vfs: remove open_flags from d_real()

Opening regular files on overlayfs is now handled via ovl_open().  Remove
the now unused "open_flags" argument from d_op->d_real() and the d_real()
helper.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Documentation/filesystems/vfs.txt

@@ -1000,8 +1000,7 @@ struct dentry_operations {
 	char *(*d_dname)(struct dentry *, char *, int);
 	struct vfsmount *(*d_automount)(struct path *);
 	int (*d_manage)(const struct path *, bool);
-	struct dentry *(*d_real)(struct dentry *, const struct inode *,
-				 unsigned int);
+	struct dentry *(*d_real)(struct dentry *, const struct inode *);
 };
 
   d_revalidate: called when the VFS needs to revalidate a dentry. This
@@ -1135,22 +1134,15 @@ struct dentry_operations {
 	dentry being transited from.
 
   d_real: overlay/union type filesystems implement this method to return one of
-	the underlying dentries hidden by the overlay.  It is used in three
+	the underlying dentries hidden by the overlay.  It is used in two
 	different modes:
 
-	Called from open it may need to copy-up the file depending on the
-	supplied open flags.  This mode is selected with a non-zero flags
-	argument.  In this mode the d_real method can return an error.
-
 	Called from file_dentry() it returns the real dentry matching the inode
 	argument.  The real dentry may be from a lower layer already copied up,
 	but still referenced from the file.  This mode is selected with a
-	non-NULL inode argument.  This will always succeed.
+	non-NULL inode argument.
 
-	With NULL inode and zero flags the topmost real underlying dentry is
-	returned.  This will always succeed.
-
-	This method is never called with both non-NULL inode and non-zero flags.
+	With NULL inode the topmost real underlying dentry is returned.
 
 Each dentry has a pointer to its parent dentry, as well as a hash list
 of child dentries. Child dentries are basically like files in a