4 files changed, 115 insertions, 14 deletions

diff --git a/net/rxrpc/ar-ack.c b/net/rxrpc/ar-ack.c
index fc07a926df56..657ee69f2133 100644
--- a/net/rxrpc/ar-ack.c
+++ b/net/rxrpc/ar-ack.c
@@ -543,6 +543,38 @@ static void rxrpc_zap_tx_window(struct rxrpc_call *call)
 }
 
 /*
+ * process the extra information that may be appended to an ACK packet
+ */
+static void rxrpc_extract_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
+                                  unsigned latest, int nAcks)
+{
+        struct rxrpc_ackinfo ackinfo;
+        struct rxrpc_peer *peer;
+        unsigned mtu;
+
+        if (skb_copy_bits(skb, nAcks + 3, &ackinfo, sizeof(ackinfo)) < 0) {
+                _leave(" [no ackinfo]");
+                return;
+        }
+
+        _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
+               latest,
+               ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU),
+               ntohl(ackinfo.rwind), ntohl(ackinfo.jumbo_max));
+
+        mtu = min(ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU));
+
+        peer = call->conn->trans->peer;
+        if (mtu < peer->maxdata) {
+                spin_lock_bh(&peer->lock);
+                peer->maxdata = mtu;
+                peer->mtu = mtu + peer->hdrsize;
+                spin_unlock_bh(&peer->lock);
+                _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
+        }
+}
+
+/*
  * process packets in the reception queue
  */
 static int rxrpc_process_rx_queue(struct rxrpc_call *call,
@@ -606,6 +638,8 @@ process_further:
                        rxrpc_acks[ack.reason],
                        ack.nAcks);
 
+                rxrpc_extract_ackinfo(call, skb, latest, ack.nAcks);
+
                 if (ack.reason == RXRPC_ACK_PING) {
                         _proto("Rx ACK %%%u PING Request", latest);
                         rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
@@ -801,9 +835,9 @@ void rxrpc_process_call(struct work_struct *work)
         struct msghdr msg;
         struct kvec iov[5];
         unsigned long bits;
-        __be32 data;
+        __be32 data, pad;
         size_t len;
-        int genbit, loop, nbit, ioc, ret;
+        int genbit, loop, nbit, ioc, ret, mtu;
         u32 abort_code = RX_PROTOCOL_ERROR;
         u8 *acks = NULL;
 
@@ -899,9 +933,30 @@ void rxrpc_process_call(struct work_struct *work)
         }
 
         if (test_bit(RXRPC_CALL_ACK_FINAL, &call->events)) {
-                hdr.type = RXRPC_PACKET_TYPE_ACKALL;
                 genbit = RXRPC_CALL_ACK_FINAL;
-                goto send_message;
+
+                ack.bufferSpace = htons(8);
+                ack.maxSkew     = 0;
+                ack.serial      = 0;
+                ack.reason      = RXRPC_ACK_IDLE;
+                ack.nAcks       = 0;
+                call->ackr_reason = 0;
+
+                spin_lock_bh(&call->lock);
+                ack.serial = call->ackr_serial;
+                ack.previousPacket = call->ackr_prev_seq;
+                ack.firstPacket = htonl(call->rx_data_eaten + 1);
+                spin_unlock_bh(&call->lock);
+
+                pad = 0;
+
+                iov[1].iov_base = &ack;
+                iov[1].iov_len  = sizeof(ack);
+                iov[2].iov_base = &pad;
+                iov[2].iov_len  = 3;
+                iov[3].iov_base = &ackinfo;
+                iov[3].iov_len  = sizeof(ackinfo);
+                goto send_ACK;
         }
 
         if (call->events & ((1 << RXRPC_CALL_RCVD_BUSY) |
@@ -971,8 +1026,6 @@ void rxrpc_process_call(struct work_struct *work)
 
         /* consider sending an ordinary ACK */
         if (test_bit(RXRPC_CALL_ACK, &call->events)) {
-                __be32 pad;
-
                 _debug("send ACK: window: %d - %d { %lx }",
                        call->rx_data_eaten, call->ackr_win_top,
                        call->ackr_window[0]);
@@ -997,12 +1050,6 @@ void rxrpc_process_call(struct work_struct *work)
                 ack.serial      = 0;
                 ack.reason      = 0;
 
