kcm: Sendpage support

Implement kcm_sendpage. Set in sendpage to kcm_sendpage in both
dgram and seqpacket ops.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 145 insertions, 2 deletions

diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 982ea5f77bfc..9ac24995691c 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -990,6 +990,149 @@ static void kcm_push(struct kcm_sock *kcm)
                 kcm_write_msgs(kcm);
 }
 
+static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
+                            int offset, size_t size, int flags)
+
+{
+        struct sock *sk = sock->sk;
+        struct kcm_sock *kcm = kcm_sk(sk);
+        struct sk_buff *skb = NULL, *head = NULL;
+        long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
+        bool eor;
+        int err = 0;
+        int i;
+
+        if (flags & MSG_SENDPAGE_NOTLAST)
+                flags |= MSG_MORE;
+
+        /* No MSG_EOR from splice, only look at MSG_MORE */
+        eor = !(flags & MSG_MORE);
+
+        lock_sock(sk);
+
+        sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+
+        err = -EPIPE;
+        if (sk->sk_err)
+                goto out_error;
+
+        if (kcm->seq_skb) {
+                /* Previously opened message */
+                head = kcm->seq_skb;
+                skb = kcm_tx_msg(head)->last_skb;
+                i = skb_shinfo(skb)->nr_frags;
+
+                if (skb_can_coalesce(skb, i, page, offset)) {
+                        skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
+                        skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
+                        goto coalesced;
+                }
+
+                if (i >= MAX_SKB_FRAGS) {
+                        struct sk_buff *tskb;
+
+                        tskb = alloc_skb(0, sk->sk_allocation);
+                        while (!tskb) {
+                                kcm_push(kcm);
+                                err = sk_stream_wait_memory(sk, &timeo);
+                                if (err)
+                                        goto out_error;
+                        }
+
+                        if (head == skb)
+                                skb_shinfo(head)->frag_list = tskb;
+                        else
+                                skb->next = tskb;
+
+                        skb = tskb;
+                        skb->ip_summed = CHECKSUM_UNNECESSARY;
+                        i = 0;
+                }
+        } else {
+                /* Call the sk_stream functions to manage the sndbuf mem. */
+                if (!sk_stream_memory_free(sk)) {
+                        kcm_push(kcm);
+                        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+                        err = sk_stream_wait_memory(sk, &timeo);
+                        if (err)
+                                goto out_error;
+                }
+
+                head = alloc_skb(0, sk->sk_allocation);
+                while (!head) {
+                        kcm_push(kcm);
+                        err = sk_stream_wait_memory(sk, &timeo);
+                        if (err)
+                                goto out_error;
+                }
+
+                skb = head;
+                i = 0;
+        }
+
+        get_page(page);
+        skb_fill_page_desc(skb, i, page, offset, size);
+        skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
+
+coalesced:
+        skb->len += size;
+        skb->data_len += size;
+        skb->truesize += size;
+        sk->sk_wmem_queued += size;
+        sk_mem_charge(sk, size);
+
+        if (head != skb) {
+                head->len += size;
+                head->data_len += size;
+                head->truesize += size;
+        }
+
+        if (eor) {
+                bool not_busy = skb_queue_empty(&sk->sk_write_queue);
+
+                /* Message complete, queue it on send buffer */
+                __skb_queue_tail(&sk->sk_write_queue, head);
+                kcm->seq_skb = NULL;
+                KCM_STATS_INCR(kcm->stats.tx_msgs);
+
+                if (flags & MSG_BATCH) {
+                        kcm->tx_wait_more = true;
+                } else if (kcm->tx_wait_more || not_busy) {
+                        err = kcm_write_msgs(kcm);
+                        if (err < 0) {
+                                /* We got a hard error in write_msgs but have
+                                 * already queued this message. Report an error
+                                 * in the socket, but don't affect return value
+                                 * from sendmsg
+                                 */
+                                pr_warn("KCM: Hard failure on kcm_write_msgs\n");
+                                report_csk_error(&kcm->sk, -err);
+                        }
+                }
+        } else {
+                /* Message not complete, save state */
+                kcm->seq_skb = head;
+                kcm_tx_msg(head)->last_skb = skb;
+        }
+
+        KCM_STATS_ADD(kcm->stats.tx_bytes, size);
+
+        release_sock(sk);
+        return size;
+
+out_error:
+        kcm_push(kcm);
+
+        err = sk_stream_error(sk, flags, err);
+
+        /* make sure we wake any epoll edge trigger waiter */
+        if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
+                sk->sk_write_space(sk);
+
+        release_sock(sk);
+        return err;
+}
+
 static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 {
         struct sock *sk = sock->sk;
@@ -1995,7 +2138,7 @@ static const struct proto_ops kcm_dgram_ops = {
         .sendmsg =      kcm_sendmsg,
         .recvmsg =      kcm_recvmsg,
         .mmap =         sock_no_mmap,
-        .sendpage =     sock_no_sendpage,
+        .sendpage =     kcm_sendpage,
 };
 
 static const struct proto_ops kcm_seqpacket_ops = {
@@ -2016,7 +2159,7 @@ static const struct proto_ops kcm_seqpacket_ops = {
         .sendmsg =      kcm_sendmsg,
         .recvmsg =      kcm_recvmsg,
         .mmap =         sock_no_mmap,
-        .sendpage =     sock_no_sendpage,
+        .sendpage =     kcm_sendpage,
         .splice_read =  kcm_splice_read,
 };