[PATCHv2 1/4] nvme: support <device> option in show-topology command

[Hannes Reinecke]

On 8/12/25 14:56, Nilay Shroff wrote:
> Although the help text for the nvme show-topology command indicates
> support for a <device> option, this option has no effect in practice
> — specifying an NVMe device name does not filter the output.
> 
> This commit adds proper support for the <device> option, enabling users
> to filter the topology output based on the specified NVMe device.
> 
> Signed-off-by: Nilay Shroff <nilay at linux.ibm.com>
> ---
>   nvme-print-stdout.c |  9 +++++++++
>   nvme.c              | 17 ++++++++++++++++-
>   2 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/nvme-print-stdout.c b/nvme-print-stdout.c
> index c597b608..eb56349a 100644
> --- a/nvme-print-stdout.c
> +++ b/nvme-print-stdout.c
> @@ -5683,6 +5683,15 @@ static void stdout_simple_topology(nvme_root_t r,
>   
>   	nvme_for_each_host(r, h) {
>   		nvme_for_each_subsystem(h, s) {
> +			bool no_ctrl = true;
> +			nvme_ctrl_t c;
> +
> +			nvme_subsystem_for_each_ctrl(s, c)
> +				no_ctrl = false;
> +
> +			if (no_ctrl)
> +				continue;
> +
>   			if (!first)
>   				printf("\n");
>   			first = false;
> diff --git a/nvme.c b/nvme.c
> index 27dac37b..c6779cf4 100644
> --- a/nvme.c
> +++ b/nvme.c
> @@ -10155,6 +10155,8 @@ static int show_topology_cmd(int argc, char **argv, struct command *command, str
>   	const char *ranking = "Ranking order: namespace|ctrl";
>   	nvme_print_flags_t flags;
>   	_cleanup_nvme_root_ nvme_root_t r = NULL;
> +	char *devname = NULL;
> +	nvme_scan_filter_t filter = NULL;
>   	enum nvme_cli_topo_ranking rank;
>   	int err;
>   
> @@ -10197,7 +10199,20 @@ static int show_topology_cmd(int argc, char **argv, struct command *command, str
>   		return -errno;
>   	}
>   
> -	err = nvme_scan_topology(r, NULL, NULL);
> +	if (optind < argc)
> +		devname = basename(argv[optind++]);
> +
> +	if (devname) {
> +		int subsys_id, nsid;
> +
> +		if (sscanf(devname, "nvme%dn%d", &subsys_id, &nsid) != 2) {
> +			nvme_show_error("Invalid device name %s\n", devname);
> +			return -EINVAL;
> +		}
> +		filter = nvme_match_device_filter;
> +	}
> +
> +	err = nvme_scan_topology(r, filter, (void *)devname);
>   	if (err < 0) {
>   		nvme_show_error("Failed to scan topology: %s", nvme_strerror(errno));
>   		return err;

While I welcome this change, we've had discussions that
'nvme show-topology <device>' really should _not_ print out
anything if the device does not exist.
Have you checked this for your patch?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare at suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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