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unix: Convert unix_stream_sendpage() to use MSG_SPLICE_PAGES

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Convert unix_stream_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@redhat.com>
cc: Kuniyuki Iwashima <kuniyu@amazon.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Howells 2023-05-22 13:11:25 +01:00 committed by Jakub Kicinski
parent a0dbf5f818
commit 57d44a354a
1 changed files with 7 additions and 127 deletions
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134
net/unix/af_unix.c
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@ -1839,24 +1839,6 @@ static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
}
}
static int maybe_init_creds(struct scm_cookie *scm,
struct socket *socket,
const struct sock *other)
{
int err;
struct msghdr msg = { .msg_controllen = 0 };
err = scm_send(socket, &msg, scm, false);
if (err)
return err;
if (unix_passcred_enabled(socket, other)) {
scm->pid = get_pid(task_tgid(current));
current_uid_gid(&scm->creds.uid, &scm->creds.gid);
}
return err;
}
static bool unix_skb_scm_eq(struct sk_buff *skb,
struct scm_cookie *scm)
{
@ -2292,117 +2274,15 @@ out_err:
static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page,
int offset, size_t size, int flags)
{
int err;
bool send_sigpipe = false;
bool init_scm = true;
struct scm_cookie scm;
struct sock *other, *sk = socket->sk;
struct sk_buff *skb, *newskb = NULL, *tail = NULL;
struct bio_vec bvec;
struct msghdr msg = { .msg_flags = flags | MSG_SPLICE_PAGES };
if (flags & MSG_OOB)
return -EOPNOTSUPP;
if (flags & MSG_SENDPAGE_NOTLAST)
msg.msg_flags |= MSG_MORE;
other = unix_peer(sk);
if (!other || sk->sk_state != TCP_ESTABLISHED)
return -ENOTCONN;
if (false) {
alloc_skb:
unix_state_unlock(other);
mutex_unlock(&unix_sk(other)->iolock);
newskb = sock_alloc_send_pskb(sk, 0, 0, flags & MSG_DONTWAIT,
&err, 0);
if (!newskb)
goto err;
}
/* we must acquire iolock as we modify already present
* skbs in the sk_receive_queue and mess with skb->len
*/
err = mutex_lock_interruptible(&unix_sk(other)->iolock);
if (err) {
err = flags & MSG_DONTWAIT ? -EAGAIN : -ERESTARTSYS;
goto err;
}
if (sk->sk_shutdown & SEND_SHUTDOWN) {
err = -EPIPE;
send_sigpipe = true;
goto err_unlock;
}
unix_state_lock(other);
if (sock_flag(other, SOCK_DEAD) ||
other->sk_shutdown & RCV_SHUTDOWN) {
err = -EPIPE;
send_sigpipe = true;
goto err_state_unlock;
}
if (init_scm) {
err = maybe_init_creds(&scm, socket, other);
if (err)
goto err_state_unlock;
init_scm = false;
}
skb = skb_peek_tail(&other->sk_receive_queue);
if (tail && tail == skb) {
skb = newskb;
} else if (!skb || !unix_skb_scm_eq(skb, &scm)) {
if (newskb) {
skb = newskb;
} else {
tail = skb;
goto alloc_skb;
}
} else if (newskb) {
/* this is fast path, we don't necessarily need to
* call to kfree_skb even though with newskb == NULL
* this - does no harm
*/
consume_skb(newskb);
newskb = NULL;
}
if (skb_append_pagefrags(skb, page, offset, size, MAX_SKB_FRAGS)) {
tail = skb;
goto alloc_skb;
}
skb->len += size;
skb->data_len += size;
skb->truesize += size;
refcount_add(size, &sk->sk_wmem_alloc);
if (newskb) {
err = unix_scm_to_skb(&scm, skb, false);
if (err)
goto err_state_unlock;
spin_lock(&other->sk_receive_queue.lock);
__skb_queue_tail(&other->sk_receive_queue, newskb);
spin_unlock(&other->sk_receive_queue.lock);
}
unix_state_unlock(other);
mutex_unlock(&unix_sk(other)->iolock);
other->sk_data_ready(other);
scm_destroy(&scm);
return size;
err_state_unlock:
unix_state_unlock(other);
err_unlock:
mutex_unlock(&unix_sk(other)->iolock);
err:
kfree_skb(newskb);
if (send_sigpipe && !(flags & MSG_NOSIGNAL))
send_sig(SIGPIPE, current, 0);
if (!init_scm)
scm_destroy(&scm);
return err;
bvec_set_page(&bvec, page, size, offset);
iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
return unix_stream_sendmsg(socket, &msg, size);
}
static int unix_seqpacket_sendmsg(struct socket *sock, struct msghdr *msg,