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, 5 insertions, 13 deletions

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index b18c155cbb60..e83ed9945a80 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -243,7 +243,6 @@ struct swap_map_page {
 struct swap_map_handle {
         struct swap_map_page *cur;
         sector_t cur_swap;
-        struct bitmap_page *bitmap;
         unsigned int k;
 };
 
@@ -252,9 +251,6 @@ static void release_swap_writer(struct swap_map_handle *handle)
         if (handle->cur)
                 free_page((unsigned long)handle->cur);
         handle->cur = NULL;
-        if (handle->bitmap)
-                free_bitmap(handle->bitmap);
-        handle->bitmap = NULL;
 }
 
 static int get_swap_writer(struct swap_map_handle *handle)
@@ -262,12 +258,7 @@ static int get_swap_writer(struct swap_map_handle *handle)
         handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
         if (!handle->cur)
                 return -ENOMEM;
-        handle->bitmap = alloc_bitmap(count_swap_pages(root_swap, 0));
-        if (!handle->bitmap) {
-                release_swap_writer(handle);
-                return -ENOMEM;
-        }
-        handle->cur_swap = alloc_swapdev_block(root_swap, handle->bitmap);
+        handle->cur_swap = alloc_swapdev_block(root_swap);
         if (!handle->cur_swap) {
                 release_swap_writer(handle);
                 return -ENOSPC;
@@ -284,7 +275,7 @@ static int swap_write_page(struct swap_map_handle *handle, void *buf,
 
         if (!handle->cur)
                 return -EINVAL;
-        offset = alloc_swapdev_block(root_swap, handle->bitmap);
+        offset = alloc_swapdev_block(root_swap);
         error = write_page(buf, offset, bio_chain);
         if (error)
                 return error;
@@ -293,7 +284,7 @@ static int swap_write_page(struct swap_map_handle *handle, void *buf,
                 error = wait_on_bio_chain(bio_chain);
                 if (error)
                         goto out;
-                offset = alloc_swapdev_block(root_swap, handle->bitmap);
+                offset = alloc_swapdev_block(root_swap);
                 if (!offset)
                         return -ENOSPC;
                 handle->cur->next_swap = offset;
@@ -430,7 +421,8 @@ int swsusp_write(void)
                 }
         }
         if (error)
-                free_all_swap_pages(root_swap, handle.bitmap);
+                free_all_swap_pages(root_swap);
+
         release_swap_writer(&handle);
  out:
         swsusp_close();