[PATCH] swsusp: clean up browsing of pfns

Clean up some loops over pfns for each zone in snapshot.c: reduce the
number of additions to perform, rework detection of saveable pages and make
the code a bit less difficult to understand, hopefully.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 591301a..979096c 100644 (file)
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -156,7 +156,7 @@ static inline int save_highmem(void) {return 0;}
 static inline int restore_highmem(void) {return 0;}
 #endif
 
-static int pfn_is_nosave(unsigned long pfn)
+static inline int pfn_is_nosave(unsigned long pfn)
 {
        unsigned long nosave_begin_pfn = __pa(&__nosave_begin) >> PAGE_SHIFT;
        unsigned long nosave_end_pfn = PAGE_ALIGN(__pa(&__nosave_end)) >> PAGE_SHIFT;
@@ -167,43 +167,43 @@ static int pfn_is_nosave(unsigned long pfn)
  *     saveable - Determine whether a page should be cloned or not.
  *     @pfn:   The page
  *
- *     We save a page if it's Reserved, and not in the range of pages
- *     statically defined as 'unsaveable', or if it isn't reserved, and
- *     isn't part of a free chunk of pages.
+ *     We save a page if it isn't Nosave, and is not in the range of pages
+ *     statically defined as 'unsaveable', and it
+ *     isn't a part of a free chunk of pages.
  */
 
-static int saveable(struct zone *zone, unsigned long *zone_pfn)
+static struct page *saveable_page(unsigned long pfn)
 {
-       unsigned long pfn = *zone_pfn + zone->zone_start_pfn;
        struct page *page;
 
        if (!pfn_valid(pfn))
-               return 0;
+               return NULL;
 
        page = pfn_to_page(pfn);
-       BUG_ON(PageReserved(page) && PageNosave(page));
+
        if (PageNosave(page))
-               return 0;
+               return NULL;
        if (PageReserved(page) && pfn_is_nosave(pfn))
-               return 0;
+               return NULL;
        if (PageNosaveFree(page))
-               return 0;
+               return NULL;
 
-       return 1;
+       return page;
 }
 
 unsigned int count_data_pages(void)
 {
        struct zone *zone;
-       unsigned long zone_pfn;
+       unsigned long pfn, max_zone_pfn;
        unsigned int n = 0;
 
        for_each_zone (zone) {
                if (is_highmem(zone))
                        continue;
                mark_free_pages(zone);
-               for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
-                       n += saveable(zone, &zone_pfn);
+               max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
+               for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
+                       n += !!saveable_page(pfn);
        }
        return n;
 }
@@ -211,7 +211,7 @@ unsigned int count_data_pages(void)
 static void copy_data_pages(struct pbe *pblist)
 {
        struct zone *zone;
-       unsigned long zone_pfn;
+       unsigned long pfn, max_zone_pfn;
        struct pbe *pbe, *p;
 
        pbe = pblist;
@@ -224,13 +224,14 @@ static void copy_data_pages(struct pbe *pblist)
                        SetPageNosaveFree(virt_to_page(p));
                for_each_pbe (p, pblist)
                        SetPageNosaveFree(virt_to_page(p->address));
-               for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
-                       if (saveable(zone, &zone_pfn)) {
-                               struct page *page;
+               max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
+               for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
+                       struct page *page = saveable_page(pfn);
+
+                       if (page) {
                                long *src, *dst;
                                int n;
 
-                               page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
                                BUG_ON(!pbe);
                                pbe->orig_address = (unsigned long)page_address(page);
                                /* copy_page and memcpy are not usable for copying task structs. */
@@ -383,13 +384,14 @@ static struct pbe *alloc_pagedir(unsigned int nr_pages, gfp_t gfp_mask,
 void swsusp_free(void)
 {
        struct zone *zone;
-       unsigned long zone_pfn;
+       unsigned long pfn, max_zone_pfn;
 
        for_each_zone(zone) {
-               for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
-                       if (pfn_valid(zone_pfn + zone->zone_start_pfn)) {
-                               struct page *page;
-                               page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
+               max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
+               for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
+                       if (pfn_valid(pfn)) {
+                               struct page *page = pfn_to_page(pfn);
+
                                if (PageNosave(page) && PageNosaveFree(page)) {
                                        ClearPageNosave(page);
                                        ClearPageNosaveFree(page);
@@ -598,7 +600,7 @@ int snapshot_read_next(struct snapshot_handle *handle, size_t count)
 static int mark_unsafe_pages(struct pbe *pblist)
 {
        struct zone *zone;
-       unsigned long zone_pfn;
+       unsigned long pfn, max_zone_pfn;
        struct pbe *p;
 
        if (!pblist) /* a sanity check */
@@ -606,10 +608,10 @@ static int mark_unsafe_pages(struct pbe *pblist)
 
        /* Clear page flags */
        for_each_zone (zone) {
-               for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
-                       if (pfn_valid(zone_pfn + zone->zone_start_pfn))
-                               ClearPageNosaveFree(pfn_to_page(zone_pfn +
-                                       zone->zone_start_pfn));
+               max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
+               for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
+                       if (pfn_valid(pfn))
+                               ClearPageNosaveFree(pfn_to_page(pfn));
        }
 
        /* Mark orig addresses */