blk-cgroup: move struct blkg_stat to bfq

This structure and assorted infrastructure is only used by the bfq I/O
scheduler.  Move it there instead of bloating the common code.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 167 insertions, 100 deletions

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 624374a99c6e..a691dca7e966 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -17,6 +17,124 @@
 
 #if defined(CONFIG_BFQ_GROUP_IOSCHED) &&  defined(CONFIG_DEBUG_BLK_CGROUP)
 
+static int bfq_stat_init(struct bfq_stat *stat, gfp_t gfp)
+{
+        int ret;
+
+        ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
+        if (ret)
+                return ret;
+
+        atomic64_set(&stat->aux_cnt, 0);
+        return 0;
+}
+
+static void bfq_stat_exit(struct bfq_stat *stat)
+{
+        percpu_counter_destroy(&stat->cpu_cnt);
+}
+
+/**
+ * bfq_stat_add - add a value to a bfq_stat
+ * @stat: target bfq_stat
+ * @val: value to add
+ *
+ * Add @val to @stat.  The caller must ensure that IRQ on the same CPU
+ * don't re-enter this function for the same counter.
+ */
+static inline void bfq_stat_add(struct bfq_stat *stat, uint64_t val)
+{
+        percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
+}
+
+/**
+ * bfq_stat_read - read the current value of a bfq_stat
+ * @stat: bfq_stat to read
+ */
+static inline uint64_t bfq_stat_read(struct bfq_stat *stat)
+{
+        return percpu_counter_sum_positive(&stat->cpu_cnt);
+}
+
+/**
+ * bfq_stat_reset - reset a bfq_stat
+ * @stat: bfq_stat to reset
+ */
+static inline void bfq_stat_reset(struct bfq_stat *stat)
+{
+        percpu_counter_set(&stat->cpu_cnt, 0);
+        atomic64_set(&stat->aux_cnt, 0);
+}
+
+/**
+ * bfq_stat_add_aux - add a bfq_stat into another's aux count
+ * @to: the destination bfq_stat
+ * @from: the source
+ *
+ * Add @from's count including the aux one to @to's aux count.
+ */
+static inline void bfq_stat_add_aux(struct bfq_stat *to,
+                                     struct bfq_stat *from)
+{
+        atomic64_add(bfq_stat_read(from) + atomic64_read(&from->aux_cnt),
+                     &to->aux_cnt);
+}
+
+/**
+ * bfq_stat_recursive_sum - collect hierarchical bfq_stat
+ * @blkg: blkg of interest
+ * @pol: blkcg_policy which contains the bfq_stat
+ * @off: offset to the bfq_stat in blkg_policy_data or @blkg
+ *
+ * Collect the bfq_stat specified by @blkg, @pol and @off and all its
+ * online descendants and their aux counts.  The caller must be holding the
+ * queue lock for online tests.
+ *
+ * If @pol is NULL, bfq_stat is at @off bytes into @blkg; otherwise, it is
+ * at @off bytes into @blkg's blkg_policy_data of the policy.
+ */
+static u64 bfq_stat_recursive_sum(struct blkcg_gq *blkg,
+                            struct blkcg_policy *pol, int off)
+{
+        struct blkcg_gq *pos_blkg;
+        struct cgroup_subsys_state *pos_css;
+        u64 sum = 0;
+
+        lockdep_assert_held(&blkg->q->queue_lock);
+
+        rcu_read_lock();
+        blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
+                struct bfq_stat *stat;
+
+                if (!pos_blkg->online)
+                        continue;
+
+                if (pol)
+                        stat = (void *)blkg_to_pd(pos_blkg, pol) + off;
+                else
+                        stat = (void *)blkg + off;
+
+                sum += bfq_stat_read(stat) + atomic64_read(&stat->aux_cnt);
+        }
+        rcu_read_unlock();
+
+        return sum;
+}
+
+/**
+ * blkg_prfill_stat - prfill callback for bfq_stat
+ * @sf: seq_file to print to
+ * @pd: policy private data of interest
+ * @off: offset to the bfq_stat in @pd
+ *
+ * prfill callback for printing a bfq_stat.
+ */
+static u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd,
+                int off)
+{
+        return __blkg_prfill_u64(sf, pd, bfq_stat_read((void *)pd + off));
+}
+
 /* bfqg stats flags */
 enum bfqg_stats_flags {
         BFQG_stats_waiting = 0,
@@ -53,7 +171,7 @@ static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
 
         now = ktime_get_ns();
         if (now > stats->start_group_wait_time)
-                blkg_stat_add(&stats->group_wait_time,
+                bfq_stat_add(&stats->group_wait_time,
                               now - stats->start_group_wait_time);
         bfqg_stats_clear_waiting(stats);
 }
@@ -82,14 +200,14 @@ static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
 
         now = ktime_get_ns();
         if (now > stats->start_empty_time)
-                blkg_stat_add(&stats->empty_time,
+                bfq_stat_add(&stats->empty_time,
                               now - stats->start_empty_time);
         bfqg_stats_clear_empty(stats);
 }
 
 void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
 {
-        blkg_stat_add(&bfqg->stats.dequeue, 1);
+        bfq_stat_add(&bfqg->stats.dequeue, 1);
 }
 
