nfs_common: add nfs_localio trace events

The nfs_localio.ko now exposes /sys/kernel/tracing/events/nfs_localio
with nfs_localio_enable_client and nfs_localio_disable_client events.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

fs/nfs_common/Makefile

@@ -6,8 +6,9 @@
 obj-$(CONFIG_NFS_ACL_SUPPORT) += nfs_acl.o
 nfs_acl-objs := nfsacl.o
 
+CFLAGS_localio_trace.o += -I$(src)
 obj-$(CONFIG_NFS_COMMON_LOCALIO_SUPPORT) += nfs_localio.o
-nfs_localio-objs := nfslocalio.o
+nfs_localio-objs := nfslocalio.o localio_trace.o
 
 obj-$(CONFIG_GRACE_PERIOD) += grace.o
 obj-$(CONFIG_NFS_V4_2_SSC_HELPER) += nfs_ssc.o

fs/nfs_common/localio_trace.c

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2024 Trond Myklebust <trond.myklebust@hammerspace.com>
+ * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
+ */
+#include <linux/nfs_fs.h>
+#include <linux/namei.h>
+
+#define CREATE_TRACE_POINTS
+#include "localio_trace.h"

fs/nfs_common/localio_trace.h

@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2024 Trond Myklebust <trond.myklebust@hammerspace.com>
+ * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM nfs_localio
+
+#if !defined(_TRACE_NFS_COMMON_LOCALIO_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_NFS_COMMON_LOCALIO_H
+
+#include <linux/tracepoint.h>
+
+#include <trace/misc/fs.h>
+#include <trace/misc/nfs.h>
+#include <trace/misc/sunrpc.h>
+
+DECLARE_EVENT_CLASS(nfs_local_client_event,
+		TP_PROTO(
+			const struct nfs_client *clp
+		),
+
+		TP_ARGS(clp),
+
+		TP_STRUCT__entry(
+			__field(unsigned int, protocol)
+			__string(server, clp->cl_hostname)
+		),
+
+		TP_fast_assign(
+			__entry->protocol = clp->rpc_ops->version;
+			__assign_str(server);
+		),
+
+		TP_printk(
+			"server=%s NFSv%u", __get_str(server), __entry->protocol
+		)
+);
+
+#define DEFINE_NFS_LOCAL_CLIENT_EVENT(name) \
+	DEFINE_EVENT(nfs_local_client_event, name, \
+			TP_PROTO( \
+				const struct nfs_client *clp \
+			), \
+			TP_ARGS(clp))
+
+DEFINE_NFS_LOCAL_CLIENT_EVENT(nfs_localio_enable_client);
+DEFINE_NFS_LOCAL_CLIENT_EVENT(nfs_localio_disable_client);
+
+#endif /* _TRACE_NFS_COMMON_LOCALIO_H */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#define TRACE_INCLUDE_FILE localio_trace
+/* This part must be outside protection */
+#include <trace/define_trace.h>

fs/nfs_common/nfslocalio.c

@@ -12,6 +12,8 @@
 #include <linux/nfs_fs.h>
 #include <net/netns/generic.h>
 
+#include "localio_trace.h"
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("NFS localio protocol bypass support");
 
@@ -141,6 +143,7 @@ void nfs_localio_enable_client(struct nfs_client *clp)
 
 	spin_lock(&nfs_uuid->lock);
 	set_bit(NFS_CS_LOCAL_IO, &clp->cl_flags);
+	trace_nfs_localio_enable_client(clp);
 	spin_unlock(&nfs_uuid->lock);
 }
 EXPORT_SYMBOL_GPL(nfs_localio_enable_client);
@@ -199,6 +202,7 @@ void nfs_localio_disable_client(struct nfs_client *clp)
 	if (test_and_clear_bit(NFS_CS_LOCAL_IO, &clp->cl_flags)) {
 		/* &clp->cl_uuid is always not NULL, using as bool here */
 		nfs_uuid = &clp->cl_uuid;
+		trace_nfs_localio_disable_client(clp);
 	}
 	spin_unlock(&clp->cl_uuid.lock);