f2fs: add tracepoint for f2fs_direct_IO

This patch adds a tracepoint for f2fs_direct_IO.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index ec3c886..03313099 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1086,9 +1086,14 @@
 	/* clear fsync mark to recover these blocks */
 	fsync_mark_clear(F2FS_SB(inode->i_sb), inode->i_ino);
 
+	trace_f2fs_direct_IO_enter(inode, offset, count, rw);
+
 	err = blockdev_direct_IO(rw, iocb, inode, iter, offset, get_data_block);
 	if (err < 0 && (rw & WRITE))
 		f2fs_write_failed(mapping, offset + count);
+
+	trace_f2fs_direct_IO_exit(inode, offset, count, rw, err);
+
 	return err;
 }