new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/acct.c b/kernel/acct.c
index 051e071..0d29813 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -205,7 +205,7 @@
 	if (IS_ERR(file))
 		return PTR_ERR(file);
 
-	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) {
+	if (!S_ISREG(file_inode(file)->i_mode)) {
 		filp_close(file, NULL);
 		return -EACCES;
 	}