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SubjectRe: [PATCH v2] nvme: use uuid_t in nvme_ns
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On 06/12/2017 11:50 AM, Andy Shevchenko wrote:
>> len = NVME_NIDT_UUID_LEN;
>> - memcpy(ns->uuid, data + pos + sizeof(*cur), len);
>> + uuid_copy(&ns->uuid, data + pos + sizeof(*cur));
>
> So, this reveals two thins:
> 1) shall we define NVME_NIDT_UUID_LEN to be UUID_LEN or substitute it
> completely with the latter?

No, we have NVME_NIDT_UUID_LEN but also NVME_NIDT_NGUID_LEN and
NVME_NIDT_EUI64_LEN.

> 2) Is the len variable used later in the function?

Yes, we have to iterate the buffer by len, which can (currently) be
either 8 or 16 bytes. New types which may emerge someday in the future
might have a different length.

>
>> - if (!memchr_inv(ns->uuid, 0, sizeof(ns->uuid)) ||
>> + if (uuid_is_null(&ns->uuid) ||
>> !memchr_inv(ns->nguid, 0, sizeof(ns->nguid)))
>
>> u8 nguid[16];
>> - u8 uuid[16];
>> + uuid_t uuid;
>
> Do you plan to switch nguid to be guid_t / uuid_t ?
>

I'm not sure the NVMe NGUID is the same as a GUID (a.k.a little endian
UUID). Quoting from the spec:

"This field uses the EUI-64 based 16-byte designator format. Bytes
114:112 contain the 24-bit Organizationally Unique Identifier (OUI)
value assigned by the IEEE Registration Authority. Bytes 119:115 contain
an extension identifer assigned by the corresponding organization. Bytes
111:104 contain the vendor specific extension identifier assigned by the
corresponding organization. See the IEEE EUI-64 guidelines for more
information."

But maybe Christoph can clarify it.

Byte,
Johannes
--
Johannes Thumshirn Storage
jthumshirn@suse.de +49 911 74053 689
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