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Date:      Thu, 16 Mar 2000 16:39:43 +0100
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        Julian Elischer <julian@elischer.org>
Cc:        current@freebsd.org
Subject:   Re: B_WRITE cleanup patch, please test! 
Message-ID:  <2067.953221183@critter.freebsd.dk>
In-Reply-To: Your message of "Thu, 16 Mar 2000 07:27:38 PST." <38D0FD6A.167EB0E7@elischer.org> 

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In message <38D0FD6A.167EB0E7@elischer.org>, Julian Elischer writes:

>1/ I think the removal of IPSEC from LINT is by mistake in this patch

yes, that is a mistake.

>2/ The change of separating buffer management from IO management
>is long overdue and the introduction of b_iocmd is a good first step
>for this. The selection of values is in my mind arguable either way.
>
>As the field is an 'op-code' I would have chosen the values to be:
>#define BIO_NOP 0
>#define BIO_READ 1
>#define BIO_WRITE 2
>#define BIO_DELETE 3

I decided to use binary values, because there is a simple arithmetic
test for "exactly one bit set" (See BUF_STRATEGY).  I wanted to
catch as many bogus cases of B_WRITE zeroness being abused as possible,
ie, people initializing b_flags = 0 knowing that would give them
a write.

>4/ does this produce compatibility problems with any 3rd party code?

This is 5.0-CURRENT, they will have to adopt to much worse things
before it becomes 5.0-RELEASE.

--
Poul-Henning Kamp             FreeBSD coreteam member
phk@FreeBSD.ORG               "Real hackers run -current on their laptop."
FreeBSD -- It will take a long time before progress goes too far!


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