ext4: Add debugging markers that can be used by systemtap

This debugging markers are designed to debug problems such as the
random filesystem latency problems reported by Arjan.

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

2 files changed, 9 insertions, 0 deletions

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index af4651bf3570..42895d369458 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -20,6 +20,7 @@
 #include <linux/time.h>
 #include <linux/fs.h>
 #include <linux/jbd2.h>
+#include <linux/marker.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
 
@@ -328,6 +329,8 @@ int jbd2_log_do_checkpoint(journal_t *journal)
          * journal straight away.
          */
         result = jbd2_cleanup_journal_tail(journal);
+        trace_mark(jbd2_checkpoint, "dev %s need_checkpoint %d",
+                   journal->j_devname, result);
         jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
         if (result <= 0)
                 return result;
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index b091e5378fe0..e91f051a9859 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -16,6 +16,7 @@
 #include <linux/time.h>
 #include <linux/fs.h>
 #include <linux/jbd2.h>
+#include <linux/marker.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
@@ -368,6 +369,8 @@ void jbd2_journal_commit_transaction(journal_t *journal)
         commit_transaction = journal->j_running_transaction;
         J_ASSERT(commit_transaction->t_state == T_RUNNING);
 
+        trace_mark(jbd2_start_commit, "dev %s transaction %d",
+                   journal->j_devname, commit_transaction->t_tid);
         jbd_debug(1, "JBD: starting commit of transaction %d\n",
                         commit_transaction->t_tid);
 
@@ -985,6 +988,9 @@ restart_loop:
         }
         spin_unlock(&journal->j_list_lock);
 
+        trace_mark(jbd2_end_commit, "dev %s transaction %d head %d",
+                   journal->j_devname, commit_transaction->t_tid,
+                   journal->j_tail_sequence);
         jbd_debug(1, "JBD: commit %d complete, head %d\n",
                   journal->j_commit_sequence, journal->j_tail_sequence);