[dm-devel] [Bcache v13 02/16] Bio pool freeing

[Tejun Heo]

On Wed, May 09, 2012 at 11:08:34PM -0400, Kent Overstreet wrote:
> When you allocate a bio from a bio pool, to free it you have to know
> where it came from; this adds a flag which, if set, means bi_destructor
> is the pointer to the pool and bio_put() can do the right thing.
> 
> This is used in bcache, so we can cleanly use per device bio pools.
> 
> Signed-off-by: Kent Overstreet <koverstreet at google.com>
> ---
> @@ -417,7 +418,11 @@ void bio_put(struct bio *bio)
>  	 */
>  	if (atomic_dec_and_test(&bio->bi_cnt)) {
>  		bio->bi_next = NULL;
> -		bio->bi_destructor(bio);
> +
> +		if (bio_flagged(bio, BIO_HAS_POOL))
> +			bio_free(bio, (void *) bio->bi_destructor);
> +		else
> +			bio->bi_destructor(bio);

Ummm... this is way too cryptic.  Please just add another field to
bio.

Thanks.

-- 
tejun