if (unlikely(dst == old)) /* deadlock avoidance */
return;
bdi_lock_two(&old->wb, &dst->wb);
spin_lock(&inode->i_lock);
inode->i_data.backing_dev_info = dst;
if (unlikely(dst == old)) /* deadlock avoidance */
return;
bdi_lock_two(&old->wb, &dst->wb);
spin_lock(&inode->i_lock);
inode->i_data.backing_dev_info = dst;