hfs/hfxplus: use kzalloc_flex()

Instead of doing the math manually, use kzalloc_flex() which does it in
a cleaner way.

Also clarifies which is the flexible array member.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/20260425014441.441252-1-rosenp@gmail.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>

Author: neheb

fs/hfs/bnode.c

@@ -344,17 +344,15 @@ static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
 	struct hfs_bnode *node, *node2;
 	struct address_space *mapping;
 	struct page *page;
-	int size, block, i, hash;
+	int block, i, hash;
 	loff_t off;
 
 	if (cnid >= tree->node_count) {
 		pr_err("request for non-existent node %d in B*Tree\n", cnid);
 		return NULL;
 	}
 
-	size = sizeof(struct hfs_bnode) + tree->pages_per_bnode *
-		sizeof(struct page *);
-	node = kzalloc(size, GFP_KERNEL);
+	node = kzalloc_flex(*node, page, tree->pages_per_bnode, GFP_KERNEL);
 	if (!node)
 		return NULL;
 	node->tree = tree;

fs/hfsplus/bnode.c

@@ -455,7 +455,7 @@ static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
 	struct hfs_bnode *node, *node2;
 	struct address_space *mapping;
 	struct page *page;
-	int size, block, i, hash;
+	int block, i, hash;
 	loff_t off;
 
 	if (cnid >= tree->node_count) {
@@ -464,9 +464,7 @@ static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
 		return NULL;
 	}
 
-	size = sizeof(struct hfs_bnode) + tree->pages_per_bnode *
-		sizeof(struct page *);
-	node = kzalloc(size, GFP_KERNEL);
+	node = kzalloc_flex(*node, page, tree->pages_per_bnode);
 	if (!node)
 		return NULL;
 	node->tree = tree;