[RFC PATCH v2 25/48] crypto: af_alg: Convert af_alg_sendpage() to use MSG_SPLICE_PAGES

David Howells
2023-03-29T14:19:28Z

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.

[!] Note that this makes use of netfs_extract_iter_to_sg() from netfslib.
This probably needs moving to core code somewhere.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
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: linux-crypto@vger.kernel.org
cc: netdev@vger.kernel.org
---
crypto/af_alg.c | 53 +++++++++----------------------------------------
1 file changed, 9 insertions(+), 44 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 3088ab298632..7fe8c8db6bb5 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -1118,53 +1118,18 @@ 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;
-
- 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);
+ struct bio_vec bvec;
+ struct msghdr msg = {
+ .msg_flags = flags | MSG_SPLICE_PAGES,
+ };

- sg_mark_end(sgl->sg + sgl->cur);
+ bvec_set_page(&bvec, page, size, offset);
+ iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);

- 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);
+ if (flags & MSG_SENDPAGE_NOTLAST)
+ msg.msg_flags |= MSG_MORE;

- return err ?: size;
+ return sock_sendmsg(sock, &msg);
}
EXPORT_SYMBOL_GPL(af_alg_sendpage);