Re: [dm-devel] [PATCH v2 02/14] dm: kill dm_rq_bio_destructor

[Kent Overstreet <koverstreet@google.com>]

On Thu, May 24, 2012 at 09:19:12AM +0900, Jun'ichi Nomura wrote:
> Hi,
> 
> On 05/24/12 09:02, Kent Overstreet wrote:
> > @@ -1438,15 +1439,6 @@ void dm_dispatch_request(struct request *rq)
> >  }
> >  EXPORT_SYMBOL_GPL(dm_dispatch_request);
> >  
> > -static void dm_rq_bio_destructor(struct bio *bio)
> > -{
> > -	struct dm_rq_clone_bio_info *info = bio->bi_private;
> > -	struct mapped_device *md = info->tio->md;
> > -
> > -	free_bio_info(info);
> > -	bio_free(bio, md->bs);
> > -}
> > -
> >  static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
> >  				 void *data)
> >  {
> > @@ -1461,7 +1453,6 @@ static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
> >  	info->tio = tio;
> >  	bio->bi_end_io = end_clone_bio;
> >  	bio->bi_private = info;
> > -	bio->bi_destructor = dm_rq_bio_destructor;
> 
> The destructor may also be called from blk_rq_unprep_clone(),
> which just puts bio.
> So this patch will introduce a memory leak.

Well, keeping around bi_destructor solely for that reason would be
pretty lousy. Can you come up with a better solution?