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To: Colin Percival <colin.percival@wadham.ox.ac.uk>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Thu, 11 Mar 2004 06:30:28 GMT."
             <6.0.1.1.1.20040311062306.03f9ade0@imap.sfu.ca> 
Date: Thu, 11 Mar 2004 07:35:50 +0100
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cc: cvs-src@FreeBSD.org
cc: src-committers@FreeBSD.org
cc: cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/sys mdioctl.h src/sys/dev/md md.c
	src/sbin/mdconfig mdconfig.8 mdconfig.c 
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In message <6.0.1.1.1.20040311062306.03f9ade0@imap.sfu.ca>, Colin Percival writ
es:
>At 06:13 11/03/2004, Poul-Henning Kamp wrote:
> >That is a matter of taste more than anything else.  A vnode backed md(4)
>>device is technically a layering violation, so either the syncer or
>>the md(4) code itself (or both) needs to be aware of the special case.
>
><kernelnewbie>
>   Is it really necessary for vnode-backed memory disks to be
>accessed through the filesystem?  Why can't md(4) hijack the
>disk blocks which constitute the file (telling the filesystem
>not to touch them, of course) and translate I/O operations
>directly into I/O on the underlying device?
></kernelnewbie>

That would be a really complex solution to a problem which should not
exist in the first place :-)

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.