[PATCH v2] nvme-fabrics: Ignore nr_io_queues option for discovery controllers

[PATCH v2] nvme-fabrics: Ignore nr_io_queues option for discovery controllers

[Roland Dreier]

From: Roland Dreier <roland@purestorage.com>

This removes a dependency on the order options are passed when creating
a fabrics controller.  With the old code, if "nr_io_queues" appears before
an "nqn" option specifying the discovery controller, then nr_io_queues
is overridden with zero.  If "nr_io_queues" appears after specifying the
discovery controller, then the nr_io_queues option is used to set the
number of queues, and the driver attempts to establish IO connections
to the discovery controller (which doesn't work).

It seems better to ignore (and warn about) the "nr_io_queues" option
if userspace has already asked to connect to the discovery controller.

Signed-off-by: Roland Dreier <roland at purestorage.com>
---
 drivers/nvme/host/fabrics.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
index 5dd4ceefed8f..6ec6b13fa582 100644
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -650,6 +650,11 @@ static int nvmf_parse_options(struct nvmf_ctrl_options *opts,
 				ret = -EINVAL;
 				goto out;
 			}
+			if (opts->discovery_nqn) {
+				pr_debug("Ignoring nr_io_queues value for discovery controller\n");
+				break;
+			}
+
 			opts->nr_io_queues = min_t(unsigned int,
 					num_online_cpus(), token);
 			break;
-- 
2.15.1

[PATCH v2] nvme-fabrics: Ignore nr_io_queues option for discovery controllers

[James Smart]

On 3/5/2018 11:59 AM, Roland Dreier wrote:
> From: Roland Dreier <roland at purestorage.com>
>
> This removes a dependency on the order options are passed when creating
> a fabrics controller.  With the old code, if "nr_io_queues" appears before
> an "nqn" option specifying the discovery controller, then nr_io_queues
> is overridden with zero.  If "nr_io_queues" appears after specifying the
> discovery controller, then the nr_io_queues option is used to set the
> number of queues, and the driver attempts to establish IO connections
> to the discovery controller (which doesn't work).
>
> It seems better to ignore (and warn about) the "nr_io_queues" option
> if userspace has already asked to connect to the discovery controller.
>
> Signed-off-by: Roland Dreier <roland at purestorage.com>
> ---
>   drivers/nvme/host/fabrics.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
> index 5dd4ceefed8f..6ec6b13fa582 100644
> --- a/drivers/nvme/host/fabrics.c
> +++ b/drivers/nvme/host/fabrics.c
> @@ -650,6 +650,11 @@ static int nvmf_parse_options(struct nvmf_ctrl_options *opts,
>   				ret = -EINVAL;
>   				goto out;
>   			}
> +			if (opts->discovery_nqn) {
> +				pr_debug("Ignoring nr_io_queues value for discovery controller\n");
> +				break;
> +			}
> +
>   			opts->nr_io_queues = min_t(unsigned int,
>   					num_online_cpus(), token);
>   			break;

Reviewed-by: James Smart <james.smart at broadcom.com>

-- james

[PATCH v2] nvme-fabrics: Ignore nr_io_queues option for discovery controllers

[Christoph Hellwig]

Looks fine,

Reviewed-by: Christoph Hellwig <hch at lst.de>

[PATCH v2] nvme-fabrics: Ignore nr_io_queues option for discovery controllers

[Keith Busch]

Thanks, applied.