blk-mq: init hctx sched after update ctx and hctx mapping
Currently, when update nr_hw_queues, IO scheduler's init_hctx will
be invoked before the mapping between ctx and hctx is adapted
correctly by blk_mq_map_swqueue. The IO scheduler init_hctx (kyber)
may depend on this mapping and get wrong result and panic finally.
A simply way to fix this is that switch the IO scheduler to 'none'
before update the nr_hw_queues, and then switch it back after
update nr_hw_queues. blk_mq_sched_init_/exit_hctx are removed due
to nobody use them any more.
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/elevator.c b/block/elevator.c
index fa828b5..5ea6e7d 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -933,16 +933,13 @@
}
EXPORT_SYMBOL_GPL(elv_unregister);
-static int elevator_switch_mq(struct request_queue *q,
+int elevator_switch_mq(struct request_queue *q,
struct elevator_type *new_e)
{
int ret;
lockdep_assert_held(&q->sysfs_lock);
- blk_mq_freeze_queue(q);
- blk_mq_quiesce_queue(q);
-
if (q->elevator) {
if (q->elevator->registered)
elv_unregister_queue(q);
@@ -968,8 +965,6 @@
blk_add_trace_msg(q, "elv switch: none");
out:
- blk_mq_unquiesce_queue(q);
- blk_mq_unfreeze_queue(q);
return ret;
}
@@ -1021,8 +1016,17 @@
lockdep_assert_held(&q->sysfs_lock);
- if (q->mq_ops)
- return elevator_switch_mq(q, new_e);
+ if (q->mq_ops) {
+ blk_mq_freeze_queue(q);
+ blk_mq_quiesce_queue(q);
+
+ err = elevator_switch_mq(q, new_e);
+
+ blk_mq_unquiesce_queue(q);
+ blk_mq_unfreeze_queue(q);
+
+ return err;
+ }
/*
* Turn on BYPASS and drain all requests w/ elevator private data.