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Date:      Sun, 14 Jun 1998 22:25:32 -0700 (PDT)
From:      Julian Elischer <julian@whistle.com>
To:        Poul-Henning Kamp <phk@critter.freebsd.dk>
Cc:        Brian Somers <brian@awfulhak.org>, current@FreeBSD.ORG
Subject:   Re: RFC: Change to the device interface 
Message-ID:  <Pine.BSF.3.95.980614221307.6899A-100000@current1.whistle.com>
In-Reply-To: <3413.897885129@critter.freebsd.dk>

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On Mon, 15 Jun 1998, Poul-Henning Kamp wrote:

> In message <Pine.BSF.3.95.980614161243.6576C-100000@current1.whistle.com>, Juli
> an Elischer writes:
> >
> >
> >On Mon, 15 Jun 1998, Poul-Henning Kamp wrote:
> >
> >> In message <Pine.BSF.3.95.980614143541.6528A-100000@current1.whistle.com>, Juli
> >> 
> >> Julian, I think this is needless generality.
> >> 
> >> Just add one new entrypoint to the devsw structure "openclose"
> >> which receives as argument the number of currently open R/O and
> >> R/W opens, as well as the delta which is causing this call, and
> >> the credentials of the process affecting the change.
> >> 
> >
> >Ok, so you need to keep the opens counted somewhere else..
> >where? In the vnode?
> 
> Wouldn't that be the logical place ?
> 

It would certainly be so if you didn't want to allow the driver
itself to associate an IO request with an open() session.

SLICE on the other hand has to aggregate these counts so it has to 
keep track of all this anyhow. so it would be duplicating this
It also doesnt take aliased vnodes into account very well.

maybe its a better idea to specify what the AIM is first :-)

I have a request from Justin that he wants to be associate an open 
(or mode upgrade) with a user (we can already do that) and 
an IO request with a particular open and to be aware at any time
of how many clients he has.

point 1 is normal (struct proc *)
point 2 needs something like what I suggest
point 3 would be covered by your suggestion.

so the question is: what do we want?

I personally like th idea of ALWAYS being able to link an io request 
to some session, even if just for accounting purposes.

julian


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