-                ackinfo.rxMTU   = htonl(5692);
-//              ackinfo.rxMTU   = htonl(call->conn->trans->peer->maxdata);
-                ackinfo.maxMTU  = htonl(call->conn->trans->peer->maxdata);
-                ackinfo.rwind   = htonl(32);
-                ackinfo.jumbo_max = htonl(4);
-
                 spin_lock_bh(&call->lock);
                 ack.reason = call->ackr_reason;
                 ack.serial = call->ackr_serial;
@@ -1116,6 +1163,15 @@ send_ACK_with_skew:
         ack.maxSkew = htons(atomic_read(&call->conn->hi_serial) -
                             ntohl(ack.serial));
 send_ACK:
+        mtu = call->conn->trans->peer->if_mtu;
+        mtu -= call->conn->trans->peer->hdrsize;
+        ackinfo.maxMTU  = htonl(mtu);
+        ackinfo.rwind   = htonl(32);
+
+        /* permit the peer to send us jumbo packets if it wants to */
+        ackinfo.rxMTU   = htonl(5692);
+        ackinfo.jumbo_max = htonl(4);
+
         hdr.serial = htonl(atomic_inc_return(&call->conn->serial));
         _proto("Tx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
                ntohl(hdr.serial),
diff --git a/net/rxrpc/ar-error.c b/net/rxrpc/ar-error.c
index 2c27df1ffa17..6cb3e8890e7e 100644
--- a/net/rxrpc/ar-error.c
+++ b/net/rxrpc/ar-error.c
@@ -100,8 +100,10 @@ void rxrpc_UDP_error_report(struct sock *sk)
                 }
 
                 if (mtu < peer->mtu) {
+                        spin_lock_bh(&peer->lock);
                         peer->mtu = mtu;
                         peer->maxdata = peer->mtu - peer->hdrsize;
+                        spin_unlock_bh(&peer->lock);
                         _net("Net MTU %u (maxdata %u)",
                              peer->mtu, peer->maxdata);
                 }
diff --git a/net/rxrpc/ar-output.c b/net/rxrpc/ar-output.c
index 5cdde4a48ed1..591c4422205e 100644
--- a/net/rxrpc/ar-output.c
+++ b/net/rxrpc/ar-output.c
@@ -582,7 +582,7 @@ static int rxrpc_send_data(struct kiocb *iocb,
                         max &= ~(call->conn->size_align - 1UL);
 
                         chunk = max;
-                        if (chunk > len)
+                        if (chunk > len && !more)
                                 chunk = len;
 
                         space = chunk + call->conn->size_align;
diff --git a/net/rxrpc/ar-peer.c b/net/rxrpc/ar-peer.c
index d399de4a7fe2..ce08b78647ce 100644
--- a/net/rxrpc/ar-peer.c
+++ b/net/rxrpc/ar-peer.c
@@ -19,6 +19,7 @@
 #include <net/sock.h>
 #include <net/af_rxrpc.h>
 #include <net/ip.h>
+#include <net/route.h>
 #include "ar-internal.h"
 
 static LIST_HEAD(rxrpc_peers);
@@ -28,6 +29,47 @@ static DECLARE_WAIT_QUEUE_HEAD(rxrpc_peer_wq);
 static void rxrpc_destroy_peer(struct work_struct *work);
 
 /*
+ * assess the MTU size for the network interface through which this peer is
+ * reached
+ */
+static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
+{
+        struct rtable *rt;
+        struct flowi fl;
+        int ret;
+
+        peer->if_mtu = 1500;
+
+        memset(&fl, 0, sizeof(fl));
+
+        switch (peer->srx.transport.family) {
+        case AF_INET:
+                fl.oif = 0;
+                fl.proto = IPPROTO_UDP,
+                fl.nl_u.ip4_u.saddr = 0;
+                fl.nl_u.ip4_u.daddr = peer->srx.transport.sin.sin_addr.s_addr;
+                fl.nl_u.ip4_u.tos = 0;
+                /* assume AFS.CM talking to AFS.FS */
+                fl.uli_u.ports.sport = htons(7001);
+                fl.uli_u.ports.dport = htons(7000);
+                break;
+        default:
+                BUG();
+        }
+
+        ret = ip_route_output_key(&rt, &fl);
+        if (ret < 0) {
+                kleave(" [route err %d]", ret);
+                return;
+        }
+
+        peer->if_mtu = dst_mtu(&rt->u.dst);
+        dst_release(&rt->u.dst);
+
+        kleave(" [if_mtu %u]", peer->if_mtu);
+}
+
+/*
  * allocate a new peer
  */
 static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
@@ -47,7 +89,8 @@ static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
                 peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
                 memcpy(&peer->srx, srx, sizeof(*srx));
 
-                peer->mtu = peer->if_mtu = 65535;
+                rxrpc_assess_MTU_size(peer);
+                peer->mtu = peer->if_mtu;
 
                 if (srx->transport.family == AF_INET) {
                         peer->hdrsize = sizeof(struct iphdr);