net: Make sock_splice_read() use copy_splice_read() by default

Make sock_splice_read() use copy_splice_read() by default as
file_splice_read() will return immediately with 0 as a socket has no
pagecache and is a zero-size file.

Signed-off-by: David Howells <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Christoph Hellwig <[email protected]>
cc: Al Viro <[email protected]>
cc: Jens Axboe <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: dhowells

net/socket.c

@@ -1093,7 +1093,7 @@ 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 generic_file_splice_read(file, ppos, pipe, len, flags);
+		return copy_splice_read(file, ppos, pipe, len, flags);
 
 	return sock->ops->splice_read(sock, ppos, pipe, len, flags);
 }