fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
	DECLARE_COMPLETION_ONSTACK(wait);
	ssize_t ret = 0;
	struct file *file = iocb->ki_filp;
	struct fuse_file *ff = file->private_data;
	loff_t pos = 0;
	struct inode *inode;
	loff_t i_size;
	size_t count = iov_iter_count(iter), shortened = 0;
	loff_t offset = iocb->ki_pos;
	struct fuse_io_priv *io;

	pos = offset;
	inode = file->f_mapping->host;
	i_size = i_size_read(inode);

	if ((iov_iter_rw(iter) == READ) && (offset >= i_size))
		return 0;

	io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
	if (!io)
		return -ENOMEM;
	spin_lock_init(&io->lock);
	kref_init(&io->refcnt);
	io->reqs = 1;
	io->bytes = -1;
	io->size = 0;
	io->offset = offset;
	io->write = (iov_iter_rw(iter) == WRITE);
	io->err = 0;
	/*
	 * By default, we want to optimize all I/Os with async request
	 * submission to the client filesystem if supported.
	 */
	io->async = ff->fm->fc->async_dio;
	io->iocb = iocb;
	io->blocking = is_sync_kiocb(iocb);

	/* optimization for short read */
	if (io->async && !io->write && offset + count > i_size) {
		iov_iter_truncate(iter, fuse_round_up(ff->fm->fc, i_size - offset));
		shortened = count - iov_iter_count(iter);
		count -= shortened;
	}

	/*
	 * We cannot asynchronously extend the size of a file.
	 * In such case the aio will behave exactly like sync io.
	 */
	if ((offset + count > i_size) && io->write)
		io->blocking = true;

	if (io->async && io->blocking) {
		/*
		 * Additional reference to keep io around after
		 * calling fuse_aio_complete()
		 */
		kref_get(&io->refcnt);
		io->done = &wait;
	}

	if (iov_iter_rw(iter) == WRITE) {
		ret = fuse_direct_io(io, iter, &pos, FUSE_DIO_WRITE);
		fuse_invalidate_attr(inode);
	} else {
		ret = __fuse_direct_read(io, iter, &pos);
	}
	iov_iter_reexpand(iter, iov_iter_count(iter) + shortened);

	if (io->async) {
		bool blocking = io->blocking;

		fuse_aio_complete(io, ret < 0 ? ret : 0, -1);

		/* we have a non-extending, async request, so return */
		if (!blocking)
			return -EIOCBQUEUED;

		wait_for_completion(&wait);
		ret = fuse_get_res_by_io(io);
	}

	kref_put(&io->refcnt, fuse_io_release);

	if (iov_iter_rw(iter) == WRITE) {
		if (ret > 0)
			fuse_write_update_size(inode, pos);
		else if (ret < 0 && offset + count > i_size)
			fuse_do_truncate(file);
	}

	return ret;
}
fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
	DECLARE_COMPLETION_ONSTACK(wait);
	ssize_t ret = 0;
	struct file *file = iocb->ki_filp;
	struct fuse_file *ff = file->private_data;
	loff_t pos = 0;
	struct inode *inode;
	loff_t i_size;
	size_t count = iov_iter_count(iter), shortened = 0;
	loff_t offset = iocb->ki_pos;
	struct fuse_io_priv *io;

	pos = offset;
	inode = file->f_mapping->host;
	i_size = i_size_read(inode);

	if ((iov_iter_rw(iter) == READ) && (offset >= i_size))
		return 0;

	io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
	if (!io)
		return -ENOMEM;
	spin_lock_init(&io->lock);
	kref_init(&io->refcnt);
	io->reqs = 1;
	io->bytes = -1;
	io->size = 0;
	io->offset = offset;
	io->write = (iov_iter_rw(iter) == WRITE);
	io->err = 0;
	 
	io->async = ff->fm->fc->async_dio;
	io->iocb = iocb;
	io->blocking = is_sync_kiocb(iocb);

	 
	if (io->async && !io->write && offset + count > i_size) {
		iov_iter_truncate(iter, fuse_round_up(ff->fm->fc, i_size - offset));
		shortened = count - iov_iter_count(iter);
		count -= shortened;
	}

	 
	if ((offset + count > i_size) && io->write)
		io->blocking = true;

	if (io->async && io->blocking) {
		 
		kref_get(&io->refcnt);
		io->done = &wait;
	}

	if (iov_iter_rw(iter) == WRITE) {
		ret = fuse_direct_io(io, iter, &pos, FUSE_DIO_WRITE);
		fuse_invalidate_attr(inode);
	} else {
		ret = __fuse_direct_read(io, iter, &pos);
	}
	iov_iter_reexpand(iter, iov_iter_count(iter) + shortened);

	if (io->async) {
		bool blocking = io->blocking;

		fuse_aio_complete(io, ret < 0 ? ret : 0, -1);

		 
		if (!blocking)
			return -EIOCBQUEUED;

		wait_for_completion(&wait);
		ret = fuse_get_res_by_io(io);
	}

	kref_put(&io->refcnt, fuse_io_release);

	if (iov_iter_rw(iter) == WRITE) {
		if (ret > 0)
			fuse_write_update_size(inode, pos);
		else if (ret < 0 && offset + count > i_size)
			fuse_do_truncate(file);
	}

	return ret;
}