[PATCH 02/13] blk-wbt: make wbt pluggable

From: Wang Jianchao
Date: Mon Jan 10 2022 - 04:15:02 EST


From: Wang Jianchao <wangjianchao@xxxxxxxxxxxx>

This patch makes wbt pluggable through /sys/block/xxx/queue/qos.

Signed-off-by: Wang Jianchao <wangjianchao@xxxxxxxxxxxx>
---
block/blk-mq-debugfs.c | 2 --
block/blk-rq-qos.h | 8 ++------
block/blk-sysfs.c | 7 ++-----
block/blk-wbt.c | 30 +++++++++++++++++++++++++-----
block/blk-wbt.h | 8 ++++----
5 files changed, 33 insertions(+), 22 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index e3e8d54c836f..e225db3c271f 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -820,8 +820,6 @@ void blk_mq_debugfs_unregister_sched(struct request_queue *q)
static const char *rq_qos_id_to_name(enum rq_qos_id id)
{
switch (id) {
- case RQ_QOS_WBT:
- return "wbt";
case RQ_QOS_LATENCY:
return "latency";
case RQ_QOS_COST:
diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h
index c2b9b41f8fd4..de82eb951bdd 100644
--- a/block/blk-rq-qos.h
+++ b/block/blk-rq-qos.h
@@ -14,7 +14,6 @@
struct blk_mq_debugfs_attr;

enum rq_qos_id {
- RQ_QOS_WBT,
RQ_QOS_LATENCY,
RQ_QOS_COST,
RQ_QOS_IOPRIO,
@@ -86,11 +85,6 @@ static inline struct rq_qos *rq_qos_by_id(struct request_queue *q, int id)
return rqos;
}

-static inline struct rq_qos *wbt_rq_qos(struct request_queue *q)
-{
- return rq_qos_by_id(q, RQ_QOS_WBT);
-}
-
static inline struct rq_qos *blkcg_rq_qos(struct request_queue *q)
{
return rq_qos_by_id(q, RQ_QOS_LATENCY);
@@ -158,6 +152,8 @@ ssize_t queue_qos_store(struct request_queue *q, const char *page,
size_t count);
struct rq_qos *rq_qos_get(struct request_queue *q, int id);
void rq_qos_put(struct rq_qos *rqos);
+int rq_qos_switch(struct request_queue *q, const struct rq_qos_ops *ops,
+ struct rq_qos *rqos);

static inline struct rq_qos *rq_qos_by_name(struct request_queue *q,
const char *name)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 91f980985b1b..12399e491670 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -482,11 +482,8 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
return -EINVAL;

rqos = wbt_rq_qos(q);
- if (!rqos) {
- ret = wbt_init(q);
- if (ret)
- return ret;
- }
+ if (!rqos)
+ return -EOPNOTSUPP;

if (val == -1)
val = wbt_default_latency_nsec(q);
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 88265ae4fa41..ce4b41e50564 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -31,6 +31,13 @@
#define CREATE_TRACE_POINTS
#include <trace/events/wbt.h>

+static struct rq_qos_ops wbt_rqos_ops;
+
+struct rq_qos *wbt_rq_qos(struct request_queue *q)
+{
+ return rq_qos_by_id(q, wbt_rqos_ops.id);
+}
+
static inline void wbt_clear_state(struct request *rq)
{
rq->wbt_flags = 0;
@@ -656,7 +663,7 @@ void wbt_enable_default(struct request_queue *q)
return;

if (queue_is_mq(q) && IS_ENABLED(CONFIG_BLK_WBT_MQ))
- wbt_init(q);
+ rq_qos_switch(q, &wbt_rqos_ops, NULL);
}
EXPORT_SYMBOL_GPL(wbt_enable_default);

@@ -696,6 +703,7 @@ static void wbt_exit(struct rq_qos *rqos)
struct rq_wb *rwb = RQWB(rqos);
struct request_queue *q = rqos->q;

+ rq_qos_deactivate(rqos);
blk_stat_remove_callback(q, rwb->cb);
blk_stat_free_callback(rwb->cb);
kfree(rwb);
@@ -806,7 +814,9 @@ static const struct blk_mq_debugfs_attr wbt_debugfs_attrs[] = {
};
#endif

+int wbt_init(struct request_queue *q);
static struct rq_qos_ops wbt_rqos_ops = {
+ .name = "wbt",
.throttle = wbt_wait,
.issue = wbt_issue,
.track = wbt_track,
@@ -815,6 +825,7 @@ static struct rq_qos_ops wbt_rqos_ops = {
.cleanup = wbt_cleanup,
.queue_depth_changed = wbt_queue_depth_changed,
.exit = wbt_exit,
+ .init = wbt_init,
#ifdef CONFIG_BLK_DEBUG_FS
.debugfs_attrs = wbt_debugfs_attrs,
#endif
@@ -838,9 +849,6 @@ int wbt_init(struct request_queue *q)
for (i = 0; i < WBT_NUM_RWQ; i++)
rq_wait_init(&rwb->rq_wait[i]);

- rwb->rqos.id = RQ_QOS_WBT;
- rwb->rqos.ops = &wbt_rqos_ops;
- rwb->rqos.q = q;
rwb->last_comp = rwb->last_issue = jiffies;
rwb->win_nsec = RWB_WINDOW_NSEC;
rwb->enable_state = WBT_STATE_ON_DEFAULT;
@@ -850,7 +858,7 @@ int wbt_init(struct request_queue *q)
/*
* Assign rwb and add the stats callback.
*/
- rq_qos_add(q, &rwb->rqos);
+ rq_qos_activate(q, &rwb->rqos, &wbt_rqos_ops);
blk_stat_add_callback(q, rwb->cb);

rwb->min_lat_nsec = wbt_default_latency_nsec(q);
@@ -860,3 +868,15 @@ int wbt_init(struct request_queue *q)

return 0;
}
+
+static __init int wbt_mod_init(void)
+{
+ return rq_qos_register(&wbt_rqos_ops);
+}
+
+static __exit void wbt_mod_exit(void)
+{
+ return rq_qos_unregister(&wbt_rqos_ops);
+}
+module_init(wbt_mod_init);
+module_exit(wbt_mod_exit);
diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index 2eb01becde8c..72e9602df330 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -88,7 +88,7 @@ static inline unsigned int wbt_inflight(struct rq_wb *rwb)

#ifdef CONFIG_BLK_WBT

-int wbt_init(struct request_queue *);
+struct rq_qos *wbt_rq_qos(struct request_queue *q);
void wbt_disable_default(struct request_queue *);
void wbt_enable_default(struct request_queue *);

@@ -101,12 +101,12 @@ u64 wbt_default_latency_nsec(struct request_queue *);

#else

-static inline void wbt_track(struct request *rq, enum wbt_flags flags)
+static inline struct rq_qos *wbt_rq_qos(struct request_queue *q)
{
+ return NULL;
}
-static inline int wbt_init(struct request_queue *q)
+static inline void wbt_track(struct request *rq, enum wbt_flags flags)
{
- return -EINVAL;
}
static inline void wbt_disable_default(struct request_queue *q)
{
--
2.17.1