[PATCH 1/3] nvme-fabrics: introduce existing_ctrl operation

[Sagi Grimberg]

> The check if the connection request matches an existing controller is
> duplicated in several transports (such as RDMA and TCP). Move it to
> common code as optional operation.
> 
> Also, this check can be done before creating the controller to simplify
> the flow.
> 
> Reviewed-by: Israel Rukshin <israelr at nvidia.com>
> Signed-off-by: Max Gurtovoy <mgurtovoy at nvidia.com>
> ---
>   drivers/nvme/host/fabrics.c | 7 +++++++
>   drivers/nvme/host/fabrics.h | 3 +++
>   2 files changed, 10 insertions(+)
> 
> diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
> index ce27276f552d..3d5035331b9f 100644
> --- a/drivers/nvme/host/fabrics.c
> +++ b/drivers/nvme/host/fabrics.c
> @@ -1100,6 +1100,13 @@ nvmf_create_ctrl(struct device *dev, const char *buf)
>   	if (ret)
>   		goto out_module_put;
>   
> +	if (ops->existing_ctrl) {
> +		if (!opts->duplicate_connect && ops->existing_ctrl(opts)) {
> +			ret = -EALREADY;
> +			goto out_module_put;
> +		}
> +	}
> +
>   	ctrl = ops->create_ctrl(dev, opts);
>   	if (IS_ERR(ctrl)) {
>   		ret = PTR_ERR(ctrl);
> diff --git a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h
> index a6e22116e139..587b92575a9b 100644
> --- a/drivers/nvme/host/fabrics.h
> +++ b/drivers/nvme/host/fabrics.h
> @@ -153,6 +153,8 @@ struct nvmf_ctrl_options {
>    *			that would go into starting up that fabric
>    *			for the purpose of conneciton to an NVMe controller
>    *			using that fabric technology.
> + * @existing_ctrl():	optional function pointer that checks if a connection
> + * 			request matches an existing controller.
>    *
>    * Notes:
>    *	1. At minimum, 'required_opts' and 'allowed_opts' should
> @@ -170,6 +172,7 @@ struct nvmf_transport_ops {
>   	int			allowed_opts;
>   	struct nvme_ctrl	*(*create_ctrl)(struct device *dev,
>   					struct nvmf_ctrl_options *opts);
> +	bool			(*existing_ctrl)(struct nvmf_ctrl_options *opts);
>   };
>   
>   static inline bool

Maybe do nvmf_existing_ctrl() that iterates with device_for_each_child 
and filters by transport?

This will eliminate the identical code from rdma/tcp and potentially
from fc?