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>

1 files changed, 0 insertions, 44 deletions

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index cf9c66c6d35a..29bfe8017a2d 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -462,50 +462,6 @@ static void blk_mq_sched_tags_teardown(struct request_queue *q)
 		blk_mq_sched_free_tags(set, hctx, i);
 }
 
-int blk_mq_sched_init_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
-			   unsigned int hctx_idx)
-{
-	struct elevator_queue *e = q->elevator;
-	int ret;
-
-	if (!e)
-		return 0;
-
-	ret = blk_mq_sched_alloc_tags(q, hctx, hctx_idx);
-	if (ret)
-		return ret;
-
-	if (e->type->ops.mq.init_hctx) {
-		ret = e->type->ops.mq.init_hctx(hctx, hctx_idx);
-		if (ret) {
-			blk_mq_sched_free_tags(q->tag_set, hctx, hctx_idx);
-			return ret;
-		}
-	}
-
-	blk_mq_debugfs_register_sched_hctx(q, hctx);
-
-	return 0;
-}
-
-void blk_mq_sched_exit_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
-			    unsigned int hctx_idx)
-{
-	struct elevator_queue *e = q->elevator;
-
-	if (!e)
-		return;
-
-	blk_mq_debugfs_unregister_sched_hctx(hctx);
-
-	if (e->type->ops.mq.exit_hctx && hctx->sched_data) {
-		e->type->ops.mq.exit_hctx(hctx, hctx_idx);
-		hctx->sched_data = NULL;
-	}
-
-	blk_mq_sched_free_tags(q->tag_set, hctx, hctx_idx);
-}
-
 int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 {
 	struct blk_mq_hw_ctx *hctx;