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Date:      Sun, 21 Jul 1996 09:54:23 +0200
From:      Poul-Henning Kamp <phk@critter.tfs.com>
To:        davidg@root.com
Cc:        "Michael L. VanLoon -- HeadCandy.com" <michaelv@HeadCandy.com>, John Dyson <dyson@dyson.iquest.net>, hsu@clinet.fi (Heikki Suonsivu), freebsd-current@freebsd.org
Subject:   Re: vm work helps 
Message-ID:  <751.837935663@critter.tfs.com>
In-Reply-To: Your message of "Sat, 20 Jul 1996 19:24:47 PDT." <199607210224.TAA16881@root.com> 

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>   Just a wild guess: The vop_bmap() code in it is probably broken. We rely
>heavily on this and if it's broken, the filesystem will be corrupted. NetBSD
>won't suffer from this because they have much more limited use of the vop_bmap
>function. Further guessing, I'd guess that the problem is that CCD doesn't
>limit the forward/behind contiguousness to be within the underlying device's
>cluster, or something of this nature.

Sort of my conclusion too, but I'd be damned if I can find out where the
problem is.  Havn't spent more than one hour though.

It is actually an interesting thing to think about.

I guess our clustering code should communicate four block#'s downward:
	First block that could be any use
	First block that is strictly needed
	Last block that is strictly needed
	Last block that would be any use.

And then ccd could select chop between these boundaries to match 
entire stripes.

I doubt we'd gain much though :-)

--
Poul-Henning Kamp           | phk@FreeBSD.ORG       FreeBSD Core-team.
http://www.freebsd.org/~phk | phk@login.dknet.dk    Private mailbox.
whois: [PHK]                | phk@ref.tfs.com       TRW Financial Systems, Inc.
Future will arrive by its own means, progress not so.



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