nilfs2: remove redundant pointer checks in bmap lookup functions

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: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/btree.c

@@ -555,17 +555,13 @@ static int nilfs_btree_lookup(const struct nilfs_bmap *btree,
 			      __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);
 

fs/nilfs2/direct.c

@@ -56,8 +56,7 @@ static int nilfs_direct_lookup(const struct nilfs_bmap *direct,
 	if (ptr == NILFS_BMAP_INVALID_PTR)
 		return -ENOENT;
 
-	if (ptrp != NULL)
-		*ptrp = ptr;
+	*ptrp = ptr;
 	return 0;
 }