Re: [PATCH 6/7] nvme: Add connect option 'discovery'

[James Smart <jsmart2021@gmail.com>]

On 9/21/2021 11:35 PM, Hannes Reinecke wrote:
> Add a connect option 'discovery' to specify that the connection
> should be made to a discovery controller, not a normal I/O controller.
> With discovery controllers supporting unique subsystem NQNs we
> cannot easily distinguish by the subsystem NQN if this should be
> a discovery connection, but we need this information to blank out
> options not supported by discovery controllers.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
> ---
>   drivers/nvme/host/core.c    | 7 +++++++
>   drivers/nvme/host/fabrics.c | 6 +++++-
>   drivers/nvme/host/fabrics.h | 1 +
>   3 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 1ed1b7be2812..ad01e2778cb6 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -2715,6 +2715,13 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
>   	else
>   		subsys->subtype = NVME_NQN_NVME;
>   
> +	if (nvme_discovery_ctrl(ctrl) && subsys->subtype != NVME_NQN_DISC) {
> +		dev_err(ctrl->device,
> +			"Subsystem %s is not a discovery controller",
> +			subsys->subnqn);
> +		kfree(subsys);
> +		return -EINVAL;
> +	}
>   	subsys->awupf = le16_to_cpu(id->awupf);
>   #ifdef CONFIG_NVME_MULTIPATH
>   	subsys->iopolicy = NVME_IOPOLICY_NUMA;
> diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
> index 668c6bb7a567..c5a2b71c5268 100644
> --- a/drivers/nvme/host/fabrics.c
> +++ b/drivers/nvme/host/fabrics.c
> @@ -548,6 +548,7 @@ static const match_table_t opt_tokens = {
>   	{ NVMF_OPT_NR_POLL_QUEUES,	"nr_poll_queues=%d"	},
>   	{ NVMF_OPT_TOS,			"tos=%d"		},
>   	{ NVMF_OPT_FAIL_FAST_TMO,	"fast_io_fail_tmo=%d"	},
> +	{ NVMF_OPT_DISCOVERY,		"discovery"		},
>   	{ NVMF_OPT_ERR,			NULL			}
>   };
>   
> @@ -823,6 +824,9 @@ static int nvmf_parse_options(struct nvmf_ctrl_options *opts,
>   			}
>   			opts->tos = token;
>   			break;
> +		case NVMF_OPT_DISCOVERY:
> +			opts->discovery_nqn = true;
> +			break;
>   		default:
>   			pr_warn("unknown parameter or missing value '%s' in ctrl creation request\n",
>   				p);
> @@ -949,7 +953,7 @@ EXPORT_SYMBOL_GPL(nvmf_free_options);
>   #define NVMF_ALLOWED_OPTS	(NVMF_OPT_QUEUE_SIZE | NVMF_OPT_NR_IO_QUEUES | \
>   				 NVMF_OPT_KATO | NVMF_OPT_HOSTNQN | \
>   				 NVMF_OPT_HOST_ID | NVMF_OPT_DUP_CONNECT |\
> -				 NVMF_OPT_DISABLE_SQFLOW |\
> +				 NVMF_OPT_DISABLE_SQFLOW | NVMF_OPT_DISCOVERY |\
>   				 NVMF_OPT_FAIL_FAST_TMO)
>   
>   static struct nvme_ctrl *
> diff --git a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h
> index a146cb903869..b61b666e10ec 100644
> --- a/drivers/nvme/host/fabrics.h
> +++ b/drivers/nvme/host/fabrics.h
> @@ -67,6 +67,7 @@ enum {
>   	NVMF_OPT_TOS		= 1 << 19,
>   	NVMF_OPT_FAIL_FAST_TMO	= 1 << 20,
>   	NVMF_OPT_HOST_IFACE	= 1 << 21,
> +	NVMF_OPT_DISCOVERY	= 1 << 22,
>   };
>   
>   /**
> 


I think you need to be patching __nvme_find_get_subsystem(), which looks 
for subsystem name and opts out (allowing multiple connects to discovery 
subsystems) if discovery controller nqn.

e.g. the loop matching subsys name (assuming discovery ctlr now has a 
unique name) continues if subsys->subtype is NVME_NQN_DISC

-- james


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