blk-mq: prevent unmapped hw queue from being scheduled

When one hardware queue has no mapped software queues, it
shouldn't have been scheduled. Otherwise WARNING or OOPS
can triggered.

blk_mq_hw_queue_mapped() helper is introduce for fixing
the problem.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/block/blk-mq.h b/block/blk-mq.h
index d567d5283ffa..206230e64f79 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -115,4 +115,9 @@ static inline void blk_mq_set_alloc_data(struct blk_mq_alloc_data *data,
         data->hctx = hctx;
 }
 
+static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
+{
+        return hctx->nr_ctx && hctx->tags;
+}
+
 #endif