0001-kernel-trace-open.patch

commit e9c4f51ad2b76ddbf90863c44085574197247ba3
Author: Auke Kok <auke-jan.h.kok@intel.com>
Date:   Tue Jan 27 11:26:00 2009 -0800

    trace: tracer for sys_open() - sreadahead
    
    This tracer monitors regular file open() syscalls. This is a fast
    and low-overhead alternative to strace, and does not allow or
    require to be attached to every process.
    
    Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>

diff --git a/fs/open.c b/fs/open.c
index a3a78ce..bd9eb9d 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -30,6 +30,10 @@
 #include <linux/audit.h>
 #include <linux/falloc.h>
 
+#include <trace/fs.h>
+
+DEFINE_TRACE(do_sys_open);
+
 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	int retval = -ENODEV;
@@ -1039,6 +1043,7 @@ long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
 			} else {
 				fsnotify_open(f->f_path.dentry);
 				fd_install(fd, f);
+				trace_do_sys_open(f, flags, mode, fd);
 			}
 		}
 		putname(tmp);
diff --git a/include/trace/fs.h b/include/trace/fs.h
new file mode 100644
index 0000000..870eec2
--- /dev/null
+++ b/include/trace/fs.h
@@ -0,0 +1,11 @@
+#ifndef _TRACE_FS_H
+#define _TRACE_FS_H
+
+#include <linux/fs.h>
+#include <linux/tracepoint.h>
+
+DECLARE_TRACE(do_sys_open,
+	TPPROTO(struct file *filp, int flags, int mode, long fd),
+		TPARGS(filp, flags, mode, fd));
+
+#endif
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index e2a4ff6..d2a1ec1 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -149,6 +149,15 @@ config CONTEXT_SWITCH_TRACER
 	  This tracer gets called from the context switch and records
 	  all switching of tasks.
 
+config OPEN_TRACER
+	bool "Trace open() calls"
+	depends on DEBUG_KERNEL
+	select TRACING
+	select MARKERS
+	help
+	  This tracer records open() syscalls. These calls are made when
+	  files are accessed on disk.
+
 config BOOT_TRACER
 	bool "Trace boot initcalls"
 	depends on DEBUG_KERNEL
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 349d5a9..7f2a366 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_RING_BUFFER) += ring_buffer.o
 
 obj-$(CONFIG_TRACING) += trace.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
+obj-$(CONFIG_OPEN_TRACER) += trace_open.o
 obj-$(CONFIG_SYSPROF_TRACER) += trace_sysprof.o
 obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
 obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 4d3d381..24c17d2 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -30,6 +30,7 @@ enum trace_type {
 	TRACE_USER_STACK,
 	TRACE_HW_BRANCHES,
 	TRACE_POWER,
+	TRACE_OPEN,
 
 	__TRACE_LAST_TYPE
 };
diff --git a/kernel/trace/trace_open.c b/kernel/trace/trace_open.c
new file mode 100644
index 0000000..7153dfc
--- /dev/null
+++ b/kernel/trace/trace_open.c
@@ -0,0 +1,149 @@
+/*
+ * trace open calls
+ * Copyright (C) 2009 Intel Corporation
+ *
+ * Based extensively on trace_sched_switch.c
+ * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <trace/fs.h>
+
+#include "trace.h"
+
+
+static struct trace_array	*ctx_trace;
+static int __read_mostly	open_trace_enabled;
+static atomic_t			open_ref;
+
+static void probe_do_sys_open(struct file *filp, int flags, int mode, long fd)
+{
+	char *buf;
+	char *fname;
+
+	if (!atomic_read(&open_ref))
+		return;
+
+	if (!open_trace_enabled)
+		return;
+
+	buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return;
+
+	fname = d_path(&filp->f_path, buf, PAGE_SIZE);
+	if (IS_ERR(fname))
+		goto out;
+
+	ftrace_printk("%s: open(\"%s\", %d, %d) = %ld\n",
+		current->comm, fname, flags, mode, fd);
+
+out:
+	kfree(buf);
+}
+
+static void open_trace_reset(struct trace_array *tr)
+{
+	tr->time_start = ftrace_now(tr->cpu);
+	tracing_reset_online_cpus(tr);
+}
+
+static int open_trace_register(void)
+{
+	int ret;
+
+	ret = register_trace_do_sys_open(probe_do_sys_open);
+	if (ret) {
+		pr_info("open trace: Could not activate tracepoint"
+			" probe to do_open\n");
+	}
+
+	return ret;
+}
+
+static void open_trace_unregister(void)
+{
+	unregister_trace_do_sys_open(probe_do_sys_open);
+}
+
+static void open_trace_start(void)
+{
+	long ref;
+
+	ref = atomic_inc_return(&open_ref);
+	if (ref == 1)
+		open_trace_register();
+}
+
+static void open_trace_stop(void)
+{
+	long ref;
+
+	ref = atomic_dec_and_test(&open_ref);
+	if (ref)
+		open_trace_unregister();
+}
+
+void open_trace_start_cmdline_record(void)
+{
+	open_trace_start();
+}
+
+void open_trace_stop_cmdline_record(void)
+{
+	open_trace_stop();
+}
+
+static void open_start_trace(struct trace_array *tr)
+{
+	open_trace_reset(tr);
+	open_trace_start_cmdline_record();
+	open_trace_enabled = 1;
+}
+
+static void open_stop_trace(struct trace_array *tr)
+{
+	open_trace_enabled = 0;
+	open_trace_stop_cmdline_record();
+}
+
+static int open_trace_init(struct trace_array *tr)
+{
+	ctx_trace = tr;
+
+	open_start_trace(tr);
+	return 0;
+}
+
+static void reset_open_trace(struct trace_array *tr)
+{
+	open_stop_trace(tr);
+}
+
+static struct tracer open_trace __read_mostly =
+{
+	.name		= "open",
+	.init		= open_trace_init,
+	.reset		= reset_open_trace,
+};
+
+__init static int init_open_trace(void)
+{
+	int ret = 0;
+
+	if (atomic_read(&open_ref))
+		ret = open_trace_register();
+	if (ret) {
+		pr_info("error registering open trace\n");
+		return ret;
+	}
+	return register_tracer(&open_trace);
+}
+device_initcall(init_open_trace);
+