[RFC V2 5/6] blk-ioprio: make ioprio pluggable and modular
From: Wang Jianchao (Kuaishou)
Date: Tue Feb 15 2022 - 07:38:59 EST
Make blk-ioprio pluggable and modular. Then we can close or open
it through /sys/block/xxx/queue/qos and rmmod the module if we don't
need it which can release one blkcg policy slot.
Signed-off-by: Wang Jianchao (Kuaishou) <jianchao.wan9@xxxxxxxxx>
---
block/Kconfig | 2 +-
block/Makefile | 3 ++-
block/blk-cgroup.c | 5 -----
block/blk-ioprio.c | 50 ++++++++++++++++++++++++++++--------------
block/blk-ioprio.h | 19 ----------------
block/blk-mq-debugfs.c | 4 ----
block/blk-rq-qos.c | 2 +-
block/blk-rq-qos.h | 2 +-
8 files changed, 38 insertions(+), 49 deletions(-)
delete mode 100644 block/blk-ioprio.h
diff --git a/block/Kconfig b/block/Kconfig
index d5d4197b7ed2..9cc8e4688953 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -145,7 +145,7 @@ config BLK_CGROUP_IOCOST
their share of the overall weight distribution.
config BLK_CGROUP_IOPRIO
- bool "Cgroup I/O controller for assigning an I/O priority class"
+ tristate "Cgroup I/O controller for assigning an I/O priority class"
depends on BLK_CGROUP
help
Enable the .prio interface for assigning an I/O priority class to
diff --git a/block/Makefile b/block/Makefile
index f38eaa612929..f6a3995af285 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -17,7 +17,8 @@ obj-$(CONFIG_BLK_DEV_BSGLIB) += bsg-lib.o
obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o
obj-$(CONFIG_BLK_CGROUP_RWSTAT) += blk-cgroup-rwstat.o
obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o
-obj-$(CONFIG_BLK_CGROUP_IOPRIO) += blk-ioprio.o
+io-prio-y := blk-ioprio.o
+obj-$(CONFIG_BLK_CGROUP_IOPRIO) += io-prio.o
obj-$(CONFIG_BLK_CGROUP_IOLATENCY) += blk-iolatency.o
obj-$(CONFIG_BLK_CGROUP_IOCOST) += blk-iocost.o
obj-$(CONFIG_MQ_IOSCHED_DEADLINE) += mq-deadline.o
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 3ae2aa557aef..f617f7ba311d 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -32,7 +32,6 @@
#include <linux/psi.h>
#include <linux/part_stat.h>
#include "blk.h"
-#include "blk-ioprio.h"
#include "blk-throttle.h"
/*
@@ -1195,10 +1194,6 @@ int blkcg_init_queue(struct request_queue *q)
if (preloaded)
radix_tree_preload_end();
- ret = blk_ioprio_init(q);
- if (ret)
- goto err_destroy_all;
-
ret = blk_throtl_init(q);
if (ret)
goto err_destroy_all;
diff --git a/block/blk-ioprio.c b/block/blk-ioprio.c
index 2e7f10e1c03f..074cc0978d0b 100644
--- a/block/blk-ioprio.c
+++ b/block/blk-ioprio.c
@@ -17,7 +17,6 @@
#include <linux/blk_types.h>
#include <linux/kernel.h>
#include <linux/module.h>
-#include "blk-ioprio.h"
#include "blk-rq-qos.h"
/**
@@ -216,15 +215,23 @@ static void blkcg_ioprio_exit(struct rq_qos *rqos)
container_of(rqos, typeof(*blkioprio_blkg), rqos);
blkcg_deactivate_policy(rqos->q, &ioprio_policy);
+ rq_qos_deactivate(rqos);
kfree(blkioprio_blkg);
}
+static int blk_ioprio_init(struct request_queue *q);
static struct rq_qos_ops blkcg_ioprio_ops = {
+#if IS_MODULE(CONFIG_BLK_CGROUP_IOPRIO)
+ .owner = THIS_MODULE,
+#endif
+ .flags = RQOS_FLAG_CGRP_POL,
+ .name = "io-prio",
.track = blkcg_ioprio_track,
.exit = blkcg_ioprio_exit,
+ .init = blk_ioprio_init,
};
-int blk_ioprio_init(struct request_queue *q)
+static int blk_ioprio_init(struct request_queue *q)
{
struct blk_ioprio *blkioprio_blkg;
struct rq_qos *rqos;
@@ -234,36 +241,45 @@ int blk_ioprio_init(struct request_queue *q)
if (!blkioprio_blkg)
return -ENOMEM;
+ /*
+ * No need to worry ioprio_blkcg_from_css return NULL as
+ * the queue is frozen right now.
