blk-mq-sched: (un)register elevator when (un)registering queue
I noticed that when booting with a default blk-mq I/O scheduler, the
/sys/block/*/queue/iosched directory was missing. However, switching
after boot did create the directory. This is because we skip the initial
elevator register/unregister when we don't have a ->request_fn(), but we
should still do it for the ->mq_ops case.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 3ce12177..48032c4 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -903,16 +903,15 @@ int blk_register_queue(struct gendisk *disk)
blk_wb_init(q);
- if (!q->request_fn)
- return 0;
-
- ret = elv_register_queue(q);
- if (ret) {
- kobject_uevent(&q->kobj, KOBJ_REMOVE);
- kobject_del(&q->kobj);
- blk_trace_remove_sysfs(dev);
- kobject_put(&dev->kobj);
- return ret;
+ if (q->request_fn || (q->mq_ops && q->elevator)) {
+ ret = elv_register_queue(q);
+ if (ret) {
+ kobject_uevent(&q->kobj, KOBJ_REMOVE);
+ kobject_del(&q->kobj);
+ blk_trace_remove_sysfs(dev);
+ kobject_put(&dev->kobj);
+ return ret;
+ }
}
return 0;
@@ -928,7 +927,7 @@ void blk_unregister_queue(struct gendisk *disk)
if (q->mq_ops)
blk_mq_unregister_dev(disk_to_dev(disk), q);
- if (q->request_fn)
+ if (q->request_fn || (q->mq_ops && q->elevator))
elv_unregister_queue(q);
kobject_uevent(&q->kobj, KOBJ_REMOVE);