netdev - [PATCH net-next v3 09/10] crypto: af_alg: Convert af_alg_sendpage() to use MSG_SPLICE

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Date: Tue,  6 Jun 2023 14:08:55 +0100
From: David Howells <dhowells@...hat.com>
To: netdev@...r.kernel.org
Cc: David Howells <dhowells@...hat.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Willem de Bruijn <willemdebruijn.kernel@...il.com>,
	David Ahern <dsahern@...nel.org>,
	Matthew Wilcox <willy@...radead.org>,
	Jens Axboe <axboe@...nel.dk>,
	linux-crypto@...r.kernel.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net-next v3 09/10] crypto: af_alg: Convert af_alg_sendpage() to use MSG_SPLICE_PAGES

Convert af_alg_sendpage() to use sendmsg() with MSG_SPLICE_PAGES rather
than directly splicing in the pages itself.

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: Herbert Xu <herbert@...dor.apana.org.au>
cc: "David S. Miller" <davem@...emloft.net>
cc: Eric Dumazet <edumazet@...gle.com>
cc: Jakub Kicinski <kuba@...nel.org>
cc: Paolo Abeni <pabeni@...hat.com>
cc: Jens Axboe <axboe@...nel.dk>
cc: Matthew Wilcox <willy@...radead.org>
cc: linux-crypto@...r.kernel.org
cc: netdev@...r.kernel.org
---
 crypto/af_alg.c | 52 ++++++++-----------------------------------------
 1 file changed, 8 insertions(+), 44 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 9c12530d604a..3cf734835ccb 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -1114,53 +1114,17 @@ EXPORT_SYMBOL_GPL(af_alg_sendmsg);
 ssize_t af_alg_sendpage(struct socket *sock, struct page *page,
 			int offset, size_t size, int flags)
 {
-	struct sock *sk = sock->sk;
-	struct alg_sock *ask = alg_sk(sk);
-	struct af_alg_ctx *ctx = ask->private;
-	struct af_alg_tsgl *sgl;
-	int err = -EINVAL;
+	struct bio_vec bvec;
+	struct msghdr msg = {
+		.msg_flags = flags | MSG_SPLICE_PAGES,
+	};
 
 	if (flags & MSG_SENDPAGE_NOTLAST)
-		flags |= MSG_MORE;
-
-	lock_sock(sk);
-	if (!ctx->more && ctx->used)
-		goto unlock;
-
-	if (!size)
-		goto done;
-
-	if (!af_alg_writable(sk)) {
-		err = af_alg_wait_for_wmem(sk, flags);
-		if (err)
-			goto unlock;
-	}
-
-	err = af_alg_alloc_tsgl(sk);
-	if (err)
-		goto unlock;
-
-	ctx->merge = 0;
-	sgl = list_entry(ctx->tsgl_list.prev, struct af_alg_tsgl, list);
-
-	if (sgl->cur)
-		sg_unmark_end(sgl->sg + sgl->cur - 1);
-
-	sg_mark_end(sgl->sg + sgl->cur);
-
-	get_page(page);
-	sg_set_page(sgl->sg + sgl->cur, page, size, offset);
-	sgl->cur++;
-	ctx->used += size;
-
-done:
-	ctx->more = flags & MSG_MORE;
-
-unlock:
-	af_alg_data_wakeup(sk);
-	release_sock(sk);
+		msg.msg_flags |= MSG_MORE;
 
-	return err ?: size;
+	bvec_set_page(&bvec, page, size, offset);
+	iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
+	return sock_sendmsg(sock, &msg);
 }
 EXPORT_SYMBOL_GPL(af_alg_sendpage);