don't open-code file_inode()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/target/target_core_configfs.c

@@ -143,7 +143,7 @@ static ssize_t target_core_item_dbroot_store(struct config_item *item,
 		pr_err("db_root: cannot open: %s\n", db_root_stage);
 		return -EINVAL;
 	}
-	if (!S_ISDIR(fp->f_inode->i_mode)) {
+	if (!S_ISDIR(file_inode(fp)->i_mode)) {
 		filp_close(fp, 0);
 		mutex_unlock(&g_tf_lock);
 		pr_err("db_root: not a directory: %s\n", db_root_stage);