block: initialize bio issue time in blk_mq_submit_bio()

bio->issue_time_ns is only used by blk-iolatency, which can only be
enabled for rq-based disk, hence it's not necessary to initialize
the time for bio-based disk.

Meanwhile, if bio is split by blk_crypto_fallback_split_bio_if_needed(),
the issue time is not initialized for new split bio, this can be fixed
as well.

Noted the next patch will optimize better that bio issue time will
only be used when blk-iolatency is really enabled by the disk.

Fixes: 488f6682c832 ("block: blk-crypto-fallback for Inline Encryption")
Signed-off-by: Yu Kuai <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

block/blk-cgroup.h

···
 		if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css),	\
 					    (p_blkg)->q)))
 
-static inline void blkcg_bio_issue_init(struct bio *bio)
-{
-	bio->issue_time_ns = blk_time_get_ns();
-}
-
 static inline void blkcg_use_delay(struct blkcg_gq *blkg)
 {
 	if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
···
 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 static inline void blkg_get(struct blkcg_gq *blkg) { }
 static inline void blkg_put(struct blkcg_gq *blkg) { }
-static inline void blkcg_bio_issue_init(struct bio *bio) { }
 static inline void blk_cgroup_bio_start(struct bio *bio) { }
 static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) { return true; }
 

block/blk-core.c

···
 void submit_bio_noacct_nocheck(struct bio *bio)
 {
 	blk_cgroup_bio_start(bio);
-	blkcg_bio_issue_init(bio);
 
 	if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
 		trace_block_bio_queue(bio);

block/blk-merge.c

···
 			goto error;
 		}
 		split->bi_opf |= REQ_NOMERGE;
-		blkcg_bio_issue_init(split);
 		bio_chain(split, bio);
 		trace_block_split(split, bio->bi_iter.bi_sector);
 		WARN_ON_ONCE(bio_zone_write_plugging(bio));

block/blk-mq.c

···
 #endif
 }
 
+static inline void blk_mq_bio_issue_init(struct bio *bio)
+{
+#ifdef CONFIG_BLK_CGROUP
+	bio->issue_time_ns = blk_time_get_ns();
+#endif
+}
+
 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 		struct blk_mq_tags *tags, unsigned int tag)
 {
···
 	if (!bio_integrity_prep(bio))
 		goto queue_exit;
 
+	blk_mq_bio_issue_init(bio);
 	if (blk_mq_attempt_bio_merge(q, bio, nr_segs))
 		goto queue_exit;