[PATCH 3/4] block: reuse wbt_set_min_lat for setting wbt->min_lat_nsec

[Ming Lei <ming.lei@redhat.com>]

We need to freeze queue when setting wbt->min_lat_nsec because
wbt enabled state can be changed, so reuse wbt_set_min_lat() for doing
that for users of wbt_init().

Meantime move wbt_enable_default() out of q->sysfs_lock, since we
don't need that lock for enabling wbt.

Reported-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-sysfs.c | 16 +++-------------
 block/blk-wbt.c   | 29 ++++++++++++++++++++++-------
 block/blk-wbt.h   |  4 ++--
 3 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 7fd4ffadcdfa..925043f926c5 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -498,18 +498,7 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
 	if (wbt_get_min_lat(q) == val)
 		return count;
 
-	/*
-	 * Ensure that the queue is idled, in case the latency update
-	 * ends up either enabling or disabling wbt completely. We can't
-	 * have IO inflight if that happens.
-	 */
-	blk_mq_freeze_queue(q);
-	blk_mq_quiesce_queue(q);
-
-	wbt_set_min_lat(q, val);
-
-	blk_mq_unquiesce_queue(q);
-	blk_mq_unfreeze_queue(q);
+	wbt_set_min_lat(q, val, true);
 
 	return count;
 }
@@ -918,7 +907,6 @@ int blk_register_queue(struct gendisk *disk)
 	}
 
 	blk_queue_flag_set(QUEUE_FLAG_REGISTERED, q);
-	wbt_enable_default(q);
 	blk_throtl_register_queue(q);
 
 	/* Now everything is ready and send out KOBJ_ADD uevent */
@@ -927,6 +915,8 @@ int blk_register_queue(struct gendisk *disk)
 		kobject_uevent(&q->elevator->kobj, KOBJ_ADD);
 	mutex_unlock(&q->sysfs_lock);
 
+	wbt_enable_default(q);
+
 	ret = 0;
 unlock:
 	mutex_unlock(&q->sysfs_dir_lock);
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 5da48294e3e9..5d2db197cce6 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -24,6 +24,7 @@
 #include <linux/slab.h>
 #include <linux/backing-dev.h>
 #include <linux/swap.h>
+#include <linux/blk-mq.h>
 
 #include "blk-wbt.h"
 #include "blk-rq-qos.h"
@@ -425,13 +426,27 @@ u64 wbt_get_min_lat(struct request_queue *q)
 	return RQWB(rqos)->min_lat_nsec;
 }
 
-void wbt_set_min_lat(struct request_queue *q, u64 val)
+void wbt_set_min_lat(struct request_queue *q, u64 val, bool manual)
 {
 	struct rq_qos *rqos = wbt_rq_qos(q);
 
+	/*
+	 * Ensure that the queue is idled, in case the latency update
+	 * ends up either enabling or disabling wbt completely. We can't
+	 * have IO inflight if that happens.
+	 */
+	blk_mq_freeze_queue(q);
+	blk_mq_quiesce_queue(q);
+
 	RQWB(rqos)->min_lat_nsec = val;
-	RQWB(rqos)->enable_state = WBT_STATE_ON_MANUAL;
+	if (manual)
+		RQWB(rqos)->enable_state = WBT_STATE_ON_MANUAL;
+	else
+		RQWB(rqos)->enable_state = WBT_STATE_ON_DEFAULT;
 	wbt_update_limits(RQWB(rqos));
+
+	blk_mq_unquiesce_queue(q);
+	blk_mq_unfreeze_queue(q);
 }
 
 
@@ -844,11 +859,11 @@ int wbt_alloc(struct request_queue *q)
 
 void wbt_init(struct request_queue *q)
 {
-	struct rq_wb *rwb = RQWB(wbt_rq_qos(q));
-
-	rwb->enable_state = WBT_STATE_ON_DEFAULT;
-	rwb->min_lat_nsec = wbt_default_latency_nsec(q);
+	struct rq_qos *rqos = wbt_rq_qos(q);
+	struct rq_wb *rwb = RQWB(rqos);
 
-	wbt_queue_depth_changed(&rwb->rqos);
+	rwb->rq_depth.queue_depth = blk_queue_depth(rqos->q);
 	wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
+
+	wbt_set_min_lat(q, wbt_default_latency_nsec(q), false);
 }
diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index de07963f3544..d9b643a55407 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -93,7 +93,7 @@ void wbt_disable_default(struct request_queue *);
 void wbt_enable_default(struct request_queue *);
 
 u64 wbt_get_min_lat(struct request_queue *q);
-void wbt_set_min_lat(struct request_queue *q, u64 val);
+void wbt_set_min_lat(struct request_queue *q, u64 val, bool manual);
 
 void wbt_set_write_cache(struct request_queue *, bool);
 
@@ -124,7 +124,7 @@ static inline u64 wbt_get_min_lat(struct request_queue *q)
 {
 	return 0;
 }
-static inline void wbt_set_min_lat(struct request_queue *q, u64 val)
+static inline void wbt_set_min_lat(struct request_queue *q, u64 val, bool manual)
 {
 }
 static inline u64 wbt_default_latency_nsec(struct request_queue *q)
-- 
2.29.2