Re: [nfsv4] [pnfs] [PATCH 1/1] pnfsd: DLM file layout only support read iomode layouts

"William A. (Andy) Adamson" <androsadamson@gmail.com> Wed, 16 December 2009 15:43 UTC

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Date: Wed, 16 Dec 2009 10:42:59 -0500
Message-ID: <89c397150912160742x2b57e31cp7b5b4fd36d6566fd@mail.gmail.com>
From: "William A. (Andy) Adamson" <androsadamson@gmail.com>
To: "J. Bruce Fields" <bfields@fieldses.org>
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Cc: Benny Halevy <bhalevy@panasas.com>, pnfs@linux-nfs.org, NFSv4 <nfsv4@ietf.org>
Subject: Re: [nfsv4] [pnfs] [PATCH 1/1] pnfsd: DLM file layout only support read iomode layouts
Precedence: list

On Wed, Dec 16, 2009 at 10:37 AM, J. Bruce Fields <bfields@fieldses.org> wrote:
> On Wed, Dec 16, 2009 at 10:26:57AM -0500, William A. (Andy) Adamson wrote:
>> On Wed, Dec 16, 2009 at 7:18 AM, Benny Halevy <bhalevy@panasas.com> wrote:
>> >
>> > 15.1.10.4.  NFS4ERR_LAYOUTUNAVAILABLE (Error Code 10059)
>> >
>> >   Returned when layouts are not available for the current file system
>> >   or the particular specified file.
>> >
>> > NFS4ERR_BADIOMODE seems to make more sense since layouts are available,
>> > just not for the requested iomode. However its definition indicates that
>> > the iomode in the client request is "invalid or inappropriate".
>> > It is not clear what "inappropriate" means in this context.
>>
>> What difference does 'what inappropriate means' make to the client?
>> None! It's up to the server.
>
> We do have to worry how clients will react to the error:
>
>        - If clients really assume that this error can only result from
>          a bug, then they may choose to return an IO error to the
>          application, turn off pnfs entirely for this server, or
>          something similarly drastic.

Then that client implementation won't be used for very long. This is
Darwin in action!

>
>        - If they assume it means that the server doesn't feel like
>          giving out a layout of that iomode right now, then we're good.
>
> You're probably right that the latter is a reasonable interpretation of
> "inappropriate".
>
> However, the spec isn't entirely explicit about this, and the only
> specific example given of BADIOMODE use is an "invalid" case (client
> supplying IOMODE4_ANY on getlayout), so I think it would be easy for a
> client to get this wrong.

Perhaps. Linux doesn't. What does the only other client (Solaris) do?

-->Andy

>
> --b.
>

Re: [nfsv4] [PATCH 1/1] pnfsd: DLM file layout on… Benny Halevy
Re: [nfsv4] [pnfs] [PATCH 1/1] pnfsd: DLM file la… William A. (Andy) Adamson
Re: [nfsv4] [pnfs] [PATCH 1/1] pnfsd: DLM file la… J. Bruce Fields
Re: [nfsv4] [pnfs] [PATCH 1/1] pnfsd: DLM file la… William A. (Andy) Adamson
Re: [nfsv4] [pnfs] [PATCH 1/1] pnfsd: DLM file la… Benny Halevy
Re: [nfsv4] [pnfs] [PATCH 1/1] pnfsd: DLM file la… William A. (Andy) Adamson
Re: [nfsv4] [PATCH 1/1] pnfsd: DLM file layout on… J. Bruce Fields