nfs: pass the correct prototype to read_cache_page

Fix the callbacks NFS passes to read_cache_page to actually have the
proper type expected.  Casting around function pointers can easily
hide typing bugs, and defeats control flow protection.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/dir.c

@@ -714,8 +714,9 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
  * We only need to convert from xdr once so future lookups are much simpler
  */
 static
-int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page* page)
+int nfs_readdir_filler(void *data, struct page* page)
 {
+	nfs_readdir_descriptor_t *desc = data;
 	struct inode	*inode = file_inode(desc->file);
 	int ret;
 
@@ -762,8 +763,8 @@ void cache_page_release(nfs_readdir_descriptor_t *desc)
 static
 struct page *get_cache_page(nfs_readdir_descriptor_t *desc)
 {
-	return read_cache_page(desc->file->f_mapping,
-			desc->page_index, (filler_t *)nfs_readdir_filler, desc);
+	return read_cache_page(desc->file->f_mapping, desc->page_index,
+			nfs_readdir_filler, desc);
 }
 
 /*

fs/nfs/symlink.c

@@ -26,8 +26,9 @@
  * and straight-forward than readdir caching.
  */
 
-static int nfs_symlink_filler(struct inode *inode, struct page *page)
+static int nfs_symlink_filler(void *data, struct page *page)
 {
+	struct inode *inode = data;
 	int error;
 
 	error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE);
@@ -65,8 +66,8 @@ static const char *nfs_get_link(struct dentry *dentry,
 		err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
 		if (err)
 			return err;
-		page = read_cache_page(&inode->i_data, 0,
-					(filler_t *)nfs_symlink_filler, inode);
+		page = read_cache_page(&inode->i_data, 0, nfs_symlink_filler,
+				inode);
 		if (IS_ERR(page))
 			return ERR_CAST(page);
 	}