bootmem: revisit bitmap size calculations

Reincarnate get_mapsize as bootmap_bytes and implement
bootmem_bootmap_pages on top of it.

Adjust users of these helpers and make free_all_bootmem_core use
bootmem_bootmap_pages instead of open-coding it.

Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/bootmem.c b/mm/bootmem.c
index 4e085ee..484849b 100644 (file)
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -50,17 +50,11 @@ early_param("bootmem_debug", bootmem_debug_setup);
                        __FUNCTION__, ## args);         \
 })
 
-/*
- * Given an initialised bdata, it returns the size of the boot bitmap
- */
-static unsigned long __init get_mapsize(bootmem_data_t *bdata)
+static unsigned long __init bootmap_bytes(unsigned long pages)
 {
-       unsigned long mapsize;
-       unsigned long start = PFN_DOWN(bdata->node_boot_start);
-       unsigned long end = bdata->node_low_pfn;
+       unsigned long bytes = (pages + 7) / 8;
 
-       mapsize = ((end - start) + 7) / 8;
-       return ALIGN(mapsize, sizeof(long));
+       return ALIGN(bytes, sizeof(long));
 }
 
 /**
@@ -69,13 +63,9 @@ static unsigned long __init get_mapsize(bootmem_data_t *bdata)
  */
 unsigned long __init bootmem_bootmap_pages(unsigned long pages)
 {
-       unsigned long mapsize;
-
-       mapsize = (pages+7)/8;
-       mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
-       mapsize >>= PAGE_SHIFT;
+       unsigned long bytes = bootmap_bytes(pages);
 
-       return mapsize;
+       return PAGE_ALIGN(bytes) >> PAGE_SHIFT;
 }
 
 /*
@@ -117,7 +107,7 @@ static unsigned long __init init_bootmem_core(bootmem_data_t *bdata,
         * Initially all pages are reserved - setup_arch() has to
         * register free RAM areas explicitly.
         */
-       mapsize = get_mapsize(bdata);
+       mapsize = bootmap_bytes(end - start);
        memset(bdata->node_bootmem_map, 0xff, mapsize);
 
        bdebug("nid=%td start=%lx map=%lx end=%lx mapsize=%lx\n",
@@ -160,7 +150,7 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
        struct page *page;
        unsigned long pfn;
        unsigned long i, count;
-       unsigned long idx;
+       unsigned long idx, pages;
        unsigned long *map;
        int gofast = 0;
 
@@ -211,7 +201,8 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
         * needed anymore:
         */
        page = virt_to_page(bdata->node_bootmem_map);
-       idx = (get_mapsize(bdata) + PAGE_SIZE-1) >> PAGE_SHIFT;
+       pages = bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start);
+       idx = bootmem_bootmap_pages(pages);
        for (i = 0; i < idx; i++, page++)
                __free_pages_bootmem(page, 0);
        count += i;