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Subject[PATCH net-next v4 10/15] drbd: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage()
Date
Use sendmsg() conditionally with MSG_SPLICE_PAGES in _drbd_send_page()
rather than calling sendpage() or _drbd_no_send_page().

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Philipp Reisner <philipp.reisner@linbit.com>
cc: Lars Ellenberg <lars.ellenberg@linbit.com>
cc: "Christoph Böhmwalder" <christoph.boehmwalder@linbit.com>
cc: Jens Axboe <axboe@kernel.dk>
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: drbd-dev@lists.linbit.com
cc: linux-block@vger.kernel.org
cc: netdev@vger.kernel.org
---

Notes:
ver #4)
- Don't look at msg.msg_iter after calling sendmsg. There's no guarantee
it has changed.

ver #2)
- Wrap lines at 80.

drivers/block/drbd/drbd_main.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 83987e7a5ef2..ea82d6733313 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -1540,6 +1540,8 @@ static int _drbd_send_page(struct drbd_peer_device *peer_device, struct page *pa
int offset, size_t size, unsigned msg_flags)
{
struct socket *socket = peer_device->connection->data.socket;
+ struct msghdr msg = { .msg_flags = msg_flags, };
+ struct bio_vec bvec;
int len = size;
int err = -EIO;

@@ -1549,15 +1551,17 @@ static int _drbd_send_page(struct drbd_peer_device *peer_device, struct page *pa
* put_page(); and would cause either a VM_BUG directly, or
* __page_cache_release a page that would actually still be referenced
* by someone, leading to some obscure delayed Oops somewhere else. */
- if (drbd_disable_sendpage || !sendpage_ok(page))
- return _drbd_no_send_page(peer_device, page, offset, size, msg_flags);
+ if (!drbd_disable_sendpage && sendpage_ok(page))
+ msg.msg_flags |= MSG_NOSIGNAL | MSG_SPLICE_PAGES;

- msg_flags |= MSG_NOSIGNAL;
drbd_update_congested(peer_device->connection);
do {
int sent;

- sent = socket->ops->sendpage(socket, page, offset, len, msg_flags);
+ bvec_set_page(&bvec, page, offset, len);
+ iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, len);
+
+ sent = sock_sendmsg(socket, &msg);
if (sent <= 0) {
if (sent == -EAGAIN) {
if (we_should_drop_the_connection(peer_device->connection, socket))
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