null_blk: warning on ignored submit_queues param

Let the user know when the number of submission queues are being
ignored.

Signed-off-by: Matias Bjorling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index f0aeb2a7a9ca..8f2e7c330d6d 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -590,9 +590,12 @@ static int __init null_init(void)
         }
 #endif
 
-        if (queue_mode == NULL_Q_MQ && use_per_node_hctx)
+        if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {
+                if (submit_queues > 0)
+                        pr_warn("null_blk: submit_queues param is set to %u.",
+                                                        nr_online_nodes);
                 submit_queues = nr_online_nodes;
-        else if (submit_queues > nr_cpu_ids)
+        } else if (submit_queues > nr_cpu_ids)
                 submit_queues = nr_cpu_ids;
         else if (!submit_queues)
                 submit_queues = 1;