compat_iovec
struct compat_iovec sgl[MAX_IOCTL_SGE];
if (count * sizeof(struct compat_iovec) == transferred) {
struct compat_iovec *ciov = src;
struct compat_iovec __user *uiov;
struct compat_iovec tmp_iov;
user_data += sizeof(struct compat_iovec);
arg += sizeof(struct compat_iovec);
struct compat_iovec __user *uiov = u64_to_user_ptr(rw->addr);
struct compat_iovec iov;
struct compat_iovec __user *uiov =
(struct compat_iovec __user *) datap;
const struct compat_iovec __user *uiov =
(const struct compat_iovec __user *)uvec;