[PATCH 4/4] zcache: add pageframes count once compress zero-filled pages twice

[Wanpeng Li]

Since zbudpage consist of two zpages, two zero-filled pages compression
contribute to one [eph|pers]pageframe count accumulated.

Signed-off-by: Wanpeng Li <liw...@linux.vnet.ibm.com>
---
 drivers/staging/zcache/zcache-main.c |   25 +++++++++++++++++++++++--
 1 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/zcache/zcache-main.c 
b/drivers/staging/zcache/zcache-main.c
index dd52975..7860ff0 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -544,6 +544,8 @@ static struct page *zcache_evict_eph_pageframe(void);
 static void *zcache_pampd_eph_create(char *data, size_t size, bool raw,
                                        struct tmem_handle *th)
 {
+       static ssize_t second_eph_zero_page;
+       static atomic_t second_eph_zero_page_atomic = ATOMIC_INIT(0);
        void *pampd = NULL, *cdata = data;
        unsigned clen = size;
        bool zero_filled = false;
@@ -561,7 +563,14 @@ static void *zcache_pampd_eph_create(char *data, size_t 
size, bool raw,
                clen = 0;
                zero_filled = true;
                zcache_pages_zero++;
-               goto got_pampd;
+               second_eph_zero_page = atomic_inc_return(
+                               &second_eph_zero_page_atomic);
+               if (second_eph_zero_page % 2 == 1)
+                       goto got_pampd;
+               else {
+                       atomic_sub(2, &second_eph_zero_page_atomic);
+                       goto count_zero_page;
+               }
        }
        kunmap_atomic(user_mem);
 
@@ -597,6 +606,7 @@ static void *zcache_pampd_eph_create(char *data, size_t 
size, bool raw,
 create_in_new_page:
        pampd = (void *)zbud_create_prep(th, true, cdata, clen, newpage);
        BUG_ON(pampd == NULL);
+count_zero_page:
        zcache_eph_pageframes =
                atomic_inc_return(&zcache_eph_pageframes_atomic);
        if (zcache_eph_pageframes > zcache_eph_pageframes_max)
@@ -621,6 +631,8 @@ out:
 static void *zcache_pampd_pers_create(char *data, size_t size, bool raw,
                                        struct tmem_handle *th)
 {
+       static ssize_t second_pers_zero_page;
+       static atomic_t second_pers_zero_page_atomic = ATOMIC_INIT(0);
        void *pampd = NULL, *cdata = data;
        unsigned clen = size, zero_filled = 0;
        struct page *page = (struct page *)(data), *newpage;
@@ -644,7 +656,15 @@ static void *zcache_pampd_pers_create(char *data, size_t 
size, bool raw,
                clen = 0;
                zero_filled = 1;
                zcache_pages_zero++;
-               goto got_pampd;
+               second_pers_zero_page = atomic_inc_return(
+                               &second_pers_zero_page_atomic);
+               if (second_pers_zero_page % 2 == 1)
+                       goto got_pampd;
+               else {
+                       atomic_sub(2, &second_pers_zero_page_atomic);
+                       goto count_zero_page;
+               }
+
        }
        kunmap_atomic(user_mem);
 
@@ -698,6 +718,7 @@ create_pampd:
 create_in_new_page:
        pampd = (void *)zbud_create_prep(th, false, cdata, clen, newpage);
        BUG_ON(pampd == NULL);
+count_zero_page:
        zcache_pers_pageframes =
                atomic_inc_return(&zcache_pers_pageframes_atomic);
        if (zcache_pers_pageframes > zcache_pers_pageframes_max)
-- 
1.7.7.6

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