nvdimm(4): Only expose namespaces for accessible data SPAs

[scottph]

Summary

Apply the same user accessible filter to namespaces as is applied
to full-SPA devices. Also, explicitly filter out control region
SPAs which don't expose the nvdimm data area.

MFC after: 1 week
Sponsored by: Intel Corporation

[imp]

sys/dev/nvdimm/nvdimm_spa.c

164 ↗

(On Diff #63170)

Why the loop? Why not just a single line that's return? I'm guessing there is a field we need to check

[scottph]

sys/dev/nvdimm/nvdimm_spa.c

164 ↗

(On Diff #63170)

SPA_TYPE_UNKNOWN = 127,
is outside the bounds of the array. How about:

return (spa_type >= 0 && spa_type < nitems(nvdimm_SPA_uuid_list) ? nvdimm_SPA_uuid_list[spa_type].u_usr_acc : false);

[cem]

Do Control Region SPAs have namespaces? I'm still fairly new to NFIT.

sys/dev/nvdimm/nvdimm_spa.c

164 ↗

(On Diff #63170)

I like the suggestion and the proposal. I'm not sure it needs to be a one-liner but I'm on-board with the bounds check approach. I'd probably spell it more like:

if ((int)spa_type < 0 || spa_type >= nitems(nvdimm_SPA_uuid_list))
    return (false);
return (nvdimm_SPA_uuid_list[spa_type].u_usr_acc);

But it doesn't really matter to me how it's formatted.

[scottph]

In D21987#480367, @cem wrote:

Do Control Region SPAs have namespaces? I'm still fairly new to NFIT.

No, namespaces should only apply to areas where there's a mapping to the dimm physical addresses, which I believe is never the case with a control region. Which leads me to think that this check is necessary (don't show namespaces for regions that we also hide) but not sufficient on its own.