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>

1 files changed, 28 insertions, 31 deletions

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 26d991d..d4cfd6d 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -410,10 +410,10 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	if (commit_transaction->t_synchronous_commit)
 		write_op = WRITE_SYNC_PLUG;
 	trace_jbd2_commit_locking(journal, commit_transaction);
-	stats.u.run.rs_wait = commit_transaction->t_max_wait;
-	stats.u.run.rs_locked = jiffies;
-	stats.u.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
-						stats.u.run.rs_locked);
+	stats.run.rs_wait = commit_transaction->t_max_wait;
+	stats.run.rs_locked = jiffies;
+	stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
+					      stats.run.rs_locked);
 
 	spin_lock(&commit_transaction->t_handle_lock);
 	while (commit_transaction->t_updates) {
@@ -486,9 +486,9 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	jbd2_journal_switch_revoke_table(journal);
 
 	trace_jbd2_commit_flushing(journal, commit_transaction);
-	stats.u.run.rs_flushing = jiffies;
-	stats.u.run.rs_locked = jbd2_time_diff(stats.u.run.rs_locked,
-					       stats.u.run.rs_flushing);
+	stats.run.rs_flushing = jiffies;
+	stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
+					     stats.run.rs_flushing);
 
 	commit_transaction->t_state = T_FLUSH;
 	journal->j_committing_transaction = commit_transaction;
@@ -523,11 +523,11 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	spin_unlock(&journal->j_state_lock);
 
 	trace_jbd2_commit_logging(journal, commit_transaction);
-	stats.u.run.rs_logging = jiffies;
-	stats.u.run.rs_flushing = jbd2_time_diff(stats.u.run.rs_flushing,
-						 stats.u.run.rs_logging);
-	stats.u.run.rs_blocks = commit_transaction->t_outstanding_credits;
-	stats.u.run.rs_blocks_logged = 0;
+	stats.run.rs_logging = jiffies;
+	stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
+					       stats.run.rs_logging);
+	stats.run.rs_blocks = commit_transaction->t_outstanding_credits;
+	stats.run.rs_blocks_logged = 0;
 
 	J_ASSERT(commit_transaction->t_nr_buffers <=
 		 commit_transaction->t_outstanding_credits);
@@ -695,7 +695,7 @@ start_journal_io:
 				submit_bh(write_op, bh);
 			}
 			cond_resched();
-			stats.u.run.rs_blocks_logged += bufs;
+			stats.run.rs_blocks_logged += bufs;
 
 			/* Force a new descriptor to be generated next
                            time round the loop. */
@@ -988,33 +988,30 @@ restart_loop:
 	J_ASSERT(commit_transaction->t_state == T_COMMIT);
 
 	commit_transaction->t_start = jiffies;
-	stats.u.run.rs_logging = jbd2_time_diff(stats.u.run.rs_logging,
-						commit_transaction->t_start);
+	stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
+					      commit_transaction->t_start);
 
 	/*
-	 * File the transaction for history
+	 * File the transaction statistics
 	 */
-	stats.ts_type = JBD2_STATS_RUN;
 	stats.ts_tid = commit_transaction->t_tid;
-	stats.u.run.rs_handle_count = commit_transaction->t_handle_count;
-	spin_lock(&journal->j_history_lock);
-	memcpy(journal->j_history + journal->j_history_cur, &stats,
-			sizeof(stats));
-	if (++journal->j_history_cur == journal->j_history_max)
-		journal->j_history_cur = 0;
+	stats.run.rs_handle_count = commit_transaction->t_handle_count;
+	trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
+			     commit_transaction->t_tid, &stats.run);
 
 	/*
 	 * Calculate overall stats
 	 */
+	spin_lock(&journal->j_history_lock);
 	journal->j_stats.ts_tid++;
-	journal->j_stats.u.run.rs_wait += stats.u.run.rs_wait;
-	journal->j_stats.u.run.rs_running += stats.u.run.rs_running;
-	journal->j_stats.u.run.rs_locked += stats.u.run.rs_locked;
-	journal->j_stats.u.run.rs_flushing += stats.u.run.rs_flushing;
-	journal->j_stats.u.run.rs_logging += stats.u.run.rs_logging;
-	journal->j_stats.u.run.rs_handle_count += stats.u.run.rs_handle_count;
-	journal->j_stats.u.run.rs_blocks += stats.u.run.rs_blocks;
-	journal->j_stats.u.run.rs_blocks_logged += stats.u.run.rs_blocks_logged;
+	journal->j_stats.run.rs_wait += stats.run.rs_wait;
+	journal->j_stats.run.rs_running += stats.run.rs_running;
+	journal->j_stats.run.rs_locked += stats.run.rs_locked;
+	journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
+	journal->j_stats.run.rs_logging += stats.run.rs_logging;
+	journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
+	journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
+	journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
 	spin_unlock(&journal->j_history_lock);
 
 	commit_transaction->t_state = T_FINISHED;