linux-kernel - [PATCH block/for-linus] blkcg: allow blkcg_policy->pd

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Message-ID: <20190716145749.GB680549@devbig004.ftw2.facebook.com>
Date:   Tue, 16 Jul 2019 07:58:31 -0700
From:   Tejun Heo <tj@...nel.org>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, kernel-team@...com,
        Josef Bacik <josef@...icpanda.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH block/for-linus] blkcg: allow blkcg_policy->pd_stat() to
 print non-debug info too

Currently, ->pd_stat() is called only when moduleparam
blkcg_debug_stats is set which prevents it from printing non-debug
policy-specific statistics.  Let's move debug testing down so that
->pd_stat() can print non-debug stat too.  This patch doesn't cause
any visible behavior change.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Josef Bacik <josef@...icpanda.com>
---
 block/blk-cgroup.c         |    9 +++------
 block/blk-iolatency.c      |    3 +++
 include/linux/blk-cgroup.h |    1 +
 3 files changed, 7 insertions(+), 6 deletions(-)

--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -54,7 +54,7 @@ static struct blkcg_policy *blkcg_policy
 
 static LIST_HEAD(all_blkcgs);		/* protected by blkcg_pol_mutex */
 
-static bool blkcg_debug_stats = false;
+bool blkcg_debug_stats = false;
 static struct workqueue_struct *blkcg_punt_bio_wq;
 
 static bool blkcg_policy_enabled(struct request_queue *q,
@@ -968,10 +968,7 @@ static int blkcg_print_stat(struct seq_f
 					 dbytes, dios);
 		}
 
-		if (!blkcg_debug_stats)
-			goto next;
-
-		if (atomic_read(&blkg->use_delay)) {
+		if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) {
 			has_stats = true;
 			off += scnprintf(buf+off, size-off,
 					 " use_delay=%d delay_nsec=%llu",
@@ -991,7 +988,7 @@ static int blkcg_print_stat(struct seq_f
 				has_stats = true;
 			off += written;
 		}
-next:
+
 		if (has_stats) {
 			if (off < size - 1) {
 				off += scnprintf(buf+off, size-off, "\n");
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -917,6 +917,9 @@ static size_t iolatency_pd_stat(struct b
 	unsigned long long avg_lat;
 	unsigned long long cur_win;
 
+	if (!blkcg_debug_stats)
+		return 0;
+
 	if (iolat->ssd)
 		return iolatency_ssd_stat(iolat, buf, size);
 
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -182,6 +182,7 @@ struct blkcg_policy {
 
 extern struct blkcg blkcg_root;
 extern struct cgroup_subsys_state * const blkcg_root_css;
+extern bool blkcg_debug_stats;
 
 struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
 				      struct request_queue *q, bool update_hint);