nfs_finish_open(): don't open-code file_inode()

Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/nfs/dir.c

@@ -2022,7 +2022,7 @@ static int nfs_finish_open(struct nfs_open_context *ctx,
 	err = finish_open(file, dentry, do_open);
 	if (err)
 		goto out;
-	if (S_ISREG(file->f_path.dentry->d_inode->i_mode))
+	if (S_ISREG(file_inode(file)->i_mode))
 		nfs_file_set_open_context(file, ctx);
 	else
 		err = -EOPENSTALE;