ext4_find_shared
partial = ext4_find_shared(inode, n, offsets, chain, &nr);
partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);