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Message-ID: <20100701124609.GA19605@redhat.com>
Date: Thu, 1 Jul 2010 08:46:09 -0400
From: Mike Snitzer <snitzer@...hat.com>
To: Mikulas Patocka <mpatocka@...hat.com>
Cc: James Bottomley <James.Bottomley@...e.de>,
device-mapper development <dm-devel@...hat.com>,
axboe@...nel.dk, linux-scsi@...r.kernel.org,
martin.petersen@...cle.com, linux-kernel@...r.kernel.org,
akpm@...ux-foundation.org, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 1/2] block: fix leaks associated with discard request
payload
On Thu, Jul 01 2010 at 8:28am -0400,
Mikulas Patocka <mpatocka@...hat.com> wrote:
> > > It is either/or choice. If the interface isn't fixed NOW, the existing
> > > flawed zeroed-page-allocation interface gets into RHEL
> >
> > That's a false dichotomy. You might see an either apply this hack now
> > or support the interface choice with RHEL, but upstream has the option
> > to fix stuff correctly. RHEL has never needed my blessing to apply
> > random crap to their kernel before ... why is this patch any different?
>
> We can't apply non-upstream patches (except few exceptions such as
> dm-raid45). It makes sense, non-upstream patches have smaller test
> coverage.
>
> > And the rest of this rubbish is based on that false premise. It might
> > help you to take off your SCSI antipathy and see this as a system
> > problem: it actually originates in block and spills out from there.
> > Thus it requires a system solution.
> >
> > James
>
> Imagine this: I take a FPGA PCI board, I design a storage controller on it
> and this controller will need 3 pages to process a discard request. Now I
> say: I refuse to allocate these 3 pages in the driver because the driver
> would look ugly --- instead, I demand that everyone in the Linux kernel
> who creates a discard request must attach 3 pages to the request for my
> driver.
>
> Do you think it is correct behavior? Would you accept such a driver? I
> guess you wouldn't! But this is the same thing that you are doing with
> SCSI.
>
> Now lets take it a bit further and I say "I may clean up the driver for my
> controller one day, when I do it, I remove that 3-page requirement --- and
> then, everyone who allocated those pages will have to change his code and
> remove the allocations".
>
> And this is what you are intending to do with SCSI.
Mikulas,
Jens has already queued up a comprehensive fix (3 patches) that James
and Tomo developed. Please stop the hostility.. it has no place.
Others,
I'd encourage you to not respond to this thread further ;)
Regards,
Mike
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