From owner-freebsd-hackers  Thu Dec 13 11: 0:44 2001
Delivered-To: freebsd-hackers@freebsd.org
Received: from albatross.prod.itd.earthlink.net (albatross.mail.pas.earthlink.net [207.217.120.120])
	by hub.freebsd.org (Postfix) with ESMTP
	id 4B16537B425; Thu, 13 Dec 2001 11:00:33 -0800 (PST)
Received: from pool0215.cvx22-bradley.dialup.earthlink.net ([209.179.198.215] helo=mindspring.com)
	by albatross.prod.itd.earthlink.net with esmtp (Exim 3.33 #1)
	id 16Eb5g-0005u5-00; Thu, 13 Dec 2001 11:00:20 -0800
Message-ID: <3C18FAC9.E743DAA5@mindspring.com>
Date: Thu, 13 Dec 2001 11:00:25 -0800
From: Terry Lambert <tlambert2@mindspring.com>
X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony}  (Win98; U)
X-Accept-Language: en
MIME-Version: 1.0
To: Matthew Dillon <dillon@apollo.backplane.com>
Cc: David Greenman <dg@root.com>,
	Jordan Hubbard <jkh@winston.freebsd.org>,
	Peter Wemm <peter@wemm.org>, Mike Smith <msmith@FreeBSD.ORG>,
	hackers@FreeBSD.ORG, msmith@mass.dis.org
Subject: Re: NFS Patch #4 -- survived overnight test. (was Re: Found NFS data 
 corruption bug... (was Re:...))
References: <58885.1008217148@winston.freebsd.org> <200112130608.fBD689K49906@apollo.backplane.com> <20011212224927.A73226@nexus.root.com> <200112131835.fBDIZuL70031@apollo.backplane.com>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-hackers.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-hackers>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-hackers>
X-Loop: FreeBSD.ORG

Matthew Dillon wrote:
[ ... ]
>     I would appreciate other VM gurus taking a look at the
>     vm_page_set_validclean() changes.
[ ... ]

Not to appoint myself a guru or anything...

> +#if 1
> +       if ((base & (DEV_BSIZE - 1)) || (size & (DEV_BSIZE - 1))) {
> +           int adj;
> +
> +           adj = DEV_BSIZE - (base & (DEV_BSIZE - 1));
> +           base += adj;
> +           if (size < adj)
> +               size = 0;
> +           else
> +               size = (size - adj) & ~(DEV_BSIZE - 1);
> +           pagebits = vm_page_bits(base, size);
> +       }
> +#endif

This seems wrong.

Specifically, it seems to only get the first block, in the case that
(integer math: / is "div"):

	((size - adj)/DEV_BSIZE) > 1

How about:

		else {
			/*
			 * Drop partial trailing blocks from the size
			 * calculation to maintain correct dirty bits;
			 * note that 'size' might still span more than
			 * one block, though.
			 */
			int n_size;	/* probably not int? */

			n_size = (size - adj) / DEV_BSIZE;
			size = (size - adj) & ~(DEV_BSIZE - 1);
			size += n_size * DEV_BSIZE;
			
		}

-- Terry

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message