[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>

1 files changed, 32 insertions, 30 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 591301ae8b7d..979096c27773 100644
--- 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 */