Function swp_pager_meta_transfer

freebsd/vm/swap_pager.c:2111–2155

* SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap * metadata, or transfer it into dstobject. * * This routine will free swap metadata structures as they are cleaned * out. */

 *	out.
 */
static void
swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject,
    vm_pindex_t pindex, vm_pindex_t count)
{
	struct swblk *sb;
	daddr_t n_free, s_free;
	vm_pindex_t offset, last;
	int i, limit, start;

	VM_OBJECT_ASSERT_WLOCKED(srcobject);
	if (srcobject->type != OBJT_SWAP || count == 0)
		return;

	swp_pager_init_freerange(&s_free, &n_free);
	offset = pindex;
	last = pindex + count;
	for (;;) {
		sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks,
		    rounddown(pindex, SWAP_META_PAGES));
		if (sb == NULL || sb->p >= last)
			break;
		start = pindex > sb->p ? pindex - sb->p : 0;
		limit = last - sb->p < SWAP_META_PAGES ? last - sb->p :
		    SWAP_META_PAGES;
		for (i = start; i < limit; i++) {
			if (sb->d[i] == SWAPBLK_NONE)
				continue;
			if (dstobject == NULL ||
			    !swp_pager_xfer_source(srcobject, dstobject, 
			    sb->p + i - offset, sb->d[i])) {
				swp_pager_update_freerange(&s_free, &n_free,
				    sb->d[i]);
			}
			sb->d[i] = SWAPBLK_NONE;
		}
		pindex = sb->p + SWAP_META_PAGES;
		if (swp_pager_swblk_empty(sb, 0, start) &&
		    swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) {
			SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks,
			    sb->p);
			uma_zfree(swblk_zone, sb);
		}
	}
	swp_pager_freeswapspace(s_free, n_free);
}

/*
 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata