block: Make writeback throttling defaults consistent for SQ devices
When CFQ is used as an elevator, it disables writeback throttling
because they don't play well together. Later when a different elevator
is chosen for the device, writeback throttling doesn't get enabled
again as it should. Make sure CFQ enables writeback throttling (if it
should be enabled by default) when we switch from it to another IO
scheduler.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index fc20489..f857233 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -844,23 +844,6 @@
.release = blk_release_queue,
};
-static void blk_wb_init(struct request_queue *q)
-{
-#ifndef CONFIG_BLK_WBT_MQ
- if (q->mq_ops)
- return;
-#endif
-#ifndef CONFIG_BLK_WBT_SQ
- if (q->request_fn)
- return;
-#endif
-
- /*
- * If this fails, we don't get throttling
- */
- wbt_init(q);
-}
-
int blk_register_queue(struct gendisk *disk)
{
int ret;
@@ -908,7 +891,7 @@
kobject_uevent(&q->kobj, KOBJ_ADD);
- blk_wb_init(q);
+ wbt_enable_default(q);
blk_throtl_register_queue(q);
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index b3b7914..26e1bb6 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -665,6 +665,25 @@
}
EXPORT_SYMBOL_GPL(wbt_disable_default);
+/*
+ * Enable wbt if defaults are configured that way
+ */
+void wbt_enable_default(struct request_queue *q)
+{
+ /* Throttling already enabled? */
+ if (q->rq_wb)
+ return;
+
+ /* Queue not registered? Maybe shutting down... */
+ if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags))
+ return;
+
+ if ((q->mq_ops && IS_ENABLED(CONFIG_BLK_WBT_MQ)) ||
+ (q->request_fn && IS_ENABLED(CONFIG_BLK_WBT_SQ)))
+ wbt_init(q);
+}
+EXPORT_SYMBOL_GPL(wbt_enable_default);
+
u64 wbt_default_latency_nsec(struct request_queue *q)
{
/*
diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index ad6c785..df6de50 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -117,6 +117,7 @@
void wbt_requeue(struct rq_wb *, struct blk_issue_stat *);
void wbt_issue(struct rq_wb *, struct blk_issue_stat *);
void wbt_disable_default(struct request_queue *);
+void wbt_enable_default(struct request_queue *);
void wbt_set_queue_depth(struct rq_wb *, unsigned int);
void wbt_set_write_cache(struct rq_wb *, bool);
@@ -155,6 +156,9 @@
static inline void wbt_disable_default(struct request_queue *q)
{
}
+static inline void wbt_enable_default(struct request_queue *q)
+{
+}
static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
{
}
diff --git a/block/elevator.c b/block/elevator.c
index dbeecf7..fb50416 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -41,6 +41,7 @@
#include "blk.h"
#include "blk-mq-sched.h"
+#include "blk-wbt.h"
static DEFINE_SPINLOCK(elv_list_lock);
static LIST_HEAD(elv_list);
@@ -877,6 +878,8 @@
kobject_uevent(&e->kobj, KOBJ_REMOVE);
kobject_del(&e->kobj);
e->registered = 0;
+ /* Re-enable throttling in case elevator disabled it */
+ wbt_enable_default(q);
}
}
EXPORT_SYMBOL(elv_unregister_queue);