 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
@@ -119,7 +237,7 @@ void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
                 u64 now = ktime_get_ns();
 
                 if (now > stats->start_idle_time)
-                        blkg_stat_add(&stats->idle_time,
+                        bfq_stat_add(&stats->idle_time,
                                       now - stats->start_idle_time);
                 bfqg_stats_clear_idling(stats);
         }
@@ -137,9 +255,9 @@ void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
 {
         struct bfqg_stats *stats = &bfqg->stats;
 
-        blkg_stat_add(&stats->avg_queue_size_sum,
+        bfq_stat_add(&stats->avg_queue_size_sum,
                       blkg_rwstat_total(&stats->queued));
-        blkg_stat_add(&stats->avg_queue_size_samples, 1);
+        bfq_stat_add(&stats->avg_queue_size_samples, 1);
         bfqg_stats_update_group_wait_time(stats);
 }
 
@@ -279,13 +397,13 @@ static void bfqg_stats_reset(struct bfqg_stats *stats)
         blkg_rwstat_reset(&stats->merged);
         blkg_rwstat_reset(&stats->service_time);
         blkg_rwstat_reset(&stats->wait_time);
-        blkg_stat_reset(&stats->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);
+        bfq_stat_reset(&stats->time);
+        bfq_stat_reset(&stats->avg_queue_size_sum);
+        bfq_stat_reset(&stats->avg_queue_size_samples);
+        bfq_stat_reset(&stats->dequeue);
+        bfq_stat_reset(&stats->group_wait_time);
+        bfq_stat_reset(&stats->idle_time);
+        bfq_stat_reset(&stats->empty_time);
 #endif
 }
 
@@ -300,14 +418,14 @@ static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
         blkg_rwstat_add_aux(&to->merged, &from->merged);
         blkg_rwstat_add_aux(&to->service_time, &from->service_time);
         blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
-        blkg_stat_add_aux(&from->time, &from->time);
-        blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
-        blkg_stat_add_aux(&to->avg_queue_size_samples,
+        bfq_stat_add_aux(&from->time, &from->time);
+        bfq_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
+        bfq_stat_add_aux(&to->avg_queue_size_samples,
                           &from->avg_queue_size_samples);
-        blkg_stat_add_aux(&to->dequeue, &from->dequeue);
-        blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
-        blkg_stat_add_aux(&to->idle_time, &from->idle_time);
-        blkg_stat_add_aux(&to->empty_time, &from->empty_time);
+        bfq_stat_add_aux(&to->dequeue, &from->dequeue);
+        bfq_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
+        bfq_stat_add_aux(&to->idle_time, &from->idle_time);
+        bfq_stat_add_aux(&to->empty_time, &from->empty_time);
 #endif
 }
 
@@ -360,13 +478,13 @@ static void bfqg_stats_exit(struct bfqg_stats *stats)
         blkg_rwstat_exit(&stats->service_time);
         blkg_rwstat_exit(&stats->wait_time);
         blkg_rwstat_exit(&stats->queued);
-        blkg_stat_exit(&stats->time);
-        blkg_stat_exit(&stats->avg_queue_size_sum);
-        blkg_stat_exit(&stats->avg_queue_size_samples);
-        blkg_stat_exit(&stats->dequeue);
-        blkg_stat_exit(&stats->group_wait_time);
-        blkg_stat_exit(&stats->idle_time);
-        blkg_stat_exit(&stats->empty_time);
+        bfq_stat_exit(&stats->time);
+        bfq_stat_exit(&stats->avg_queue_size_sum);
+        bfq_stat_exit(&stats->avg_queue_size_samples);
+        bfq_stat_exit(&stats->dequeue);
+        bfq_stat_exit(&stats->group_wait_time);
+        bfq_stat_exit(&stats->idle_time);
+        bfq_stat_exit(&stats->empty_time);
 #endif
 }
 
