[PATCH] vfs: Add a trace point in the mark_inode_dirty function

[Arjan van de Ven <arjan@infradead.org>]

long time overdue to clean this guy up;
this patch adds a very basic trace point for tracking who dirties an inode
(this is the guy who is the real cause for a disk to spin up, so PowerTOP would
like to know this...)

compared to earlier patches the trace point is done a lot simpler, and consistent with how others
(ext4 etc) do their vfs level tracepoints; with a device number and inode number


>From 880a17e27f0b90d32c0c0b9cf4cd9b4e5d779c73 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan@linux.intel.com>
Date: Fri, 26 Nov 2010 12:18:03 -0800
Subject: [PATCH] vfs: Add a trace point in the mark_inode_dirty function

PowerTOP would like to be able to show who is keeping the disk
busy by dirtying data. The most logical spot for this is in the vfs
in the mark_inode_dirty() function, doing this on the block level
is not possible because by the time the IO hits the block layer the
guilty party can no longer be found ("kjournald" and "pdflush" are not
useful answers to "who caused this file to be dirty).

The trace point follows the same logic/style as the block_dump code
and pretty much dumps the same data, just not to dmesg (and thus to
/var/log/messages) but via the trace events streams.

Eventually we should be able to phase out the block dump code, but that's
for later on after a transition time.

Signed-of-by: Arjan van de Ven <arjan@linux.intel.com>
---
 fs/fs-writeback.c          |    4 ++++
 fs/inode.c                 |    4 ++++
 include/trace/events/vfs.h |   35 +++++++++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 0 deletions(-)
 create mode 100644 include/trace/events/vfs.h

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 3d06ccc..6c93517 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -27,6 +27,7 @@
 #include <linux/backing-dev.h>
 #include <linux/buffer_head.h>
 #include <linux/tracepoint.h>
+#include <trace/events/vfs.h>
 #include "internal.h"
 
 /*
@@ -942,6 +943,9 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 			sb->s_op->dirty_inode(inode);
 	}
 
+	if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES))
+		trace_inode_dirty(inode);
+
 	/*
 	 * make sure that changes are seen by all cpus before we test i_state
 	 * -- mikulas
diff --git a/fs/inode.c b/fs/inode.c
index ae2727a..e8b1d42 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1708,3 +1708,7 @@ void inode_init_owner(struct inode *inode, const struct inode *dir,
 	inode->i_mode = mode;
 }
 EXPORT_SYMBOL(inode_init_owner);
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/vfs.h>
+
diff --git a/include/trace/events/vfs.h b/include/trace/events/vfs.h
new file mode 100644
index 0000000..7e5c135
--- /dev/null
+++ b/include/trace/events/vfs.h
@@ -0,0 +1,35 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM vfs
+
+#if !defined(_TRACE_VFS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_VFS_H
+
+/*
+ * Tracepoint for dirtying an inode:
+ */
+TRACE_EVENT(inode_dirty,
+
+	TP_PROTO(struct inode *inode),
+
+	TP_ARGS(inode),
+
+	TP_STRUCT__entry(
+		__field(	int,	dev_major		)
+		__field(	int,	dev_minor		)
+		__field(	ino_t,	ino			)
+	),
+
+	TP_fast_assign(
+		__entry->dev_major = MAJOR(inode->i_sb->s_dev);
+		__entry->dev_minor = MINOR(inode->i_sb->s_dev);
+		__entry->ino	   = inode->i_ino;
+	),
+
+	TP_printk("dev %d,%d ino %lu ", __entry->dev_major, __entry->dev_minor,
+		  (unsigned long) __entry->ino)
+);
+
+#endif /* _TRACE_VFS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
1.7.2.3


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
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