Re: [PATCH] ndctl: Use the same align value as original namespace on reconfigure

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> writes:

> "Verma, Vishal L" <vishal.l.verma@intel.com> writes:
>
>> On Wed, 2019-08-07 at 10:14 +0530, Aneesh Kumar K.V wrote:
>>> When using reconfigure command to add a `name` to the namespace we end
>>> up updating the align attribute. Avoid this by using the value from
>>> the original namespace. Do this only if we are keeping the namespace mode
>>> same.
>>> 
>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>> ---
>>>  ndctl/namespace.c | 16 ++++++++++++++++
>>>  1 file changed, 16 insertions(+)
>>
>> Hi Aneesh,
>>
>> A few comments below:
>>
>>> 
>>> diff --git a/ndctl/namespace.c b/ndctl/namespace.c
>>> index 1f212a2b3a9b..24e51bb35ae1 100644
>>> --- a/ndctl/namespace.c
>>> +++ b/ndctl/namespace.c
>>> @@ -596,6 +596,22 @@ static int validate_namespace_options(struct ndctl_region *region,
>>>  			return -ENXIO;
>>>  		}
>>>  	} else {
>>> +
>>> +		/*
>>> +		 * If we are tryint to reconfigure with the same namespace mode
>>
>>                              ^trying
>>
>>> +		 * Use the align details from the origin namespace. Otherwise
>>
>> s/origin/original/
>>
>>> +		 * pick the align details from seed namespace
>>> +		 */
>>> +		if (ndns && p->mode == ndctl_namespace_get_mode(ndns)) {
>>
>> Do we need to depend on the mode here?
>>
>> I'm thinking it should be sufficient to do:
>>   1. Check We're in 'reconfigure'
>>   2. Check param.align was not supplied
>>   3. Get alignment from the pfn/dax personality, and just use that.
>>
>> Does this make sense (Maybe I'm missing something).
>
> We want to use the align value from the seed when we are trying
> to reconfigure a namespace with a different mode. ie, if we are moving a
> fsdax namespace with align value 64K to a devdax, IMHO we should pick 16M
> as alignment for devdax.
>
>>
>>> +			struct ndctl_pfn *ns_pfn = ndctl_namespace_get_pfn(ndns);
>>> +			struct ndctl_dax *ns_dax = ndctl_namespace_get_dax(ndns);
>>> +			if (ns_pfn)
>>> +				p->align = ndctl_pfn_get_align(ns_pfn);
>>> +			else if (ns_dax)
>>> +				p->align = ndctl_dax_get_align(ns_dax);
>>> +			else
>>> +				p->align = sysconf(_SC_PAGE_SIZE);
>>
>> Do we need the page size fallback here - there are other checks after
>> this point that also do a similar fallback, do they not catch the
>> default case?
>
>
> I did that to simplify the code with that `else if`  
>
>>
>>> +		} else
>>>  		/*
>>>  		 * Use the seed namespace alignment as the default if we need
>>>  		 * one. If we don't then use PAGE_SIZE so the size_align

Any update on this.?

-aneesh
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org