NFSv4: Fix problems with close in the presence of a delegation

NFSv4: Fix problems with close in the presence of a delegation

commit aee7af356e151494d5014f57b33460b162f181b5 upstream.

In the presence of delegations, we can no longer assume that the
state->n_rdwr, state->n_rdonly, state->n_wronly reflect the open
stateid share mode, and so we need to calculate the initial value
for calldata->arg.fmode using the state->flags.

Reported-by: James Drews <drews@engr.wisc.edu>
Fixes: 88069f77e1ac5 (NFSv41: Fix a potential state leakage when...)
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>