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

[Hannes Reinecke]

On 8/19/25 06:43, Nilay Shroff wrote:
> 
> 
> On 8/18/25 12:42 PM, Hannes Reinecke wrote:
>> 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?
>>
> Yes I checked that. If <device> doesn't exist then
> nvme show-topology would print nothing.
> 
Thanks.
So you can add:

Reviewed-by: Hannes Reinecke <hare at suse.de>

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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