blk-cgroup: remove blkcg_bio_issue_check

blkcg_bio_issue_check is a giant inline function that does three entirely
different things.  Factor out the blk-cgroup related bio initalization
into a new helper, and the open code the sequence in the only caller,
relying on the fact that all the actual functionality is stubbed out for
non-cgroup builds.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

@@ -1813,6 +1813,40 @@ void bio_clone_blkg_association(struct bio *dst, struct bio *src)
 }
 EXPORT_SYMBOL_GPL(bio_clone_blkg_association);
 
+static int blk_cgroup_io_type(struct bio *bio)
+{
+	if (op_is_discard(bio->bi_opf))
+		return BLKG_IOSTAT_DISCARD;
+	if (op_is_write(bio->bi_opf))
+		return BLKG_IOSTAT_WRITE;
+	return BLKG_IOSTAT_READ;
+}
+
+void blk_cgroup_bio_start(struct bio *bio)
+{
+	int rwd = blk_cgroup_io_type(bio), cpu;
+	struct blkg_iostat_set *bis;
+
+	cpu = get_cpu();
+	bis = per_cpu_ptr(bio->bi_blkg->iostat_cpu, cpu);
+	u64_stats_update_begin(&bis->sync);
+
+	/*
+	 * If the bio is flagged with BIO_CGROUP_ACCT it means this is a split
+	 * bio and we would have already accounted for the size of the bio.
+	 */
+	if (!bio_flagged(bio, BIO_CGROUP_ACCT)) {
+		bio_set_flag(bio, BIO_CGROUP_ACCT);
+			bis->cur.bytes[rwd] += bio->bi_iter.bi_size;
+	}
+	bis->cur.ios[rwd]++;
+
+	u64_stats_update_end(&bis->sync);
+	if (cgroup_subsys_on_dfl(io_cgrp_subsys))
+		cgroup_rstat_updated(bio->bi_blkg->blkcg->css.cgroup, cpu);
+	put_cpu();
+}
+
 static int __init blkcg_init(void)
 {
 	blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio",

block/blk-core.c

@@ -1073,8 +1073,13 @@ generic_make_request_checks(struct bio *bio)
 	if (unlikely(!current->io_context))
 		create_task_io_context(current, GFP_ATOMIC, q->node);
 
-	if (!blkcg_bio_issue_check(q, bio))
+	if (blk_throtl_bio(bio)) {
+		blkcg_bio_issue_init(bio);
 		return false;
+	}
+
+	blk_cgroup_bio_start(bio);
+	blkcg_bio_issue_init(bio);
 
 	if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
 		trace_block_bio_queue(q, bio);

block/blk-throttle.c

@@ -2158,9 +2158,10 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td)
 }
 #endif
 
-bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
-		    struct bio *bio)
+bool blk_throtl_bio(struct bio *bio)
 {
+	struct request_queue *q = bio->bi_disk->queue;
+	struct blkcg_gq *blkg = bio->bi_blkg;
 	struct throtl_qnode *qn = NULL;
 	struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg);
 	struct throtl_service_queue *sq;

block/blk.h

@@ -288,10 +288,12 @@ int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
 extern int blk_throtl_init(struct request_queue *q);
 extern void blk_throtl_exit(struct request_queue *q);
 extern void blk_throtl_register_queue(struct request_queue *q);
+bool blk_throtl_bio(struct bio *bio);
 #else /* CONFIG_BLK_DEV_THROTTLING */
 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 static inline void blk_throtl_exit(struct request_queue *q) { }
 static inline void blk_throtl_register_queue(struct request_queue *q) { }
+static inline bool blk_throtl_bio(struct bio *bio) { return false; }
 #endif /* CONFIG_BLK_DEV_THROTTLING */
 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
 extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);

include/linux/blk-cgroup.h

@@ -517,14 +517,6 @@ static inline void blkg_put(struct blkcg_gq *blkg)
 		if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),	\
 					      (p_blkg)->q, false)))
 
-#ifdef CONFIG_BLK_DEV_THROTTLING
-extern bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
-			   struct bio *bio);
-#else
-static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
-				  struct bio *bio) { return false; }
-#endif
-
 bool __blkcg_punt_bio_submit(struct bio *bio);
 
 static inline bool blkcg_punt_bio_submit(struct bio *bio)
@@ -540,50 +532,6 @@ static inline void blkcg_bio_issue_init(struct bio *bio)
 	bio_issue_init(&bio->bi_issue, bio_sectors(bio));
 }
 
-static inline bool blkcg_bio_issue_check(struct request_queue *q,
-					 struct bio *bio)
-{
-	struct blkcg_gq *blkg = bio->bi_blkg;
-	bool throtl = false;
-
-	throtl = blk_throtl_bio(q, blkg, bio);
-	if (!throtl) {
-		struct blkg_iostat_set *bis;
-		int rwd, cpu;
-
-		if (op_is_discard(bio->bi_opf))
-			rwd = BLKG_IOSTAT_DISCARD;
-		else if (op_is_write(bio->bi_opf))
-			rwd = BLKG_IOSTAT_WRITE;
-		else
-			rwd = BLKG_IOSTAT_READ;
-
-		cpu = get_cpu();
-		bis = per_cpu_ptr(blkg->iostat_cpu, cpu);
-		u64_stats_update_begin(&bis->sync);
-
-		/*
-		 * If the bio is flagged with BIO_CGROUP_ACCT it means this is a
-		 * split bio and we would have already accounted for the size of
-		 * the bio.
-		 */
-		if (!bio_flagged(bio, BIO_CGROUP_ACCT)) {
-			bio_set_flag(bio, BIO_CGROUP_ACCT);
-			bis->cur.bytes[rwd] += bio->bi_iter.bi_size;
-		}
-		bis->cur.ios[rwd]++;
-
-		u64_stats_update_end(&bis->sync);
-		if (cgroup_subsys_on_dfl(io_cgrp_subsys))
-			cgroup_rstat_updated(blkg->blkcg->css.cgroup, cpu);
-		put_cpu();
-	}
-
-	blkcg_bio_issue_init(bio);
-
-	return !throtl;
-}
-
 static inline void blkcg_use_delay(struct blkcg_gq *blkg)
 {
 	if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
@@ -657,6 +605,7 @@ static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
 		atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
 }
 
+void blk_cgroup_bio_start(struct bio *bio);
 void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
 void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay);
 void blkcg_maybe_throttle_current(void);
@@ -710,8 +659,7 @@ static inline void blkg_put(struct blkcg_gq *blkg) { }
 
 static inline bool blkcg_punt_bio_submit(struct bio *bio) { return false; }
 static inline void blkcg_bio_issue_init(struct bio *bio) { }
-static inline bool blkcg_bio_issue_check(struct request_queue *q,
-					 struct bio *bio) { return true; }
+static inline void blk_cgroup_bio_start(struct bio *bio) { }
 
 #define blk_queue_for_each_rl(rl, q)	\
 	for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)