swsusp: use rbtree for tracking allocated swap

Make swsusp use extents instead of a bitmap to trace swap pages allocated
for saving the image (the tracking is only needed in case there's an error,
so that the allocated swap pages can be released).

This should allow us to reduce the memory usage, practically always, and
improve performance.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 24 deletions

diff --git a/kernel/power/power.h b/kernel/power/power.h
index a64d3f22de97..a3e47cbdaf31 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -143,30 +143,9 @@ struct resume_swap_area {
 /* If unset, the snapshot device cannot be open. */
 extern atomic_t snapshot_device_available;
 
-/**
- *      The bitmap is used for tracing allocated swap pages
- *
- *      The entire bitmap consists of a number of bitmap_page
- *      structures linked with the help of the .next member.
- *      Thus each page can be allocated individually, so we only
- *      need to make 0-order memory allocations to create
- *      the bitmap.
- */
-
-#define BITMAP_PAGE_SIZE        (PAGE_SIZE - sizeof(void *))
-#define BITMAP_PAGE_CHUNKS      (BITMAP_PAGE_SIZE / sizeof(long))
-#define BITS_PER_CHUNK          (sizeof(long) * 8)
-#define BITMAP_PAGE_BITS        (BITMAP_PAGE_CHUNKS * BITS_PER_CHUNK)
-
-struct bitmap_page {
-        unsigned long           chunks[BITMAP_PAGE_CHUNKS];
-        struct bitmap_page      *next;
-};
-
-extern void free_bitmap(struct bitmap_page *bitmap);
-extern struct bitmap_page *alloc_bitmap(unsigned int nr_bits);
-extern sector_t alloc_swapdev_block(int swap, struct bitmap_page *bitmap);
-extern void free_all_swap_pages(int swap, struct bitmap_page *bitmap);
+extern sector_t alloc_swapdev_block(int swap);
+extern void free_all_swap_pages(int swap);
+extern int swsusp_swap_in_use(void);
 
 extern int swsusp_check(void);
 extern int swsusp_shrink_memory(void);