On Thu, Oct 04 2007, Pierre Ossman wrote:
quoted text
> On Thu, 4 Oct 2007 11:30:14 +0200
> Jens Axboe <jens.axboe@oracle.com> wrote:
> 
> > On Thu, Oct 04 2007, Pierre Ossman wrote:
> > > 
> > > I assume sg_init_one() still can work on an uninitialized sg entry?
> > 
> > Yes, but only if that sg entry is not part of a chained list.
> > 
> 
> Is that a yes or a no? You said that the ->page field was involved in

It's a conditional yes, re-read it :-)

quoted text
> list chaining, so does or doesn't it have to be initialized before a
> call to sg_init_one()?

That's not the problem. It has to be initialized before calling
blk_rq_map_sg(). sg_init_one() will zero the entire sg entry, and that
breaks if that particular sg entry is part of a larger sg table AND that
sg entry happens to be the chain element.

-- 
Jens Axboe

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