[dm-devel] [PATCH 03/13] block: Add bio_clone_bioset()

[Kent Overstreet]

On Fri, May 18, 2012 at 09:05:11AM -0700, Tejun Heo wrote:
> Hey, Kent.
> 
> On Thu, May 17, 2012 at 10:59:50PM -0400, koverstreet at google.com wrote:
> > From: Kent Overstreet <koverstreet at google.com>
> > 
> > This consolidates some code, and will help in a later patch changing how
> > bio cloning works.
> > 
> > Signed-off-by: Kent Overstreet <koverstreet at google.com>
> 
> I'd prefer a bit more explanation on what's going on generally and why
> and how dm conversion is different.

Well, besides the removal of idx it's all just removing stuff that
bio_clone_bioset() does for it.

> > diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> > index 3cc2169..3e33039 100644
> > --- a/drivers/md/dm.c
> > +++ b/drivers/md/dm.c
> > @@ -1072,26 +1072,19 @@ static struct bio *split_bvec(struct bio *bio, sector_t sector,
> >   * Creates a bio that consists of range of complete bvecs.
> >   */
> >  static struct bio *clone_bio(struct bio *bio, sector_t sector,
> > -			     unsigned short idx, unsigned short bv_count,
> > +			     unsigned short bv_count,
> >  			     unsigned int len, struct bio_set *bs)
> >  {
> >  	struct bio *clone;
> >  
> > -	clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
> > -	__bio_clone(clone, bio);
> > +	clone = bio_clone_bioset(bio, GFP_NOIO, bs);
> >  	clone->bi_sector = sector;
> > -	clone->bi_idx = idx;
> > -	clone->bi_vcnt = idx + bv_count;
> > +	clone->bi_vcnt = bv_count;
> >  	clone->bi_size = to_bytes(len);
> > -	clone->bi_flags &= ~(1 << BIO_SEG_VALID);
> 
> Maybe removal of @idx deserves a separate patch?

I'm gonna back that out, I'm not sure it was correct now.

> > -	if (bio_integrity(bio)) {
> > -		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
> > -
> > -		if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
> > -			bio_integrity_trim(clone,
> > -					   bio_sector_offset(bio, idx, 0), len);
> > -	}
> > +	if (bio_integrity(bio) &&
> > +	    clone->bi_size < bio->bi_size)
> 
> Unnecessary line break.
> 
> Other than that, looks good to me.
> 
> Thanks.
> 
> -- 
> tejun