netdev - [PATCH v3 27/55] tls/device: Support MSG_SPLICE

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Message-Id: <20230331160914.1608208-28-dhowells@redhat.com>
Date:   Fri, 31 Mar 2023 17:08:46 +0100
From:   David Howells <dhowells@...hat.com>
To:     Matthew Wilcox <willy@...radead.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     David Howells <dhowells@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, Jeff Layton <jlayton@...nel.org>,
        Christian Brauner <brauner@...nel.org>,
        Chuck Lever III <chuck.lever@...cle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        netdev@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Boris Pismenny <borisp@...dia.com>,
        John Fastabend <john.fastabend@...il.com>
Subject: [PATCH v3 27/55] tls/device: Support MSG_SPLICE_PAGES

Make TLS's device sendmsg() support MSG_SPLICE_PAGES.  This causes pages to
be spliced from the source iterator if possible and copied the data if not.

This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.

Signed-off-by: David Howells <dhowells@...hat.com>
cc: Chuck Lever <chuck.lever@...cle.com>
cc: Boris Pismenny <borisp@...dia.com>
cc: John Fastabend <john.fastabend@...il.com>
cc: Jakub Kicinski <kuba@...nel.org>
cc: Eric Dumazet <edumazet@...gle.com>
cc: "David S. Miller" <davem@...emloft.net>
cc: Paolo Abeni <pabeni@...hat.com>
cc: Jens Axboe <axboe@...nel.dk>
cc: Matthew Wilcox <willy@...radead.org>
cc: netdev@...r.kernel.org
---
 net/tls/tls_device.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index 6c593788dc25..f5c3b56ac1ce 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -508,7 +508,30 @@ static int tls_push_data(struct sock *sk,
 			zc_pfrag.offset = iter_offset.offset;
 			zc_pfrag.size = copy;
 			tls_append_frag(record, &zc_pfrag, copy);
+		} else if (copy && (flags & MSG_SPLICE_PAGES)) {
+			struct page_frag zc_pfrag;
+			struct page **pages = &zc_pfrag.page;
+			size_t off;
+
+			rc = iov_iter_extract_pages(iter_offset.msg_iter, &pages,
+						    copy, 1, 0, &off);
+			if (rc <= 0) {
+				if (rc == 0)
+					rc = -EIO;
+				goto handle_error;
+			}
+			copy = rc;
+
+			if (!sendpage_ok(zc_pfrag.page)) {
+				iov_iter_revert(iter_offset.msg_iter, copy);
+				goto no_zcopy_this_page;
+			}
+
+			zc_pfrag.offset = off;
+			zc_pfrag.size = copy;
+			tls_append_frag(record, &zc_pfrag, copy);
 		} else if (copy) {
+no_zcopy_this_page:
 			copy = min_t(size_t, copy, pfrag->size - pfrag->offset);
 
 			rc = tls_device_copy_data(page_address(pfrag->page) +
@@ -571,6 +594,9 @@ int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	union tls_iter_offset iter;
 	int rc;
 
+	if (!tls_ctx->zerocopy_sendfile)
+		msg->msg_flags &= ~MSG_SPLICE_PAGES;
+
 	mutex_lock(&tls_ctx->tx_lock);
 	lock_sock(sk);