do_dentry_open(): kill inode argument

should've been done as soon as overlayfs stopped messing with fake
paths...

Reviewed-by: Christian Brauner <[e-mail]>
Signed-off-by: Al Viro <[e-mail]>

fs/open.c

···
 }
 
 static int do_dentry_open(struct file *f,
-			  struct inode *inode,
 			  int (*open)(struct inode *, struct file *))
 {
 	static const struct file_operations empty_fops = {};
+	struct inode *inode = f->f_path.dentry->d_inode;
 	int error;
 
 	path_get(&f->f_path);
···
 	BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
 
 	file->f_path.dentry = dentry;
-	return do_dentry_open(file, d_backing_inode(dentry), open);
+	return do_dentry_open(file, open);
 }
 EXPORT_SYMBOL(finish_open);
 
···
 int vfs_open(const struct path *path, struct file *file)
 {
 	file->f_path = *path;
-	return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
+	return do_dentry_open(file, NULL);
 }
 
 struct file *dentry_open(const struct path *path, int flags,
···
 		return f;
 
 	f->f_path = *path;
-	error = do_dentry_open(f, d_inode(path->dentry), NULL);
+	error = do_dentry_open(f, NULL);
 	if (error) {
 		fput(f);
 		f = ERR_PTR(error);