[PATCH 08/10] blkcg: make blkg_[rw]stat_recursive_sum() to be able to index into blkcg_gq

Tejun Heo
2015-07-12T18:00:59Z

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>
---
block/blk-cgroup.c | 69 ++++++++++++++++++++++++++++------------------
block/cfq-iosched.c | 8 +++---
include/linux/blk-cgroup.h | 7 +++--
3 files changed, 50 insertions(+), 34 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index caabda1..6ca7187 100644
--- 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 9a0d8e8..782ab58 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1875,16 +1875,16 @@ 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 ddbf580..d930690 100644
--- 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;
--
2.4.3