nfsd4: delegation-based open reclaims should bypass permissions

We saw a v4.0 client's create fail as follows:

	- open create succeeds and gets a read delegation
	- client attempts to set mode on new file, gets DELAY while
	  server recalls delegation.
	- client attempts a CLAIM_DELEGATE_CUR open using the
	  delegation, gets error because of new file mode.

This probably can't happen on a recent kernel since we're no longer
giving out delegations on create opens.  Nevertheless, it's a
bug--reclaim opens should bypass permission checks.
Reported-by: Steve Dickson <steved@redhat.com>
Reported-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4proc.c

@@ -296,7 +296,8 @@ do_open_lookup(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, stru
 
 	nfsd4_set_open_owner_reply_cache(cstate, open, resfh);
 	accmode = NFSD_MAY_NOP;
-	if (open->op_created)
+	if (open->op_created ||
+			open->op_claim_type == NFS4_OPEN_CLAIM_DELEGATE_CUR)
 		accmode |= NFSD_MAY_OWNER_OVERRIDE;
 	status = do_open_permission(rqstp, resfh, open, accmode);
 	set_change_info(&open->op_cinfo, current_fh);