,9 +68,10 @@ static inline void nfsd_stats_drc_mem_usage_sub(struct nfsd_net *nn, s64 amount)
}
#ifdef CONFIG_NFSD_V4
-static inline void nfsd_stats_wdeleg_getattr_inc(struct nfsd_net *nn)
+static inline void nfsd_stats_cb_op_inc(struct nfsd_net *nn, u32 opcode)
{
- percpu_counter_inc(&nn->counter[NFSD_STATS_WDELEG_GETATTR]);
+ if (opcode >= OP_CB_GETATTR && opcode <= OP_CB_OFFLOAD)
+ percpu_counter_inc(&nn->cb_counter[opcode]);
}
#endif
#endif /* _NFSD_STATS_H */
--
2.54.0