pNFS/flexfiles: If the layout is invalid, it must be updated before retrying

commit df3ab232e462bce20710596d697ade6b72497694 upstream.

If we see that our pNFS READ/WRITE/COMMIT operation failed, but we
also see that our layout segment is no longer valid, then we need to
get a new layout segment before retrying.

Fixes: 90816d1d ("NFSv4.1/flexfiles: Don't mark the entire deviceid...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>