blkcg: move io_service_bytes and io_serviced stats into blkcg_gq

Currently, both cfq-iosched and blk-throttle keep track of
io_service_bytes and io_serviced stats.  While keeping track of them
separately may be useful during development, it doesn't make much
sense otherwise.  Also, blk-throttle was counting bio's as IOs while
cfq-iosched request's, which is more confusing than informative.

This patch adds ->stat_bytes and ->stat_ios to blkg (blkcg_gq),
removes the counterparts from cfq-iosched and blk-throttle and let
them print from the common blkg counters.  The common counters are
incremented during bio issue in blkcg_bio_issue_check().

The outputs are still filtered by whether the policy has
blkg_policy_data on a given blkg, so cfq's output won't show up if it
has never been used for a given blkg.  The only times when the outputs
would differ significantly are when policies are attached on the fly
or elevators are switched back and forth.  Those are quite exceptional
operations and I don't think they warrant keeping separate counters.

v3: Update blkio-controller.txt accordingly.

v2: Account IOs during bio issues instead of request completions so
    that bio-based drivers can be handled the same way.

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

1 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 4630ce8f9425a..286e1bde249f2 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -127,6 +127,9 @@ struct blkcg_gq {
 	/* is this blkg online? protected by both blkcg and q locks */
 	bool				online;
 
+	struct blkg_rwstat		stat_bytes;
+	struct blkg_rwstat		stat_ios;
+
 	struct blkg_policy_data		*pd[BLKCG_MAX_POLS];
 
 	struct rcu_head			rcu_head;
@@ -190,6 +193,10 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 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);
+int blkg_print_stat_ios(struct seq_file *sf, void *v);
+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);
@@ -700,6 +707,13 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q,
 
 	throtl = blk_throtl_bio(q, blkg, bio);
 
+	if (!throtl) {
+		blkg = blkg ?: q->root_blkg;
+		blkg_rwstat_add(&blkg->stat_bytes, bio->bi_flags,
+				bio->bi_iter.bi_size);
+		blkg_rwstat_add(&blkg->stat_ios, bio->bi_flags, 1);
+	}
+
 	rcu_read_unlock();
 	return !throtl;
 }