NFSv4.1: Fix session initialisation races

Session initialisation is not complete until the lease manager
has run. We need to ensure that both nfs4_init_session and
nfs4_init_ds_session do so, and that they check for any resulting
errors in clp->cl_cons_state.

Only after this is done, can nfs4_ds_connect check the contents
of clp->cl_exchange_flags.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Andy Adamson <andros@netapp.com>

fs/nfs/client.c

@@ -591,22 +591,6 @@ void nfs_mark_client_ready(struct nfs_client *clp, int state)
 	wake_up_all(&nfs_client_active_wq);
 }
 
-/*
- * With sessions, the client is not marked ready until after a
- * successful EXCHANGE_ID and CREATE_SESSION.
- *
- * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
- * other versions of NFS can be tried.
- */
-int nfs4_check_client_ready(struct nfs_client *clp)
-{
-	if (!nfs4_has_session(clp))
-		return 0;
-	if (clp->cl_cons_state < NFS_CS_READY)
-		return -EPROTONOSUPPORT;
-	return 0;
-}
-
 /*
  * Initialise the timeout values for a connection
  */

fs/nfs/internal.h

@@ -169,7 +169,6 @@ extern struct nfs_server *nfs_clone_server(struct nfs_server *,
 					   struct nfs_fattr *,
 					   rpc_authflavor_t);
 extern void nfs_mark_client_ready(struct nfs_client *clp, int state);
-extern int nfs4_check_client_ready(struct nfs_client *clp);
 extern struct nfs_client *nfs4_set_ds_client(struct nfs_client* mds_clp,
 					     const struct sockaddr *ds_addr,
 					     int ds_addrlen, int ds_proto,
@@ -234,7 +233,7 @@ extern const u32 nfs41_maxwrite_overhead;
 extern struct rpc_procinfo nfs4_procedures[];
 #endif
 
-extern int nfs4_init_ds_session(struct nfs_client *clp);
+extern int nfs4_init_ds_session(struct nfs_client *, unsigned long);
 
 /* proc.c */
 void nfs_close_context(struct nfs_open_context *ctx, int is_sync);

fs/nfs/nfs4filelayoutdev.c

@@ -203,28 +203,7 @@ nfs4_ds_connect(struct nfs_server *mds_srv, struct nfs4_pnfs_ds *ds)
 		goto out;
 	}
 
-	if ((clp->cl_exchange_flags & EXCHGID4_FLAG_MASK_PNFS) != 0) {
-		if (!is_ds_client(clp)) {
-			status = -ENODEV;
-			goto out_put;
-		}
-		ds->ds_clp = clp;
-		dprintk("%s [existing] server=%s\n", __func__,
-			ds->ds_remotestr);
-		goto out;
-	}
-
-	/*
-	 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the DS lease to
-	 * be equal to the MDS lease. Renewal is scheduled in create_session.
-	 */
-	spin_lock(&mds_srv->nfs_client->cl_lock);
-	clp->cl_lease_time = mds_srv->nfs_client->cl_lease_time;
-	spin_unlock(&mds_srv->nfs_client->cl_lock);
-	clp->cl_last_renewal = jiffies;
-
-	/* New nfs_client */
-	status = nfs4_init_ds_session(clp);
+	status = nfs4_init_ds_session(clp, mds_srv->nfs_client->cl_lease_time);
 	if (status)
 		goto out_put;
 

fs/nfs/nfs4proc.c

@@ -5603,19 +5603,39 @@ int nfs4_proc_destroy_session(struct nfs4_session *session)
 	return status;
 }
 
+/*
+ * With sessions, the client is not marked ready until after a
+ * successful EXCHANGE_ID and CREATE_SESSION.
+ *
+ * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
+ * other versions of NFS can be tried.
+ */
+static int nfs41_check_session_ready(struct nfs_client *clp)
+{
+	int ret;
+	
+	if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
+		ret = nfs4_client_recover_expired_lease(clp);
+		if (ret)
+			return ret;
+	}
+	if (clp->cl_cons_state < NFS_CS_READY)
+		return -EPROTONOSUPPORT;
+	return 0;
+}
+
 int nfs4_init_session(struct nfs_server *server)
 {
 	struct nfs_client *clp = server->nfs_client;
 	struct nfs4_session *session;
 	unsigned int rsize, wsize;
-	int ret;
 
 	if (!nfs4_has_session(clp))
 		return 0;
 
 	session = clp->cl_session;
-	if (!test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state))
-		return 0;
+	spin_lock(&clp->cl_lock);
+	if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
 
 		rsize = server->rsize;
 		if (rsize == 0)
@@ -5626,30 +5646,35 @@ int nfs4_init_session(struct nfs_server *server)
 
 		session->fc_attrs.max_rqst_sz = wsize + nfs41_maxwrite_overhead;
 		session->fc_attrs.max_resp_sz = rsize + nfs41_maxread_overhead;
+	}
+	spin_unlock(&clp->cl_lock);
 
-	ret = nfs4_recover_expired_lease(server);
-	if (!ret)
-		ret = nfs4_check_client_ready(clp);
-	return ret;
+	return nfs41_check_session_ready(clp);
 }
 
-int nfs4_init_ds_session(struct nfs_client *clp)
+int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
 {
 	struct nfs4_session *session = clp->cl_session;
 	int ret;
 
-	if (!test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state))
-		return 0;
+	spin_lock(&clp->cl_lock);
+	if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
+		/*
+		 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
+		 * DS lease to be equal to the MDS lease.
+		 */
+		clp->cl_lease_time = lease_time;
+		clp->cl_last_renewal = jiffies;
+	}
+	spin_unlock(&clp->cl_lock);
 
-	ret = nfs4_client_recover_expired_lease(clp);
-	if (!ret)
+	ret = nfs41_check_session_ready(clp);
+	if (ret)
+		return ret;
 	/* Test for the DS role */
 	if (!is_ds_client(clp))
-			ret = -ENODEV;
-	if (!ret)
-		ret = nfs4_check_client_ready(clp);
-	return ret;
-
+		return -ENODEV;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(nfs4_init_ds_session);