Re: [PATCH 2.6.30] xprtrdma: The frmr iova_start values are truncated by the nfs rdma client.

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Trond Myklebust wrote:
On Mon, 2009-05-11 at 21:14 -0400, Tom Talpey wrote:
At 08:44 PM 5/11/2009, Trond Myklebust wrote:
On Mon, 2009-05-11 at 19:13 -0500, Steve Wise wrote:
Trond Myklebust wrote:
On Mon, 2009-05-11 at 17:25 -0500, Steve Wise wrote:
Hey Trond,

Will this bug fix make 2.6.30?

Thanks,

Steve.
Not in the form it is in now. As I've said earlier, I'm not happy about
the sunrpc layer having to circumvent ordinary type checking on
non-sunrpc structures.

Cheers
    Trond
How is it circumventing? It's currently incorrectly casting a pointer into a u64. That seems just broken to me. Also, its really the sunrpc rdma transport layer. It deals specifically with rdma. It _should_ know about rdma interfaces and types.
The fact is that I'm simply not interested enough in rdma to tolerate
hacks. If it isn't done cleanly, in a manner that I can maintain, then
the whole transport layer comes out...
I know exactly what you want - it's not what the code does now and
it's not an accessor function to set the hardware's u64 field. What's
needed is a new function to manage the entire RDMA triplet, and the
memory registration behind it, in the OFA code side. Put the hardware
goop below the line, IOW. I'll dust up Steve on this.

This does indeed sound like what I'd looking for.

There is a huge difference between having code that depends on well
defined rdma interfaces, and code that depends on rdma hacks. A piece of
code that requires casts from a non-local opaque type into another
protocol-dependent non-local type will definitely fall in the latter
category. I really don't care what the current code does, but a fix for
that code is something that does it _correctly_; it is not yet another
hack, whether or not it fixes a bug in the short term.

   Trond


Trond, I get your point, and we can certainly work on improving this with the rdma developer community. But removing the one-line-broken cast will resolve a current crash situation for 2.6.30. Can't we get this fix in 2.6.30 and work on the API improvements for 2.6.31? I've CCed Roland and the ofa general list to get everyone involved in this thread so we can get this API design change going.

I agree we can clean this up moving forward, but lets fix the broken 2.6.30 code.
Will this work?

Steve.

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