Subject: [PATCH] SUNRPC: fix shutdown of NFS TCP client socket NFS server Duplicate Request Cache (DRC) algorithms rely on NFS clients reconnecting using the same local TCP port. Unique NFS operations are identified by the per-TCP connection set of XIDs. This prevents file corruption when non-idempotent NFS operations are retried. Currently, NFS client TCP connections are using different local TCP ports when reconnecting to NFS servers. After an NFS server initiates shutdown of the TCP connection, the NFS client's TCP socket is set to NULL after the socket state has reached TCP_LAST_ACK(9). When reconnecting, the new socket attempts to reuse the same local port but fails with EADDRNOTAVAIL (99). This forces the socket to use a different local TCP port to reconnect to the remote NFS server. State Transition and Events: TCP_CLOSING(8) TCP_LAST_ACK(9) connect(fail EADDRNOTAVAIL(99)) TCP_CLOSE(7) bind on new port connect success dmesg excerpts showing reconnect switching from local port of 688 to 1014: [590701.200229] NFS: mkdir(0:61/560857152), testQ [590701.200231] NFS call mkdir testQ [590701.200259] RPC: xs_tcp_send_request(224) = 0 [590751.883111] RPC: xs_tcp_state_change client 0000000051f4e000... [590751.883146] RPC: state 8 conn 1 dead 0 zapped 1 sk_shutdown 1 [590751.883160] RPC: xs_data_ready... [590751.883232] RPC: xs_tcp_state_change client 0000000051f4e000... [590751.883235] RPC: state 9 conn 0 dead 0 zapped 1 sk_shutdown 3 [590751.883238] RPC: xs_tcp_state_change client 0000000051f4e000... [590751.883239] RPC: state 9 conn 0 dead 0 zapped 1 sk_shutdown 3 [590751.883283] RPC: xs_connect scheduled xprt 0000000051f4e000 [590751.883314] RPC: xs_bind 0.0.0.0:688: ok (0) [590751.883321] RPC: worker connecting xprt 0000000051f4e000 via tcp to 10.101.1.30 (port 2049) [590751.883330] RPC: 0000000051f4e000 connect status 99 connected 0 sock state 7 [590751.883342] RPC: xs_tcp_state_change client 0000000051f4e000... [590751.883343] RPC: state 7 conn 0 dead 0 zapped 1 sk_shutdown 3 [590751.883356] RPC: xs_connect scheduled xprt 0000000051f4e000 [590751.883383] RPC: xs_bind 0.0.0.0:1014: ok (0) [590751.883388] RPC: worker connecting xprt 0000000051f4e000 via tcp to 10.101.1.30 (port 2049) [590751.883420] RPC: 0000000051f4e000 connect status 115 connected 0 sock state 2 ... State Transition and Events with patch applied: TCP_CLOSING(8) TCP_LAST_ACK(9) TCP_CLOSE(7) connect(reuse of port succeeds) dmesg excerpts showing reconnect on same port (936): [ 257.139935] NFS: mkdir(0:59/560857152), testQ [ 257.139937] NFS call mkdir testQ ... [ 307.822702] RPC: state 8 conn 1 dead 0 zapped 1 sk_shutdown 1 [ 307.822714] RPC: xs_data_ready... [ 307.822817] RPC: xs_tcp_state_change client 00000000ce702f14... [ 307.822821] RPC: state 9 conn 0 dead 0 zapped 1 sk_shutdown 3 [ 307.822825] RPC: xs_tcp_state_change client 00000000ce702f14... [ 307.822826] RPC: state 9 conn 0 dead 0 zapped 1 sk_shutdown 3 [ 307.823606] RPC: xs_tcp_state_change client 00000000ce702f14... [ 307.823609] RPC: state 7 conn 0 dead 0 zapped 1 sk_shutdown 3 [ 307.823629] RPC: xs_tcp_state_change client 00000000ce702f14... [ 307.823632] RPC: state 7 conn 0 dead 0 zapped 1 sk_shutdown 3 [ 307.823676] RPC: xs_connect scheduled xprt 00000000ce702f14 [ 307.823704] RPC: xs_bind 0.0.0.0:936: ok (0) [ 307.823709] RPC: worker connecting xprt 00000000ce702f14 via tcp to 10.101.1.30 (port 2049) [ 307.823748] RPC: 00000000ce702f14 connect status 115 connected 0 sock state 2 ... [ 314.916193] RPC: state 7 conn 0 dead 0 zapped 1 sk_shutdown 3 [ 314.916251] RPC: xs_connect scheduled xprt 00000000ce702f14 [ 314.916282] RPC: xs_bind 0.0.0.0:936: ok (0) [ 314.916292] RPC: worker connecting xprt 00000000ce702f14 via tcp to 10.101.1.30 (port 2049) [ 314.916342] RPC: 00000000ce702f14 connect status 115 connected 0 sock state 2 Fixes: 7c81e6a9d75b (SUNRPC: Tweak TCP socket shutdown in the RPC client) Signed-off-by: Siddharth Rajendra Kawar <sikawar@xxxxxxxxxxxxx> --- diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index d8ee06a9650a..e55e380bc10c 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -2094,6 +2094,7 @@ static void xs_tcp_shutdown(struct rpc_xprt *xprt) break; case TCP_ESTABLISHED: case TCP_CLOSE_WAIT: + case TCP_LAST_ACK: kernel_sock_shutdown(sock, SHUT_RDWR); trace_rpc_socket_shutdown(xprt, sock); break;
