[lustre-devel] lprocfs Helper Issues

[Christopher J. Morrone <morrone2@llnl.gov>]

On 09/30/2015 08:21 PM, Drokin, Oleg wrote:
>
> On Sep 30, 2015, at 8:32 PM, Christopher J. Morrone wrote:
>
>> On 09/30/2015 12:46 PM, Di Natale, Giuseppe wrote:
>>> I looked around to see where the helpers are used. It looks to me that they are always used in proc related functions. I agree with the issues you mentioned at the top of the email as well.
>>
>> Yes, but I meant to say we need to consider future use.  Largely motivated by the effort to upstream the Lustre client into Linux, the /proc interfaces are slowly going away.  So I was just suggesting that we should check that these functions will still be used by the new debugfs/sysfs/whatever interfaces in the future.  Nothing really needed to consider though; they are generic enough to still be used well into the future.
>
> The thing with the upstream kernel is that effectively procfs was split into two parts. The parts that are 1 value per file are in sysfs, the rest is in ldiskfs and resuses huge chunks
> of old code (including the functions mentioned).
> This is not to say we cannot replace them, of course.
> But upstream they want us to explore other avenues for many of our stuff too, like perf code for performance/usage gathering.
>
> Bye,
>      Oleg

Yes, and ultimately they might be opposed to even doing this much 
parsing of user strings in kernel space.  I can see an argument for sys 
files only taking simple integers, and leaving it to lustre libraries 
and command line tools to all niceties like specifying a number with units.

But in the sort term, cleaning up these functions is only a good thing, 
I think.

Chris