Re: struct request members, etc..

[Jens Axboe <jens.axboe@oracle.com>]

On Tue, Jan 02 2007, Christoph Hellwig wrote:
> This gets a little offtopic for the original issue, so let's cut the Cc
> list and change the subject.
> 
> On Tue, Dec 12, 2006 at 04:21:23PM +0200, Boaz Harrosh wrote:
> > I'm afraid this might not be enough because of code in drivers/ide/ide-cd.c. It does IO off of request->data.
> 
> Only for FS requests, but we do BLOCK_PC requests here.

->buffer is the old style FS requests, ->data is never used for FS
requests. BLOCK_PC requests should use just ->data, but I would not be
surprised if ide-cd and others still map it to ->buffer.

> > [background]
> > pkt_generic_packet and ton of other places mainly cd(s), floppy(s), and
> > other ide code paths, are using what I call BLACK requests. They put some
> > data on request->buffer or request->data stick it in the Q and than advance
> > on them later down the ladder. Remove of "buffer" and "data" from
> > struct request will reveal all these places. At one time I had plans to do
> > just that. But 1/2 way through I gave up, it is too risky, too much
> > Hardware that I don't have, that needs checking.
> 
> Removing this old code would definitly be worthwile, but I understand
> that you don't want to get too deeply into the mess of floppy.c and the
> old ide code :)

I'd suggest moving everything to ->data, and get rid of ->buffer. You
probably cannot remove both without complicating things, I'm not sure
it's worth it.

-- 
Jens Axboe