[PATCH,v2] writeback: show raw dirtied_when in trace writeback_single_inode

[Wu Fengguang <fengguang.wu@intel.com>]

[since v1: added Christoph's ack and make it actually work]

Save inode->dirtied_when in the raw trace output for reliable scripting,
and to also show in formatted output the relative age in seconds for
easy human reading.

CC: Jan Kara <jack@suse.cz>
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 include/trace/events/writeback.h |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- linux-next.orig/include/trace/events/writeback.h	2011-08-29 09:51:12.000000000 +0800
+++ linux-next/include/trace/events/writeback.h	2011-08-29 17:14:16.000000000 +0800
@@ -433,7 +433,7 @@ DECLARE_EVENT_CLASS(writeback_single_ino
 		__array(char, name, 32)
 		__field(unsigned long, ino)
 		__field(unsigned long, state)
-		__field(unsigned long, age)
+		__field(unsigned long, dirtied_when)
 		__field(unsigned long, writeback_index)
 		__field(long, nr_to_write)
 		__field(unsigned long, wrote)
@@ -444,19 +444,19 @@ DECLARE_EVENT_CLASS(writeback_single_ino
 			dev_name(inode->i_mapping->backing_dev_info->dev), 32);
 		__entry->ino		= inode->i_ino;
 		__entry->state		= inode->i_state;
-		__entry->age		= (jiffies - inode->dirtied_when) *
-								1000 / HZ;
+		__entry->dirtied_when	= inode->dirtied_when;
 		__entry->writeback_index = inode->i_mapping->writeback_index;
 		__entry->nr_to_write	= nr_to_write;
 		__entry->wrote		= nr_to_write - wbc->nr_to_write;
 	),
 
-	TP_printk("bdi %s: ino=%lu state=%s age=%lu "
+	TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu "
 		  "index=%lu to_write=%ld wrote=%lu",
 		  __entry->name,
 		  __entry->ino,
 		  show_inode_state(__entry->state),
-		  __entry->age,
+		  __entry->dirtied_when,
+		  (jiffies - __entry->dirtied_when) / HZ,
 		  __entry->writeback_index,
 		  __entry->nr_to_write,
 		  __entry->wrote