[PATCH v3 6/6] nbd: add nr_hw_queues module parameter for pre-created devices

[Yang Erkun <yangerkun@huawei.com>]

Previous commit can help remove all freeze for netlink newly created nbd
device. But for the devices pre-created at module load(nbds_max default
as 16), the nr_hw_queues was setting default as 1, then ioctl/netlink
path will set the real connection count, and blk_mq_update_nr_hw_queues
in nbd_start_device will introduce freeze.

Add an nr_hw_queues module parameter so that users who know their
expected connection count can pre-created devices with the right queue
count to avoid this freeze too.

Signed-off-by: Yang Erkun <yangerkun@huawei.com>
---
 drivers/block/nbd.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 2c7b09c70da2..f918c9efa9b2 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -166,6 +166,7 @@ static struct dentry *nbd_dbg_dir;
 
 static unsigned int nbds_max = 16;
 static int max_part = 16;
+static int nr_hw_queues = 1;
 static int part_shift;
 
 static int nbd_dev_dbg_init(struct nbd_device *nbd);
@@ -2752,8 +2753,10 @@ static int __init nbd_init(void)
 	}
 	nbd_dbg_init();
 
+	if (nr_hw_queues < 1)
+		nr_hw_queues = 1;
 	for (i = 0; i < nbds_max; i++)
-		nbd_dev_add(i, 1, 1);
+		nbd_dev_add(i, 1, nr_hw_queues);
 	return 0;
 }
 
@@ -2814,3 +2817,6 @@ module_param(nbds_max, int, 0444);
 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
 module_param(max_part, int, 0444);
 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");
+module_param(nr_hw_queues, int, 0444);
+MODULE_PARM_DESC(nr_hw_queues,
+"number of hardware queues for devices pre-created at module load (default: 1). ");
-- 
2.52.0