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Subject: [PATCH v4 3/8] NFSD: Add tracepoints to report NFSv4 callback
 completions
From:   Chuck Lever <chuck.lever@oracle.com>
To:     linux-nfs@vger.kernel.org
Date:   Thu, 08 Sep 2022 18:13:54 -0400
Message-ID: <166267523469.1842.1189895674276197366.stgit@manet.1015granger.net>
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Wireshark has always been lousy about dissecting NFSv4 callbacks,
especially NFSv4.0 backchannel requests. Add tracepoints so we
can surgically capture these events in the trace log.

Tracepoints are time-stamped and ordered so that we can now observe
the timing relationship between a CB_RECALL Reply and the client's
DELEGRETURN Call. Example:

            nfsd-1153  [002]   211.986391: nfsd_cb_recall:       addr=192.168.1.67:45767 client 62ea82e4:fee7492a stateid 00000003:00000001

            nfsd-1153  [002]   212.095634: nfsd_compound:        xid=0x0000002c opcnt=2
            nfsd-1153  [002]   212.095647: nfsd_compound_status: op=1/2 OP_PUTFH status=0
            nfsd-1153  [002]   212.095658: nfsd_file_put:        hash=0xf72 inode=0xffff9291148c7410 ref=3 flags=HASHED|REFERENCED may=READ file=0xffff929103b3ea00
            nfsd-1153  [002]   212.095661: nfsd_compound_status: op=2/2 OP_DELEGRETURN status=0
   kworker/u25:8-148   [002]   212.096713: nfsd_cb_recall_done:  client 62ea82e4:fee7492a stateid 00000003:00000001 status=0

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs4layouts.c |    2 +-
 fs/nfsd/nfs4proc.c    |    4 ++++
 fs/nfsd/nfs4state.c   |    4 ++++
 fs/nfsd/trace.h       |   39 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index 2c05692a9abf..3564d1c6f610 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -658,7 +658,7 @@ nfsd4_cb_layout_done(struct nfsd4_callback *cb, struct rpc_task *task)
 	ktime_t now, cutoff;
 	const struct nfsd4_layout_ops *ops;
 
-
+	trace_nfsd_cb_layout_done(&ls->ls_stid.sc_stateid, task);
 	switch (task->tk_status) {
 	case 0:
 	case -NFS4ERR_DELAY:
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index d43beb732987..2a193e84e422 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1621,6 +1621,10 @@ static void nfsd4_cb_offload_release(struct nfsd4_callback *cb)
 static int nfsd4_cb_offload_done(struct nfsd4_callback *cb,
 				 struct rpc_task *task)
 {
+	struct nfsd4_cb_offload *cbo =
+		container_of(cb, struct nfsd4_cb_offload, co_cb);
+
+	trace_nfsd_cb_offload_done(&cbo->co_res.cb_stateid, task);
 	return 1;
 }
 
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c5d199d7e6b4..561f3556b1d2 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -357,6 +357,8 @@ nfsd4_cb_notify_lock_prepare(struct nfsd4_callback *cb)
 static int
 nfsd4_cb_notify_lock_done(struct nfsd4_callback *cb, struct rpc_task *task)
 {
+	trace_nfsd_cb_notify_lock_done(&zero_stateid, task);
+
 	/*
 	 * Since this is just an optimization, we don't try very hard if it
 	 * turns out not to succeed. We'll requeue it on NFS4ERR_DELAY, and
@@ -4743,6 +4745,8 @@ static int nfsd4_cb_recall_done(struct nfsd4_callback *cb,
 {
 	struct nfs4_delegation *dp = cb_to_delegation(cb);
 
+	trace_nfsd_cb_recall_done(&dp->dl_stid.sc_stateid, task);
+
 	if (dp->dl_stid.sc_type == NFS4_CLOSED_DELEG_STID ||
 	    dp->dl_stid.sc_type == NFS4_REVOKED_DELEG_STID)
 	        return 1;
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index 0c35a1a844e6..ec8e08315779 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -1448,6 +1448,45 @@ TRACE_EVENT(nfsd_cb_offload,
 		__entry->fh_hash, __entry->count, __entry->status)
 );
 
+DECLARE_EVENT_CLASS(nfsd_cb_done_class,
+	TP_PROTO(
+		const stateid_t *stp,
+		const struct rpc_task *task
+	),
+	TP_ARGS(stp, task),
+	TP_STRUCT__entry(
+		__field(u32, cl_boot)
+		__field(u32, cl_id)
+		__field(u32, si_id)
+		__field(u32, si_generation)
+		__field(int, status)
+	),
+	TP_fast_assign(
+		__entry->cl_boot = stp->si_opaque.so_clid.cl_boot;
+		__entry->cl_id = stp->si_opaque.so_clid.cl_id;
+		__entry->si_id = stp->si_opaque.so_id;
+		__entry->si_generation = stp->si_generation;
+		__entry->status = task->tk_status;
+	),
+	TP_printk("client %08x:%08x stateid %08x:%08x status=%d",
+		__entry->cl_boot, __entry->cl_id, __entry->si_id,
+		__entry->si_generation, __entry->status
+	)
+);
+
+#define DEFINE_NFSD_CB_DONE_EVENT(name)			\
+DEFINE_EVENT(nfsd_cb_done_class, name,			\
+	TP_PROTO(					\
+		const stateid_t *stp,			\
+		const struct rpc_task *task		\
+	),						\
+	TP_ARGS(stp, task))
+
+DEFINE_NFSD_CB_DONE_EVENT(nfsd_cb_recall_done);
+DEFINE_NFSD_CB_DONE_EVENT(nfsd_cb_notify_lock_done);
+DEFINE_NFSD_CB_DONE_EVENT(nfsd_cb_layout_done);
+DEFINE_NFSD_CB_DONE_EVENT(nfsd_cb_offload_done);
+
 #endif /* _NFSD_TRACE_H */
 
 #undef TRACE_INCLUDE_PATH