Re: [nfsv4] parallel LAYOUTGETs using open stateid

On Thu, Oct 7, 2010 at 9:50 AM, Benny Halevy <bhalevy@panasas.com> wrote:
> On Thu, Oct 7, 2010 at 9:21 AM, Fred Isaman <iisaman@citi.umich.edu> wrote:
>> This question came up as I was going through our layout stateid code.
>>
>> Can the client send multiple LAYOUTGETs in parallel before getting a
>> layoutstateid by using an open stateid?
>> If so, what is the server response?  The spec is not clear, but I
>> would assume it would do one of:
>> a) returning an error (what error?) on all but the first LAYOUTGET it sees
>> b) matching the openstateid to the layoutstateid it has already given
>> out and sending a reply with that stateid and a bumped seqid
>
> I'm in favour of (b).
> Are there any problems you see in that approach?
>
> Benny
>

The wrinkle it adds is that, in the normal case, after the CB_RECALL
is resolved, any stale LAYOUTGETs (sent by the client before it
received the CB_RECALL) that the server receives will either be
processed normally with a bumped seqid or an error (if the server
invalidated the "other" part of the stateid.)  In the openstateid
case, the server loses the option of returning an error, instead it
wuold create a new "other" with seqid=1.  That said, I don't see that
this causes any problems apart from extra bookkeeping.

Fred

>> Fred
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>