[PATCH] swsusp: simplify pagedir relocation

This patch simplifies the relocation of the page backup list (aka pagedir)
during resume.

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

3 files changed, 28 insertions, 53 deletions

diff --git a/kernel/power/power.h b/kernel/power/power.h
index c98923e13e75..893ee655085c 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -66,6 +66,7 @@ extern asmlinkage int swsusp_arch_suspend(void);
 extern asmlinkage int swsusp_arch_resume(void);
 
 extern int restore_highmem(void);
+extern void free_pagedir(struct pbe *pblist);
 extern struct pbe *alloc_pagedir(unsigned nr_pages, gfp_t gfp_mask, int safe_needed);
 extern void create_pbe_list(struct pbe *pblist, unsigned nr_pages);
 extern void swsusp_free(void);
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 96cc3e21e97d..b8a2e9a63206 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -216,7 +216,7 @@ static void copy_data_pages(struct pbe *pblist)
  *      free_pagedir - free pages allocated with alloc_pagedir()
  */
 
-static void free_pagedir(struct pbe *pblist)
+void free_pagedir(struct pbe *pblist)
 {
         struct pbe *pbe;
 
diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
index a456ffe7a3c8..8511c7f3386a 100644
--- a/kernel/power/swsusp.c
+++ b/kernel/power/swsusp.c
@@ -629,74 +629,43 @@ int swsusp_resume(void)
 }
 
 /**
- *      swsusp_pagedir_relocate - It is possible, that some memory pages
- *      occupied by the list of PBEs collide with pages where we're going to
- *      restore from the loaded pages later.  We relocate them here.
+ *      mark_unsafe_pages - mark the pages that cannot be used for storing
+ *      the image during resume, because they conflict with the pages that
+ *      had been used before suspend
  */
 
-static struct pbe *swsusp_pagedir_relocate(struct pbe *pblist)
+static void mark_unsafe_pages(struct pbe *pblist)
 {
         struct zone *zone;
         unsigned long zone_pfn;
-        struct pbe *pbpage, *tail, *p;
-        void *m;
-        int rel = 0;
+        struct pbe *p;
 
         if (!pblist) /* a sanity check */
-                return NULL;
-
-        pr_debug("swsusp: Relocating pagedir (%lu pages to check)\n",
-                        swsusp_info.pagedir_pages);
+                return;
 
         /* 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 +
+                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));
         }
 
         /* Mark orig addresses */
-
         for_each_pbe (p, pblist)
                 SetPageNosaveFree(virt_to_page(p->orig_address));
 
-        tail = pblist + PB_PAGE_SKIP;
-
-        /* Relocate colliding pages */
-
-        for_each_pb_page (pbpage, pblist) {
-                if (PageNosaveFree(virt_to_page((unsigned long)pbpage))) {
-                        m = (void *)get_safe_page(GFP_ATOMIC | __GFP_COLD);
-                        if (!m)
-                                return NULL;
-                        memcpy(m, (void *)pbpage, PAGE_SIZE);
-                        if (pbpage == pblist)
-                                pblist = (struct pbe *)m;
-                        else
-                                tail->next = (struct pbe *)m;
-                        pbpage = (struct pbe *)m;
-
-                        /* We have to link the PBEs again */
-                        for (p = pbpage; p < pbpage + PB_PAGE_SKIP; p++)
-                                if (p->next) /* needed to save the end */
-                                        p->next = p + 1;
-
-                        rel++;
-                }
-                tail = pbpage + PB_PAGE_SKIP;
-        }
+}
 
-        /* This is for swsusp_free() */
-        for_each_pb_page (pbpage, pblist) {
-                SetPageNosave(virt_to_page(pbpage));
-                SetPageNosaveFree(virt_to_page(pbpage));
+static void copy_page_backup_list(struct pbe *dst, struct pbe *src)
+{
+        /* We assume both lists contain the same number of elements */
+        while (src) {
+                dst->orig_address = src->orig_address;
+                dst->swap_address = src->swap_address;
+                dst = dst->next;
+                src = src->next;
         }
-
-        printk("swsusp: Relocated %d pages\n", rel);
-
-        return pblist;
 }
 
 /*
@@ -942,10 +911,15 @@ static int read_suspend_image(void)
 
         if ((error = read_pagedir(p)))
                 return error;
-
         create_pbe_list(p, nr_copy_pages);
-
-        if (!(pagedir_nosave = swsusp_pagedir_relocate(p)))
+        mark_unsafe_pages(p);
+        pagedir_nosave = alloc_pagedir(nr_copy_pages, GFP_ATOMIC, 1);
+        if (pagedir_nosave) {
+                create_pbe_list(pagedir_nosave, nr_copy_pages);
+                copy_page_backup_list(pagedir_nosave, p);
+        }
+        free_pagedir(p);
+        if (!pagedir_nosave)
                 return -ENOMEM;
 
         /* Allocate memory for the image and read the data from swap */