[PATCHv3 1/7] blk-mq: introduce blk_map_iter

[Kanchan Joshi]

On 7/29/2025 8:04 PM, Keith Busch wrote:
> @@ -39,12 +33,11 @@ static bool blk_map_iter_next(struct request *req, struct req_iterator *iter,
>   	 * one could be merged into it.  This typically happens when moving to
>   	 * the next bio, but some callers also don't pack bvecs tight.
>   	 */
> -	while (!iter->iter.bi_size || !iter->iter.bi_bvec_done) {
> +	while (!iter->iter.bi_size ||
> +	       (!iter->iter.bi_bvec_done && iter->bio->bi_next)) {
>   		struct bio_vec next;
>   
>   		if (!iter->iter.bi_size) {
> -			if (!iter->bio->bi_next)
> -				break;
>   			iter->bio = iter->bio->bi_next;
>   			iter->iter = iter->bio->bi_iter;

This can crash here if we come inside the loop because 
iter->iter.bi_size is 0
and if this is the last bio i.e., iter->bio->bi_next is NULL?