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cc: julian@whistle.com, hackers@freebsd.org
Subject: Re: DEVFS problem 
In-reply-to: Your message of "Sun, 27 Oct 1996 23:17:45 +0100."
             <166.846454665@critter.tfs.com> 
Date: Sun, 27 Oct 1996 23:59:42 +0100
Message-ID: <287.846457182@critter.tfs.com>
From: Poul-Henning Kamp <phk@critter.tfs.com>
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I compiled DEVFS with debugging, and the output looks like this:
	[...]
		vntodn  vntodn write
	read
		vntodn read
		vntodn reclaim
		vntodn reclaim
		vntodn read
		vntodn  vntodn write
	read
		vntodn reclaim
		vntodn reclaim
		vntodn read
		vntodn  vntodn write
	read
		vntodn read
		vntodn reclaim
		vntodn reclaim
		vntodn read
		vntodn  vntodn write
	read
		vntodn read
		vntodn reclaim
		vntodn reclaim
		vntodn read
		vntodn 
	[hang]

If I have understood things right, DEVFS has no vnodes that need
cleaning as often as that, and I generally belive that the refcount/
usecount on vnodes associated with DEVFS is bogus, right ?

Wouldn't it be smarter to allocate the vnode when a DEVFS bdev
node is created, and ref' it so we're sure it stays around ?

That way all the block-dev alias crap can be done by pointing the
DEVFS nodes at the same (& correct) vnode.

Of course we tie up a number of vnodes that way, but since most
bdev's tend to be used, with the exception of slices that are not 
mounted, I think that is a very small loss, compared to the 
mess the alias code really is.

This would also mean that if a driver adds two bdev names for the 
same dev_t, they will effectively become hardlinks to the same 
"inode" rather than two separate "inodes", which I think is more
correct behaviour when we're talking about block devices anyway.

--
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.