nfsd: don't run get_file if nfs4_preprocess_stateid_op return error

commit b022032e upstream.

we should return error status directly when nfs4_preprocess_stateid_op
return error.
Signed-off-by: fanchaoting <fanchaoting@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Rui Xiang <rui.xiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/nfsd/nfs4proc.c

@@ -904,14 +904,14 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 
 	nfs4_lock_state();
 	status = nfs4_preprocess_stateid_op(cstate, stateid, WR_STATE, &filp);
-	if (filp)
-		get_file(filp);
-	nfs4_unlock_state();
-
 	if (status) {
+		nfs4_unlock_state();
 		dprintk("NFSD: nfsd4_write: couldn't process stateid!\n");
 		return status;
 	}
+	if (filp)
+		get_file(filp);
+	nfs4_unlock_state();
 
 	cnt = write->wr_buflen;
 	write->wr_how_written = write->wr_stable_how;