blkcg: make blkg_[rw]stat_recursive_sum() to be able to index into blkcg_gq

Currently, blkg_[rw]stat_recursive_sum() assume that the target
counter is located in pd (blkg_policy_data); however, some counters
are planned to be moved to blkg (blkcg_gq).

This patch updates blkg_[rw]stat_recursive_sum() to take blkg and
blkg_policy pointers instead of pd.  If policy is NULL, it indexes
into blkg.  If non-NULL, into the blkg's pd of the policy.

The existing usages are updated to maintain the current behaviors.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 02a2d02..b263207 100644 (file)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -581,30 +581,39 @@ EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
 
 /**
  * blkg_stat_recursive_sum - collect hierarchical blkg_stat
- * @pd: policy private data of interest
- * @off: offset to the blkg_stat in @pd
+ * @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 @off from @pd and all its online
- * descendants and their aux counts.  The caller must be holding the queue
- * lock for online tests.
+ * 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 blkg_policy_data *pd, int off)
+u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
+                           struct blkcg_policy *pol, int off)
 {
-       struct blkcg_policy *pol = blkcg_policy[pd->plid];
        struct blkcg_gq *pos_blkg;
        struct cgroup_subsys_state *pos_css;
        u64 sum = 0;
 
-       lockdep_assert_held(pd->blkg->q->queue_lock);
+       lockdep_assert_held(blkg->q->queue_lock);
 
        rcu_read_lock();
-       blkg_for_each_descendant_pre(pos_blkg, pos_css, pd_to_blkg(pd)) {
-               struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
-               struct blkg_stat *stat = (void *)pos_pd + off;
+       blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
+               struct blkg_stat *stat;
+
+               if (!pos_blkg->online)
+                       continue;
 
-               if (pos_blkg->online)
-                       sum += blkg_stat_read(stat) +
-                               atomic64_read(&stat->aux_cnt);
+               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();
 
@@ -614,33 +623,39 @@ EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
 
 /**
  * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
- * @pd: policy private data of interest
- * @off: offset to the blkg_stat in @pd
+ * @blkg: blkg of interest
+ * @pol: blkcg_policy which contains the blkg_rwstat
+ * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
  *
- * Collect the blkg_rwstat specified by @off from @pd and all its online
- * descendants and their aux counts.  The caller must be holding the queue
- * lock for online tests.
+ * Collect the blkg_rwstat 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_rwstat is at @off bytes into @blkg; otherwise, it
+ * is at @off bytes into @blkg's blkg_policy_data of the policy.
  */
-struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
-                                            int off)
+struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
+                                            struct blkcg_policy *pol, int off)
 {
-       struct blkcg_policy *pol = blkcg_policy[pd->plid];
        struct blkcg_gq *pos_blkg;
        struct cgroup_subsys_state *pos_css;
        struct blkg_rwstat sum = { };
        int i;
 
-       lockdep_assert_held(pd->blkg->q->queue_lock);
+       lockdep_assert_held(blkg->q->queue_lock);
 
        rcu_read_lock();
-       blkg_for_each_descendant_pre(pos_blkg, pos_css, pd_to_blkg(pd)) {
-               struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol);
-               struct blkg_rwstat *rwstat = (void *)pos_pd + off;
-               struct blkg_rwstat tmp;
+       blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
+               struct blkg_rwstat *rwstat, tmp;
 
                if (!pos_blkg->online)
                        continue;
 
+               if (pol)
+                       rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
+               else
+                       rwstat = (void *)pos_blkg + off;
+
                tmp = blkg_rwstat_read(rwstat);
 
                for (i = 0; i < BLKG_RWSTAT_NR; i++)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 71e55c9..e861cc1 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1886,16 +1886,16 @@ static int cfqg_print_rwstat(struct seq_file *sf, void *v)
 static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
                                      struct blkg_policy_data *pd, int off)
 {
-       u64 sum = blkg_stat_recursive_sum(pd, off);
-
+       u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
+                                         &blkcg_policy_cfq, off);
        return __blkg_prfill_u64(sf, pd, sum);
 }
 
 static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
                                        struct blkg_policy_data *pd, int off)
 {
-       struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd, off);
-
+       struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
+                                                       &blkcg_policy_cfq, off);
        return __blkg_prfill_rwstat(sf, pd, &sum);
 }
 

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index fdc7ac0..4630ce8 100644 (file)
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -191,9 +191,10 @@ 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);
 
-u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
-struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
-                                            int off);
+u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
+                           struct blkcg_policy *pol, int off);
+struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
+                                            struct blkcg_policy *pol, int off);
 
 struct blkg_conf_ctx {
        struct gendisk                  *disk;