From d19afebca47602bd9909944eb0ee406dce66174d Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@redhat.com>
Date: Mon, 17 Dec 2018 09:46:01 +0800
Subject: [PATCH] blk-wbt: export internal state via debugfs

This information is helpful to either investigate issues, or understand
wbt's internal behaviour.

Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-wbt.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)

diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 463e4eb80287..f0c56649775f 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -715,6 +715,94 @@ void wbt_disable_default(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(wbt_disable_default);
 
+#ifdef CONFIG_BLK_DEBUG_FS
+static int wbt_curr_win_nsec_show(void *data, struct seq_file *m)
+{
+	struct rq_qos *rqos = data;
+	struct rq_wb *rwb = RQWB(rqos);
+
+	seq_printf(m, "%llu\n", rwb->cur_win_nsec);
+	return 0;
+}
+
+static int wbt_enabled_show(void *data, struct seq_file *m)
+{
+	struct rq_qos *rqos = data;
+	struct rq_wb *rwb = RQWB(rqos);
+
+	seq_printf(m, "%d\n", rwb->enable_state);
+	return 0;
+}
+
+static int wbt_id_show(void *data, struct seq_file *m)
+{
+	struct rq_qos *rqos = data;
+
+	seq_printf(m, "%u\n", rqos->id);
+	return 0;
+}
+
+static int wbt_inflight_show(void *data, struct seq_file *m)
+{
+	struct rq_qos *rqos = data;
+	struct rq_wb *rwb = RQWB(rqos);
+	int i;
+
+	for (i = 0; i < WBT_NUM_RWQ; i++)
+		seq_printf(m, "%d: inflight %d\n", i,
+			   atomic_read(&rwb->rq_wait[i].inflight));
+	return 0;
+}
+
+static int wbt_min_lat_nsec_show(void *data, struct seq_file *m)
+{
+	struct rq_qos *rqos = data;
+	struct rq_wb *rwb = RQWB(rqos);
+
+	seq_printf(m, "%lu\n", rwb->min_lat_nsec);
+	return 0;
+}
+
+static int wbt_unknown_cnt_show(void *data, struct seq_file *m)
+{
+	struct rq_qos *rqos = data;
+	struct rq_wb *rwb = RQWB(rqos);
+
+	seq_printf(m, "%u\n", rwb->unknown_cnt);
+	return 0;
+}
+
+static int wbt_normal_show(void *data, struct seq_file *m)
+{
+	struct rq_qos *rqos = data;
+	struct rq_wb *rwb = RQWB(rqos);
+
+	seq_printf(m, "%u\n", rwb->wb_normal);
+	return 0;
+}
+
+static int wbt_background_show(void *data, struct seq_file *m)
+{
+	struct rq_qos *rqos = data;
+	struct rq_wb *rwb = RQWB(rqos);
+
+	seq_printf(m, "%u\n", rwb->wb_background);
+	return 0;
+}
+
+static const struct blk_mq_debugfs_attr wbt_debugfs_attrs[] = {
+	{"curr_win_nsec", 0400, wbt_curr_win_nsec_show},
+	{"enabled", 0400, wbt_enabled_show},
+	{"id", 0400, wbt_id_show},
+	{"inflight", 0400, wbt_inflight_show},
+	{"min_lat_nsec", 0400, wbt_min_lat_nsec_show},
+	{"unknown_cnt", 0400, wbt_unknown_cnt_show},
+	{"wb_normal", 0400, wbt_normal_show},
+	{"wb_background", 0400, wbt_background_show},
+	{},
+};
+#endif
+
 static struct rq_qos_ops wbt_rqos_ops = {
 	.throttle = wbt_wait,
 	.issue = wbt_issue,
@@ -723,6 +811,9 @@ static struct rq_qos_ops wbt_rqos_ops = {
 	.done = wbt_done,
 	.cleanup = wbt_cleanup,
 	.exit = wbt_exit,
+#ifdef CONFIG_BLK_DEBUG_FS
+	.debugfs_attrs = wbt_debugfs_attrs,
+#endif
 };
 
 int wbt_init(struct request_queue *q)