net/smc: Cork when sendpage with MSG_SENDPAGE_NOTLAST flag

This introduces a new corked flag, MSG_SENDPAGE_NOTLAST, which is
involved in syscall sendfile() [1], it indicates this is not the last
page. So we can cork the data until the page is not specify this flag.
It has the same effect as MSG_MORE, but existed in sendfile() only.

This patch adds a option MSG_SENDPAGE_NOTLAST for corking data, try to
cork more data before sending when using sendfile(), which acts like
TCP's behaviour. Also, this reimplements the default sendpage to inform
that it is supported to some extent.

[1] https://man7.org/linux/man-pages/man2/sendfile.2.html

Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 3137d8e5956dddb4457c5d30e4e773ab2515d660..9ea45a3686199031978cc5d701800adcc5bf0e2f 100644 (file)
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -2662,8 +2662,10 @@ static ssize_t smc_sendpage(struct socket *sock, struct page *page,
                rc = kernel_sendpage(smc->clcsock, page, offset,
                                     size, flags);
        } else {
+               lock_sock(sk);
+               rc = smc_tx_sendpage(smc, page, offset, size, flags);
+               release_sock(sk);
                SMC_STAT_INC(smc, sendpage_cnt);
-               rc = sock_no_sendpage(sock, page, offset, size, flags);
        }
 
 out:

diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
index 9cec62cae7cb273dfd56bb97d2213a438ad8ebc9..a96ce162825e35a570e12e578505a63bd8567b32 100644 (file)
--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c
@@ -235,7 +235,8 @@ int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
                 */
                if ((msg->msg_flags & MSG_OOB) && !send_remaining)
                        conn->urg_tx_pend = true;
-               if ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc)) &&
+               if ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc) ||
+                    msg->msg_flags & MSG_SENDPAGE_NOTLAST) &&
                    (atomic_read(&conn->sndbuf_space)))
                        /* for a corked socket defer the RDMA writes if
                         * sndbuf_space is still available. The applications
@@ -257,6 +258,22 @@ out_err:
        return rc;
 }
 
+int smc_tx_sendpage(struct smc_sock *smc, struct page *page, int offset,
+                   size_t size, int flags)
+{
+       struct msghdr msg = {.msg_flags = flags};
+       char *kaddr = kmap(page);
+       struct kvec iov;
+       int rc;
+
+       iov.iov_base = kaddr + offset;
+       iov.iov_len = size;
+       iov_iter_kvec(&msg.msg_iter, WRITE, &iov, 1, size);
+       rc = smc_tx_sendmsg(smc, &msg, size);
+       kunmap(page);
+       return rc;
+}
+
 /***************************** sndbuf consumer *******************************/
 
 /* sndbuf consumer: actual data transfer of one target chunk with ISM write */

diff --git a/net/smc/smc_tx.h b/net/smc/smc_tx.h
index a59f370b8b43279adc4437c64938ff2fc419623a..34b578498b1f1cd78a75fc9bed698e9bd1080dae 100644 (file)
--- a/net/smc/smc_tx.h
+++ b/net/smc/smc_tx.h
@@ -31,6 +31,8 @@ void smc_tx_pending(struct smc_connection *conn);
 void smc_tx_work(struct work_struct *work);
 void smc_tx_init(struct smc_sock *smc);
 int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len);
+int smc_tx_sendpage(struct smc_sock *smc, struct page *page, int offset,
+                   size_t size, int flags);
 int smc_tx_sndbuf_nonempty(struct smc_connection *conn);
 void smc_tx_sndbuf_nonfull(struct smc_sock *smc);
 void smc_tx_consumer_update(struct smc_connection *conn, bool force);