memcg: clean up existing move charge code

- Replace lengthy function name is_target_pte_for_mc() with a shorter
  one in order to avoid ugly line breaks.

- explicitly use MC_TARGET_* instead of simply using integers.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Acked-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 9 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 61102938f119..c8d00a9780bc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5110,7 +5110,7 @@ one_by_one:
 }
 
 /**
- * is_target_pte_for_mc - check a pte whether it is valid for move charge
+ * get_mctgt_type - get target type of moving charge
  * @vma: the vma the pte to be checked belongs
  * @addr: the address corresponding to the pte to be checked
  * @ptent: the pte to be checked
@@ -5133,7 +5133,7 @@ union mc_target {
 };
 
 enum mc_target_type {
-        MC_TARGET_NONE, /* not used */
+        MC_TARGET_NONE = 0,
         MC_TARGET_PAGE,
         MC_TARGET_SWAP,
 };
@@ -5214,12 +5214,12 @@ static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
         return page;
 }
 
-static int is_target_pte_for_mc(struct vm_area_struct *vma,
+static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
                 unsigned long addr, pte_t ptent, union mc_target *target)
 {
         struct page *page = NULL;
         struct page_cgroup *pc;
-        int ret = 0;
+        enum mc_target_type ret = MC_TARGET_NONE;
         swp_entry_t ent = { .val = 0 };
 
         if (pte_present(ptent))
@@ -5230,7 +5230,7 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
                 page = mc_handle_file_pte(vma, addr, ptent, &ent);
 
         if (!page && !ent.val)
-                return 0;
+                return ret;
         if (page) {
                 pc = lookup_page_cgroup(page);
                 /*
@@ -5270,7 +5270,7 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
 
         pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
         for (; addr != end; pte++, addr += PAGE_SIZE)
-                if (is_target_pte_for_mc(vma, addr, *pte, NULL))
+                if (get_mctgt_type(vma, addr, *pte, NULL))
                         mc.precharge++; /* increment precharge temporarily */
         pte_unmap_unlock(pte - 1, ptl);
         cond_resched();
@@ -5442,8 +5442,7 @@ retry:
                 if (!mc.precharge)
                         break;
 
-                type = is_target_pte_for_mc(vma, addr, ptent, &target);
-                switch (type) {
+                switch (get_mctgt_type(vma, addr, ptent, &target)) {
                 case MC_TARGET_PAGE:
                         page = target.page;
                         if (isolate_lru_page(page))
@@ -5456,7 +5455,7 @@ retry:
                                 mc.moved_charge++;
                         }
                         putback_lru_page(page);
-put:                    /* is_target_pte_for_mc() gets the page */
+put:                    /* get_mctgt_type() gets the page */
                         put_page(page);
                         break;
                 case MC_TARGET_SWAP: