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Subject[PATCH v2 1/3] wbt: don't show valid wbt_lat_usec in sysfs while wbt is disabled
Date
From: Yu Kuai <yukuai3@huawei.com>

Currently, if wbt is initialized and then disabled by
wbt_disable_default(), sysfs will still show valid wbt_lat_usec, which
will confuse users that wbt is still enabled.

This patch shows wbt_lat_usec as zero and forbid to set it while wbt
is disabled.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reported-and-tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
---
block/blk-sysfs.c | 9 ++++++++-
block/blk-wbt.c | 7 +++++++
block/blk-wbt.h | 5 +++++
3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index e1f009aba6fd..1955bb6a284d 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -467,10 +467,14 @@ static ssize_t queue_io_timeout_store(struct request_queue *q, const char *page,

static ssize_t queue_wb_lat_show(struct request_queue *q, char *page)
{
+ u64 lat;
+
if (!wbt_rq_qos(q))
return -EINVAL;

- return sprintf(page, "%llu\n", div_u64(wbt_get_min_lat(q), 1000));
+ lat = wbt_disabled(q) ? 0 : div_u64(wbt_get_min_lat(q), 1000);
+
+ return sprintf(page, "%llu\n", lat);
}

static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
@@ -493,6 +497,9 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
return ret;
}

+ if (wbt_disabled(q))
+ return -EINVAL;
+
if (val == -1)
val = wbt_default_latency_nsec(q);
else if (val >= 0)
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index a9982000b667..68851c2c02d2 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -422,6 +422,13 @@ static void wbt_update_limits(struct rq_wb *rwb)
rwb_wake_all(rwb);
}

+bool wbt_disabled(struct request_queue *q)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+
+ return !rqos || RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT;
+}
+
u64 wbt_get_min_lat(struct request_queue *q)
{
struct rq_qos *rqos = wbt_rq_qos(q);
diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index 7e44eccc676d..e42465ddcbb6 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -94,6 +94,7 @@ 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);
+bool wbt_disabled(struct request_queue *);

void wbt_set_write_cache(struct request_queue *, bool);

@@ -125,6 +126,10 @@ static inline u64 wbt_default_latency_nsec(struct request_queue *q)
{
return 0;
}
+static inline bool wbt_disabled(struct request_queue *q)
+{
+ return true;
+}

#endif /* CONFIG_BLK_WBT */

--
2.31.1
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