[PATCH] swsusp: rework image freeing

The following patch makes swsusp use PG_nosave and PG_nosave_free flags to
mark pages that should be freed after the state of the system has been
restored from the image (or in case of an error during suspend).

This allows us to avoid storing metadata in swap twice and to reduce the
amount of memory needed by swsusp.  �Additionally, it allows us to simplify
the code by removing a couple of functions that are no longer necessary.

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

kernel/power/swsusp.c

@@ -708,24 +708,28 @@ static void count_data_pages(void)
 	}
 }
 
-
 static void copy_data_pages(void)
 {
 	struct zone *zone;
 	unsigned long zone_pfn;
-	struct pbe * pbe = pagedir_nosave;
+	struct pbe *pbe = pagedir_nosave, *p;
 
 	pr_debug("copy_data_pages(): pages to copy: %d\n", nr_copy_pages);
 	for_each_zone (zone) {
 		if (is_highmem(zone))
 			continue;
 		mark_free_pages(zone);
+		/* This is necessary for swsusp_free() */
+		for_each_pb_page (p, pagedir_nosave)
+			SetPageNosaveFree(virt_to_page(p));
+		for_each_pbe(p, pagedir_nosave)
+			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;
 				page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
 				BUG_ON(!pbe);
-				pbe->orig_address = (long) page_address(page);
+				pbe->orig_address = (unsigned long)page_address(page);
 				/* copy_page is not usable for copying task structs. */
 				memcpy((void *)pbe->address, (void *)pbe->orig_address, PAGE_SIZE);
 				pbe = pbe->next;
@@ -736,15 +740,6 @@ static void copy_data_pages(void)
 }
 
 
-/**
- *	calc_nr - Determine the number of pages needed for a pbe list.
- */
-
-static int calc_nr(int nr_copy)
-{
-	return nr_copy + (nr_copy+PBES_PER_PAGE-2)/(PBES_PER_PAGE-1);
-}
-
 /**
  *	free_pagedir - free pages allocated with alloc_pagedir()
  */
@@ -755,6 +750,8 @@ static inline void free_pagedir(struct pbe *pblist)
 
 	while (pblist) {
 		pbe = (pblist + PB_PAGE_SKIP)->next;
+		ClearPageNosave(virt_to_page(pblist));
+		ClearPageNosaveFree(virt_to_page(pblist));
 		free_page((unsigned long)pblist);
 		pblist = pbe;
 	}
@@ -800,6 +797,16 @@ static void create_pbe_list(struct pbe *pblist, unsigned nr_pages)
 	pr_debug("create_pbe_list(): initialized %d PBEs\n", num);
 }
 
+static void *alloc_image_page(void)
+{
+	void *res = (void *)get_zeroed_page(GFP_ATOMIC | __GFP_COLD);
+	if (res) {
+		SetPageNosave(virt_to_page(res));
+		SetPageNosaveFree(virt_to_page(res));
+	}
+	return res;
+}
+
 /**
  *	alloc_pagedir - Allocate the page directory.
  *
@@ -822,11 +829,11 @@ static struct pbe * alloc_pagedir(unsigned nr_pages)
 		return NULL;
 
 	pr_debug("alloc_pagedir(): nr_pages = %d\n", nr_pages);
-	pblist = (struct pbe *)get_zeroed_page(GFP_ATOMIC | __GFP_COLD);
+	pblist = (struct pbe *)alloc_image_page();
 	for (pbe = pblist, num = PBES_PER_PAGE; pbe && num < nr_pages;
         		pbe = pbe->next, num += PBES_PER_PAGE) {
 		pbe += PB_PAGE_SKIP;
-		pbe->next = (struct pbe *)get_zeroed_page(GFP_ATOMIC | __GFP_COLD);
+		pbe->next = (struct pbe *)alloc_image_page();
 	}
 	if (!pbe) { /* get_zeroed_page() failed */
 		free_pagedir(pblist);
@@ -836,51 +843,29 @@ static struct pbe * alloc_pagedir(unsigned nr_pages)
 }
 
 /**
- *	free_image_pages - Free pages allocated for snapshot
+ * Free pages we allocated for suspend. Suspend pages are alocated
+ * before atomic copy, so we need to free them after resume.
  */
 
-static void free_image_pages(void)
+void swsusp_free(void)
 {
-	struct pbe * p;
+	struct zone *zone;
+	unsigned long zone_pfn;
 
-	for_each_pbe (p, pagedir_save) {
-		if (p->address) {
-			ClearPageNosave(virt_to_page(p->address));
-			free_page(p->address);
-			p->address = 0;
-		}
+	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);
+				if (PageNosave(page) && PageNosaveFree(page)) {
+					ClearPageNosave(page);
+					ClearPageNosaveFree(page);
+					free_page((long) page_address(page));
+				}
+			}
 	}
 }
 
