page_cgroup: add helper function to get swap_cgroup
There are multiple places which need to get the swap_cgroup address, so
add a helper function:
static struct swap_cgroup *swap_cgroup_getsc(swp_entry_t ent,
struct swap_cgroup_ctrl **ctrl);
to simplify the code.
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index e910524..b99d19edf8 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -334,7 +334,6 @@
unsigned short id;
};
#define SC_PER_PAGE (PAGE_SIZE/sizeof(struct swap_cgroup))
-#define SC_POS_MASK (SC_PER_PAGE - 1)
/*
* SwapCgroup implements "lookup" and "exchange" operations.
@@ -376,6 +375,21 @@
return -ENOMEM;
}
+static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent,
+ struct swap_cgroup_ctrl **ctrlp)
+{
+ pgoff_t offset = swp_offset(ent);
+ struct swap_cgroup_ctrl *ctrl;
+ struct page *mappage;
+
+ ctrl = &swap_cgroup_ctrl[swp_type(ent)];
+ if (ctrlp)
+ *ctrlp = ctrl;
+
+ mappage = ctrl->map[offset / SC_PER_PAGE];
+ return page_address(mappage) + offset % SC_PER_PAGE;
+}
+
/**
* swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.
* @end: swap entry to be cmpxchged
@@ -388,21 +402,13 @@
unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
unsigned short old, unsigned short new)
{
- int type = swp_type(ent);
- unsigned long offset = swp_offset(ent);
- unsigned long idx = offset / SC_PER_PAGE;
- unsigned long pos = offset & SC_POS_MASK;
struct swap_cgroup_ctrl *ctrl;
- struct page *mappage;
struct swap_cgroup *sc;
unsigned long flags;
unsigned short retval;
- ctrl = &swap_cgroup_ctrl[type];
+ sc = lookup_swap_cgroup(ent, &ctrl);
- mappage = ctrl->map[idx];
- sc = page_address(mappage);
- sc += pos;
spin_lock_irqsave(&ctrl->lock, flags);
retval = sc->id;
if (retval == old)
@@ -423,21 +429,13 @@
*/
unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
{
- int type = swp_type(ent);
- unsigned long offset = swp_offset(ent);
- unsigned long idx = offset / SC_PER_PAGE;
- unsigned long pos = offset & SC_POS_MASK;
struct swap_cgroup_ctrl *ctrl;
- struct page *mappage;
struct swap_cgroup *sc;
unsigned short old;
unsigned long flags;
- ctrl = &swap_cgroup_ctrl[type];
+ sc = lookup_swap_cgroup(ent, &ctrl);
- mappage = ctrl->map[idx];
- sc = page_address(mappage);
- sc += pos;
spin_lock_irqsave(&ctrl->lock, flags);
old = sc->id;
sc->id = id;
@@ -447,28 +445,14 @@
}
/**
- * lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
+ * lookup_swap_cgroup_id - lookup mem_cgroup id tied to swap entry
* @ent: swap entry to be looked up.
*
* Returns CSS ID of mem_cgroup at success. 0 at failure. (0 is invalid ID)
*/
-unsigned short lookup_swap_cgroup(swp_entry_t ent)
+unsigned short lookup_swap_cgroup_id(swp_entry_t ent)
{
- int type = swp_type(ent);
- unsigned long offset = swp_offset(ent);
- unsigned long idx = offset / SC_PER_PAGE;
- unsigned long pos = offset & SC_POS_MASK;
- struct swap_cgroup_ctrl *ctrl;
- struct page *mappage;
- struct swap_cgroup *sc;
- unsigned short ret;
-
- ctrl = &swap_cgroup_ctrl[type];
- mappage = ctrl->map[idx];
- sc = page_address(mappage);
- sc += pos;
- ret = sc->id;
- return ret;
+ return lookup_swap_cgroup(ent, NULL)->id;
}
int swap_cgroup_swapon(int type, unsigned long max_pages)