NFS: Refactor trace_nfs4_offload_cancel

Add a trace_nfs4_offload_status trace point that looks just like
trace_nfs4_offload_cancel. Promote that event to an event class to
avoid duplicating code.

An alternative approach would be to expand trace_nfs4_offload_status
to report more of the actual OFFLOAD_STATUS result.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Link: https://lore.kernel.org/r/20250113153235.48706-16-cel@kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: chucklever

fs/nfs/nfs42proc.c

@@ -648,6 +648,7 @@ _nfs42_proc_offload_status(struct nfs_server *server, struct file *file,
 	status = nfs4_call_sync(server->client, server, &msg,
 				&data->args.osa_seq_args,
 				&data->res.osr_seq_res, 1);
+	trace_nfs4_offload_status(&data->args, status);
 	switch (status) {
 	case 0:
 		break;

fs/nfs/nfs4trace.h

@@ -2608,7 +2608,7 @@ TRACE_EVENT(nfs4_copy_notify,
 		)
 );
 
-TRACE_EVENT(nfs4_offload_cancel,
+DECLARE_EVENT_CLASS(nfs4_offload_class,
 		TP_PROTO(
 			const struct nfs42_offload_status_args *args,
 			int error
@@ -2640,6 +2640,15 @@ TRACE_EVENT(nfs4_offload_cancel,
 			__entry->stateid_seq, __entry->stateid_hash
 		)
 );
+#define DEFINE_NFS4_OFFLOAD_EVENT(name) \
+	DEFINE_EVENT(nfs4_offload_class, name,  \
+			TP_PROTO( \
+				const struct nfs42_offload_status_args *args, \
+				int error \
+			), \
+			TP_ARGS(args, error))
+DEFINE_NFS4_OFFLOAD_EVENT(nfs4_offload_cancel);
+DEFINE_NFS4_OFFLOAD_EVENT(nfs4_offload_status);
 
 DECLARE_EVENT_CLASS(nfs4_xattr_event,
 		TP_PROTO(