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>

diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 463e4eb..f0c5664 100644 (file)
--- 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)