Due to commit 
1cd96c242a829d52f7a5ae98f554ca9775429685 ("block: WARN
in __blk_put_request() for potential bio leak"), BSG SMP requests get
the false warnings:
WARNING: at block/blk-core.c:1068 __blk_put_request+0x52/0xc0()
This sets rq->bio to NULL to avoid that false warnings.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
        blk_put_request(rq);
        if (next_rq) {
                blk_rq_unmap_user(next_rq->bio);
+               next_rq->bio = NULL;
                blk_put_request(next_rq);
        }
        return ERR_PTR(ret);
                hdr->dout_resid = rq->data_len;
                hdr->din_resid = rq->next_rq->data_len;
                blk_rq_unmap_user(bidi_bio);
+               rq->next_rq->bio = NULL;
                blk_put_request(rq->next_rq);
        } else if (rq_data_dir(rq) == READ)
                hdr->din_resid = rq->data_len;
        blk_rq_unmap_user(bio);
        if (rq->cmd != rq->__cmd)
                kfree(rq->cmd);
+       rq->bio = NULL;
        blk_put_request(rq);
 
        return ret;