pipe: switch to ->read_iter()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/pipe.c

@@ -271,24 +271,18 @@ static const struct pipe_buf_operations packet_pipe_buf_ops = {
 };
 
 static ssize_t
-pipe_read(struct kiocb *iocb, const struct iovec *_iov,
-	   unsigned long nr_segs, loff_t pos)
+pipe_read(struct kiocb *iocb, struct iov_iter *to)
 {
+	size_t total_len = iov_iter_count(to);
 	struct file *filp = iocb->ki_filp;
 	struct pipe_inode_info *pipe = filp->private_data;
 	int do_wakeup;
 	ssize_t ret;
-	struct iovec *iov = (struct iovec *)_iov;
-	size_t total_len;
-	struct iov_iter iter;
 
-	total_len = iov_length(iov, nr_segs);
 	/* Null read succeeds. */
 	if (unlikely(total_len == 0))
 		return 0;
 
-	iov_iter_init(&iter, READ, iov, nr_segs, total_len);
-
 	do_wakeup = 0;
 	ret = 0;
 	__pipe_lock(pipe);
@@ -312,7 +306,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
 				break;
 			}
 
-			written = copy_page_to_iter(buf->page, buf->offset, chars, &iter);
+			written = copy_page_to_iter(buf->page, buf->offset, chars, to);
 			if (unlikely(written < chars)) {
 				if (!ret)
 					ret = -EFAULT;
@@ -1044,8 +1038,8 @@ static int fifo_open(struct inode *inode, struct file *filp)
 const struct file_operations pipefifo_fops = {
 	.open		= fifo_open,
 	.llseek		= no_llseek,
-	.read		= do_sync_read,
-	.aio_read	= pipe_read,
+	.read		= new_sync_read,
+	.read_iter	= pipe_read,
 	.write		= do_sync_write,
 	.aio_write	= pipe_write,
 	.poll		= pipe_poll,