swap: revert special hibernation allocation

Please revert 2.6.36-rc commit d2997b1042ec150616c1963b5e5e919ffd0b0ebf
"hibernation: freeze swap at hibernation".  It complicated matters by
adding a second swap allocation path, just for hibernation; without in any
way fixing the issue that it was intended to address - page reclaim after
fixing the hibernation image might free swap from a page already imaged as
swapcache, letting its swap be reallocated to store a different page of
the image: resulting in data corruption if the imaged page were freed as
clean then swapped back in.  Pages freed to si->swap_map were still in
danger of being reallocated by the alternative allocation path.

I guess it inadvertently fixed slow SSD swap allocation for hibernation,
as reported by Nigel Cunningham: by missing out the discards that occur on
the usual swap allocation path; but that was unintentional, and needs a
separate fix.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ondrej Zary <linux@rainbow-software.org>
Cc: Andrea Gelmini <andrea.gelmini@gmail.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nigel Cunningham <nigel@tuxonice.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 3 insertions, 5 deletions

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index c77963938bc..8dc31e02ae1 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -338,7 +338,6 @@ int hibernation_snapshot(int platform_mode)
                 goto Close;
 
         suspend_console();
-        hibernation_freeze_swap();
         saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
         error = dpm_suspend_start(PMSG_FREEZE);
         if (error)
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 5e7edfb05e6..f6cd6faf84f 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1086,7 +1086,6 @@ void swsusp_free(void)
         buffer = NULL;
         alloc_normal = 0;
         alloc_highmem = 0;
-        hibernation_thaw_swap();
 }
 
 /* Helper functions used for the shrinking of memory. */
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 5d0059eed3e..e6a5bdf61a3 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -136,10 +136,10 @@ sector_t alloc_swapdev_block(int swap)
 {
         unsigned long offset;
 
-        offset = swp_offset(get_swap_for_hibernation(swap));
+        offset = swp_offset(get_swap_page_of_type(swap));
         if (offset) {
                 if (swsusp_extents_insert(offset))
-                        swap_free_for_hibernation(swp_entry(swap, offset));
+                        swap_free(swp_entry(swap, offset));
                 else
                         return swapdev_block(swap, offset);
         }
@@ -163,7 +163,7 @@ void free_all_swap_pages(int swap)
                 ext = container_of(node, struct swsusp_extent, node);
                 rb_erase(node, &swsusp_extents);
                 for (offset = ext->start; offset <= ext->end; offset++)
-                        swap_free_for_hibernation(swp_entry(swap, offset));
+                        swap_free(swp_entry(swap, offset));
 
                 kfree(ext);
         }