[PATCH RFC -next 7/7] blk-iocost: support to build iocost as kernel module

[Yu Kuai]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
 block/Kconfig             |  2 +-
 block/blk-iocost.c        | 14 +++++++++++++-
 include/linux/blk_types.h |  2 +-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/block/Kconfig b/block/Kconfig
index dc12af58dbae..b94b93158e57 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -156,7 +156,7 @@ config BLK_CGROUP_FC_APPID
 	  application specific identification into the FC frame.
 
 config BLK_CGROUP_IOCOST
-	bool "Enable support for cost model based cgroup IO controller"
+	tristate "Enable support for cost model based cgroup IO controller"
 	depends on BLK_CGROUP
 	select BLK_RQ_ALLOC_TIME
 	help
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 708a43a7c6a0..2a69db547045 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -2850,6 +2850,7 @@ static void ioc_rqos_queue_depth_changed(struct rq_qos *rqos)
 
 static void __ioc_exit(struct ioc *ioc)
 {
+	module_put(THIS_MODULE);
 	blkcg_deactivate_policy(ioc->rqos.disk, &blkcg_policy_iocost);
 
 	spin_lock_irq(&ioc->lock);
@@ -2882,13 +2883,19 @@ static int blk_iocost_init(struct gendisk *disk)
 	struct ioc *ioc;
 	int i, cpu, ret;
 
+	if (!try_module_get(THIS_MODULE))
+		return -ENODEV;
+
 	ioc = kzalloc(sizeof(*ioc), GFP_KERNEL);
-	if (!ioc)
+	if (!ioc) {
+		module_put(THIS_MODULE);
 		return -ENOMEM;
+	}
 
 	ioc->pcpu_stat = alloc_percpu(struct ioc_pcpu_stat);
 	if (!ioc->pcpu_stat) {
 		kfree(ioc);
+		module_put(THIS_MODULE);
 		return -ENOMEM;
 	}
 
@@ -2938,6 +2945,7 @@ static int blk_iocost_init(struct gendisk *disk)
 	rq_qos_del(&ioc->rqos);
 err_free_ioc:
 	free_percpu(ioc->pcpu_stat);
+	module_put(THIS_MODULE);
 	kfree(ioc);
 	return ret;
 }
@@ -3616,3 +3624,7 @@ static void __exit ioc_exit(void)
 
 module_init(ioc_init);
 module_exit(ioc_exit);
+
+MODULE_AUTHOR("Tejun Heo");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Cost model based cgroup IO controller");
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 781c4500491b..8da12ebc7777 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -234,7 +234,7 @@ struct bio {
 	 */
 	struct blkcg_gq		*bi_blkg;
 	struct bio_issue	bi_issue;
-#ifdef CONFIG_BLK_CGROUP_IOCOST
+#if IS_ENABLED(CONFIG_BLK_CGROUP_IOCOST)
 	u64			bi_iocost_cost;
 #endif
 #endif
-- 
2.39.2