nfsd: Ensure exclusion between CLONE and WRITE errors

	struct file *src = nf_src->nf_file;

	struct file *dst = nf_dst->nf_file;

	loff_t cloned;

	__be32 ret = 0;

	down_write(&nf_dst->nf_rwsem);

	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);

	if (cloned < 0)

		return nfserrno(cloned);

	if (count && cloned != count)

		return nfserrno(-EINVAL);

	if (cloned < 0) {

		ret = nfserrno(cloned);

		goto out_err;

	}

	if (count && cloned != count) {

		ret = nfserrno(-EINVAL);

		goto out_err;

	}

	if (sync) {

		loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;

		int status = vfs_fsync_range(dst, dst_pos, dst_end, 0);

		if (!status)

			status = commit_inode_metadata(file_inode(src));

		if (status < 0)

			return nfserrno(status);

		if (status < 0) {

			nfsd_reset_boot_verifier(net_generic(nf_dst->nf_net,

						 nfsd_net_id));

			ret = nfserrno(status);

		}

	return 0;

	}

out_err:

	up_write(&nf_dst->nf_rwsem);

	return ret;

}

ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,