NFSv4: Don't recheck permissions on open in case of recovery cached open

If we already checked the user access permissions on the original open,
then don't bother checking again on recovery. Doing so can cause a
deadlock with NFSv4.1, since the may_open() operation is not privileged.
Furthermore, we can't report an access permission failure here anyway.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -769,6 +769,7 @@ struct nfs4_opendata {
 	struct iattr attrs;
 	unsigned long timestamp;
 	unsigned int rpc_done : 1;
+	unsigned int is_recover : 1;
 	int rpc_status;
 	int cancelled;
 };
@@ -1101,9 +1102,11 @@ static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata)
 		/* Save the delegation */
 		nfs4_stateid_copy(&stateid, &delegation->stateid);
 		rcu_read_unlock();
-		ret = nfs_may_open(state->inode, state->owner->so_cred, open_mode);
-		if (ret != 0)
-			goto out;
+		if (!opendata->is_recover) {
+			ret = nfs_may_open(state->inode, state->owner->so_cred, open_mode);
+			if (ret != 0)
+				goto out;
+		}
 		ret = -EAGAIN;
 
 		/* Try to update the stateid using the delegation */
@@ -1670,8 +1673,11 @@ static int nfs4_run_open_task(struct nfs4_opendata *data, int isrecover)
 	data->rpc_done = 0;
 	data->rpc_status = 0;
 	data->cancelled = 0;
-	if (isrecover)
+	data->is_recover = 0;
+	if (isrecover) {
 		nfs4_set_sequence_privileged(&o_arg->seq_args);
+		data->is_recover = 1;
+	}
 	task = rpc_run_task(&task_setup_data);
         if (IS_ERR(task))
                 return PTR_ERR(task);