rxrpc: Use a large kvec[] in rxrpc_local rather than every rxrpc_txbuf

Use a single large kvec[] in the rxrpc_local struct rather than one in
every rxrpc_txbuf struct to build large packets to save on memory.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241204074710.990092-9-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index d0fd37bdcfe9c8653192b8c7d9f07a55e938fb90..ab8e565cb20bcfecbf309c9748d8e0f251eacc88 100644 (file)
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -320,6 +320,12 @@ struct rxrpc_local {
        struct list_head        new_client_calls; /* Newly created client calls need connection */
        spinlock_t              client_call_lock; /* Lock for ->new_client_calls */
        struct sockaddr_rxrpc   srx;            /* local address */
+       /* Provide a kvec table sufficiently large to manage either a DATA
+        * packet with a maximum set of jumbo subpackets or a PING ACK padded
+        * out to 64K with zeropages for PMTUD.
+        */
+       struct kvec             kvec[RXRPC_MAX_NR_JUMBO > 3 + 16 ?
+                                    RXRPC_MAX_NR_JUMBO : 3 + 16];
 };
 
 /*

diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index b93a5d50be3e446408c9935a60b73442c1591340..f8bb5250e849580123491f52637937d3f557da6e 100644 (file)
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -175,9 +175,11 @@ no_slot:
 /*
  * Transmit an ACK packet.
  */
-static void rxrpc_send_ack_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
+static void rxrpc_send_ack_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb,
+                                 int nr_kv)
 {
-       struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
+       struct kvec *kv = call->local->kvec;
+       struct rxrpc_wire_header *whdr = kv[0].iov_base;
        struct rxrpc_connection *conn;
        struct rxrpc_ackpacket *ack = (struct rxrpc_ackpacket *)(whdr + 1);
        struct msghdr msg;
@@ -206,8 +208,9 @@ static void rxrpc_send_ack_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t
 
        rxrpc_inc_stat(call->rxnet, stat_tx_ack_send);
 
-       iov_iter_kvec(&msg.msg_iter, WRITE, txb->kvec, txb->nr_kvec, txb->len);
+       iov_iter_kvec(&msg.msg_iter, WRITE, kv, nr_kv, txb->len);
        rxrpc_local_dont_fragment(conn->local, false);
+
        ret = do_udp_sendmsg(conn->local->socket, &msg, txb->len);
        call->peer->last_tx_at = ktime_get_seconds();
        if (ret < 0) {
@@ -233,6 +236,8 @@ void rxrpc_send_ACK(struct rxrpc_call *call, u8 ack_reason,
                    rxrpc_serial_t serial, enum rxrpc_propose_ack_trace why)
 {
        struct rxrpc_txbuf *txb;
+       struct kvec *kv = call->local->kvec;
+       int nr_kv;
 
        if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
                return;
@@ -248,12 +253,19 @@ void rxrpc_send_ACK(struct rxrpc_call *call, u8 ack_reason,
        txb->ack_why = why;
 
        rxrpc_fill_out_ack(call, txb, ack_reason, serial);
+
+       nr_kv = txb->nr_kvec;
+       kv[0] = txb->kvec[0];
+       kv[1] = txb->kvec[1];
+       kv[2] = txb->kvec[2];
+       // TODO: Extend a path MTU probe ACK
+
        call->ackr_nr_unacked = 0;
        atomic_set(&call->ackr_nr_consumed, 0);
        clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags);
 
        trace_rxrpc_send_ack(call, why, ack_reason, serial);
-       rxrpc_send_ack_packet(call, txb);
+       rxrpc_send_ack_packet(call, txb, nr_kv);
        rxrpc_put_txbuf(txb, rxrpc_txbuf_put_ack_tx);
 }
 
@@ -324,12 +336,15 @@ int rxrpc_send_abort_packet(struct rxrpc_call *call)
 /*
  * Prepare a (sub)packet for transmission.
  */
-static void rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_txbuf *txb,
-                                        rxrpc_serial_t serial)
+static size_t rxrpc_prepare_data_subpacket(struct rxrpc_call *call, struct rxrpc_txbuf *txb,
+                                          rxrpc_serial_t serial,
+                                          int subpkt)
 {
        struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
        enum rxrpc_req_ack_trace why;
        struct rxrpc_connection *conn = call->conn;
+       struct kvec *kv = &call->local->kvec[subpkt];
+       size_t len = txb->len;
        bool last, more;
        u8 flags;
 
@@ -385,8 +400,13 @@ dont_set_request_ack:
        whdr->flags     = flags;
        whdr->serial    = htonl(txb->serial);
        whdr->cksum     = txb->cksum;
+       whdr->serviceId = htons(conn->service_id);
+       kv->iov_base    = whdr;
+       // TODO: Convert into a jumbo header for tail subpackets
 
        trace_rxrpc_tx_data(call, txb->seq, txb->serial, flags, false);
+       kv->iov_len = len;
+       return len;
 }
 
 /*
@@ -395,13 +415,15 @@ dont_set_request_ack:
 static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 {
        rxrpc_serial_t serial;
+       size_t len = 0;
 
        /* Each transmission of a Tx packet needs a new serial number */
        serial = rxrpc_get_next_serial(call->conn);
 
-       rxrpc_prepare_data_subpacket(call, txb, serial);
+       len += rxrpc_prepare_data_subpacket(call, txb, serial, 0);
+       // TODO: Loop around adding tail subpackets
 
-       return txb->len;
+       return len;
 }
 
 /*
@@ -442,7 +464,6 @@ static void rxrpc_tstamp_data_packets(struct rxrpc_call *call, struct rxrpc_txbu
  */
 static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 {
-       struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
        struct rxrpc_connection *conn = call->conn;
        enum rxrpc_tx_point frag;
        struct msghdr msg;
@@ -463,7 +484,7 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t
                }
        }
 
-       iov_iter_kvec(&msg.msg_iter, WRITE, txb->kvec, txb->nr_kvec, len);
+       iov_iter_kvec(&msg.msg_iter, WRITE, call->local->kvec, 1, len);
 
        msg.msg_name    = &call->peer->srx.transport;
        msg.msg_namelen = call->peer->srx.transport_len;
@@ -480,7 +501,7 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t
 
        /* send the packet with the don't fragment bit set if we currently
         * think it's small enough */
-       if (txb->len >= call->peer->maxdata) {
+       if (len >= sizeof(struct rxrpc_wire_header) + call->peer->maxdata) {
                rxrpc_local_dont_fragment(conn->local, false);
                frag = rxrpc_tx_point_call_data_frag;
        } else {
@@ -503,7 +524,7 @@ retry:
                rxrpc_inc_stat(call->rxnet, stat_tx_data_send_fail);
                trace_rxrpc_tx_fail(call->debug_id, txb->serial, ret, frag);
        } else {
-               trace_rxrpc_tx_packet(call->debug_id, whdr, frag);
+               trace_rxrpc_tx_packet(call->debug_id, call->local->kvec[0].iov_base, frag);
        }
 
        rxrpc_tx_backoff(call, ret);