[nfsv4] More layout stuff: layout return on close

[Trond Myklebust <[e-mail]>]

Another conflict between the forgetful pNFS client model and RFC5661.

Currently, section 18.43.3 states that:

        "The logr_return_on_close result field is a directive to return
        the layout before closing the file.  When the metadata server
        sets this return value to TRUE, it MUST be prepared to recall
        the layout in the case in which the client fails to return the
        layout before close."

The point is that the client is fully entitled by section 12.5.5.1 to
forget that it holds a layout for this file altogether. With this in
mind, the requirement in 18.43.3 appears excessively bureaucratic:
      * the server _knows_ that the client is required to return layouts
        on close,
      * it _knows_ that the client may have forgotten it holds layouts
yet it is required to go through the motions of issuing a layout recall?

Can anyone think of a reason why we should not just allow the server to
assume the client has forgotten all layouts when it issues the close in
apparent violation of the 'return on close' here?

Cheers
  Trond

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
[e-mail]
www.netapp.com