Re: [PATCH RFC 1/2] block: Add blk_bio_map_sg() helper

[Asias He]

On 06/14/2012 03:29 PM, Jens Axboe wrote:
> On 2012-06-14 04:31, Tejun Heo wrote:
> > On Wed, Jun 13, 2012 at 03:41:46PM +0800, Asias He wrote:
> > > Add a helper to map a bio to a scatterlist, modelled after
> > > blk_rq_map_sg.
> > >
> > > This helper is useful for any driver that wants to create
> > > a scatterlist from its ->make_request_fn method.
> >
> > This may not be possible but I really wanna avoid having two copies of
> > that complex logic.  Any chance blk_rq_map_bio() can be implemented in
> > a way that allows blk_rq_map_sg() can be built on top of it?  Also,
>
> Was thinking the same thing, definitely code we don't want to have
> duplicated. We've had mapping bugs in the past.
>
> Asias, this should be trivial to do, except that blk_rq_map_sg()
> potentially maps across bio's as well. The tracking of the prev bio_vec
> does not care about cross bio boundaries.

Sure. I will try this and send v2.


--
Asias


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