-/**
- *	alloc_image_pages - Allocate pages for the snapshot.
- */
-
-static int alloc_image_pages(void)
-{
-	struct pbe * p;
-
-	for_each_pbe (p, pagedir_save) {
-		p->address = get_zeroed_page(GFP_ATOMIC | __GFP_COLD);
-		if (!p->address)
-			return -ENOMEM;
-		SetPageNosave(virt_to_page(p->address));
-	}
-	return 0;
-}
-
-/* Free pages we allocated for suspend. Suspend pages are alocated
- * before atomic copy, so we need to free them after resume.
- */
-void swsusp_free(void)
-{
-	BUG_ON(PageNosave(virt_to_page(pagedir_save)));
-	BUG_ON(PageNosaveFree(virt_to_page(pagedir_save)));
-	free_image_pages();
-	free_pagedir(pagedir_save);
-}
-
-
 /**
  *	enough_free_mem - Make sure we enough free memory to snapshot.
  *
@@ -890,12 +875,9 @@ void swsusp_free(void)
 
 static int enough_free_mem(void)
 {
-	if (nr_free_pages() < (nr_copy_pages + PAGES_FOR_IO)) {
-		pr_debug("swsusp: Not enough free pages: Have %d\n",
-			 nr_free_pages());
-		return 0;
-	}
-	return 1;
+	pr_debug("swsusp: available memory: %u pages\n", nr_free_pages());
+	return nr_free_pages() > (nr_copy_pages + PAGES_FOR_IO +
+		nr_copy_pages/PBES_PER_PAGE + !!(nr_copy_pages%PBES_PER_PAGE));
 }
 
 
@@ -914,33 +896,16 @@ static int enough_swap(void)
 	struct sysinfo i;
 
 	si_swapinfo(&i);
-	if (i.freeswap < (nr_copy_pages + PAGES_FOR_IO))  {
-		pr_debug("swsusp: Not enough swap. Need %ld\n",i.freeswap);
-		return 0;
-	}
-	return 1;
+	pr_debug("swsusp: available swap: %lu pages\n", i.freeswap);
+	return i.freeswap > (nr_copy_pages + PAGES_FOR_IO +
+		nr_copy_pages/PBES_PER_PAGE + !!(nr_copy_pages%PBES_PER_PAGE));
 }
 
 static int swsusp_alloc(void)
 {
-	int error;
+	struct pbe * p;
 
 	pagedir_nosave = NULL;
-	nr_copy_pages = calc_nr(nr_copy_pages);
-	nr_copy_pages_check = nr_copy_pages;
-
-	pr_debug("suspend: (pages needed: %d + %d free: %d)\n",
-		 nr_copy_pages, PAGES_FOR_IO, nr_free_pages());
-
-	if (!enough_free_mem())
-		return -ENOMEM;
-
-	if (!enough_swap())
-		return -ENOSPC;
-
-	if (MAX_PBES < nr_copy_pages / PBES_PER_PAGE +
-	    !!(nr_copy_pages % PBES_PER_PAGE))
-		return -ENOSPC;
 
 	if (!(pagedir_save = alloc_pagedir(nr_copy_pages))) {
 		printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
@@ -948,10 +913,14 @@ static int swsusp_alloc(void)
 	}
 	create_pbe_list(pagedir_save, nr_copy_pages);
 	pagedir_nosave = pagedir_save;
-	if ((error = alloc_image_pages())) {
-		printk(KERN_ERR "suspend: Allocating image pages failed.\n");
-		swsusp_free();
-		return error;
+
+	for_each_pbe (p, pagedir_save) {
+		p->address = (unsigned long)alloc_image_page();
+		if (!p->address) {
+			printk(KERN_ERR "suspend: Allocating image pages failed.\n");
+			swsusp_free();
+			return -ENOMEM;
+		}
 	}
 
 	return 0;
@@ -963,7 +932,7 @@ static int suspend_prepare_image(void)
 
 	pr_debug("swsusp: critical section: \n");
 	if (save_highmem()) {
-		printk(KERN_CRIT "Suspend machine: Not enough free pages for highmem\n");
+		printk(KERN_CRIT "swsusp: Not enough free pages for highmem\n");
 		restore_highmem();
 		return -ENOMEM;
 	}
@@ -971,6 +940,28 @@ static int suspend_prepare_image(void)
 	drain_local_pages();
 	count_data_pages();
 	printk("swsusp: Need to copy %u pages\n", nr_copy_pages);
+	nr_copy_pages_check = nr_copy_pages;
+
+	pr_debug("swsusp: pages needed: %u + %lu + %u, free: %u\n",
+		 nr_copy_pages,
+		 nr_copy_pages/PBES_PER_PAGE + !!(nr_copy_pages%PBES_PER_PAGE),
+		 PAGES_FOR_IO, nr_free_pages());
+
+	if (!enough_free_mem()) {
+		printk(KERN_ERR "swsusp: Not enough free memory\n");
+		return -ENOMEM;
+	}
+
+	if (MAX_PBES < nr_copy_pages / PBES_PER_PAGE +
+	    !!(nr_copy_pages % PBES_PER_PAGE)) {
+		printk(KERN_ERR "swsusp: Too many image pages\n");
+		return -ENOSPC;
+	}
+
+	if (!enough_swap()) {
+		printk(KERN_ERR "swsusp: Not enough free swap\n");
+		return -ENOSPC;
+	}
 
 	error = swsusp_alloc();
 	if (error)