new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index b78fbe2..6e8af6d 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -160,7 +160,7 @@
 {
 	loff_t ret;
 
-	mutex_lock(&file->f_dentry->d_inode->i_mutex);
+	mutex_lock(&file_inode(file)->i_mutex);
 
 	switch (orig) {
 	case 0:
@@ -176,7 +176,7 @@
 		ret = -EINVAL;
 	}
 
-	mutex_unlock(&file->f_dentry->d_inode->i_mutex);
+	mutex_unlock(&file_inode(file)->i_mutex);
 	return ret;
 }
 
@@ -1970,7 +1970,7 @@
 				void __user *p)
 {
 	struct dev_state *ps = file->private_data;
-	struct inode *inode = file->f_path.dentry->d_inode;
+	struct inode *inode = file_inode(file);
 	struct usb_device *dev = ps->dev;
 	int ret = -ENOTTY;