Re: [PATCH 1/3] NFS41: add pnfs_dio_begin/dio_end

[Boaz Harrosh <bharrosh@panasas.com>]

On 05/28/2012 01:44 PM, Boaz Harrosh wrote:

> On 05/28/2012 07:13 AM, tao.peng@emc.com wrote:
> 
>>> -----Original Message-----
>>> From: Myklebust, Trond [mailto:Trond.Myklebust@netapp.com]
>>> Sent: Monday, May 28, 2012 11:43 AM
>>> To: Peng, Tao
>>> Cc: bergwolf@gmail.com; linux-nfs@vger.kernel.org
>>> Subject: RE: [PATCH 1/3] NFS41: add pnfs_dio_begin/dio_end
>>>
>>> On Sun, 2012-05-27 at 22:30 -0400, tao.peng@emc.com wrote:
>>>> I'm afraid there is. There is no way to pass struct blk_plug around pg_init/pg_doio, unless we put
>>> it in struct nfs_pageio_descriptor, which I think is more intrusive and less efficient as it is only
>>> useful for block layout driver in DIO case.
>>>
>>> Then add a 'void *pg_layout_private' field to nfs_pageio_descriptor and
>>> allocate the struct blk_plug dynamically.
>>>
> 
>> OK. I thought data structure change is more intrusive because it
>> affects all layout drivers and generic NFS as well. But since you
>> think it is OK, I will change it as you suggested.
>>
> 
> 
> I want a pg_layout_private in nfs_pageio_descriptor as well. I even wrote
> the ML about it. And everyone agreed. (Just never had time to finish)
> 
> So yes please do add it. it will have more users.
> 


I forgot to say. You might want/need to pass this pg_layout_private
back to LD->paglist_write/read. (If you need to, I will)

(In fact one optimization I wanted for a long time is to pass
nfs_pageio_descriptor to paglist_write/read directly instead of
duplicating all it's members (back and forth). In a new invented
structures where the worse is that the common code of read and write
can't be common because it is not the same types.
But that's for another patch)

Ciao
Boaz

> 
>> Thanks,
>> Tao
>>
> 
> 
> Thanks
> Boaz