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, 7 insertions, 0 deletions

diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index c37d1e86f51a..5afe4370840b 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -28,6 +28,7 @@
 #include <linux/writeback.h>
 #include <linux/jbd2.h>
 #include <linux/blkdev.h>
+#include <linux/marker.h>
 #include "ext4.h"
 #include "ext4_jbd2.h"
 
@@ -51,6 +52,10 @@ int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync)
 
         J_ASSERT(ext4_journal_current_handle() == NULL);
 
+        trace_mark(ext4_sync_file, "dev %s datasync %d ino %ld parent %ld",
+                   inode->i_sb->s_id, datasync, inode->i_ino,
+                   dentry->d_parent->d_inode->i_ino);
+
         /*
          * data=writeback:
          *  The caller's filemap_fdatawrite()/wait will sync the data.
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index dfcd41fafb9f..9c0214689de0 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -35,6 +35,7 @@
 #include <linux/quotaops.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
+#include <linux/marker.h>
 #include <linux/log2.h>
 #include <linux/crc16.h>
 #include <asm/uaccess.h>
@@ -2951,6 +2952,7 @@ static int ext4_sync_fs(struct super_block *sb, int wait)
 {
         tid_t target;
 
+        trace_mark(ext4_sync_fs, "dev %s wait %d", sb->s_id, wait);
         sb->s_dirt = 0;
         if (jbd2_journal_start_commit(EXT4_SB(sb)->s_journal, &target)) {
                 if (wait)