Re: [PATCH 1/5] pNFS: recoalesce when ld write pagelist fails

[Boaz Harrosh <bharrosh@panasas.com>]

On 08/10/2011 05:03 PM, Peng Tao wrote:
> On Thu, Aug 11, 2011 at 1:52 AM, Boaz Harrosh <bharrosh@panasas.com> wrote:
>> On 08/06/2011 07:53 PM, Peng Tao wrote:
>>> For pnfs pagelist write failure, we need to pg_recoalesce and resend
>>> IO to mds.
>>>
>>
>> I have not given this subject any thought or investigation, so I don't
>> know what we should do, but the gut feeling is that I have seen all this
>> code else where and we could be having a bigger re-use of existing code.
>>
>> What if we dig into:
>>        data->mds_ops->rpc_call_done(&data->task, data);
>>        data->mds_ops->rpc_release(data);
>>
>> And do all the pages tear-down and unlocks but if there is an error
>> not set them as clean. That is keep them dirty. Then mark the layout
>> as error and let the normal code choose an MDS write_out. (Just a wild
>> thought)
> This may work only for write failures. But for read, we will have to
> recoalesce and send to MDS. So I prefer to let read and write have
> similar retry code path like this.
> 

I disagree. Look even now the read path is very different then the write
path. (See your two patches: write-patch is 3 times bigger the read-patch)

You should see if what I say is possible for write. And then maybe some
thing will come up also for read. They do not necessarily need to be the
same. (I think)

>>
>> Trond please look in here, can't it be made simpler?

Thanks
Boaz