#include <linux/mm.h>
#include <linux/page-isolation.h>
#include <linux/pageblock-flags.h>
#include "internal.h"

static inline struct page *
__first_valid_page(unsigned long pfn, unsigned long nr_pages)
{
	int i;
	for (i = 0; i < nr_pages; i++)
		if (pfn_valid_within(pfn + i))
			break;
	if (unlikely(i == nr_pages))
		return NULL;
	return pfn_to_page(pfn + i);
}

int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
			     unsigned migratetype)
{
	unsigned long pfn;
	unsigned long undo_pfn;
	struct page *page;

	BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
	BUG_ON((end_pfn) & (pageblock_nr_pages - 1));

	for (pfn = start_pfn;
	     pfn < end_pfn;
	     pfn += pageblock_nr_pages) {
		page = __first_valid_page(pfn, pageblock_nr_pages);
		if (page && set_migratetype_isolate(page)) {
			undo_pfn = pfn;
			goto undo;
		}
	}
	return 0;
undo:
	for (pfn = start_pfn;
	     pfn < undo_pfn;
	     pfn += pageblock_nr_pages)
		unset_migratetype_isolate(pfn_to_page(pfn), migratetype);

	return -EBUSY;
}

int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
			    unsigned migratetype)
{
	unsigned long pfn;
	struct page *page;
	BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
	BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
	for (pfn = start_pfn;
	     pfn < end_pfn;
	     pfn += pageblock_nr_pages) {
		page = __first_valid_page(pfn, pageblock_nr_pages);
		if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
			continue;
		unset_migratetype_isolate(page, migratetype);
	}
	return 0;
}
static int
__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
{
	struct page *page;

	while (pfn < end_pfn) {
		if (!pfn_valid_within(pfn)) {
			pfn++;
			continue;
		}
		page = pfn_to_page(pfn);
		if (PageBuddy(page))
			pfn += 1 << page_order(page);
		else if (page_count(page) == 0 &&
				page_private(page) == MIGRATE_ISOLATE)
			pfn += 1;
		else
			break;
	}
	if (pfn < end_pfn)
		return 0;
	return 1;
}

int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
{
	unsigned long pfn, flags;
	struct page *page;
	struct zone *zone;
	int ret;

	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
		page = __first_valid_page(pfn, pageblock_nr_pages);
		if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
			break;
	}
	page = __first_valid_page(start_pfn, end_pfn - start_pfn);
	if ((pfn < end_pfn) || !page)
		return -EBUSY;
	
	zone = page_zone(page);
	spin_lock_irqsave(&zone->lock, flags);
	ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn);
	spin_unlock_irqrestore(&zone->lock, flags);
	return ret ? 0 : -EBUSY;
}