> Does the NFSv4 spec allows the server to return file size that doesn't 
> include the unstable write to the writer or any other NFS client?  

I would say "no".   Consider the followiing sentence in the description of COMMIT.

If the count is zero, a flush from the offset to the end of the file is done.

Note that he size returned by GETATTR gives you the end of the file so that, if it did not
reflect the unstable writes, COMMIT wouldn't work right. 

On Fri, Feb 22, 2019 at 6:25 PM Marc Eshel <eshel@us.ibm.com> wrote:
What is the file size returned by the NFS server for getattr after an
unstable write to the NFS client that did the write or to other NFS
clients.

As far as I know most file systems will always return the file size that
includes the unstable writes.

Does the NFSv4 spec allows the server to return file size that doesn't
include the unstable write to the writer or any other NFS client?

Marc.