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 52695d3dfd0..f1011f7f3d4 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 b851f0b4701..3c60b75adb9 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 */