new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/readdir.c b/fs/readdir.c
index 5e69ef5..fee38e0 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -22,7 +22,7 @@
 
 int vfs_readdir(struct file *file, filldir_t filler, void *buf)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
+	struct inode *inode = file_inode(file);
 	int res = -ENOTDIR;
 	if (!file->f_op || !file->f_op->readdir)
 		goto out;