Re: [nfsv4] RFC 7530: Available attributes for READDIR and Absent File Systems

[David Noveck <[e-mail]>]

> In other words, can other attributes than fs_locations, fsid,
mounted_on_fileid, rdattr_error
> be available for a root of absent filesystem in READDIR reply?

According to the spec. yes.  Realistically, it is hard to come up with a
case where the server would have this information or in which a client
would be prepared to do anything with it.

On Sun, May 21, 2017 at 7:05 PM, Vitaliy Gusev <[e-mail]>
wrote:

>
> On 21 May 2017, at 22:26, David Noveck <[e-mail]> wrote:
> …
> The other relevant case for READDIR is one in which the operation is being
> done in a directory within a present file system and some of objects within
> the directory are the roots of absent file systems.  Given that context,
> the document could have been clearer if it had mentioned fsid and
> mounted_on_filled which need to be provided  (it is a SHOULD) for GETATTR.
> At the time RFC7530 was done we could have made these "SHOULD"s as they are
> for GETATTR but we didn't do that since this is not a very important case
> and the client has the option to follow up with GETATTR.
>
> As it is, the server MAY return these attributes.  If one is doing a
> server-side implementation, it is best to to provide them since they need
> to be available for GETATTR.  On the other hand, if one is doing a
> client-side implementation, you can’t assume they will be present and need
> to be prepared to follow up with an OTW GETATTR (which has to specify
> fs_locations to prevent it from being rejected).
>
>
> So you specify case when server can return READDIR the same or lesser
> quantity of attributes as GETATTR
> returns. This case is reasonable.
>
> But what if list of attributes returned by READDIR for root of absent
> filesystem is more widely than GETATTR returns?
> In other words, can other attributes than fs_locations, fsid,
> mounted_on_fileid, rdattr_error
> be available for a root of absent filesystem in READDIR reply?
>
> ———
> Thanks,
> Vitaliy Gusev
>
>