@@ -377,13 +495,13 @@ static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
             blkg_rwstat_init(&stats->service_time, gfp) ||
             blkg_rwstat_init(&stats->wait_time, gfp) ||
             blkg_rwstat_init(&stats->queued, gfp) ||
-            blkg_stat_init(&stats->time, gfp) ||
-            blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
-            blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
-            blkg_stat_init(&stats->dequeue, gfp) ||
-            blkg_stat_init(&stats->group_wait_time, gfp) ||
-            blkg_stat_init(&stats->idle_time, gfp) ||
-            blkg_stat_init(&stats->empty_time, gfp)) {
+            bfq_stat_init(&stats->time, gfp) ||
+            bfq_stat_init(&stats->avg_queue_size_sum, gfp) ||
+            bfq_stat_init(&stats->avg_queue_size_samples, gfp) ||
+            bfq_stat_init(&stats->dequeue, gfp) ||
+            bfq_stat_init(&stats->group_wait_time, gfp) ||
+            bfq_stat_init(&stats->idle_time, gfp) ||
+            bfq_stat_init(&stats->empty_time, gfp)) {
                 bfqg_stats_exit(stats);
                 return -ENOMEM;
         }
@@ -927,7 +1045,7 @@ static int bfqg_print_rwstat(struct seq_file *sf, void *v)
 static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
                                       struct blkg_policy_data *pd, int off)
 {
-        u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
+        u64 sum = bfq_stat_recursive_sum(pd_to_blkg(pd),
                                           &blkcg_policy_bfq, off);
         return __blkg_prfill_u64(sf, pd, sum);
 }
@@ -996,11 +1114,11 @@ static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
                                       struct blkg_policy_data *pd, int off)
 {
         struct bfq_group *bfqg = pd_to_bfqg(pd);
-        u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples);
+        u64 samples = bfq_stat_read(&bfqg->stats.avg_queue_size_samples);
         u64 v = 0;
 
         if (samples) {
-                v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum);
+                v = bfq_stat_read(&bfqg->stats.avg_queue_size_sum);
                 v = div64_u64(v, samples);
         }
         __blkg_prfill_u64(sf, pd, v);
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index c2faa77824f8..aef4fa0046b8 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -777,6 +777,11 @@ enum bfqq_expiration {
         BFQQE_PREEMPTED         /* preemption in progress */
 };
 
+struct bfq_stat {
+        struct percpu_counter           cpu_cnt;
+        atomic64_t                      aux_cnt;
+};
+
 struct bfqg_stats {
 #if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
         /* number of ios merged */
@@ -788,19 +793,19 @@ struct bfqg_stats {
         /* number of IOs queued up */
         struct blkg_rwstat              queued;
         /* total disk time and nr sectors dispatched by this group */
-        struct blkg_stat                time;
+        struct bfq_stat         time;
         /* sum of number of ios queued across all samples */
-        struct blkg_stat                avg_queue_size_sum;
+        struct bfq_stat         avg_queue_size_sum;
         /* count of samples taken for average */
-        struct blkg_stat                avg_queue_size_samples;
+        struct bfq_stat         avg_queue_size_samples;
         /* how many times this group has been removed from service tree */
-        struct blkg_stat                dequeue;
+        struct bfq_stat         dequeue;
         /* total time spent waiting for it to be assigned a timeslice. */
-        struct blkg_stat                group_wait_time;
+        struct bfq_stat         group_wait_time;
         /* time spent idling for this blkcg_gq */
-        struct blkg_stat                idle_time;
+        struct bfq_stat         idle_time;
         /* total time with empty current active q with other requests queued */
-        struct blkg_stat                empty_time;
+        struct bfq_stat         empty_time;
         /* fields after this shouldn't be cleared on stat reset */
         u64                             start_group_wait_time;
         u64                             start_idle_time;
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 664c09866839..53b7bd4c7000 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -573,20 +573,6 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
 
 /**
- * blkg_prfill_stat - prfill callback for blkg_stat
- * @sf: seq_file to print to
- * @pd: policy private data of interest
- * @off: offset to the blkg_stat in @pd
- *
- * prfill callback for printing a blkg_stat.
- */
-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 + off));
-}
-EXPORT_SYMBOL_GPL(blkg_prfill_stat);
-
-/**
  * blkg_prfill_rwstat - prfill callback for blkg_rwstat
  * @sf: seq_file to print to
  * @pd: policy private data of interest
@@ -688,48 +674,6 @@ int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v)
 EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive);
 
 /**
- * blkg_stat_recursive_sum - collect hierarchical blkg_stat
- * @blkg: blkg of interest
- * @pol: blkcg_policy which contains the blkg_stat
- * @off: offset to the blkg_stat in blkg_policy_data or @blkg
- *
- * Collect the blkg_stat specified by @blkg, @pol and @off and all its
- * online descendants and their aux counts.  The caller must be holding the
- * queue lock for online tests.
- *
- * If @pol is NULL, blkg_stat is at @off bytes into @blkg; otherwise, it is
- * at @off bytes into @blkg's blkg_policy_data of the policy.
- */
-u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
-                            struct blkcg_policy *pol, int off)
-{
-        struct blkcg_gq *pos_blkg;
-        struct cgroup_subsys_state *pos_css;
-        u64 sum = 0;
-
-        lockdep_assert_held(&blkg->q->queue_lock);
-
-        rcu_read_lock();
-        blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
-                struct blkg_stat *stat;
-
-                if (!pos_blkg->online)
-                        continue;
-
-                if (pol)
-                        stat = (void *)blkg_to_pd(pos_blkg, pol) + off;
-                else
-                        stat = (void *)blkg + off;
-
-                sum += blkg_stat_read(stat) + atomic64_read(&stat->aux_cnt);
-        }
-        rcu_read_unlock();
-
-        return sum;
-}
-EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
-
-/**
  * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
  * @blkg: blkg of interest
  * @pol: blkcg_policy which contains the blkg_rwstat