socket: do a generic_file_splice_read when proto_ops has no splice_read

From: Slavomir Kaslev <[email protected]>

splice(2) fails with -EINVAL when called reading on a socket with no splice_read set in its proto_ops (such as vsock sockets). Switch this to fallbacks to a generic_file_splice_read instead.

---
 net/socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 593826e11a53..334fcc617ef2 100644
@@ -853,7 +853,7 @@ static ssize_t sock_splice_read(struct file *file, loff_t *ppos,
 	struct socket *sock = file->private_data;
 
 	if (unlikely(!sock->ops->splice_read))
-		return -EINVAL;
+		return generic_file_splice_read(file, ppos, pipe, len, flags);
 
 	return sock->ops->splice_read(sock, ppos, pipe, len, flags);
 }

2.19.1

From: [email protected]
Date: Fri, 16 Nov 2018 11:27:53 +0200

Applied.

I wonder why we left things this way for so long.