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>

Conflicts:
	fs/f2fs/data.c

Change-Id: I4153a8bd8bd5fb46c42c2917ec3405e3b4a4dce8
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 3c1cdc0..909261e 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1092,8 +1092,14 @@
 
 	err = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
 							get_data_block);
+
+	trace_f2fs_direct_IO_enter(inode, offset, count, rw);
+
 	if (err < 0 && (rw & WRITE))
 		f2fs_write_failed(mapping, offset + count);
+
+	trace_f2fs_direct_IO_exit(inode, offset, count, rw, err);
+
 	return err;
 }