[PATCH v3 28/55] tls/device: Convert tls_device_sendpage() to use MSG_SPLICE_PAGES

[David Howells]

Convert tls_device_sendpage() to use sendmsg() with MSG_SPLICE_PAGES rather
than directly splicing in the pages itself.  With that, the tls_iter_offset
union is no longer necessary and can be replaced with an iov_iter pointer
and the zc_page argument to tls_push_data() can also be removed.

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

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
cc: Boris Pismenny <borisp@xxxxxxxxxx>
cc: John Fastabend <john.fastabend@xxxxxxxxx>
cc: Jakub Kicinski <kuba@xxxxxxxxxx>
cc: Eric Dumazet <edumazet@xxxxxxxxxx>
cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
cc: Paolo Abeni <pabeni@xxxxxxxxxx>
cc: Jens Axboe <axboe@xxxxxxxxx>
cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
cc: netdev@xxxxxxxxxxxxxxx
---
 net/tls/tls_device.c | 79 ++++++++++----------------------------------
 1 file changed, 18 insertions(+), 61 deletions(-)

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index f5c3b56ac1ce..6cfd1577a212 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -424,16 +424,10 @@ static int tls_device_copy_data(void *addr, size_t bytes, struct iov_iter *i)
 	return 0;
 }
 
-union tls_iter_offset {
-	struct iov_iter *msg_iter;
-	int offset;
-};
-
 static int tls_push_data(struct sock *sk,
-			 union tls_iter_offset iter_offset,
+			 struct iov_iter *iter,
 			 size_t size, int flags,
-			 unsigned char record_type,
-			 struct page *zc_page)
+			 unsigned char record_type)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_prot_info *prot = &tls_ctx->prot_info;
@@ -501,19 +495,12 @@ static int tls_push_data(struct sock *sk,
 		record = ctx->open_record;
 
 		copy = min_t(size_t, size, max_open_record_len - record->len);
-		if (copy && zc_page) {
-			struct page_frag zc_pfrag;
-
-			zc_pfrag.page = zc_page;
-			zc_pfrag.offset = iter_offset.offset;
-			zc_pfrag.size = copy;
-			tls_append_frag(record, &zc_pfrag, copy);
-		} else if (copy && (flags & MSG_SPLICE_PAGES)) {
+		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,
+			rc = iov_iter_extract_pages(iter, &pages,
 						    copy, 1, 0, &off);
 			if (rc <= 0) {
 				if (rc == 0)
@@ -523,7 +510,7 @@ static int tls_push_data(struct sock *sk,
 			copy = rc;
 
 			if (!sendpage_ok(zc_pfrag.page)) {
-				iov_iter_revert(iter_offset.msg_iter, copy);
+				iov_iter_revert(iter, copy);
 				goto no_zcopy_this_page;
 			}
 
@@ -536,7 +523,7 @@ static int tls_push_data(struct sock *sk,
 
 			rc = tls_device_copy_data(page_address(pfrag->page) +
 						  pfrag->offset, copy,
-						  iter_offset.msg_iter);
+						  iter);
 			if (rc)
 				goto handle_error;
 			tls_append_frag(record, pfrag, copy);
@@ -591,7 +578,6 @@ int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 {
 	unsigned char record_type = TLS_RECORD_TYPE_DATA;
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
-	union tls_iter_offset iter;
 	int rc;
 
 	if (!tls_ctx->zerocopy_sendfile)
@@ -606,8 +592,7 @@ int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 			goto out;
 	}
 
-	iter.msg_iter = &msg->msg_iter;
-	rc = tls_push_data(sk, iter, size, msg->msg_flags, record_type, NULL);
+	rc = tls_push_data(sk, &msg->msg_iter, size, msg->msg_flags, record_type);
 
 out:
 	release_sock(sk);
@@ -618,44 +603,18 @@ int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 int tls_device_sendpage(struct sock *sk, struct page *page,
 			int offset, size_t size, int flags)
 {
-	struct tls_context *tls_ctx = tls_get_ctx(sk);
-	union tls_iter_offset iter_offset;
-	struct iov_iter msg_iter;
-	char *kaddr;
-	struct kvec iov;
-	int rc;
+	struct bio_vec bvec;
+	struct msghdr msg = { .msg_flags = flags | MSG_SPLICE_PAGES, };
 
 	if (flags & MSG_SENDPAGE_NOTLAST)
-		flags |= MSG_MORE;
-
-	mutex_lock(&tls_ctx->tx_lock);
-	lock_sock(sk);
+		msg.msg_flags |= MSG_MORE;
 
-	if (flags & MSG_OOB) {
-		rc = -EOPNOTSUPP;
-		goto out;
-	}
-
-	if (tls_ctx->zerocopy_sendfile) {
-		iter_offset.offset = offset;
-		rc = tls_push_data(sk, iter_offset, size,
-				   flags, TLS_RECORD_TYPE_DATA, page);
-		goto out;
-	}
-
-	kaddr = kmap(page);
-	iov.iov_base = kaddr + offset;
-	iov.iov_len = size;
-	iov_iter_kvec(&msg_iter, ITER_SOURCE, &iov, 1, size);
-	iter_offset.msg_iter = &msg_iter;
-	rc = tls_push_data(sk, iter_offset, size, flags, TLS_RECORD_TYPE_DATA,
-			   NULL);
-	kunmap(page);
+	if (flags & MSG_OOB)
+		return -EOPNOTSUPP;
 
-out:
-	release_sock(sk);
-	mutex_unlock(&tls_ctx->tx_lock);
-	return rc;
+	bvec_set_page(&bvec, page, offset, size);
+	iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
+	return tls_device_sendmsg(sk, &msg, size);
 }
 
 struct tls_record_info *tls_get_record(struct tls_offload_context_tx *context,
@@ -720,12 +679,10 @@ EXPORT_SYMBOL(tls_get_record);
 
 static int tls_device_push_pending_record(struct sock *sk, int flags)
 {
-	union tls_iter_offset iter;
-	struct iov_iter msg_iter;
+	struct iov_iter iter;
 
-	iov_iter_kvec(&msg_iter, ITER_SOURCE, NULL, 0, 0);
-	iter.msg_iter = &msg_iter;
-	return tls_push_data(sk, iter, 0, flags, TLS_RECORD_TYPE_DATA, NULL);
+	iov_iter_kvec(&iter, ITER_SOURCE, NULL, 0, 0);
+	return tls_push_data(sk, &iter, 0, flags, TLS_RECORD_TYPE_DATA);
 }
 
 void tls_device_write_space(struct sock *sk, struct tls_context *ctx)