new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 3ff0105..bf01980 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -727,7 +727,7 @@
  */
 static struct fb_info *file_fb_info(struct file *file)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
+	struct inode *inode = file_inode(file);
 	int fbidx = iminor(inode);
 	struct fb_info *info = registered_fb[fbidx];