Add 'list_namespaces_io_stats' grpc call

[VallariAg]

And make namespace_get_io_stats grpc method
wrapper around list_namespaces_io_stats.

Also change "namespace get_io_stats" cli cmd
output from dictionary of bdev stats to list
of bdev stats. Make --nsid & --subsystem optional
args, and return single device stats if present.
Otherwise, return all bdev stats in a list.

[Copilot]

Pull request overview

This PR adds a new Gateway gRPC API to fetch I/O stats across all namespaces (via SPDK bdev iostat) and exposes it through a new CLI subcommand.

Changes:

• Extend Gateway gRPC service with list_namespaces_io_stats and new response messages for aggregated bdev I/O stats.
• Implement list_namespaces_io_stats handler in the Python gRPC server using spdk_rpc_client.bdev_get_iostat().
• Add CLI command namespace ns_list_io_stats to display aggregated I/O stats in text/table or structured formats.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
control/proto/gateway.proto	Adds new RPC + request/response messages for listing all namespaces’ I/O stats.
control/grpc.py	Implements the new RPC by calling SPDK bdev_get_iostat and mapping the result into the proto response.
control/cli.py	Adds a new namespace subcommand that calls the new RPC and formats the output.

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[gbregman]

Do we need separate commands for one namespace and all the namespaces? We don't do that in other cases. We just rely on "--nsid" to execute the command for one namespace or all.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Comments suppressed due to low confidence (1)

control/cli.py:3009

• The JSON output structure for the CLI command 'namespace get_io_stats' has changed significantly. Previously, when querying a specific namespace with --subsystem and --nsid, the JSON output included top-level fields like 'subsystem_nqn', 'nsid', 'uuid', and 'bdev_name', along with the stats. Now, the stats are returned in a 'namespaces' array, and these identifying fields are no longer present in the JSON output. This is a breaking change for any scripts or tools that parse the JSON output of this CLI command. Consider documenting this breaking change in the PR description or release notes, and consider whether the old format should be preserved for backward compatibility.

        elif args.format == "json" or args.format == "yaml":
            ret_str = json_format.MessageToJson(ns_io_stats, indent=4,
                                                including_default_value_fields=True,
                                                preserving_proto_field_name=True)

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