blk-cgroup: move struct blkg_stat to bfq [Linux 5.3]

This Linux kernel change "blk-cgroup: move struct blkg_stat to bfq" is included in the Linux 5.3 release. This change is authored by Christoph Hellwig <hch [at] lst.de> on Thu Jun 6 12:26:22 2019 +0200. The commit for this change in Linux stable tree is c0ce79d (patch).

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>

There are 338 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 block/bfq-cgroup.c         | 192 ++++++++++++++++++++++++++++++++++++---------
 block/bfq-iosched.h        |  19 +++--
 block/blk-cgroup.c         |  56 -------------
 include/linux/blk-cgroup.h |  71 -----------------
 4 files changed, 167 insertions(+), 171 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 624374a9..a691dca 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 c2faa77..aef4fa0 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 664c098..53b7bd4 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
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index e4a8176..33f23a8 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -65,11 +65,6 @@ struct blkcg {
  * blkg_[rw]stat->aux_cnt is excluded for local stats but included for
  * recursive.  Used to carry stats of dead children.
  */
-struct blkg_stat {
-   struct percpu_counter       cpu_cnt;
-   atomic64_t          aux_cnt;
-};
-
 struct blkg_rwstat {
    struct percpu_counter       cpu_cnt[BLKG_RWSTAT_NR];
    atomic64_t          aux_cnt[BLKG_RWSTAT_NR];
@@ -217,7 +212,6 @@ void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
             const struct blkg_rwstat_sample *rwstat);
-u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
               int off);
 int blkg_print_stat_bytes(struct seq_file *sf, void *v);
@@ -225,8 +219,6 @@ u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v);
 int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v);

-u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
-               struct blkcg_policy *pol, int off);
 void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
        int off, struct blkg_rwstat_sample *sum);

@@ -579,69 +571,6 @@ static inline void blkg_put(struct blkcg_gq *blkg)
        if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
                          (p_blkg)->q, false)))

-static inline int blkg_stat_init(struct blkg_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 inline void blkg_stat_exit(struct blkg_stat *stat)
-{
-   percpu_counter_destroy(&stat->cpu_cnt);
-}
-
-/**
- * blkg_stat_add - add a value to a blkg_stat
- * @stat: target blkg_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 blkg_stat_add(struct blkg_stat *stat, uint64_t val)
-{
-   percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
-}
-
-/**
- * blkg_stat_read - read the current value of a blkg_stat
- * @stat: blkg_stat to read
- */
-static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
-{
-   return percpu_counter_sum_positive(&stat->cpu_cnt);
-}
-
-/**
- * blkg_stat_reset - reset a blkg_stat
- * @stat: blkg_stat to reset
- */
-static inline void blkg_stat_reset(struct blkg_stat *stat)
-{
-   percpu_counter_set(&stat->cpu_cnt, 0);
-   atomic64_set(&stat->aux_cnt, 0);
-}
-
-/**
- * blkg_stat_add_aux - add a blkg_stat into another's aux count
- * @to: the destination blkg_stat
- * @from: the source
- *
- * Add @from's count including the aux one to @to's aux count.
- */
-static inline void blkg_stat_add_aux(struct blkg_stat *to,
-                    struct blkg_stat *from)
-{
-   atomic64_add(blkg_stat_read(from) + atomic64_read(&from->aux_cnt),
-            &to->aux_cnt);
-}
-
 static inline int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
 {
    int i, ret;

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