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@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

@@ -54,7 +54,7 @@ static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
 
 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,
@@ -944,10 +944,7 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
 					 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",
@@ -967,7 +964,7 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
 				has_stats = true;
 			off += written;
 		}
-next:
+
 		if (has_stats) {
 			if (off < size - 1) {
 				off += scnprintf(buf+off, size-off, "\n");

block/blk-iolatency.c

@@ -917,6 +917,9 @@ static size_t iolatency_pd_stat(struct blkg_policy_data *pd, char *buf,
 	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);
 

include/linux/blk-cgroup.h

@@ -181,6 +181,7 @@ 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);