add support for FATTR4_OFFLINE attribute

[kofemann]

Finally, a possibility for the server to indicate that files are offline:

https://www.ietf.org/archive/id/draft-ietf-nfsv4-delstid-04.txt

[gisburn]

Question: Is this attribute read-only, or can clients set it ?

[kofemann]

I am pretty sure that offline is a read-only attribute. At least spec doesn't say that clients can set it.

[gisburn]

I am pretty sure that offline is a read-only attribute. At least spec doesn't say that clients can set it.

Thanks... :-)
... we've implemented FATTR4_OFFLINE support in the Windows NFSv4.2 client, see kofemann/ms-nfs41-client@66a1e66 ...