From owner-freebsd-current@FreeBSD.ORG Mon May 12 12:33:20 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6BB8D37B401 for ; Mon, 12 May 2003 12:33:20 -0700 (PDT) Received: from beastie.mckusick.com (beastie.mckusick.com [209.31.233.184]) by mx1.FreeBSD.org (Postfix) with ESMTP id E51A443F85 for ; Mon, 12 May 2003 12:33:19 -0700 (PDT) (envelope-from mckusick@beastie.mckusick.com) Received: from beastie.mckusick.com (localhost [127.0.0.1]) by beastie.mckusick.com (8.12.8/8.12.3) with ESMTP id h4CJXHTh037943; Mon, 12 May 2003 12:33:17 -0700 (PDT) (envelope-from mckusick@beastie.mckusick.com) Message-Id: <200305121933.h4CJXHTh037943@beastie.mckusick.com> To: Terry Lambert In-Reply-To: Your message of "Mon, 12 May 2003 07:53:49 PDT." <3EBFB57D.7376D4A8@mindspring.com> Date: Mon, 12 May 2003 12:33:17 -0700 From: Kirk McKusick cc: freebsd-current@freebsd.org cc: Julian Elischer Subject: Re: large ufs2 partitions and 'df' X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 May 2003 19:33:20 -0000 Date: Mon, 12 May 2003 07:53:49 -0700 From: Terry Lambert To: Kirk McKusick CC: Julian Elischer , freebsd-current@freebsd.org Subject: Re: large ufs2 partitions and 'df' X-ASK-Info: Whitelist match Kirk McKusick wrote: > Julian Elisher wrote: > > I think that swithing to a new syscall with a fixed structure > > and using the rules you mention above to populate the structure in > > an ostatfs call might be the best answer. > > Old binaries probably only need to know that there is > X blocks > > free and not necessarily the correct number. > > New binaries can use the new syscall. > > So right you are. It would be possible to get the space by nibbling > a bit more space from MNAMELEN, but at some point we need to just bite > the bullet and define a new structure. I am leaning towards believing > that time is now. If we do define a new structure, I would like to > clean up the existing one a bit. I would propose this: If you're going to change the structure, please put a version number as the first field, so that it's never a problem again. Also, put a spare field on the end (64 bits) to allow for future expansion that maintains binary compatability (by way of choice about what to copy in). -- Terry There are already ten spare 64-bit numbers in the middle of the proposed new structure. They are there where they are guaranteed to be 64-bit aligned rather than at the end where there is danger of them being aligned differently on different architectures since they follow character arrays. Kirk McKusick