ext4_convert_unwritten_extents
extern int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
ret2 = ext4_convert_unwritten_extents(NULL,
ret = ext4_convert_unwritten_extents(handle, io_end->inode,
error = ext4_convert_unwritten_extents(NULL, inode, pos, size);