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From: Jens Axboe <jens.axboe@oracle.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/10] i386 sg: add support for chaining scatterlists
Date: Wed, 9 May 2007 12:30:07 +0200	[thread overview]
Message-ID: <20070509103007.GS4163@kernel.dk> (raw)
In-Reply-To: <20070509031915.6e934f35.akpm@linux-foundation.org>

On Wed, May 09 2007, Andrew Morton wrote:
> On Wed, 09 May 2007 20:03:29 +1000 Herbert Xu <herbert@gondor.apana.org.au> wrote:
> 
> > Jens Axboe <jens.axboe@oracle.com> wrote:
> > > 
> > > diff --git a/include/asm-i386/scatterlist.h b/include/asm-i386/scatterlist.h
> > > index d7e45a8..794b68c 100644
> > > --- a/include/asm-i386/scatterlist.h
> > > +++ b/include/asm-i386/scatterlist.h
> > > @@ -8,8 +8,11 @@ struct scatterlist {
> > >     unsigned int       offset;
> > >     dma_addr_t         dma_address;
> > >     unsigned int       length;
> > > +    struct scatterlist *next;
> > > };
> > 
> > BTW, the crypto layer's scatterlist already has a chaining mechanism
> > using the existing structure.  The only difference is that the chained
> > pointer is stored inside the 'struct page *' rather than a new pointer.
> 
> <greps-and-fails>
> 
> Which field in the page is it using?

crypto/scatterwalk.h:

static inline struct scatterlist *scatterwalk_sg_next(struct scatterlist
*sg)
{
        return (++sg)->length ? sg : (void *)sg->page;
}

it's just using the page pointer, not a pointer in the page structure.

-- 
Jens Axboe


  parent reply	other threads:[~2007-05-09 10:33 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-09  7:59 [PATCH 0/10] Chaining sg lists for big IO commands v2 Jens Axboe
2007-05-09  7:59 ` [PATCH 1/10] crypto: don't pollute the global namespace with sg_next() Jens Axboe
2007-05-09  7:59 ` [PATCH 2/10] Add sg helpers for iterating over a scatterlist table Jens Axboe
2007-05-09  7:59 ` [PATCH 3/10] libata: convert to using sg helpers Jens Axboe
2007-05-09  7:59 ` [PATCH 4/10] block: " Jens Axboe
2007-05-09  7:59 ` [PATCH 5/10] scsi: " Jens Axboe
2007-05-09  7:59 ` [PATCH 6/10] i386 dma_map_sg: " Jens Axboe
2007-05-09  7:59 ` [PATCH 7/10] i386 sg: add support for chaining scatterlists Jens Axboe
2007-05-09 10:03   ` Herbert Xu
2007-05-09 10:19     ` Andrew Morton
2007-05-09 10:21       ` Herbert Xu
2007-05-09 10:30       ` Jens Axboe [this message]
2007-05-09 10:28     ` Jens Axboe
2007-05-09  7:59 ` [PATCH 8/10] scsi: simplify scsi_free_sgtable() Jens Axboe
2007-05-09  7:59 ` [PATCH 9/10] SCSI: support for allocating large scatterlists Jens Axboe
2007-05-09  7:59 ` [PATCH 10/10] ll_rw_blk: temporarily enable max_segments tweaking Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2007-05-16  8:31 [PATCH 0/19] Chaining sg lists for big IO commands v6 Jens Axboe
2007-05-16  8:31 ` [PATCH 7/10] i386 sg: add support for chaining scatterlists Jens Axboe

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