block: elevator quiescing helpers
Simple helper functions to quiesce the request queue. These are
currently only used for switching IO schedulers on-the-fly, but
we can use them to properly switch IO accounting on and off as well.
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk.h b/block/blk.h
index 3ee9435..22043c2 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -70,6 +70,10 @@
int blk_dev_init(void);
+void elv_quisce_start(struct request_queue *q);
+void elv_quisce_end(struct request_queue *q);
+
+
/*
* Return the threshold (number of used requests) at which the queue is
* considered to be congested. It include a little hysteresis to keep the
