[PATCH 3/5] fs: add trace events for freeze_super() and thaw_super()

[Frank Sorenson <sorenson@redhat.com>]

There is currently no visibility into when or how
a filesystem became frozen, and no record of freeze/
thaw activity.  Add tracepoints for these events.

Signed-off-by: Frank Sorenson <sorenson@redhat.com>
---
 include/trace/events/fs.h | 109 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 include/trace/events/fs.h

diff --git a/include/trace/events/fs.h b/include/trace/events/fs.h
new file mode 100644
index 0000000..d7d933e
--- /dev/null
+++ b/include/trace/events/fs.h
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2016 Red Hat, Inc., All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM fs
+#define TRACE_INCLUDE_FILE fs
+
+#if !defined(_TRACE_FS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_FS_H_
+#include <linux/tracepoint.h>
+
+struct block_device;
+struct super_block;
+#include <linux/fs.h>
+
+#define SUPER_ID_MAX_LEN FIELD_SIZEOF(struct super_block, s_id)
+#define FSTYPE_MAX_LEN 32 /* choose an arbitrary limit */
+
+DECLARE_EVENT_CLASS(super_freezethaw_class,
+	TP_PROTO(struct super_block *sb),
+	TP_ARGS(sb),
+	TP_STRUCT__entry(
+		__array(char,	comm,		TASK_COMM_LEN		)
+		__array(char,	super_id,	SUPER_ID_MAX_LEN	)
+		__array(char,	fstype,		FSTYPE_MAX_LEN		)
+		__field(dev_t,	dev					)
+		__field(int,	frozen					)
+		__field(pid_t,	pid					)
+	),
+	TP_fast_assign(
+		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+		memcpy(__entry->super_id, sb->s_id, SUPER_ID_MAX_LEN);
+		memcpy(__entry->fstype, sb->s_type->name, FSTYPE_MAX_LEN);
+		__entry->dev = sb->s_dev;
+		__entry->frozen = sb->s_writers.frozen;
+		__entry->pid	= current->pid;
+	),
+	TP_printk("comm=%s pid=%d for %s filesystem '%s' (%d:%d) frozen=%d",
+		__entry->comm, __entry->pid, __entry->fstype,
+		__entry->super_id,
+		MAJOR(__entry->dev), MINOR(__entry->dev),
+		__entry->frozen
+	)
+);
+
+DECLARE_EVENT_CLASS(super_freezethaw_exit_class,
+	TP_PROTO(struct super_block *sb, int ret),
+	TP_ARGS(sb, ret),
+	TP_STRUCT__entry(
+		__array(char,	comm,		TASK_COMM_LEN		)
+		__array(char,	super_id,	SUPER_ID_MAX_LEN	)
+		__array(char,	fstype,		FSTYPE_MAX_LEN		)
+		__field(dev_t,	dev					)
+		__field(int,	frozen					)
+		__field(pid_t,	pid					)
+		__field(int,	ret					)
+	),
+	TP_fast_assign(
+		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+		memcpy(__entry->super_id, sb->s_id, SUPER_ID_MAX_LEN);
+		memcpy(__entry->fstype, sb->s_type->name, FSTYPE_MAX_LEN);
+		__entry->dev = sb->s_dev;
+		__entry->frozen = sb->s_writers.frozen;
+		__entry->pid	= current->pid;
+		__entry->ret = ret;
+	),
+	TP_printk("comm=%s pid=%d for %s filesystem '%s' (%d:%d) frozen=%d ret=%d",
+		__entry->comm, __entry->pid, __entry->fstype,
+		__entry->super_id,
+		MAJOR(__entry->dev), MINOR(__entry->dev),
+		__entry->frozen, __entry->ret
+	)
+);
+
+DEFINE_EVENT(super_freezethaw_class, freeze_super_enter,
+	TP_PROTO(struct super_block *sb),
+	TP_ARGS(sb)
+);
+DEFINE_EVENT(super_freezethaw_exit_class, freeze_super_exit,
+	TP_PROTO(struct super_block *sb, int ret),
+	TP_ARGS(sb, ret)
+);
+
+DEFINE_EVENT(super_freezethaw_class, thaw_super_enter,
+	TP_PROTO(struct super_block *sb),
+	TP_ARGS(sb)
+);
+DEFINE_EVENT(super_freezethaw_exit_class, thaw_super_exit,
+	TP_PROTO(struct super_block *sb, int ret),
+	TP_ARGS(sb, ret)
+);
+
+#endif /* _TRACE_FS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
1.8.3.1