NFS: Don't revalidate the mapping if both size and change attr are up to date

NFS: Don't revalidate the mapping if both size and change attr are up to date

commit 85a23cee3f2c928475f31777ead5a71340a12fc3 upstream.

If we've ensured that the size and the change attribute are both correct,
then there is no point in marking those attributes as needing revalidation
again. Only do so if we know the size is incorrect and was not updated.

Fixes: f2467b6f64da ("NFS: Clear NFS_INO_REVAL_PAGECACHE when...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>