f2fs: add some tracepoints to debug volatile and atomic writes

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 486113d..241b987 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1287,9 +1287,11 @@
 			need_inplace_update(inode))) {
 		rewrite_data_page(page, fio);
 		set_inode_flag(F2FS_I(inode), FI_UPDATE_WRITE);
+		trace_f2fs_do_write_data_page(page, IPU);
 	} else {
 		write_data_page(page, &dn, fio);
 		f2fs_update_extent_cache(&dn);
+		trace_f2fs_do_write_data_page(page, OPU);
 		set_inode_flag(F2FS_I(inode), FI_APPEND_WRITE);
 		if (page->index == 0)
 			set_inode_flag(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);