xas_create

/**
 * xas_create_range() - Ensure that stores to this range will succeed
 * @xas: XArray operation state.
 *
 * Creates all of the slots in the range covered by @xas.  Sets @xas to
 * create single-index entries and positions it at the beginning of the
 * range.  This is for the benefit of users which have not yet been
 * converted to use multi-index entries.
 */
void xas_create_range(struct xa_state *xas)
{
    unsigned long index = xas->xa_index;
    unsigned char shift = xas->xa_shift;
    unsigned char sibs = xas->xa_sibs;
 
    xas->xa_index |= ((sibs + 1) << shift) - 1;
    if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
        xas->xa_offset |= sibs;
    xas->xa_shift = 0;
    xas->xa_sibs = 0;
 
    for (;;) {
        xas_create(xas, true);
        if (xas_error(xas))
            goto restore;
        if (xas->xa_index <= (index | XA_CHUNK_MASK))
            goto success;
        xas->xa_index -= XA_CHUNK_SIZE;
 
        for (;;) {
            struct xa_node *node = xas->xa_node;
            xas->xa_node = xa_parent_locked(xas->xa, node);
            xas->xa_offset = node->offset - 1;
            if (node->offset != 0)
                break;
        }
    }
 
restore:
    xas->xa_shift = shift;
    xas->xa_sibs = sibs;
    xas->xa_index = index;
    return;
success:
    xas->xa_index = index;
    if (xas->xa_node)
        xas_set_offset(xas);
}
函数源码
