blkcg: move blkio_group_stats to cfq-iosched.c

blkio_group_stats contains only fields used by cfq and has no reason
to be defined in blkcg core.

* Move blkio_group_stats to cfq-iosched.c and rename it to cfqg_stats.

* blkg_policy_data->stats is replaced with cfq_group->stats.
  blkg_prfill_[rw]stat() are updated to use offset against pd->pdata
  instead.

* All related macros / functions are renamed so that they have cfqg_
  prefix and the unnecessary @pol arguments are dropped.

* All stat functions now take cfq_group * instead of blkio_group *.

* lockdep assertion on queue lock dropped.  Elevator runs under queue
  lock by default.  There isn't much to be gained by adding lockdep
  assertions at stat function level.

* cfqg_stats_reset() implemented for blkio_reset_group_stats_fn method
  so that cfqg->stats can be reset.
Signed-off-by: Tejun Heo <tj@kernel.org>

block/blk-cgroup.c

@@ -417,25 +417,6 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
 		struct blkio_policy_type *pol;
 
 		list_for_each_entry(pol, &blkio_list, list) {
-			struct blkg_policy_data *pd = blkg->pd[pol->plid];
-			struct blkio_group_stats *stats = &pd->stats;
-
-			/* queued stats shouldn't be cleared */
-			blkg_rwstat_reset(&stats->service_bytes);
-			blkg_rwstat_reset(&stats->serviced);
-			blkg_rwstat_reset(&stats->merged);
-			blkg_rwstat_reset(&stats->service_time);
-			blkg_rwstat_reset(&stats->wait_time);
-			blkg_stat_reset(&stats->time);
-#ifdef CONFIG_DEBUG_BLK_CGROUP
-			blkg_stat_reset(&stats->unaccounted_time);
-			blkg_stat_reset(&stats->avg_queue_size_sum);
-			blkg_stat_reset(&stats->avg_queue_size_samples);
-			blkg_stat_reset(&stats->dequeue);
-			blkg_stat_reset(&stats->group_wait_time);
-			blkg_stat_reset(&stats->idle_time);
-			blkg_stat_reset(&stats->empty_time);
-#endif
 			blkio_reset_stats_cpu(blkg, pol->plid);
 
 			if (pol->ops.blkio_reset_group_stats_fn)
@@ -549,13 +530,13 @@ static u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd,
 			    int off)
 {
 	return __blkg_prfill_u64(sf, pd,
-				 blkg_stat_read((void *)&pd->stats + off));
+				 blkg_stat_read((void *)pd->pdata + off));
 }
 
 static u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 			      int off)
 {
-	struct blkg_rwstat rwstat = blkg_rwstat_read((void *)&pd->stats + off);
+	struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd->pdata + off);
 
 	return __blkg_prfill_rwstat(sf, pd, &rwstat);
 }

block/blk-cgroup.h

@@ -64,46 +64,6 @@ struct blkg_rwstat {
 	uint64_t			cnt[BLKG_RWSTAT_NR];
 };
 
-struct blkio_group_stats {
-	/* total bytes transferred */
-	struct blkg_rwstat		service_bytes;
-	/* total IOs serviced, post merge */
-	struct blkg_rwstat		serviced;
-	/* number of ios merged */
-	struct blkg_rwstat		merged;
-	/* total time spent on device in ns, may not be accurate w/ queueing */
-	struct blkg_rwstat		service_time;
-	/* total time spent waiting in scheduler queue in ns */
-	struct blkg_rwstat		wait_time;
-	/* number of IOs queued up */
-	struct blkg_rwstat		queued;
-	/* total sectors transferred */
-	struct blkg_stat		sectors;
-	/* total disk time and nr sectors dispatched by this group */
-	struct blkg_stat		time;
-#ifdef CONFIG_DEBUG_BLK_CGROUP
-	/* time not charged to this cgroup */
-	struct blkg_stat		unaccounted_time;
-	/* sum of number of ios queued across all samples */
-	struct blkg_stat		avg_queue_size_sum;
-	/* count of samples taken for average */
-	struct blkg_stat		avg_queue_size_samples;
-	/* how many times this group has been removed from service tree */
-	struct blkg_stat		dequeue;
-	/* total time spent waiting for it to be assigned a timeslice. */
-	struct blkg_stat		group_wait_time;
-	/* time spent idling for this blkio_group */
-	struct blkg_stat		idle_time;
-	/* total time with empty current active q with other requests queued */
-	struct blkg_stat		empty_time;
-	/* fields after this shouldn't be cleared on stat reset */
-	uint64_t			start_group_wait_time;
-	uint64_t			start_idle_time;
-	uint64_t			start_empty_time;
-	uint16_t			flags;
-#endif
-};
-
 /* Per cpu blkio group stats */
 struct blkio_group_stats_cpu {
 	/* total bytes transferred */
@@ -126,7 +86,6 @@ struct blkg_policy_data {
 	/* Configuration */
 	struct blkio_group_conf conf;
 
-	struct blkio_group_stats stats;
 	/* Per cpu stats pointer */
 	struct blkio_group_stats_cpu __percpu *stats_cpu;