[PATCH net-next v3 09/18] dlm: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

David Howells
2023-06-20T14:58:08Z

When transmitting data, call down a layer using a single sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced rather using
sendpage. This allows ->sendpage() to be replaced by something that can
handle multiple multipage folios in a single transaction.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christine Caulfield <ccaulfie@redhat.com>
cc: David Teigland <teigland@redhat.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: cluster-devel@redhat.com
cc: netdev@vger.kernel.org
---
fs/dlm/lowcomms.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 3d3802c47b8b..5c12d8cdfc16 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1395,8 +1395,11 @@ int dlm_lowcomms_resend_msg(struct dlm_msg *msg)
/* Send a message */
static int send_to_sock(struct connection *con)
{
- const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
struct writequeue_entry *e;
+ struct bio_vec bvec;
+ struct msghdr msg = {
+ .msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT | MSG_NOSIGNAL,
+ };
int len, offset, ret;

spin_lock_bh(&con->writequeue_lock);
@@ -1412,8 +1415,9 @@ static int send_to_sock(struct connection *con)
WARN_ON_ONCE(len == 0 && e->users == 0);
spin_unlock_bh(&con->writequeue_lock);

- ret = kernel_sendpage(con->sock, e->page, offset, len,
- msg_flags);
+ bvec_set_page(&bvec, e->page, len, offset);
+ iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, len);
+ ret = sock_sendmsg(con->sock, &msg);
trace_dlm_send(con->nodeid, ret);
if (ret == -EAGAIN || ret == 0) {
lock_sock(con->sock->sk);