Re: [dm-devel] [PATCH v2 01/14] block: Generalized bio pool freeing

[Vivek Goyal <vgoyal redhat com>]

On Wed, May 23, 2012 at 05:02:38PM -0700, Kent Overstreet wrote:
> With the old code, when you allocate a bio from a bio pool you have to
> implement your own destructor that knows how to find the bio pool the
> bio was originally allocated from.
> 
> This adds a new field to struct bio (bi_pool) and changes
> bio_alloc_bioset() to use it. This makes various bio destructors
> unnecessary, so they're then deleted.
> 

[..]
> @@ -419,7 +406,11 @@ void bio_put(struct bio *bio)
>  	 */
>  	if (atomic_dec_and_test(&bio->bi_cnt)) {
>  		bio->bi_next = NULL;
> -		bio->bi_destructor(bio);
> +
> +		if (bio->bi_pool)
> +			bio_free(bio, bio->bi_pool);
> +		else
> +			bio->bi_destructor(bio);

If you have removed all the users of bi_destructor, then I am wondering that
why are we retaining this field and trying to call into it when bio_pool
is not set?

Thanks
Vivek