nilfs_bmap_lookup and its variants are supposed to take a valid
pointer argument to return a block address, thus pointer checks in
nilfs_btree_lookup and nilfs_direct_lookup are needless.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
                              __u64 key, int level, __u64 *ptrp)
 {
        struct nilfs_btree_path *path;
-       __u64 ptr;
        int ret;
 
        path = nilfs_btree_alloc_path();
        if (path == NULL)
                return -ENOMEM;
 
-       ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level);
-
-       if (ptrp != NULL)
-               *ptrp = ptr;
+       ret = nilfs_btree_do_lookup(btree, path, key, ptrp, level);
 
        nilfs_btree_free_path(path);
 
 
        if (ptr == NILFS_BMAP_INVALID_PTR)
                return -ENOENT;
 
-       if (ptrp != NULL)
-               *ptrp = ptr;
+       *ptrp = ptr;
        return 0;
 }