ext4_double_up_write_data_sem
extern void ext4_double_up_write_data_sem(struct inode *orig_inode,
ext4_double_up_write_data_sem(inode, inode_bl);
ext4_double_up_write_data_sem(orig_inode, donor_inode);
ext4_double_up_write_data_sem(orig_inode, donor_inode);