This is purely a sanity check for grave programming errors.  Remove it
to simplify further work in this area.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
 static inline bool blkcg_bio_issue_check(struct request_queue *q,
                                         struct bio *bio)
 {
-       struct blkcg_gq *blkg;
+       struct blkcg_gq *blkg = bio->bi_blkg;
        bool throtl = false;
 
        rcu_read_lock();
-
-       if (!bio->bi_blkg) {
-               char b[BDEVNAME_SIZE];
-
-               WARN_ONCE(1,
-                         "no blkg associated for bio on block-device: %s\n",
-                         bio_devname(bio, b));
-               bio_associate_blkg(bio);
-       }
-
-       blkg = bio->bi_blkg;
-
        throtl = blk_throtl_bio(q, blkg, bio);
-
        if (!throtl) {
                struct blkg_iostat_set *bis;
                int rwd, cpu;