1 files changed, 111 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e69f19e841e5..332f46d70d2d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2931,6 +2931,41 @@ static void __meminit calculate_node_totalpages(struct pglist_data *pgdat,
                                                         realtotalpages);
 }
 
+#ifndef CONFIG_SPARSEMEM
+/*
+ * Calculate the size of the zone->blockflags rounded to an unsigned long
+ * Start by making sure zonesize is a multiple of MAX_ORDER-1 by rounding up
+ * Then figure 1 NR_PAGEBLOCK_BITS worth of bits per MAX_ORDER-1, finally
+ * round what is now in bits to nearest long in bits, then return it in
+ * bytes.
+ */
+static unsigned long __init usemap_size(unsigned long zonesize)
+{
+        unsigned long usemapsize;
+
+        usemapsize = roundup(zonesize, MAX_ORDER_NR_PAGES);
+        usemapsize = usemapsize >> (MAX_ORDER-1);
+        usemapsize *= NR_PAGEBLOCK_BITS;
+        usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long));
+
+        return usemapsize / 8;
+}
+
+static void __init setup_usemap(struct pglist_data *pgdat,
+                                struct zone *zone, unsigned long zonesize)
+{
+        unsigned long usemapsize = usemap_size(zonesize);
+        zone->pageblock_flags = NULL;
+        if (usemapsize) {
+                zone->pageblock_flags = alloc_bootmem_node(pgdat, usemapsize);
+                memset(zone->pageblock_flags, 0, usemapsize);
+        }
+}
+#else
+static void inline setup_usemap(struct pglist_data *pgdat,
+                                struct zone *zone, unsigned long zonesize) {}
+#endif /* CONFIG_SPARSEMEM */
+
 /*
  * Set up the zone data structures:
  *   - mark all pages reserved
@@ -3011,6 +3046,7 @@ static void __meminit free_area_init_core(struct pglist_data *pgdat,
                 if (!size)
                         continue;
 
+                setup_usemap(pgdat, zone, size);
                 ret = init_currently_empty_zone(zone, zone_start_pfn,
                                                 size, MEMMAP_EARLY);
                 BUG_ON(ret);
@@ -3991,4 +4027,79 @@ EXPORT_SYMBOL(pfn_to_page);
 EXPORT_SYMBOL(page_to_pfn);
 #endif /* CONFIG_OUT_OF_LINE_PFN_TO_PAGE */
 
+/* Return a pointer to the bitmap storing bits affecting a block of pages */
+static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
+                                                        unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+        return __pfn_to_section(pfn)->pageblock_flags;
+#else
+        return zone->pageblock_flags;
+#endif /* CONFIG_SPARSEMEM */
+}
+
+static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+        pfn &= (PAGES_PER_SECTION-1);
+        return (pfn >> (MAX_ORDER-1)) * NR_PAGEBLOCK_BITS;
+#else
+        pfn = pfn - zone->zone_start_pfn;
+        return (pfn >> (MAX_ORDER-1)) * NR_PAGEBLOCK_BITS;
+#endif /* CONFIG_SPARSEMEM */
+}
+
+/**
+ * get_pageblock_flags_group - Return the requested group of flags for the MAX_ORDER_NR_PAGES block of pages
+ * @page: The page within the block of interest
+ * @start_bitidx: The first bit of interest to retrieve
+ * @end_bitidx: The last bit of interest
+ * returns pageblock_bits flags
+ */
+unsigned long get_pageblock_flags_group(struct page *page,
+                                        int start_bitidx, int end_bitidx)
+{
+        struct zone *zone;
+        unsigned long *bitmap;
+        unsigned long pfn, bitidx;
+        unsigned long flags = 0;
+        unsigned long value = 1;
+
+        zone = page_zone(page);
+        pfn = page_to_pfn(page);
+        bitmap = get_pageblock_bitmap(zone, pfn);
+        bitidx = pfn_to_bitidx(zone, pfn);
+
+        for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
+                if (test_bit(bitidx + start_bitidx, bitmap))
+                        flags |= value;
 
+        return flags;
+}
+
+/**
+ * set_pageblock_flags_group - Set the requested group of flags for a MAX_ORDER_NR_PAGES block of pages
+ * @page: The page within the block of interest
+ * @start_bitidx: The first bit of interest
+ * @end_bitidx: The last bit of interest
+ * @flags: The flags to set
+ */
+void set_pageblock_flags_group(struct page *page, unsigned long flags,
+                                        int start_bitidx, int end_bitidx)
+{
+        struct zone *zone;
+        unsigned long *bitmap;
+        unsigned long pfn, bitidx;
+        unsigned long value = 1;
+
+        zone = page_zone(page);
+        pfn = page_to_pfn(page);
+        bitmap = get_pageblock_bitmap(zone, pfn);
+        bitidx = pfn_to_bitidx(zone, pfn);
+
+        for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
+                if (flags & value)
+                        __set_bit(bitidx + start_bitidx, bitmap);
+                else
+                        __clear_bit(bitidx + start_bitidx, bitmap);
+}