tmpfs: move swap_state stats update

Both unionfs and memcgroups pose challenges to tmpfs and shmem.  To help fix,
it's best to move the swap swizzling functions from swap_state.c to shmem.c.
As a preliminary to that, move swap stats updating down into
__add_to_swap_cache, which will remain internal to swap_state.c.

Well, actually, just move down the incrementation of add_total: remove
noent_race and exist_race completely, they are relics of my 2.4.11 testing.
Alt-SysRq-m users will be thrilled if 2.6.25 is at last free of "race M+N"s.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 16 deletions

diff --git a/mm/swap_state.c b/mm/swap_state.c
index e7875642e2cf..18fce3613e5a 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -52,16 +52,13 @@ static struct {
         unsigned long del_total;
         unsigned long find_success;
         unsigned long find_total;
-        unsigned long noent_race;
-        unsigned long exist_race;
 } swap_cache_info;
 
 void show_swap_cache_info(void)
 {
-        printk("Swap cache: add %lu, delete %lu, find %lu/%lu, race %lu+%lu\n",
+        printk("Swap cache: add %lu, delete %lu, find %lu/%lu\n",
                 swap_cache_info.add_total, swap_cache_info.del_total,
-                swap_cache_info.find_success, swap_cache_info.find_total,
-                swap_cache_info.noent_race, swap_cache_info.exist_race);
+                swap_cache_info.find_success, swap_cache_info.find_total);
         printk("Free swap  = %lukB\n", nr_swap_pages << (PAGE_SHIFT - 10));
         printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
 }
@@ -89,6 +86,7 @@ static int __add_to_swap_cache(struct page *page, swp_entry_t entry,
                         set_page_private(page, entry.val);
                         total_swapcache_pages++;
                         __inc_zone_page_state(page, NR_FILE_PAGES);
+                        INC_CACHE_INFO(add_total);
                 }
                 write_unlock_irq(&swapper_space.tree_lock);
                 radix_tree_preload_end();
@@ -102,10 +100,9 @@ static int add_to_swap_cache(struct page *page, swp_entry_t entry,
         int error;
 
         BUG_ON(PageLocked(page));
-        if (!swap_duplicate(entry)) {
-                INC_CACHE_INFO(noent_race);
+        if (!swap_duplicate(entry))
                 return -ENOENT;
-        }
+
         SetPageLocked(page);
         error = __add_to_swap_cache(page, entry, gfp_mask & GFP_KERNEL);
         /*
@@ -114,11 +111,8 @@ static int add_to_swap_cache(struct page *page, swp_entry_t entry,
         if (error) {
                 ClearPageLocked(page);
                 swap_free(entry);
-                if (error == -EEXIST)
-                        INC_CACHE_INFO(exist_race);
                 return error;
         }
-        INC_CACHE_INFO(add_total);
         return 0;
 }
 
@@ -178,11 +172,9 @@ int add_to_swap(struct page * page, gfp_t gfp_mask)
                 case 0:                         /* Success */
                         SetPageUptodate(page);
                         SetPageDirty(page);
-                        INC_CACHE_INFO(add_total);
                         return 1;
                 case -EEXIST:
                         /* Raced with "speculative" read_swap_cache_async */
-                        INC_CACHE_INFO(exist_race);
                         swap_free(entry);
                         continue;
                 default:
@@ -225,9 +217,7 @@ int move_to_swap_cache(struct page *page, swp_entry_t entry)
                 if (!swap_duplicate(entry))
                         BUG();
                 SetPageDirty(page);
-                INC_CACHE_INFO(add_total);
-        } else if (err == -EEXIST)
-                INC_CACHE_INFO(exist_race);
+        }
         return err;
 }