nvmet: make nvmet_wq unbound

When deleting many controllers one-by-one, it takes a very
long time as these work elements may serialize as they are
scheduled on the executing cpu instead of spreading. In general
nvmet_wq can definitely be used for long standing work elements
so its better to make it unbound regardless.

Signed-off-by: Sagi Grimberg <sagi.grimberg@vastdata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

Author: Sagi Grimberg

drivers/nvme/target/core.c

@@ -1686,7 +1686,8 @@ static int __init nvmet_init(void)
 	if (!buffered_io_wq)
 		goto out_free_zbd_work_queue;
 
-	nvmet_wq = alloc_workqueue("nvmet-wq", WQ_MEM_RECLAIM, 0);
+	nvmet_wq = alloc_workqueue("nvmet-wq",
+			WQ_MEM_RECLAIM | WQ_UNBOUND, 0);
 	if (!nvmet_wq)
 		goto out_free_buffered_work_queue;