+ */
+ rqos = &blkioprio_blkg->rqos;
+ rq_qos_activate(q, rqos, &blkcg_ioprio_ops);
+
ret = blkcg_activate_policy(q, &ioprio_policy);
if (ret) {
+ rq_qos_deactivate(rqos);
kfree(blkioprio_blkg);
- return ret;
}
- rqos = &blkioprio_blkg->rqos;
- rqos->id = RQ_QOS_IOPRIO;
- rqos->ops = &blkcg_ioprio_ops;
- rqos->q = q;
-
- /*
- * Registering the rq-qos policy after activating the blk-cgroup
- * policy guarantees that ioprio_blkcg_from_bio(bio) != NULL in the
- * rq-qos callbacks.
- */
- rq_qos_add(q, rqos);
-
- return 0;
+ return ret;
}
static int __init ioprio_init(void)
{
- return blkcg_policy_register(&ioprio_policy);
+ int ret;
+
+ ret = rq_qos_register(&blkcg_ioprio_ops);
+ if (ret)
+ return ret;
+
+ ret = blkcg_policy_register(&ioprio_policy);
+ if (ret)
+ rq_qos_unregister(&blkcg_ioprio_ops);
+
+ return ret;
}
static void __exit ioprio_exit(void)
{
blkcg_policy_unregister(&ioprio_policy);
+ rq_qos_unregister(&blkcg_ioprio_ops);
}
module_init(ioprio_init);
module_exit(ioprio_exit);
+MODULE_AUTHOR("Bart Van Assche");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Cgroup I/O controller for assigning an I/O priority class");
diff --git a/block/blk-ioprio.h b/block/blk-ioprio.h
deleted file mode 100644
index a7785c2f1aea..000000000000
--- a/block/blk-ioprio.h
+++ /dev/null
@@ -1,19 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-
-#ifndef _BLK_IOPRIO_H_
-#define _BLK_IOPRIO_H_
-
-#include <linux/kconfig.h>
-
-struct request_queue;
-
-#ifdef CONFIG_BLK_CGROUP_IOPRIO
-int blk_ioprio_init(struct request_queue *q);
-#else
-static inline int blk_ioprio_init(struct request_queue *q)
-{
- return 0;
-}
-#endif
-
-#endif /* _BLK_IOPRIO_H_ */
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 9bb1dabc223b..70a3e4599d99 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -822,10 +822,6 @@ 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_IOPRIO:
- return "ioprio";
- }
return "unknown";
}
diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c
index a94ff872722b..629d521e20a7 100644
--- a/block/blk-rq-qos.c
+++ b/block/blk-rq-qos.c
@@ -457,7 +457,7 @@ int rq_qos_register(struct rq_qos_ops *ops)
goto out;
}
- start = RQ_QOS_IOPRIO + 1;
+ start = 1;
ret = ida_simple_get(&rq_qos_ida, start, INT_MAX, GFP_KERNEL);
if (ret < 0)
goto out;
diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h
index 4eef53f2c290..ee396367a5b2 100644
--- a/block/blk-rq-qos.h
+++ b/block/blk-rq-qos.h
@@ -14,7 +14,7 @@
struct blk_mq_debugfs_attr;
enum rq_qos_id {
- RQ_QOS_IOPRIO,
+ RQ_QOS_UNUSED,
};
struct rq_wait {
--
2.17.1