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SubjectRe: fcntl(F GETLEASE) semantics??
From
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to den 11.08.2005 Klokka 10:06 (-0400) skreiv Trond Myklebust:

> The NFSv4 spec explicitly states that
>
> When a client has a read open delegation, it may not make any changes
> to the contents or attributes of the file but it is assured that no
> other client may do so. When a client has a write open delegation,
> it may modify the file data since no other client will be accessing
> the file's data. The client holding a write delegation may only
> affect file attributes which are intimately connected with the file
> data: size, time_modify, change.
>
> so NFSv4 cannot currently support this behaviour. If CIFS supports it,
> then maybe we have a case for going to the IETF and asking for a
> clarification to implement the same behaviour in NFSv4.

Note: I'm not saying that this means we _must_ implement the current
behaviour in leases. If CIFS allows the server to hand out read oplocks
when the client opened the file with a write share, then NFSv4 can
simply deal with the difference in semantics by just never requesting a
read lease in that situation.
That said, if CIFS has the same semantics as NFSv4, then why allow the
aberrant case?

Cheers,
Trond

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