On Tue, Oct 24, 2017 at 11:44:26AM +0300, Max Gurtovoy wrote:
>> + * Steal bios from a request. The request must not have been partially
>> + * completed before.
>> + */
>
> Maybe we can add to the comment that "list" is the destination for the
> stolen bio.
Sure.
>> +void blk_steal_bios(struct bio_list *list, struct request *rq)
>> +{
>> + if (rq->bio) {
>> + if (list->tail)
>> + list->tail->bi_next = rq->bio;
>> + else
>> + list->head = rq->bio;
>> + list->tail = rq->biotail;
>
> if list->tail != NULL don't we lose the "list->tail->bi_next = rq->bio;"
> assignment after assigning "list->tail = rq->biotail;" ?
the biolists are a little weird, they are a single linked list of bi_next
plus a tail pointer.
So if the list is emptry (->tail == NULL) we assign the biolist
to ->head and point ->tail to end of the list in the request.
But if the list is not empty we let ->bi_next of the last entry
(as found in ->tail) point to the list we splice on, and still update
->tail to end of the list we spliced on. So I think this looks all ok.
>> + }
>> +
>> + rq->bio = NULL;
>
> we can add this NULL assignment inside the big "if", but I'm not sure
> regarding the next 2 assignments.
> Anyway not a big deal.
We can move both the ->bio and ->biotail assignments, and I've done it.
