new helper: file_inode(file)

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

arch/s390/hypfs/hypfs_dbfs.c

@@ -54,7 +54,7 @@ static ssize_t dbfs_read(struct file *file, char __user *buf,
 	if (*ppos != 0)
 		return 0;
 
-	df = file->f_path.dentry->d_inode->i_private;
+	df = file_inode(file)->i_private;
 	mutex_lock(&df->lock);
 	if (!df->data) {
 		data = hypfs_dbfs_data_alloc(df);