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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Willem de Bruijn , David Ahern , Matthew Wilcox , Jens Axboe , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next v2 2/2] kcm: Convert kcm_sendpage() to use MSG_SPLICE_PAGES Date: Wed, 31 May 2023 12:04:22 +0100 Message-ID: <20230531110423.643196-3-dhowells@redhat.com> In-Reply-To: <20230531110423.643196-1-dhowells@redhat.com> References: <20230531110423.643196-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 X-Spam-Status: No, score=-2.3 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1767408256691086588?= X-GMAIL-MSGID: =?utf-8?q?1767408256691086588?= Convert kcm_sendpage() to use sendmsg() with MSG_SPLICE_PAGES rather than directly splicing in the pages itself. This allows ->sendpage() to be replaced by something that can handle multiple multipage folios in a single transaction. Signed-off-by: David Howells cc: Tom Herbert cc: Tom Herbert cc: Cong Wang cc: Jakub Kicinski cc: Eric Dumazet cc: "David S. Miller" cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- net/kcm/kcmsock.c | 161 ++++++---------------------------------------- 1 file changed, 18 insertions(+), 143 deletions(-) diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 8555ede66333..ba22af16b96d 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -761,149 +761,6 @@ 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)->flags |= SKBFL_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_noacc(skb, i, page, offset, size); - skb_shinfo(skb)->flags |= SKBFL_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; @@ -1111,6 +968,24 @@ static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) return err; } +static ssize_t kcm_sendpage(struct socket *sock, struct page *page, + int offset, size_t size, int flags) + +{ + struct bio_vec bvec; + struct msghdr msg = { .msg_flags = flags | MSG_SPLICE_PAGES, }; + + if (flags & MSG_SENDPAGE_NOTLAST) + msg.msg_flags |= MSG_MORE; + + if (flags & MSG_OOB) + return -EOPNOTSUPP; + + bvec_set_page(&bvec, page, size, offset); + iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size); + return kcm_sendmsg(sock, &msg, size); +} + static int kcm_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, int flags) {