Hi Dan,
"Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> writes:
> On 5/17/19 8:19 PM, Vaibhav Jain wrote:
>> Hi Aneesh,
>>
....
>>
>>> + /*
>>> + * Check whether the we support the alignment. For Dax if the
>>> + * superblock alignment is not matching, we won't initialize
>>> + * the device.
>>> + */
>>> + if (!nd_supported_alignment(align) &&
>>> + memcmp(pfn_sb->signature, DAX_SIG, PFN_SIG_LEN)) {
>> Suggestion to change this check to:
>>
>> if (memcmp(pfn_sb->signature, DAX_SIG, PFN_SIG_LEN) &&
>> !nd_supported_alignment(align))
>>
>> It would look a bit more natural i.e. "If the device has dax signature and alignment is
>> not supported".
>>
>
> I guess that should be !memcmp()? . I will send an updated patch with
> the hash failure details in the commit message.
>
We need clarification on what the expected failure behaviour should be.
The nd_pmem_probe doesn't really have a failure behaviour in this
regard. For example.
I created a dax device with 16M alignment
{
"dev":"namespace0.0",
"mode":"devdax",
"map":"dev",
"size":"9.98 GiB (10.72 GB)",
"uuid":"ba62ef22-ebdf-4779-96f5-e6135383ed22",
"raw_uuid":"7b2492f9-7160-4ee9-9c3d-2f547d9ef3ee",
"daxregion":{
"id":0,
"size":"9.98 GiB (10.72 GB)",
"align":16777216,
"devices":[
{
"chardev":"dax0.0",
"size":"9.98 GiB (10.72 GB)"
}
]
},
"align":16777216,
"numa_node":0,
"supported_alignments":[
65536,
16777216
]
}
Now what we want is to fail the initialization of the device when we
boot a kernel that doesn't support 16M page size. But with the
nd_pmem_probe failure behaviour we now end up with
[
{
"dev":"namespace0.0",
"mode":"fsdax",
"map":"mem",
"size":10737418240,
"uuid":"7b2492f9-7160-4ee9-9c3d-2f547d9ef3ee",
"blockdev":"pmem0"
}
]
So it did fallthrough the
/* if we find a valid info-block we'll come back as that personality */
if (nd_btt_probe(dev, ndns) == 0 || nd_pfn_probe(dev, ndns) == 0
|| nd_dax_probe(dev, ndns) == 0)
return -ENXIO;
/* ...otherwise we're just a raw pmem device */
return pmem_attach_disk(dev, ndns);
Is it ok if i update the code such that we don't do that default
pmem_atach_disk if we have a label area?
-aneesh
