On Tue, 2023-05-30 at 15:16 +0100, David Howells wrote:
> Make AF_ALG sendmsg() support MSG_SPLICE_PAGES. This causes pages to be
> spliced from the source iterator.
>
> 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: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> cc: Jens Axboe <axboe@xxxxxxxxx>
> cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> cc: linux-crypto@xxxxxxxxxxxxxxx
> cc: netdev@xxxxxxxxxxxxxxx
> ---
> crypto/af_alg.c | 28 ++++++++++++++++++++++++++--
> crypto/algif_aead.c | 22 +++++++++++-----------
> crypto/algif_skcipher.c | 8 ++++----
> 3 files changed, 41 insertions(+), 17 deletions(-)
>
> diff --git a/crypto/af_alg.c b/crypto/af_alg.c
> index fd56ccff6fed..62f4205d42e3 100644
> --- a/crypto/af_alg.c
> +++ b/crypto/af_alg.c
> @@ -940,6 +940,10 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
> bool init = false;
> int err = 0;
>
> + if ((msg->msg_flags & MSG_SPLICE_PAGES) &&
> + !iov_iter_is_bvec(&msg->msg_iter))
> + return -EINVAL;
> +
> if (msg->msg_controllen) {
> err = af_alg_cmsg_send(msg, &con);
> if (err)
> @@ -985,7 +989,7 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
> while (size) {
> struct scatterlist *sg;
> size_t len = size;
> - size_t plen;
> + ssize_t plen;
>
> /* use the existing memory in an allocated page */
> if (ctx->merge) {
> @@ -1030,7 +1034,27 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
> if (sgl->cur)
> sg_unmark_end(sg + sgl->cur - 1);
>
> - if (1 /* TODO check MSG_SPLICE_PAGES */) {
> + if (msg->msg_flags & MSG_SPLICE_PAGES) {
> + struct sg_table sgtable = {
> + .sgl = sg,
> + .nents = sgl->cur,
> + .orig_nents = sgl->cur,
> + };
> +
> + plen = extract_iter_to_sg(&msg->msg_iter, len, &sgtable,
> + MAX_SGL_ENTS, 0);
It looks like the above expect/supports only ITER_BVEC iterators, what
about adding a WARN_ON_ONCE(<other iov type>)?
Also, I'm keeping this series a bit more in pw to allow Herbert or
others to have a look.
Cheers,
Paolo
