mm: add swap cache interface for swap reference
In a following patch, the usage of swap cache is recorded into swap_map.
This patch is for necessary interface changes to do that.
2 interfaces:
- swapcache_prepare()
- swapcache_free()
are added for allocating/freeing refcnt from swap-cache to existing swap
entries. But implementation itself is not changed under this patch. At
adding swapcache_free(), memcg's hook code is moved under
swapcache_free(). This is better than using scattered hooks.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 1416e7e..19bdf30 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -162,11 +162,11 @@
return 1;
case -EEXIST:
/* Raced with "speculative" read_swap_cache_async */
- swap_free(entry);
+ swapcache_free(entry, NULL);
continue;
default:
/* -ENOMEM radix-tree allocation failure */
- swap_free(entry);
+ swapcache_free(entry, NULL);
return 0;
}
}
@@ -188,8 +188,7 @@
__delete_from_swap_cache(page);
spin_unlock_irq(&swapper_space.tree_lock);
- mem_cgroup_uncharge_swapcache(page, entry);
- swap_free(entry);
+ swapcache_free(entry, page);
page_cache_release(page);
}
@@ -293,7 +292,7 @@
/*
* Swap entry may have been freed since our caller observed it.
*/
- if (!swap_duplicate(entry))
+ if (!swapcache_prepare(entry))
break;
/*
@@ -317,7 +316,7 @@
}
ClearPageSwapBacked(new_page);
__clear_page_locked(new_page);
- swap_free(entry);
+ swapcache_free(entry, NULL);
} while (err != -ENOMEM);
if (new_page)