jbd2: Use tracepoints for history file

The /proc/fs/jbd2/<dev>/history was maintained manually; by using
tracepoints, we can get all of the existing functionality of the /proc
file plus extra capabilities thanks to the ftrace infrastructure.  We
save memory as a bonus.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 85 insertions, 20 deletions

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 52695d3..f1011f7 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -464,9 +464,9 @@ struct handle_s
  */
 struct transaction_chp_stats_s {
 	unsigned long		cs_chp_time;
-	unsigned long		cs_forced_to_close;
-	unsigned long		cs_written;
-	unsigned long		cs_dropped;
+	__u32			cs_forced_to_close;
+	__u32			cs_written;
+	__u32			cs_dropped;
 };
 
 /* The transaction_t type is the guts of the journaling mechanism.  It
@@ -668,23 +668,16 @@ struct transaction_run_stats_s {
 	unsigned long		rs_flushing;
 	unsigned long		rs_logging;
 
-	unsigned long		rs_handle_count;
-	unsigned long		rs_blocks;
-	unsigned long		rs_blocks_logged;
+	__u32			rs_handle_count;
+	__u32			rs_blocks;
+	__u32			rs_blocks_logged;
 };
 
 struct transaction_stats_s {
-	int 			ts_type;
 	unsigned long		ts_tid;
-	union {
-		struct transaction_run_stats_s run;
-		struct transaction_chp_stats_s chp;
-	} u;
+	struct transaction_run_stats_s run;
 };
 
-#define JBD2_STATS_RUN		1
-#define JBD2_STATS_CHECKPOINT	2
-
 static inline unsigned long
 jbd2_time_diff(unsigned long start, unsigned long end)
 {
@@ -988,12 +981,6 @@ struct journal_s
 	/*
 	 * Journal statistics
 	 */
-	struct transaction_stats_s *j_history;
-	int			j_history_max;
-	int			j_history_cur;
-	/*
-	 * Protect the transactions statistics history
-	 */
 	spinlock_t		j_history_lock;
 	struct proc_dir_entry	*j_proc_entry;
 	struct transaction_stats_s j_stats;
diff --git a/include/trace/events/jbd2.h b/include/trace/events/jbd2.h
index b851f0b..3c60b75 100644
--- a/include/trace/events/jbd2.h
+++ b/include/trace/events/jbd2.h
@@ -7,6 +7,9 @@
 #include <linux/jbd2.h>
 #include <linux/tracepoint.h>
 
+struct transaction_chp_stats_s;
+struct transaction_run_stats_s;
+
 TRACE_EVENT(jbd2_checkpoint,
 
 	TP_PROTO(journal_t *journal, int result),
@@ -162,6 +165,81 @@ TRACE_EVENT(jbd2_submit_inode_data,
 		  jbd2_dev_to_name(__entry->dev), (unsigned long) __entry->ino)
 );
 
+TRACE_EVENT(jbd2_run_stats,
+	TP_PROTO(dev_t dev, unsigned long tid,
+		 struct transaction_run_stats_s *stats),
+
+	TP_ARGS(dev, tid, stats),
+
+	TP_STRUCT__entry(
+		__field(		dev_t,	dev		)
+		__field(	unsigned long,	tid		)
+		__field(	unsigned long,	wait		)
+		__field(	unsigned long,	running		)
+		__field(	unsigned long,	locked		)
+		__field(	unsigned long,	flushing	)
+		__field(	unsigned long,	logging		)
+		__field(		__u32,	handle_count	)
+		__field(		__u32,	blocks		)
+		__field(		__u32,	blocks_logged	)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= dev;
+		__entry->tid		= tid;
+		__entry->wait		= stats->rs_wait;
+		__entry->running	= stats->rs_running;
+		__entry->locked		= stats->rs_locked;
+		__entry->flushing	= stats->rs_flushing;
+		__entry->logging	= stats->rs_logging;
+		__entry->handle_count	= stats->rs_handle_count;
+		__entry->blocks		= stats->rs_blocks;
+		__entry->blocks_logged	= stats->rs_blocks_logged;
+	),
+
+	TP_printk("dev %s tid %lu wait %u running %u locked %u flushing %u "
+		  "logging %u handle_count %u blocks %u blocks_logged %u",
+		  jbd2_dev_to_name(__entry->dev), __entry->tid,
+		  jiffies_to_msecs(__entry->wait),
+		  jiffies_to_msecs(__entry->running),
+		  jiffies_to_msecs(__entry->locked),
+		  jiffies_to_msecs(__entry->flushing),
+		  jiffies_to_msecs(__entry->logging),
+		  __entry->handle_count, __entry->blocks,
+		  __entry->blocks_logged)
+);
+
+TRACE_EVENT(jbd2_checkpoint_stats,
+	TP_PROTO(dev_t dev, unsigned long tid,
+		 struct transaction_chp_stats_s *stats),
+
+	TP_ARGS(dev, tid, stats),
+
+	TP_STRUCT__entry(
+		__field(		dev_t,	dev		)
+		__field(	unsigned long,	tid		)
+		__field(	unsigned long,	chp_time	)
+		__field(		__u32,	forced_to_close	)
+		__field(		__u32,	written		)
+		__field(		__u32,	dropped		)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= dev;
+		__entry->tid		= tid;
+		__entry->chp_time	= stats->cs_chp_time;
+		__entry->forced_to_close= stats->cs_forced_to_close;
+		__entry->written	= stats->cs_written;
+		__entry->dropped	= stats->cs_dropped;
+	),
+
+	TP_printk("dev %s tid %lu chp_time %u forced_to_close %u "
+		  "written %u dropped %u",
+		  jbd2_dev_to_name(__entry->dev), __entry->tid,
+		  jiffies_to_msecs(__entry->chp_time),
+		  __entry->forced_to_close, __entry->written, __entry->dropped)
+);
+
 #endif /* _TRACE_JBD2_H */
 
 /* This part must be outside protection */